WO2003026177A1 - Fourniture de reference d'horloge de programme mpeg pour supporter des horloges de reseau precises - Google Patents

Fourniture de reference d'horloge de programme mpeg pour supporter des horloges de reseau precises Download PDF

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Publication number
WO2003026177A1
WO2003026177A1 PCT/US2002/029585 US0229585W WO03026177A1 WO 2003026177 A1 WO2003026177 A1 WO 2003026177A1 US 0229585 W US0229585 W US 0229585W WO 03026177 A1 WO03026177 A1 WO 03026177A1
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WIPO (PCT)
Prior art keywords
clock
network
mpeg
generally
information
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PCT/US2002/029585
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English (en)
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WO2003026177A8 (fr
Inventor
John A. Ritchie, Jr.
Jiening Ao
Donald C. Sorenson
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Scientific-Atlanta, Inc.
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Priority claimed from US10/245,032 external-priority patent/US7729379B2/en
Priority claimed from US10/245,250 external-priority patent/US20030058890A1/en
Application filed by Scientific-Atlanta, Inc. filed Critical Scientific-Atlanta, Inc.
Publication of WO2003026177A1 publication Critical patent/WO2003026177A1/fr
Publication of WO2003026177A8 publication Critical patent/WO2003026177A8/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/2801—Broadband local area networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2657—Carrier synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/60—Network streaming of media packets
    • H04L65/70—Media network packetisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
    • H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
    • H04N21/236—Assembling of a multiplex stream, e.g. transport stream, by combining a video stream with other content or additional data, e.g. inserting a URL [Uniform Resource Locator] into a video stream, multiplexing software data into a video stream; Remultiplexing of multiplex streams; Insertion of stuffing bits into the multiplex stream, e.g. to obtain a constant bit-rate; Assembling of a packetised elementary stream
    • H04N21/2362—Generation or processing of Service Information [SI]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
    • H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
    • H04N21/236—Assembling of a multiplex stream, e.g. transport stream, by combining a video stream with other content or additional data, e.g. inserting a URL [Uniform Resource Locator] into a video stream, multiplexing software data into a video stream; Remultiplexing of multiplex streams; Insertion of stuffing bits into the multiplex stream, e.g. to obtain a constant bit-rate; Assembling of a packetised elementary stream
    • H04N21/2365—Multiplexing of several video streams
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
    • H04N21/4302—Content synchronisation processes, e.g. decoder synchronisation
    • H04N21/4305—Synchronising client clock from received content stream, e.g. locking decoder clock with encoder clock, extraction of the PCR packets
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
    • H04N21/437—Interfacing the upstream path of the transmission network, e.g. for transmitting client requests to a VOD server
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/60—Network structure or processes for video distribution between server and client or between remote clients; Control signalling between clients, server and network components; Transmission of management data between server and client, e.g. sending from server to client commands for recording incoming content stream; Communication details between server and client 
    • H04N21/61—Network physical structure; Signal processing
    • H04N21/6106—Network physical structure; Signal processing specially adapted to the downstream path of the transmission network
    • H04N21/6118—Network physical structure; Signal processing specially adapted to the downstream path of the transmission network involving cable transmission, e.g. using a cable modem
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/60—Network structure or processes for video distribution between server and client or between remote clients; Control signalling between clients, server and network components; Transmission of management data between server and client, e.g. sending from server to client commands for recording incoming content stream; Communication details between server and client 
    • H04N21/61—Network physical structure; Signal processing
    • H04N21/6156—Network physical structure; Signal processing specially adapted to the upstream path of the transmission network
    • H04N21/6168—Network physical structure; Signal processing specially adapted to the upstream path of the transmission network involving cable transmission, e.g. using a cable modem
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0685—Clock or time synchronisation in a node; Intranode synchronisation
    • H04J3/0688—Change of the master or reference, e.g. take-over or failure of the master
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/10—Architectures or entities
    • H04L65/1016—IP multimedia subsystem [IMS]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L7/00—Arrangements for synchronising receiver with transmitter
    • H04L7/04—Speed or phase control by synchronisation signals
    • H04L7/041—Speed or phase control by synchronisation signals using special codes as synchronising signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00—Television systems
    • H04N7/10—Adaptations for transmission by electrical cable

Definitions

  • the present invention relates generally to the field of communication networks and systems for using frequency-division multiplexing to carry data across broadband networks with the potential to support a plurality of subscribers at high data rates.
  • HFC hybrid fiber-coax
  • DOCSIS Data-Over-Cable Service Interface Specifications
  • the DOCSIS standards comprise many documents that specify mechanisms and protocols for carrying digital data between a cable modem (CM), generally located at a customer premises, and a cable modem termination system (CMTS), commonly located within the headend of the service provider.
  • CM cable modem
  • CMTS cable modem termination system
  • downstream traffic data flowing from a service provider to a customer premises
  • upstream traffic data flowing from a customer premises to a service provider
  • IP Internet Protocol
  • DOCSIS cable system operators
  • MSOs multiple system operators
  • DOCSIS cable modems
  • DOCSIS was primarily designed to meet the Internet access needs of residential users.
  • the DOCSIS standards were designed to support a large number of price-sensitive residential, Internet-access users on a single DOCSIS system.
  • home users may desire extremely high speed Internet access, generally they are unwilling to pay significantly higher monthly fees.
  • DOCSIS was designed to share the bandwidth among a large number of users.
  • DOCSIS systems are deployed on HFC networks supporting many CATV channels.
  • TDMA time-division multiple-access
  • the DOCSIS CMTS transmits to a plurality of cable modems that may share at least one downstream frequency.
  • the CMTS dynamically or statistically time-division multiplexes downstream data for a plurality of cable modems.
  • the cable modems receive this traffic and forward the proper information to user PCs or hosts.
  • the plurality of cable modems In the upstream direction the plurality of cable modems generally contend for access to transmit at a certain time on an upstream frequency. This contention for upstream slots of time has the potential of causing collisions between the upstream transmissions of multiple cable modems.
  • DOCSIS implements a media access control (MAC) algorithm.
  • MAC media access control
  • the DOCSIS layer 2 MAC protocol is defined in the DOCSIS radio frequency interface (RFI) specifications, versions 1.0, 1.1, and/or 2.0.
  • DOCSIS RFI 2.0 actually introduces a code division multiple access (CDMA) physical layer that may be used instead of or in addition to the TDMA functionality described in DOCSIS RFI 1.0 and/or 1.1.
  • CDMA code division multiple access
  • the design of DOCSIS to provide a large enough revenue stream by deploying systems shared by a large number of residential customers has some drawbacks.
  • the DOCSIS MAC is generally asymmetric with respect to bandwidth, with cable modems contending for upstream transmission and with the CMTS making downstream forwarding decisions.
  • DOCSIS supports multiple frequency channels, it does not have mechanisms to quickly and efficiently allocate additional frequency channels to users in a dynamic frequency-division multiple access (FDMA) manner.
  • FDMA dynamic frequency-division multiple access
  • the data rates of DOCSIS are a vast improvement over analog dial-up V.90 modems and Basic Rate Interface (BRI) ISDN (integrated services digital network) lines, the speeds of DOCSIS cable modems are not significantly better than other services which are targeted at business users.
  • BRI Basic Rate Interface
  • FIG. 1 shows a block diagram of central and remote transceivers connected to a cable transmission network.
  • FIG. 2a shows a block diagram of a transport modem termination system connected to a cable transmission network.
  • FIG. 2b shows a block diagram of a plurality of client transport modems connected to a cable transmission network.
  • FIG. 3 shows a block diagram of the connection-oriented relationship between client transport modems and ports of a transport modem termination system.
  • FIG. 4 shows a block diagram of the architecture for integrating a transport modem termination system and a plurality of client transport modems into a system carrying other services.
  • FIG. 5a shows a block diagram of a transport modem termination system connected in a headend.
  • FIG. 5b shows a block diagram of a client transport modem connected to a cable transmission network.
  • FIG. 6 shows a block diagram of some protocols that may be used in the system control of a transport modem termination system (TMTS) and/or a client transport modem (cTM).
  • TMTS transport modem termination system
  • cTM client transport modem
  • FIG. 7 shows a block diagram of a TMTS and a cTM providing physical layer repeater service.
  • FIG. 8 shows an expanded block diagram of the protocol sublayers within the physical layer of the TMTS and the cTM.
  • FIG. 9 shows how a cable transmission physical layer fits in the OSI model.
  • FIG. 10 shows a cable transmission physical layer that is part of a network interface card.
  • FIG. 11 shows an expansion of the cable transmission physical layer expanded into four sublayers in a network interface card.
  • FIG. 12 shows a reference diagram of the downstream and upstream functions of the four sublayers.
  • FIG. 13 shows the relationship among 802.3/ethernet media, the frame management sublayer, and the inverse multiplex sublayer.
  • FIG. 14 shows the IEEE 802.3/ethernet frame format.
  • FIG. 15 shows the control frame format.
  • FIG. 16 shows the frame management sublayer (FMS) frame format.
  • FIG. 17 shows the relationship among the frame management sublayer (FMS), the inverse multiplex sublayer (IMS), and the physical coding sublayer (PCS).
  • FIG. 18 shows the MPEG frame format.
  • FIG. 19 shows the MPEG adaptation field format.
  • FIG. 20 shows clock distribution from a TMTS to a cTM.
  • FIG. 21 shows a clock timing diagram for the TMTS and the cTM.
  • the seven-layer Open Systems Interconnect (OSI) model is a useful abstraction in analyzing and describing communication protocols and/or systems.
  • the seven layers of the OSI model from lowest to highest are: 1) the physical layer, 2) the data link layer, 3) the network layer, 4) the transport layer, 5) the session layer, 6) the presentation layer, and 7) the application layer.
  • This OSI model is well-known to those of ordinary skill in the art.
  • the OSI model layers have often been broken down into sub-layers in various contexts. For example, the level two, data link layer may be divided into a medium access control (MAC) sublayer and a logical link control (LLC) sublayer in the documentation of the IEEE (Institute for Electrical and Electronic Engineers) standard 802.
  • MAC medium access control
  • LLC logical link control
  • some of the IEEE standards break level one (i. e. , the physical layer) down into sublayers such as, but not limited to, the physical coding sublayer (PCS), the physical medium attachment layer (PMA), and the physical media dependent (PMD) sublayer.
  • PCS physical coding sublayer
  • PMA physical medium attachment layer
  • PMD physical media dependent sublayer.
  • These sublayers are described more fully in the IEEE 802 specifications and more specifically in the IEEE 802.3/ethernet specifications.
  • the specifications of IEEE 802 (including, but not limited to, IEEE 802.3) are incorporated by reference in their entirety herein.
  • the preferred embodiments of the present invention comprise physical layer protocols that may be implemented in physical layer transceivers.
  • the physical layer interfaces and/or protocols of the preferred embodiments of the present invention may be incorporated into other networking methods, devices, and/or systems to provide various types of additional functionality. Often the behavior and capabilities of networking devices are categorized based on the level of the OSI model at which the networking device operates.
  • Repeater, bridge, switch, router, and gateway are some commonly used terms for interconnection devices in networks. Though these terms are commonly used in networking their definition does vary from context to context, especially with respect to the term switch. However, a brief description of some of the terms generally associated with various types of networking devices may be useful.
  • Repeaters generally operate at the physical layer of the OSI model. In general, digital repeaters interpret incoming digital signals and generate outgoing digital signals based on the interpreted incoming signals. Basically, repeaters act to repeat the signals and generally do not make many decisions as to which signals to forward. As a non-limiting example, most ethernet hubs are repeater devices. Hubs in some contexts are called layer one switches.
  • bridges and/or layer-two switches In contrast to repeaters, bridges and/or layer-two switches generally operate at layer two of the OSI model and evaluate the data link layer or MAC layer (or sublayer) addresses in incoming frames. Bridges and/or layer two switches generally only forward frames that have destination addresses that are across the bridge. Basically, bridges or layer two switches generally are connected between two shared contention media using media access control (MAC) algorithms. In general, a bridge or layer two switch performs an instance of a MAC algorithm for each of its interfaces. In this way, bridges and/or layer two switches generally may be used to break shared or contention media into smaller collision domains.
  • MAC media access control
  • Routers and layer three switches generally make forwarding decisions based at least upon the layer three network addresses of packets. Often routers modify the frames transversing the router by changing the source and/or destination data link, MAC, or hardware addresses when a packet is forwarded.
  • gateway refers to networking devices that generally make forwarding decisions based upon information above layer three, the network layer. (Some older Internet usage of the term gateway basically referred to devices performing a layer three routing function as gateways. This usage of the term gateway is now less common.)
  • One skilled in the art will be aware of these basic categories of networking devices. Furthermore, often actual networking devices incorporate functions that are hybrids of these basic categories.
  • the preferred embodiments of the present invention may be utilized in repeaters, bridges, switches, routers, gateways, hybrid devices and/or any other type of networking device that utilizes a physical layer interface.
  • "Routing and Switching: Time of Convergence”, which was published in 2002, by Rita Puzmanova and "Interconnections, Second Edition: Bridges, Router, Switches, and Internetworking Protocols", which was published in 2000, by Radia Perlman are two books describing some of the types of networking devices that might potentially utilize the preferred embodiments of the present invention. These two books are incorporated in their entirety by reference herein.
  • the preferred embodiments of the present invention(s) involve many concepts. Because of the large number of concepts of the preferred embodiments of the present invention, to facilitate easy reading and comprehension of these concepts, the document is divided into sections with appropriate headings. None of these headings are intended to imply any limitations on the scope of the present invention(s). In general, the
  • Network Model at least partially covers the forwarding constructs of the preferred embodiments of the present invention(s).
  • the section entitled “Integration Into Existing Cable Network Architectures” generally relates to utilization of the preferred embodiments of the present invention in cable network architectures.
  • the "Protocol Models” section describes a non-limiting abstract model that might be used to facilitate understanding of the preferred embodiments of the present invention(s).
  • the "Frame Management Sublayer (FMS) Data Flows” section describes the formation of FMS data flows.
  • the section entitled “MPEG Packets' describes the format of MPEG packets as utilized in the preferred embodiments of the present invention(s).
  • the "Network Clocking” section generally covers distribution of network clock.
  • the "Downstream Multiplexing” section generally covers the downstream multiplexing using MPEG packets in the preferred embodiments of the present invention(s).
  • the "Upstream Multiplexing” section generally relates to upstream multiplexing across one or more active tones.
  • the section entitled “Division of Upstream Data” generally relates to the division of data into blocks for forward error correction
  • cTM Downstream Client Transport Modem
  • PCS Physical Coding Sublayer
  • cTM Modulation and Physical Coding Sublayer
  • PCS Physical Coding Sublayer
  • TMTS Upstream Transport Modem Termination System
  • PCS Physical Coding Sublayer
  • FEC Upstream Forward Error Correction
  • FIG. 1 generally shows one preferred embodiment of the present invention.
  • the preferred embodiment of the present invention allows physical layer connectivity over a cable transmission network 105.
  • CT cable transmission
  • One skilled in the art will be aware of the types of technologies and devices used in a cable transmission (CT) network 105.
  • CT network 105 generally has evolved from the networks designed to allow service providers to deliver community antenna television (CATV, also known as cable TV) to customers or subscribers.
  • CATV community antenna television
  • CATV community antenna television
  • service provider and subscriber or customer are used to reference various parts of CATV networks and to provide reference points in describing the interfaces found in CATV networks.
  • the CATV network may be divided into service provider and subscriber or customer portions based on the demarcation of physical ownership of the equipment and/or transmission facilities.
  • service provider and subscriber reference points and/or interfaces may refer to service provider and/or subscriber reference points and/or interfaces, one of ordinary skill in the art will be aware that the preferred embodiments of the present invention still apply to networks regardless of the legal ownership of specific devices and/or transmission facilities in the network.
  • cable transmission (CT) network 105 may be a CATV network that is primarily owned by cable service providers or multiple system operators (MSOs) with an interface at the customer or subscriber premises, one skilled in the art will be aware that the preferred embodiments of the present invention will work even if ownership of all or portions of cable transmission (CT) network 105 is different than the ownership commonly found in the industry.
  • cable transmission (CT) network 105 may be privately owned.
  • CT network 105 generally is designed for connecting service providers with subscribers or customers.
  • service provider and subscriber or customer generally are just used to describe the relative relationship of various interfaces and functions associated with CT network 105.
  • the service-provider-side of CT network 105 is located at a central site, and there are a plurality of subscriber-side interfaces located at various remote sites.
  • central and remote also are just used to refer to the relative relationship of the interfaces to cable transmission (CT) network 105.
  • CT cable transmission
  • a headend and/or distribution hub is a central location where service provider equipment is concentrated to support a plurality of remote locations at subscriber or customer premises. Given this relative relationship among equipment connected to cable transmission
  • CT network 105 the preferred embodiment of the present invention may comprise a central cable transmission (CT) physical (PHY) layer transceiver 115.
  • the central CT PHY transceiver (TX/RX) 115 generally may have at least one port on the central-side or service-provider-side of the transceiver 115. Ports 125, 126, 127, 128, and 129 are examples of the central-side ports of central CT PHY transceiver 115.
  • interface 135 may define the behavior of central CT PHY transceiver 115 with respect to at least one central-side port such as central-side ports 125, 126, 127, 128, and 129.
  • Interface 135 for the central-side ports 125, 126, 127, 128, and 129 may represent separate hardware interfaces for each port of central CT PHY transceiver 115.
  • interface 135 may be implemented using various technologies to share physical interfaces such that central-side ports 125, 126, 127, 128, and 129 may be only logical channels on a shared physical interface or media. These logical channels may use various multiplexing and/or media sharing techniques and algorithms.
  • the central-side ports 125, 126, 127, 128, and 129 of central CT PHY transceiver 115 may be serial and/or parallel interfaces and/or buses.
  • central CT PHY transceiver 115 generally is for use inside of networking devices, a serial-interface shared medium such as ethernet/802.3 could be used on each of the central-side ports 125, 126, 127, 128, and 129 inside of a networking device. Often the decision to use different technologies for interface 135 will vary based on costs and transmission line lengths.
  • Central CT PHY transceiver 115 further is connected through interface 150 to cable transmission (CT) network 105.
  • CT cable transmission
  • interface 160 In addition to the central-side or service-provider- side at interface 150 of cable transmission (CT) network 105, interface 160 generally is on the subscriber-side, customer-side, or remote-side of cable transmission (CT) network 105.
  • at least one remote transceiver such as remote cable transmission (CT) physical (PHY) transceivers 165, 166, 167, and 168) is comiected to interface 160 on the subscriber-side or remote-side of CT network 105.
  • Each remote CT PHY transceiver 165, 166, and 167 is associated with at least one remote-side port, 175, 176, and 177 respectively.
  • remote CT PHY transceiver 168 also is associated with at least one remote-side port, with the two remote-side ports 178 and 179 actually being shown in FIG. 1.
  • Each remote CT PHY transceiver 165, 166, 167, and 168 can be considered to have an interface 185, 186, 187, and 188, respectively, through which it receives information for upstream transmission and through which it delivers information from downstream reception.
  • digital transceivers (such as central CT PHY transceiver 115 and remote CT PHY transceivers 165, 166, 167, and 168) comprise a transmitter and a receiver as are generally needed to support bi-directional applications.
  • digital transmitters basically are concerned with taking discrete units of information (or digital information) and forming the proper electromagnetic signals for transmission over networks such as cable transmission (CT) network 105.
  • Digital receivers generally are concerned with recovering the digital information from the incoming electromagnetic signals.
  • central CT PHY transceiver 115 and remote CT PHY transceivers 165, 166, 167, and 168 generally are concerned with communicating information between interface 135 and interfaces 185, 186, 187, and 188, respectively.
  • the minimum quanta of information is the base-two binary digit or bit. Therefore, the information communicated by digital transceivers often is represented as bits, though the preferred embodiments of the present invention are not necessarily limited to implementations designed to communicate information in base two bits.
  • the preferred embodiments of the present invention generally have a point-to- point configuration such that there generally is a one-to-one relationship between the central-side ports 125, 126, 127, 128, and 129 of the central CT PHY transceiver 115 and the remote-side ports 175, 176, 177, 178, and 179, respectively.
  • interface 135 for a plurality of central-side ports 125, 126, 127, 128, and 129 interface 188 with a plurality of remote-side ports 178 and 179 may represent separate hardware interfaces for each port of remote CT PHY transceiver 168.
  • interface 188 may be implemented using various technologies to share physical interfaces such that remote-side ports 178 and 179 may only be logical channels on a shared physical interface or media. These logical channels may use various multiplexing and/or media sharing techniques and algorithms.
  • the remote-side ports 178 and 179 of remote CT PHY transceiver 168 may be serial and/or parallel interfaces and/or buses.
  • the preferred embodiments of the present invention comprise a one-to- one or point-to-point relationship between active central-side ports and active remote-side ports such that central-side port 125 may be associated with remote-side port 175, central- side port 126 may be associated with remote-side port 176, central-side port 127 may be associated with remote-side port 177, central-side port 128 may be associated with remote-side port 178, and central-side port 129 may be associated with remote-side port 179.
  • active central-side ports and active remote-side ports are one-to-one or point-to-point, many technologies such as, but not limited to, multiplexing and/or switching may be used to carry the point-to-point communications between active central-side ports and active remote-side ports.
  • active ports are allocated at least some bandwidth through cable transmission (CT) network 105.
  • CT cable transmission
  • PSTN public switched telephone network
  • TDM time-division multiplexing
  • Establishment of an active phone call generally allocates bandwidth in the PSTN to carry the point-to-point communications through the PSTN.
  • the preferred embodiments of the present invention generally provide point-to-point connectivity between active ports of the central CT PHY transceiver 115 and the active ports of remote CT PHY transceivers 165, 166, 167, and 168.
  • CT cable transmission
  • PPP Point-to-Point Protocol
  • central CT PHY transceiver 115 may support at least one central-side port.
  • central CT PHY transceiver 115 might communicate with at least one remote CT PHY transceiver (such as 165, 166, 167, and 168).
  • each remote CT PHY transceiver 165, 166, 167, and 168 may have at least one remote side port, and remote CT PHY transceiver 168 is shown with a plurality of remote-side ports 178 and 179.
  • FIGs. 2a and 2b show further detail on the use of central CT PHY transceiver 115 and remote CT PHY transceivers 165, 166, 167, and 168 in networking devices.
  • central CT PHY transceiver 115 generally might be incorporated into a transport modem termination system (TMTS) 215.
  • TMTS 215 comprises cable transmission (CT) physical layer (PHY) control 217 and system control 219.
  • CT PHY control 217 is concerned with handling bandwidth allocations in cable transmission (CT) network 105
  • system control 219 generally is concerned with TMTS management and/or configuration.
  • Each one of the central-side ports 125, 126, 127, 128, and 129 of central CT PHY transceiver 115 may be connected over interface 135 to central-side network physical layer (PHY) transceivers (TX/RX) 225, 226, 227, 228, and 229, respectively.
  • PHY central-side network physical layer
  • interface 135 may actually be some sort of shared interface among the various central-side ports (125, 126, 127, 128, and 129) and central-side network physical (PHY) transceivers (225, 226, 227, 228, and 229).
  • transmitters and/or receivers that handle transmitting and/or receiving signals on communication media.
  • these transmitters and/or receivers are responsible for converting between the electromagnetic signals used to convey information within a device (such as in baseband transistor-transistor logic (TTL) or complementary metal-oxide semiconductor (CMOS) signal levels) to electromagnetic signal levels that are suitable for transmission through external media that may be wired, wireless, waveguides, electrical, optical, etc.
  • TTL baseband transistor-transistor logic
  • CMOS complementary metal-oxide semiconductor
  • interface 135 is shown as individual connections between the central-side ports 125, 126, 127, 128, and 129 of central CT PHY transceiver 115 and central-side network PHY transceivers 225, 226, 227, 228, and 229, one skilled in the art will be aware that many possible implementations for interface 135 are possible including, but not limited, to serial interfaces, parallel interfaces, and/or buses that may use various technologies for multiplexing and or access control to share at least one physical communications medium at interface 135.
  • central-side network physical interfaces 225, 226, 227, 228, and 229 are connected to central networks 235, 236, 237, 238, and 239, respectively.
  • central networks 235, 236, 237, 238, and 239 may be connected together into a common network 240.
  • One skilled in the art will be aware that many different configurations for connecting central networks 235, 236, 237, 238, and 239 are possible based upon different policy decisions of the owners of the equipment and any customers paying for connectivity through the equipment.
  • Central-side network PHY transceivers 225, 226, 227, 228, and 229 generally are connected over interface 245 to central networks 235, 236, 237, 238, and 239, respectively.
  • central-side network PHY transceivers 225, 226, 227, 228, and 229 are ethernet/802.3 interfaces, and each ethernet/802.3 interface may be connected to a separate central network.
  • other connections for interface 245 are possible that allow one or more transmission media to be shared using various techniques and/or media access control algorithms the may perform various multiplexing strategies.
  • ethernet/802.3 there are many data speeds and physical layer specifications for ethernet/802.3.
  • the preferred embodiments of the present invention will work with any of the ethernet/802.3 specifications.
  • PHY central-side network physical
  • each central-side PHY transceiver 225, 226, 227, 228, and 229 might use a different ethernet/802.3 speed and/or a physical layer specification from any of the other central-side network PHY transceivers 225, 226, 227, 228, and 229.
  • FIG. 2b generally shows the remote-side, customer-side, or subscriber-side equipment and connections
  • FIG. 2a generally shows the central-side or service- provider-side equipment and connections.
  • CT cable transmission
  • FIG. 2a shows the four remote CT PHY transceivers 165, 166, 167, 168, and 169 as they might be used inside client transport modems (cTMs) 265, 266, 267, and 268, respectively.
  • cTMs client transport modems
  • Client transport modem 265 comprises remote CT PHY transceiver 165 that is connected through connection 175 across interface 185 to at least one remote-side network physical layer (PHY) transceiver (TX/RX) 275.
  • client transport modem 266 comprises remote CT PHY transceiver 166 that is connected through connection 176 across interface 186 to at least one remote-side network physical layer (PHY) transceiver (TX/RX) 276.
  • client transport modem 267 comprises remote CT PHY transceiver 167 that is connected through connection 177 across interface 187 to at least one remote-side network physical layer (PHY) transceiver (TX/RX) 277.
  • client transport modem 268 comprises remote CT PHY transceiver 168 that is connected through connection 178 across interface 188 to at least one remote-side network physical layer (PHY) transceiver (TX/RX) 278 and that is connected through connection 179 across interface 189 to at least one remote-side network physical layer (PHY) transceiver
  • PHY remote-side network physical layer
  • cTMs client transport modems
  • CT cable transmission
  • the remote-side network physical (PHY) transceivers (TX/RX) 275, 276, 277, 278, and 279 are connected across interfaces 285, 286, 287, 288, and 289 to remote networks 295, 296, 297, 298, and 299, respectively.
  • interfaces 285, 286, 287, 288, and/or 289 are ethernet/802.3 interfaces.
  • one skilled in the art will be aware that other interfaces and technologies might be used with the concepts disclosed in this specification.
  • an interface of a client transport modem might be used to support circuit emulation services (CES) to carry N X 56 kbps and/or N X 64 kbps (where N is a positive integer) digital data streams.
  • CES circuit emulation services
  • N X 56 and N X 64 configurations are commonly designated as various digital speeds such as, but not limited to, DSO, DS1, DS3, etc.
  • the various N X 56 and/or N X 64 services are often delivered over plesiochronous digital hierarchy (PDH) interfaces such as, but not limited to, Tl, T3, etc.
  • PDH plesiochronous digital hierarchy
  • synchronous digital hierarchy (SDH) interfaces such as, but not limited to, Synchronous Transport Signal, Level 1 (STS-1), STS-3, etc.
  • STS-1 Synchronous Transport Signal
  • STS-3 STS-3
  • SONET synchronous optical network
  • OC-1 optical carrier 1
  • OC-3 optical carrier 1
  • BTI basic rate interface
  • N X 56 and N X 64 kbps connections also may carry digitized voice generally using pulse code modulation (PCM) and various companding techniques such as, but not limited to, A-law and mu-law. Therefore, the remote-side network physical (PHY) transceivers (TX/RX) 275, 276, 277, 278, and 279 do not all have to use 802.3/ethernet.
  • a client transport modem (cTM) 268 with a plurality of remote-side network physical (PHY) transceivers (TX/RX) 278 and 279 may support different types of interfaces for each transceiver at interfaces 288 and 289.
  • remote-side network physical (PHY) transceiver 278 may use ethernet/802.3 to connect to an ethernet/802.3 remote network 298, and remote-side network physical (PHY) transceiver 279 may be a Tl interface to remote network 299.
  • PHY Physical
  • This non-limiting example configuration is expected to be common for many remote offices that need ethernet/802.3 connectivity to carry data and packetized real-time services such as voice or video and that also need Tl interfaces to connect to legacy circuit-switched voice for devices such as PBXs (Private Branch Exchanges).
  • PBXs Primary Branch Exchanges
  • remote-side network physical (PHY) transceivers TX/RX
  • TX/RX remote-side network physical
  • each remote-side PHY transceiver 275, 276, 277, 278, and 279 might use a different ethernet/802.3 speed and/or physical layer specification from any of the other remote-side network PHY transceivers
  • the preferred embodiments of the present invention might be considered as providing repeater functionality between the central-side network PHY transceivers 225, 226, 227, 228, and 229 and remote-side network PHY transceivers 275,
  • the repeater service may involve corresponding central-side and remote-side interfaces and transceivers having the same speeds.
  • ethernet/802.3 hubs are repeaters and that some ethernet/802.3 hubs handle speed conversions such as between 10 Mbps ethernet/802.3 and 100 Mbps fast ethernet/802.3.
  • PHY central-side and remote-side network physical
  • the transceivers may use different types of physical media and portions of the ethernet/802.3 specification such as, but not limited to, 100BaseTX on copper for a central-side network physical transceiver and 100BaseFX on fiber for a remote-side network physical transceiver.
  • the client transport modems (cTMs) 265, 266, 267, and 268 can each be thought of as having a corresponding server transport modem (sTM) 325, 326, 327, and 328, respectively, as shown in FIG. 3.
  • server transport modems (sTMs) 325, 326, 327, and 328 may not be separate equipment, but may instead be implemented using shared hardware in TMTS 215 in the preferred embodiment of the present invention.
  • a dedicated server transport modem (sTM) such as sTMs 325, 326, 327, and 328, respectively
  • server transport modems may not be actual individual hardware in the preferred embodiment of the present invention. Even though the preferred embodiments of the present invention may not use individual server transport modems, this does not preclude such implementations.
  • the server transport modems (sTMs) 325, 326, 327, and 328 as well as the corresponding comiections to the client transport modems (cTMs) 265, 266, 267, and 268, respectively, are shown as small dashed lines to indicate the virtual nature of the relationship.
  • the server transport modems (sTMs) 325, 326, 327, and 328 may be virtual in the preferred embodiments of the present invention because they generally may be implemented using shared hardware in TMTS 215.
  • the preferred embodiments of the present invention may act to transparently repeat digital signals between interfaces 245 and 385.
  • TMTS point-to-point connections between active ports on interface 245 and active ports on interface 385.
  • Active ports generally are associated with point-to-point connections between TMTS 215 and a client transport modem 265, 266, 267, or 268, when the point-to-point connection is allocated bandwidth through cable transmission (CT) network 105.
  • CT cable transmission
  • TMTS transport modem termination system
  • FIG. 4 shows a more detailed implementation of the preferred embodiment of the present invention from FIGs. 1 through 3 and its use in a cable network that may carry additional services over the cable transmission (CT) network 105.
  • FIG. 4 shows TMTS 215 and cTMs 265, 266, 267, and 268 that were briefly described with respect to FIGs. 2a and 2b.
  • each cTM 265, 266, 267, and 268 has at least one ethernet/802.3 physical (PHY) transceiver 475, 476, 477, and 478, respectively.
  • PHY physical
  • the ethernet/802.3 PHY transceivers 475, 476, 477, and 478 correspond to one non-limiting type of transceiver that may be used in the preferred embodiment of the present invention for remote-side network physical (PHY) transceivers (TX/RX) 275, 276, 277, 278, and 279 at the associated interfaces 285, 286, 287, 288, and 289 of FIG. 2b. Also each cTM
  • 265, 266, 267, 268 may have one or a plurality of physical transceivers at interface 385.
  • Each one of these transceivers may be an ethernet/802.3 physical interface or any other type of communications interface.
  • references in this specification to ethernet and/or IEEE 802.3 generally are intended to refer to networks capable of carrying any combination of the various frame types generally carried on such ethernet/802.3 networks. Because the preferred embodiments of the present invention generally provide a physical layer interface that may be used for repeater service, the preferred embodiments of the present invention generally are transparent to the various types of ethernet/802.3 frames.
  • FIG. 4 shows four cTMs and four interfaces on TMTS 215, this is only for illustrative purposes, and the preferred embodiments of the present invention are not limited to providing connectivity to exactly four client transport modems. Instead the preferred embodiment of the present invention will work with at least one client transport modem and at least one corresponding interface on TMTS 215.
  • each one of the 802.3 physical (PHY) layer interfaces or transceivers 475, 476, 477, and 478 of the client transport modems (cTMs) generally is associated with a corresponding 802.3 physical layer interface and/or transceiver 425, 426, 427, and 428, respectively, in the
  • 802.3 physical layer interfaces and/or transceivers 425, 426, 427, and 428 are one non-limiting example of the types of transceivers that may be used in the preferred embodiment of the present invention for central-side network physical (PHY) transceivers (TX/RX) 225, 226, 227, 228, and 229 at the associated interface 245 of FIG. 2a.
  • PHY central-side network physical
  • the 802.3 PHY interfaces and/or transceivers 425, 426, 427, and 428 of the TMTS 215 are further connected to a headend networking device such as hub, switch, and/or router 430 with 802.3 PHY interfaces and/or transceivers 435, 436, 437, and 438, respectively.
  • a headend networking device such as hub, switch, and/or router 430 with 802.3 PHY interfaces and/or transceivers 435, 436, 437, and 438, respectively.
  • a service-provider common network 240 may include a service provider backbone network (not shown in FIG. 4).
  • the specific device(s) may be connected to the 802.3 PHY interfaces and/or transceivers 225, 226, 227, and 228 of TMTS 215.
  • 802.3 PHY interfaces and/or transceivers 225, 226, 227, and 228 may be associated with providing connectivity to two different remote offices of a particular company. That company may just want those two 802.3 PHY interfaces and/or transceivers of TMTS 215 to be directly connected (possibly using an ethernet cross-over cable that is known to one of skill in the art by crossing pins 1 and 3 as well as pins 2 and 6 of an RJ45 connector).
  • the 802.3 PHY interfaces and/or transceivers 425, 426, 427, and 428 of TMTS 215 can be connected based on service provider policies and/or subscriber (or customer) demands.
  • the present invention is not limited to a specific type of network device or link used to connect the 802.3 PHY interfaces port 225, 226, 227, and 228 of TMTS 215 to a service provider's network, which may be a common network 240 and may include a backbone network (not shown in FIG. 4).
  • the at least one connection to headend hub/switch/router 430 over interface 245 is only one non-limiting example of how the TMTS 215 can be connected to a service provider backbone network.
  • the preferred embodiment of the present invention basically functions as a ethernet/802.3 repeater that transparently copies the bits from ethernet/802.3 frames between interfaces 245 and 385 of FIGs. 3 and 4.
  • the transparent support of ethernet/802.3 generally allows the system to transparently carry ethernet/802.3 frames with virtual LAN or label-based multiplexing information such as, but not limited to, the information defined in IEEE 802. IQ (VLAN or Virtual LAN) and/or IEEE 802.17 (RPR or Resilient Packet Ring).
  • service providers using the preferred embodiment of the present invention generally have the flexibility to specify policies for carrying, combining, and/or segregating the traffic of different subscribers based on the types of devices connected to interfaces 245 and 385. Also, subscribers or customers may choose to implement various mechanisms such as, but not limited to, 802. IQ VLAN and/or 802.17 RPR that might be used between two or more subscriber sites that are each connected to the preferred embodiment of the present invention.
  • the transparency of the preferred embodiment of the present invention to this additional information in ethernet/802.3 frames provides versatility to the service provider and the subscriber in deciding on how to use various VLAN, tag, and/or label mechanisms that are capable of being carried with ethernet/802.3 frames.
  • FIG. 4 further shows how one client transport modem (cTM) 265 with at least one 802.3 PHY interface or transceiver 475 is connected over interface 385 to
  • cTM client transport modem
  • Ethemet/802.3 PHY interface 485 may be located in a subscriber hub/switch/router 480 that has more 802.3 PHY interfaces or transceivers 491, 492, and 493 into the customer or subscriber LANs or networks, which are non-limiting examples of portions of remote networks.
  • the other client transport modems (cTMs) 266, 267, and 268 also would likely have connections over interface 385 to various devices of other customer or subscriber LANs, though these are not shown in FIG. 4.
  • the actual type of network device or connection for subscriber hub/switch/router 480 is not limited by the preferred embodiment of the present invention.
  • the preferred embodiment of the present invention generally provides transparent ethernet repeater capability over a cable transmission network 105.
  • the interfaces 250 and 260 generally correspond to the central- side or service-provider-side and to the remote-side, customer-side, or subscriber-side, respectively, of cable transmission (CT) network 105.
  • CT cable transmission
  • CT computed tomography
  • the cable transmission networks 105 may carry other services in addition to those of the preferred embodiment of the present invention.
  • a cable transmission network 105 may carry analog video, digital video, DOCSIS data, and/or cable telephony in addition to the information associated with the preferred embodiment of the present invention.
  • Each one of these services generally has equipment located at the service provider, such as analog video equipment 401, digital video equipment 402, DOCSIS data equipment 403, and cable telephony equipment 404 as well as equipment located at various customer or subscriber locations such as analog video equipment 411, digital video equipment 412, DOCSIS data equipment 413, and cable telephony equipment 414.
  • FIG. 4 further shows some of the transmission equipment that might be used in a cable transmission network 105 (generally found between interfaces 250 and 260 in FIG. 4).
  • cable transmission networks 105 might include combiner 415 and splitter 416 to combine and split electromagnetic signals, respectively.
  • cable transmission network 105 may be a hybrid fiber-coax (HFC) network, it could contain devices for converting electromagnetic signals between electrical and optical formats.
  • HFC hybrid fiber-coax
  • downstream optical/electrical (O/E) interface device 417 may convert downstream electrical signals (primarily carried over coaxial cable) to downstream optical signals (primarily carried over fiber optic lines).
  • upstream optical/electrical (O/E) interface device 418 may convert upstream optical signals (primarily carried over fiber optic lines) to upstream electrical signals (primarily carried over coaxial cable).
  • Downstream optical/electrical interface 417 and upstream optical/electrical interface 418 generally are connected to a subscriber or customer premises over at least one fiber optic connection to optical/electrical (O/E) interface 420.
  • the downstream optical communications between downstream O/E interface 417 and O/E interface 420 might be carried on different optical fibers from the fibers carrying upstream optical communications between O/E interface 420 and upstream O/E interface 418.
  • FDM frequency-division multiplexing
  • WDM wavelength division multiplexing
  • optical/electrical interface 420 may connect into a splitter/combiner 422 that divides and/or combines electrical signals associated with analog video device 411, digital video device 412, DOCSIS data device 413, and/or cable telephone device 413 that generally are located at the customer or subscriber premises.
  • This description of the splitters, combiners, and optical electrical interfaces of HFC networks that may be used for cable transmission network 105 is basic and does not cover all the other types of equipment that may be used in a cable transmission network 105.
  • Some non-limiting examples of other types of equipment used in a cable transmission network 105 include, but are not limited to, amplifiers and filters. Those skilled in the art will be aware of these as well as many other types of devices and equipment used in cable transmission networks.
  • HFC such as cable transmission networks (CT) 105.
  • CT network 105 generally is a radio frequency (RF) network that generally includes some frequency-division multiplexed (FDM) channels.
  • RF radio frequency
  • FDM frequency-division multiplexed
  • the preferred embodiments of the present invention may be used on a cable transmission (CT) network 105 that generally is not carrying information for other applications such as, but not limited to, analog video, digital video, DOCSIS data, and/or cable telephony.
  • CT cable transmission
  • the preferred embodiments of the present invention may coexist on a cable transmission (CT) network 105 that is carrying information analog video, digital video, DOCSIS data, and/or cable telephony as well as various combinations and permutations thereof.
  • the cable transmission (CT) network 105 is any type of network capable of providing frequency-division multiplexed (FDM) transport of communication signals such as but not limited to electrical and/or optical signals.
  • FDM frequency-division multiplexed
  • the FDM transport includes the variation of FDM in optical networks which is generally called wavelength- division multiplexing (WDM).
  • the preferred embodiments of the present invention may use one or more MPEG PIDs for downstream transmission of MPEG packets carrying the traffic of Frame Management Sublayer (FMS) data flows.
  • MPEG packets carrying the octets of one or more FMS data flows of the preferred embodiments of the present invention are capable of being multiplexed into the same frequency channel of a cable transmission network that also carries other MPEG packets that have different PID values and that generally are unrelated to the FMS data flows of the preferred embodiments of the present invention.
  • PAL phase alternating line
  • the preferred embodiments of the present invention are designed to fit within the 6 MHz channels commonly-used for analog NTSC signals and will also fit into cable transmission networks capable of carrying analog PAL signals
  • the multiplexing techniques utilized in the preferred embodiments of the present invention are general.
  • the scope of the embodiments of the present invention is not to be limited to just cable transmission systems, which are designed for carrying NTSC and/or PAL signals.
  • the concepts of the embodiments of the present invention generally apply to transmission facilities that use frequency division multiplexing (FDM) and have a one-to- many communication paradigm for one direction of communication as well as a many-to- one communication paradigm for the other direction of communication.
  • FDM frequency division multiplexing
  • the preferred embodiments of the present invention generally communicate using signals with similar transmission characteristics to other signals commonly found in cable transmission networks.
  • the signal transmission characteristics of the preferred embodiments of the present invention are designed to integrate into existing, already-deployed cable transmission networks that may be carrying other types of signals for other services such as, but not limited to, analog and/or digital video, analog and/or digital audio, and/or digital data.
  • the preferred embodiments of the present invention are designed to be carried in the same communications medium that also may be carrying the other services without the preferred embodiments of the present invention introducing undesirable and unexpected interference on the other services.
  • the preferred embodiments of the present invention will operate over various types of communication media including, but not limited to, coaxial (coax) cable, fiber, hybrid fiber-coax, as well as wireless. Because the preferred embodiments of the present invention generally are designed to conform to some of the historical legacy standards of cable networks, the preferred embodiments of the present invention can be used in many existing network infrastructures that are already carrying other services. Therefore, the preferred embodiments of the present invention peacefully coexist with existing historical legacy services. Also, the preferred embodiments of the present invention can be used in other environments that are not limited by historical legacy services (or services compatible with historical legacy standards).
  • FIGs. 5a and 5b generally show a more detailed system reference diagram for a communication system that might be using a preferred embodiment of the present invention.
  • FIG. 5a covers at least some of the equipment and connections commonly found on the central-side or service-provider-side in a system using the preferred embodiments of the present invention.
  • FIG. 5b generally covers at least some of the equipment and connections commonly found on the remote-side, customer-side, or subscriber-side of a system using the preferred embodiments of the present invention.
  • CT cable transmission network
  • FIG. 5a shows transport modem termination system (TMTS) 215 comprising at least one cable transmission (CT) physical (PHY) transceiver (TX/RX) 115, at least one cable transmission (CT) physical (PHY) control (CTRL) 217, at least system control (SYS CTRL) 219, and at least one central-side network physical (PHY) transceiver (TX/RX) 225.
  • CT cable transmission
  • PHY physical
  • CTRL cable transmission
  • SYS CTRL system control
  • TX/RX central-side network physical transceiver
  • TMTS 802.3 interface 531 TMTS circuit emulation service (CES) interface 532.
  • CES circuit emulation service
  • cTM client transport modem
  • cTMs client transport modems
  • the at least one TMTS 802.3 interface 531 generally is capable of transparently conveying the information in ethernet/802.3 frames.
  • the preferred embodiments of the present invention are capable of acting as an ethernet/802.3 physical layer repeater.
  • the generally physical layer concepts of the preferred embodiments of the present invention may be integrated into more complex communication devices and/or systems such as, but not limited to, bridges, switches, routers, and/or gateways.
  • At least one TMTS CES interface 532 provides circuit emulation capability that may be used to carry generally historical, legacy interfaces that are commonly associated with circuit-switched networks, such as the public switched telephone network (PSTN).
  • PSTN public switched telephone network
  • Those skilled in the art will be aware of analog and/or digital interfaces to the PSTN that are commonly found in devices interfacing to the PSTN. In digital form, these interfaces often comprise integer multiples of a DSO at 56 kbps (N X 56) and/or 64 kbps (N X 64).
  • N X 56 56 kbps
  • N X 64 64 kbps
  • a person skilled in the art will be aware of various common multiplexing technologies that may be used to aggregate the integer multiples of
  • DSOs plesiochronous digital hierarchy
  • SDH synchronous digital hierarchy
  • At least one TMTS 802.3 interface 531 may be connected into a headend hub, switch, or router 535 or any other networking device to implement various policy decisions for providing connectivity between the transport modem termination system 215 and the client transport modems (cTMs) 265.
  • cTMs client transport modems
  • At least one TMTS CES interface 532 might be connected to a telco concentrator that generally might be various switching and/or multiplexing equipment designed to interface to technologies generally used for carrying circuit-switched connections in the PSTN.
  • telco concentrator 536 might connect to TMTS 215 using analog interfaces and/or digital interfaces that generally are integer multiples of DSO (56 kbps or 64 kbps).
  • analog interfaces that are commonly found in the industry are FXS/FXO (foreign exchange station/foreign exchange office) and E&M (ear & mouth).
  • FXS/FXO foreign exchange station/foreign exchange office
  • E&M ear & mouth
  • TMTS CES interface 532 also may to carry various signaling information for establishing and releasing circuit-switched calls.
  • telco concentrator 536 may be further connected to the public switched telephone network (PSTN).
  • PSTN public switched telephone network
  • CES circuit emulation services
  • telco concentrator 536 could convert the circuit emulation services (CES) into packet-based services. For example, 64 kbps PCM voice (and associated signaling) carried across TMTS CES interface 532 might be converted into various forms of packetized voice (and associated signaling) that is carried on a connection between telco concentrator 536 and headend hub, switch, and/or router 535.
  • the connection between telco concentrator 536 and headend hub, switch, and/or router 535 may carry network management, configuration, and/or control information associated with telco concentrator 536.
  • TMTS 802.3 interface 531 and TMTS CES interface 532 may be considered to be at least part of the headend physical (PHY) interface network 540.
  • the common network 240 generally may be considered to be the backbone interface network 541.
  • the communication system generally has connections to local server facilities 543 and operations, administration, and maintenance system 544 that may both be part of common network 240.
  • Network management, configuration, maintenance, control, and administration are capabilities that, although optional, are generally expected in many communication systems today.
  • local server facility 543 may comprise servers running various protocols for functions such as, but not limited to, dynamic network address assignment (potentially using the dynamic host configuration protocol - DHCP) and/or software uploads as well as configuration file uploads and downloads (potentially using the trivial file transfer protocol - TFTP).
  • dynamic network address assignment potentially using the dynamic host configuration protocol - DHCP
  • software uploads as well as configuration file uploads and downloads (potentially using the trivial file transfer protocol - TFTP).
  • CT PHY transceiver 115 connects to a TMTS asynchronous serial interface (ASI) 551 for the downstream communication from TMTS 215 towards at least one client transport modem
  • ASI TMTS asynchronous serial interface
  • the QAM (Quadrature Amplitude Modulation) modulator 552 is external to the TMTS 215.
  • an ASI (asynchronous serial interface) interface is only one non-limiting example of a potential interface for the at least one QAM modulator 522.
  • QAM modulators 552 with ASI interfaces are commonly used in cable transmission networks 105, and reuse of existing technology and/or systems may allow lower cost implementations of the preferred embodiments of the present invention.
  • other embodiments using various internal and/or external interfaces to various kinds of modulators might be used in addition to or in place of the TMTS ASI interface 551 to at least one QAM modulator 552.
  • QAM modulators are used for many types of transmission in CATV networks, one skilled in the art will be aware of many interfaces (both internal and external) that might be used for connecting QAM modulator(s) 522 for downstream transmission.
  • the TMTS ASI interface 551 is only one non-limiting example of an interface that is often used in the art and is well-known to one of ordinary skill in the art.
  • QAM modulators have been used in CATV networks to support downstream transmission for commonly-deployed services such as, but not limited to, DOCSIS cable modems and digital TV using MPEG video.
  • TMTS 215 controls the downstream modulation formats and configurations in the preferred embodiments of the present invention.
  • external modulators such as QAM modulator 552
  • QAM control interface 553 This control messaging is shown in FIG. 5a as QAM control interface 553, which generally allows communication between at least one QAM modulator 552 and TMTS 215.
  • this communication between at least one QAM modulator 552 and TMTS 215 may go through headend hub, switch, and/or router
  • modulators such as, but not limited to, at least one QAM modulator 552 often are designed to map information onto a set of physical phenomena or electromagnetic signals that generally are known as a signal space.
  • a signal space with M signal points is known as a M-ary signal space.
  • a signal space with M signal points may completely encode the floor of log 2 M bits or binary digits of information in each clock period or cycle.
  • the floor of log 2 M is sometimes written as floor(log M) or as
  • the floor of log 2 M is the largest integer that is not greater than log 2 M.
  • M is a power of two (i.e., the signal space has 2, 4, 8, 16, 32, 64, etc. signal points)
  • the floor of log M generally is equal to log 2 M, and log
  • M generally is known as the modulation index. Because the minimum quanta of information is the base-two binary digit or bit, the information to be mapped into a signal space generally is represented as strings of bits. However, one skilled in the art will be aware that the preferred embodiment of the present invention may work with representations of information in other number bases instead of or in addition to base two or binary.
  • TMTS downstream radio frequency (RF) interface 554 carries signals that have been modulated for transmitting information downstream over an RF network.
  • TMTS upstream radio frequency (RF) interface 555 generally carries signals that have to be demodulated to recover upstream information from an RF network.
  • QAM quadrature amplitude modulation
  • Tables 1, 2, 3 and 4 generally show the transmission parameters used in the preferred embodiments of the present invention.
  • Table 1 specifies at least some of the preferred transmission parameters for downstream output from a TMTS.
  • Table 2 specifies at least some of the preferred transmission parameters for downstream input into a cTM.
  • Table 3 specifies at least some of the preferred transmission parameters for upstream output from a cTM.
  • Table 4 specifies at least some of the preferred transmission parameters for upstream input to a TMTS.
  • ⁇ 30 kHz includes an allowance of 25 kHz for the largest FCC frequency offset normally built into upconverters.
  • downstream signals associated with TMTS 215 may or may not be combined in downstream RF combiner 556 with other downstream RF signals from applications such as, but not limited to, analog video, digital video, DOCSIS data, and/or cable telephony.
  • Upstream RF splitter 557 may split the upstream signals for TMTS 215 from upstream signals for other applications such as, but not limited to, analog video, digital video, DOCSIS data, and/or cable telephony.
  • the downstream RF combiner 556 and upstream RF splitter 557 might be used to carry the communications for multiple transport modem termination systems, such as TMTS 215, over a cable transmission (CT) network 105.
  • CT cable transmission
  • the signals used in communication between a TMTS 215 and at least one client transport modem (cTM) 265 generally might be treated like any other RF signals for various applications that generally are multiplexed into cable transmission (CT) network 105 based upon 6 MHz frequency channels.
  • CT cable transmission
  • transport network 560 may include transmitter 561 receiver 562 as optical/electrical (O/E) interfaces that convert the RF signals between coaxial cable and fiber optical lines.
  • transport combiner 563 may handle combining the two directions of optical signals as well as other potential data streams for communication over at least one fiber using techniques such as, but not limited to, wavelength-division multiplexing (WDM).
  • WDM wavelength-division multiplexing
  • transport splitter 567 may provide wavelength division multiplexing (WDM) and demultiplexing to separate the signals carried in the upstream and downstream directions and possibly to multiplex other signals for other applications into the same at least one fiber.
  • WDM wavelength division multiplexing
  • transport network 560 is a fiber network and cable transmission (CT) network 105 is a hybrid fiber-coax network
  • at least one distribution node 568 may comprise optical/electrical interfaces to convert between a fiber transport network 560 and a coaxial cable distribution network 570.
  • cTM client transport modem
  • a client transport modem (cTM) 265 generally comprises a cable transmission physical (PHY) transceiver (TX/RX) 165 as well as a remote-side network physical
  • a client transport modem (cTM) 265 comprises cable transmission (CT) physical (PHY) control (CTRL) 577 and system control 579.
  • CT PHY control 577 is concerned with handling bandwidth allocations in cable transmission (CT) network 105
  • system control 579 generally is concerned with cTM management and/or configuration.
  • a client transport modem (cTM) 265 generally interfaces with at least one subscriber physical (PHY) interface network 580.
  • Interfaces such as interface 285 in FIG. 2b may comprise a cable transport modem (cTM) 802.3 interface 581 and/or a cTM circuit emulation service (CES) interface 582 in FIG. 5b.
  • a cTM may have multiple interfaces to different remote- side networks, and the interfaces may use different interface types and/or technologies.
  • a cTM 265 may have a cTM control interface 583 that is used to allow at least one provisioning terminal 585 to perform various tasks such as, but not limited to, configuration, control, operations, administration, and/or maintenance.
  • the cTM control interface 583 may use ethernet/802.3, though other interface types and technologies could be used. Also, cTM control interface 583 could use a separate interface from interfaces used to connect to remote-side networks such as subscriber local area network 595. Based on various policy decisions and criteria, such as but not limited to security, the cTM control interface 583 may be carried over the same communications medium that connects to various remote- side networks or it may be carried over separate communications medium from that used in connecting to various remote-side networks. In the preferred embodiment of the present invention, the cTM control interface 583 is carried in a separate 802.3/ethernet medium for security.
  • FIG. 5b shows client transport modem (cTM) 265 being connected over cTM circuit emulation service (CES) interface 582 to another remote-side network, the subscriber telephony network 596.
  • CES circuit emulation service
  • Many remote or subscriber locations have legacy equipment and applications that use various interfaces commonly found in connections to the PSTN.
  • the preferred embodiments of the present invention allow connection of these types of interfaces to the client transport modem (cTM) 265.
  • Some non-limiting examples of these interfaces are analog POTS lines as well as various digital interfaces generally supporting N X 56 and N X 64 (where N is any positive integer).
  • the digital interfaces may have a plurality of DSOs multiplexed into a larger stream of data using the plesiochronous digital hierarchy (PDH) and/or the synchronous digital hierarchy (PDH).
  • PDH plesiochronous digital hierarchy
  • PDH synchronous digital hierarchy
  • cTM CES interface 582 is a Tl line, which is part of the plesiochronous digital hierarchy (PDH).
  • PDH plesiochronous digital hierarchy
  • FIG. 6 shows more detail of a preferred embodiment of a transport modem termination system (TMTS) 215 and/or a client transport modem (cTM) 265.
  • TMTS transport modem termination system
  • cTM client transport modem
  • a TMTS 215 and/or a cTM 265 generally may have a capability of system control 219 and/or 579, respectively.
  • system control for various tasks such as, but not limited to, configuration, management, operations, administration, and/or maintenance, a TMTS 215 and/or a cTM 265 generally may have a capability of system control 219 and/or 579, respectively.
  • system control the system control
  • CT cable transmission
  • PHY physical
  • PHY physical
  • TX/RX cable transmission
  • At least one cable transmission (CT) physical (PHY) transceiver (TX/RX) 115 and/or 165 generally is connected to at least one cable transmission (CT) network 105.
  • At least one ethernet/802.3 physical (PHY) transceiver 225 and/or 275 is connected to at least one ethernet/802.3 media 605.
  • a single instance of a 802.3/ethemet media access control (MAC) algorithm could be used for both the 802.3 physical (PHY) transceiver (TX/RX) 225 and/or 275 as well as the cable transmission (CT) physical (PHY) transceiver (TX/RX) 115 and/or 165.
  • CT cable transmission
  • TX/RX cable transmission
  • multiple instances of a medium access control (MAC) algorithm may be used.
  • ethemet/802.3 uses a carrier sense multiple access with collision detection (CSMA/CD) MAC algorithm.
  • CSMA/CD carrier sense multiple access with collision detection
  • Each instance of the algorithm generally is responsible for handling the carrier sensing, collision detection, and/or back-off behavior of in one MAC collision domain.
  • the details of the 802.3 MAC are further defined in IEEE standard 802.3-2000, "Part 3: Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer", which was published in 2000, and is incorporated by reference in its entirety herein.
  • the preferred embodiment of the present invention generally functions as a physical layer repeater between at least one 802.3 media 605 and at least one cable transmission (CT) network 105.
  • CT cable transmission
  • repeaters may support a particular MAC algorithm for management and control purposes, generally repeaters do not break up a network into different collision domains and/or into different layer three sub-networks.
  • devices such as, but not limited to, bridges, switches, routers, and/or gateways. These other embodiments may have multiple instances of the same and/or different MAC algorithms.
  • the CSMA/CD MAC algorithm as well as the physical layer signals that generally are considered part of the ethemet/802.3 specification may be used to carry different frame types.
  • IP Internet Protocol
  • the system control 219 for TMTS 215 and/or the system control 579 for cTM 265 generally may use IP for various tasks such as, but not limited to, configuration, management, operations, administration, and/or maintenance.
  • IP datagrams commonly are carried in Digital-Intel-Xerox (DIX) 2.0 or ethernet_II frames.
  • DIX Digital-Intel-Xerox
  • ethernet_II frames ethernet_I frames.
  • other frame types may be used to carry IP datagrams including, but not limited to, 802.3 frames with 802.2 logical link control (LLC) and a sub-network access protocol (SNAP).
  • LLC logical link control
  • SNAP sub-network access protocol
  • 802.2 LLC / DIX 615 handles the correct frame type information for the IP datagrams communicated to and/or from the system control 219 and/or 579 of TMTS 215 and/or cTM 265, respectively.
  • IP internet protocol
  • a mapping should exist between logical network layer addresses (such as IP addresses) and hardware, data link, or MAC layer addresses (such as ethemet/802.3 addresses).
  • ARP address resolution protocol
  • ARP is commonly used in IP devices that are connected to broadcast media such as ethemet/802.3 media.
  • the preferred embodiments of the present invention generally support ARP 620 to allow tasks such as, but not limited to, configuration, management, operations, administration, and/or maintenance of TMTS 215 and/or cTM 265.
  • TMTS 215 and/or cTM are tasks such as, but not limited to, configuration, management, operations, administration, and/or maintenance of TMTS 215 and/or cTM 265.
  • system control 219 and/or 579 generally has an IP layer 625 that may also optionally include support for ICMP.
  • the internet control message protocol (ICMP) is commonly used for simple diagnostic tasks such as, but not limited to, echo requests and replies used in packet internet groper (PING) programs.
  • ICMP internet control message protocol
  • PING packet internet groper
  • various transport layer protocols such as, but not limited to, the user datagram protocol (UDP) 630 are carried within IP datagrams.
  • UDP is a connectionless datagram protocol that is used in some basic functions in the TCP/IP (Transmission Control Protocol/Internet Protocol) suite.
  • UDP 630 supports the dynamic host configuration protocol (DHCP) 635, which is an extension to the bootstrap protocol (BOOTP), the simple network management protocol (SNMP) 640, the trivial file transfer protocol (TFTP) 645, as well as many other protocols within the TCP/IP suite.
  • DHCP dynamic host configuration protocol
  • BOOTP bootstrap protocol
  • SNMP simple network management protocol
  • TFTP trivial file transfer protocol
  • DHCP 635 is commonly used in IP devices to allow dynamic assignment of IP addresses to devices such as TMTS 215 and/or cTM 265.
  • SNMP 640 generally supports "sets" to allow a network management system to assign values on the network devices,
  • TFTP 645 might be used to load a configuration from a file onto a network device, to save off a configuration of a network device to a file, and/or to load new code or program software onto a network device.
  • SNMP 640 may be used in the preferred embodiment for control processes 650 in system control 219 and/or 579 of TMTS 219 and/or cTM 265, respectively.
  • TMTS 219 and/or cTM 265 may support the transmission control protocol (TCP) instead of or in addition to UDP 630.
  • TCP transmission control protocol
  • control processes 650 could use other TCP/IP suite protocols such as, but not limited to, the file transfer protocol (FTP), the hyper text transfer protocol (HTTP), and the telnet protocol.
  • FTP file transfer protocol
  • HTTP hyper text transfer protocol
  • telnet a protocol for terminal user interfaces.
  • Other common use interfaces on network equipment include, but are not limited to, serial ports, such as RS-232 console interfaces, as well as LCD (Liquid Crystal Display) and/or LED (Light Emitting Diode) command panels.
  • DHCP 635 may use DHCP 635, SNMP 640, and/or TFTP 645
  • other embodiments using these other types of interfaces are possible for tasks such as, but not limited to, configuration, management, operations, administration, and/or maintenance of TMTS 215 and/or cTM 265.
  • the local server facility 543 and/or the OA&M system 544 of FIG. 5a as well as the provisioning terminal 585 of FIG. 5b are at least one host device 660 that communicated with control processes 650 of TMTS 215 and/or cTM 265. hi general, at least one host device 660 may be connected to
  • Host device 660 may have an 802.3/ethemet (ENET) media access control (MAC) layer 675, an 802.2 LLC/DIX layer 680, and higher layer protocols 685.
  • FIG. 6 shows host device 660 directly connected to the same 802.3 media 605 as TMTS 215 or cTM 265, in general there may be any type of connectivity between host device 660 and TMTS 215 and/or cTM 265. This connectivity may include networking devices such as, but not limited to, repeaters, bridges, switches, routers, and/or gateways.
  • host device 660 does not necessarily have to have the same type of MAC interface as TMTS 215 and/or cTM 265. Instead, host device 660 generally is any type of IP host that has some type of connectivity to TMTS 215 and/or cTM 265 and that supports the proper IP protocols and/or applications for tasks such as, but not limited to, configuration, management, operations, administration, and/or maintenance.
  • FIG. 7 shows a more detailed breakdown of how TMTS 215 and cTM 265 might provide communication over cable transmission network 105.
  • the preferred embodiments of the present invention might be used in a network generally divided at point 740 into a service-provider-side (or central-side) of the network 742 as well as a subscriber-side, customer-side, or remote-side of the network 744.
  • TMTS 215 would be more towards the central-side or service-provider-side of the network 742 relative to cTM 265, which would be more towards the subscriber-side, customer-side, or remote-side of the network 744 relative to the TMTS 215.
  • FIGs. 5 a and 5b and is shown again in FIG.
  • TMTS 215 may comprise a cable transmission (CT) physical (PHY) transceiver (TX/RX) 115, an ethemet/802.3 physical (PHY) transceiver (TX/RX) 225, and a cable transmission (CT) physical (PHY) control 217.
  • cTM 265 may comprise a cable transmission (CT) physical (PHY) transceiver (TX/RX) 165, an ethemet/802.3 physical (PHY) transceiver (TX/RX) 275, and a cable transmission (CT) physical (PHY) control 577.
  • TMTS 215 and cTM 265 generally provide layer one, physical level repeater service between ethernet/802.3 physical (PHY) transceiver (TX/RX) 225 and ethemet/802.3 physical (PHY) transceiver
  • CT cable transmission
  • CT cable transmission
  • CT cable transmission
  • CT cable transmission
  • CT cable transmission
  • CT cable transmission
  • RF radio frequency
  • the TMTS 215 and the cTM 265 generally are transparent to ethemet/802.3 frames communicated between ethernet/802.3 physical (PHY) transceiver (TX/RX) 225 and ethemet/802.3 physical (PHY) transceiver 275.
  • PHY physical
  • PHY physical
  • PHY control 577 generally do not significantly modify and/or disturb the ethernet frames communicated between 802.3/ethemet physical (PHY) transceiver (TX/RX) 225 and 802.3/ethemet physical (PHY) transceiver (TX/RX) 275.
  • CT cable transmission
  • CT cable transmission
  • PHY physical
  • TMTS 215 and cTM 265 respectively, while still maintaining transparency for the 802.3 physical transceivers 225 and/or 275.
  • the traffic between cable transmission (CT) physical (PHY) control 217 and 577 of TMTS 215 and cTM 265, respectively is multiplexed into the same data stream with 802.3/ethemet traffic between
  • control traffic generally uses a different frame than standard ethernet/802.3 traffic.
  • Ethernet/802.3 frames generally begin with seven octets of preamble followed by a start frame delimiter of 10101011 binary or AB hexadecimal. (In reality ethernet DIX
  • IEEE 802.3 has an eight octet preamble
  • IEEE 802.3 has a seven octet preamble followed by a start frame delimiter (SFD).
  • SFD start frame delimiter
  • these initial eight octets are generally the same for both ethernet DIX 2.0 and IEEE 802.3.
  • CT cable transmission
  • PHY physical
  • TX/RX 802.3 physical
  • a different value for the eighth octet i.e., the start frame delimiter
  • the eighth octet i.e., the start frame delimiter
  • CT cable transmission
  • PHY physical
  • TX/RX cable transmission
  • 802.3/ethemet physical (PHY) transceivers TX/RX 225 and 275, respectively.
  • TMTS 215 generally is connected to 802.3/ethemet media 745, which is further connected to at least one device with an ethernet interface 750.
  • Device with ethernet interface 750 may further comprise an 802.3/ethemet physical (PHY) transceiver (TX/RX) 755, an 802.3/ethemet medium access control layer 756, as well as other higher layer protocols 757.
  • ethernet/802.3 physical (PHY) transceiver (TX/RX) 275 in cTM 265 generally is connected to 802.3/ethemet media 785, which is further connected to at least one device with an ethernet interface 790.
  • Device with ethernet interface 790 may further comprise an 802.3/ethemet physical (PHY) transceiver (TX/RX) 795, an 802.3/ethernet medium access control layer 796, as well as other higher layer protocols
  • the preferred embodiments of the present invention provide transparent physical layer repeater capability that may carry information between device with ethernet interface 750 and device with ethernet interface 790.
  • device with ethernet interface 750 may have information from a higher layer protocol such as, but not limited to, an IP datagram.
  • this IP datagram is formed in the higher layer protocols block 757 and is passed down to 802.3/ethemet MAC layer 756, which adds data link information to form an ethernet frame.
  • 802.3 physical (PHY) transceiver (TX/RX) 755 handles generating the proper electromagnetic signals to propagate the information over 802.3/ethemet media 745.
  • PHY physical
  • TMTS 215 functions as a repeater that copies bits (or other forms of information) received from 802.3/ethernet media 745 by 802.3/ethemet physical (PHY) transceiver (TX/RX) 225.
  • the bits are copied over to cable transmission (CT) physical (PHY) transceiver (TX/RX) 115, which generates the proper signals to communicate the information over cable transmission network 105.
  • CT cable transmission
  • PHY physical
  • CT cable transmission
  • PHY physical transceiver
  • TX/RX cable transmission
  • TX/RX cable transmission
  • the bits are copied over to 802.3/ethemet physical (PHY) transceiver (TX/RX) 275, which generates the proper signals to communicate the information over 802.3/ethemet media 785.
  • 802.3/ethernet physical (PHY) transceiver (TX/RX) 795 receives the electromagnetic signals on 802.3/ethemet media 785 and recovers the bits (or other forms of information) from the electromagnetic signals.
  • 802.3/ethemet media access control (MAC) 796 generally checks the ethemet/802.3 framing and verifies the frame check sequence (FCS) or cyclic redundancy code (CRC).
  • FCS frame check sequence
  • CRC cyclic redundancy code
  • embodiments of the present invention are capable of providing similar connectivity over cable transmission (CT) network 105 to devices (such as device with ethernet interface 750 and device with ethernet interface 790), which may be directly connected to 802.3/ethemet media 745 and/or 785 as well as other devices that are not directly connected to 802.3/ethemet media 745 and/or 785.
  • CT cable transmission
  • devices such as device with ethernet interface 750 and device with ethernet interface 790
  • devices which are indirectly connected to 802.3/ethemet media through other media, links, and/or networking devices may also utilize the connectivity provided by the preferred embodiments of the present invention.
  • TMTS 215 can be thought of as providing level one, physical layer repeater service between 802.3/ethemet physical (PHY) transceiver (TX/RX) 225 and cable transmission (CT) physical (PHY) transceiver (TX/RX) 115.
  • cTM 265 can be thought of as providing level one, physical layer repeater service between 802.3/ethemet physical (PHY) transceiver (TX/RX) 275 and cable transmission (CT) physical (PHY) transceiver (TX/RX) 165.
  • TMTS 215 and cTM 265 together can be thought of as providing level one, physical layer repeater service between 802.3/ethemet physical (PHY) transceiver (TX/RX) 225 and 802.3/ethemet physical (PHY) transceiver (TX/RX) 275.
  • TX/RX 802.3/ethemet physical
  • TX/RX 802.3/ethemet physical
  • TMTS 215 and cTM 265 each may be thought of as half-repeaters of a repeater pair.
  • networking devices connecting local area networks (or LANs such as, but not limited to, ethemet/802.3 media 745 and 785) over a wide-area network (or WAN such as, but not limited to, cable transmission network 105) may be viewed using at least two abstractions or models.
  • the two devices at each end of the WAN may be viewed as independent networking devices each acting as a repeater, bridge, switch, router, gateway, or other type of networking device connecting the LAN and the WAN.
  • each networking device at the end of a WAN could be thought of as a half-repeater, half-bridge, half-switch, half-router, half-gateway, etc. for a pair of networking devices providing connectivity across a WAN.
  • the networking devices on each end of a connection may actually perform according to different forwarding constructs or models (such as, but not limited to, repeater, bridge, switch, router, and/or gateway).
  • one of the networking devices may provide services such as, but not limited to, repeater, bridge, switch, router, and/or gateway while the other networking device (either a cTM 265 or the TMTS 215, respectively) may provide the same or different services such as, but not limited to, repeater, bridge, switch, router, and/or gateway.
  • each networking device could provide different services or forwarding constructs for different protocols.
  • the preferred embodiments of the present invention have a repeater service or forwarding construct for both a TMTS 215 and a cTM 265 as well as a TMTS 215 and a cTM 265 jointly, one skilled in the art will be aware that other embodiments of the present invention are possible in which the forwarding construct for a TMTS 215 and/or a cTM may be independently chosen. Furthermore, the forwarding construct could be different for each client transport modem 265, 266, 267, and 268 connected to the same TMTS 215. Also, transport modem termination systems 215 may have different forwarding behavior or forwarding constracts for each port.
  • TMTS 215 devices might utilize different forwarding constracts but still be connected to the same cable transmission network 105.
  • hybrid forwarding constracts in addition to the general layer one repeater service, layer two bridge service, and/or layer three routing service. Any hybrid type of forwarding construct also might be used as alternative embodiments of the present invention. Therefore, one skilled in the art will be aware that alternative embodiments exist utilizing other forwarding constracts in addition to the layer one, repeater service of the preferred embodiment of the present invention.
  • FIG. 7 further shows an 802.3/ethemet media independent interface (Mil) 799 as a dashed line intersecting connections to various 802.3/ethemet physical layer interfaces or transceivers (755, 225, 275, and 795).
  • the IEEE 802.3 standards defined a media independent interface for 100 Mbps ethernet and a Gigabit media independent interface (GMII) for 1000 Mbps ethernet.
  • GMII Gigabit media independent interface
  • References in the figures and description to Mil and/or GMII are meant to include both Mil and GMII.
  • the Mil and GMII interfaces allow 802.3 interfaces to be made that can be interfaced with different physical cables.
  • 100BaseT4, 100BaseTX, and lOOOBaseFX are three different types of physical cables/optical lines that can be used in the IEEE 802.3 ethernet standards covering 100 Mbps or fast ethernet.
  • 100BaseTX is designed for twisted pair cables, whereas 100BaseFX is designed for fiber optic cables.
  • the media independent interface provides a standard interface for communicating with devices designed to form and interpret the physical electrical and/or optical signals of different types of media.
  • FIG 8. shows a more detailed diagram for connecting ethernet devices through a transport modem termination system (TMTS) 215 and a client transport modem (cTM) 265.
  • FIG. 8 further divides the cable transmission (CT) physical (PHY) transceiver (TX/RX) 115 and 165.
  • TMTS 215 comprises CT PHY 115, which further comprises signaling medium dependent (SMD) sublayer 816, physical coding sublayer (PCS) 817, inverse multiplex sublayer (IMS) 818, and frame management sublayer (FMS) 819.
  • SMD sublayer 816 communicates through cable transmission (CT) network 105 across 802.3/ethernet media dependent interface (MDI) 835.
  • CT cable transmission
  • MDI media dependent interface
  • client transport modem 265 has a cable transmission physical transceiver 165 that comprises signaling medium dependent (SMD) sublayer 866, physical coding sublayer (PCS) 867, inverse multiplex sublayer (IMS) 868, and frame management sublayer (FMS) 869.
  • SMD sublayer 866 communicates through cable transmission network 105 across 802.3 media dependent interface (MDI) 835.
  • FMS 869 provides an
  • 802.3 media independent interface (Mil) 799 which may be connected to an 802.3 ethernet physical transceiver 275.
  • FMS 819 and 869 provide management functions that allow control traffic to be combined with and separated from data traffic.
  • a frame management sublayer (such as FMS 819 and/or 869) may support a plurality of 802.X interfaces.
  • Each active 802.X port of FMS 869 in client transport modem 265 generally has a one-to-one relationship with an associated active 802.X port in a transport modem termination system 215.
  • FMS 819 within TMTS 215 has similar behavior to FMS 869 in cTM 265.
  • TMTS 215 generally is a concentrator that may support a plurality of client transport modems, such as cTM 265, FMS 819 of TMTS 215 usually has more 802.X interfaces than FMS 869 of cTM 265.
  • the inverse multiplex sublayer of IMS 818 and IMS 868 generally is responsible for multiplexing and inverse multiplexing data streams of FMS 819 and 869 across multiple frequency-division multiplexed (FDM) carriers.
  • FDM frequency-division multiplexed
  • the preferred embodiments of the present invention are still capable of providing symmetrical upstream and downstream data rates (as well as asymmetrical data rates).
  • the inverse multiplexing sublayer (IMS) splits the incoming sequential octets of FMS data flows (i.e., flows of data from and/or to FMS ports) for parallel transmission across a cable transmission network utilizing a plurality of frequency bands in parallel. This parallel transmission of data flows will tend to have lower latency than serial transmission.
  • the physical coding sublayer (such as PCS 817 and 867) generally is responsible for handling forward error correction (FEC) and quadrature amplitude modulation (QAM) coding and decoding of the information communicated between IMS sublayer peer entities (such as IMS 818 and IMS 868).
  • the signaling medium dependent (SMD) sublayer (such as the SMD peer entities 816 and 866) generally is responsible for communicating the encoded and modulated information from the physical coding sublayer onto a cable transmission network 105 at the proper frequency ranges and in the proper optical and/or electrical carrier waves.
  • FIG. 9 shows the open systems interconnect (OSI) seven-layer model, which is known to one of skill in the art, as well as the relationship of the OSI model to the physical layer specification of the preferred embodiments of the present invention and to some portions of the IEEE 802.X standards.
  • OSI open systems interconnect
  • corresponding layers such as the layer 3 Internet Protocol
  • IP hosts two communicating devices
  • peer entities such as peer entities.
  • the OSI model comprises the level 1 physical layer 901, the level 2 data link layer 902, the level 3 network layer 903, the level 4 transport layer 904, the level 5 session layer 905, the level 6 presentation layer 906, and the level 7 application layer 907.
  • the preferred embodiments of the present invention generally operate over communication media that function as cable transmission network 915.
  • CT network 915 also comprises hybrid fiber-coax (HFC) cable plants
  • CT network 915 more generally also comprises all coax and all fiber transmission plants.
  • cable transmission network 915 even more generally comprises any communication medium using frequency-division multiplexing (FDM) and/or the optical variation of frequency division multiplexing known as wavelength division multiplexing (WDM).
  • FDM frequency-division multiplexing
  • WDM wavelength division multiplexing
  • the cable transmission network 915 communicates information across a media dependent interface (MDI) 925 with cable transmission physical layer 935.
  • FIG. 9 shows that cable transmission physical layer 935 is associated with the physical layer 901 of the OSI model.
  • cable transmission PHY 935 is shown in FIG. 9 with the four sublayers of the signaling medium dependent sublayer (SMD) 945, physical coding sublayer (PCS) 955, inverse multiplex sublayer (IMS) 965, and frame management sublayer (FMS) 975.
  • SMD 945, PCS 955, IMS 965, and FMS 975 sublayers form a user plane that generally is concerned with communicating user data.
  • cable transmission PHY control 985 provides functions generally associated with management and/or control of communications through cable transmission physical layer 935 and the corresponding four sublayers (945, 955, 965, and 975).
  • FIG. 9 further shows how data link layer 902 is divided into medium access control sublayer (MAC) 998 and logical link control sublayer (LLC) 999 that are generally described in the IEEE 802 standards.
  • IEEE 802.3 generally describes the carrier sense multiple access with collision detection (CSMA CD) medium access control
  • MAC logical link control
  • IEEE 802.2 generally describes the logical link control (LLC) protocol.
  • Cable transmission physical layer 935 generally has a media independent interface (Mil) 995 that provides connectivity between FMS 975 and an IEEE 802.3 MAC.
  • Mc media independent interface
  • OSI model as well as other communication models are only abstractions that are useful in describing the functionality, behavior, and/or interrelationships among various portions of communication systems and the corresponding protocols. Thus, portions of hardware and/or software of actual networkable devices and the associated protocols may not perfectly match the abstractions of various communication models.
  • TMTS 215 and device with ethernet interface 750 are shown again in FIG. 10 but this time TMTS 215 transfers information with a client transport modem network interface card (NIC) 1065.
  • CTM NIC 1065 comprises a CT physical layer transceiver (TX/RX) 1075 that is a peer entity of CT physical layer transceiver 115 of TMTS 215.
  • cTM NIC 1065 further comprises CT physical layer control 1077 that is a peer entity of CT physical layer control 217 of TMTS 215. Also, cTM NIC 1065 comprises 802.3 /ethernet MAC 1079 that is a peer entity of 802.3/ethemet MAC 757 in device with ethernet interface 750.
  • Client transport modem NIC 1065 is shown within device with cTM NIC 1090, which further contains NIC driver software 1097 and higher layer protocols 1099. If device with cTM NIC 1090 is a personal computer, then NIC driver software 1097 might conform to one of the driver specifications, such as but not limited to, NDIS (Network Driver Interface Specification), ODI (Open Data-Link Interface), and/or the Clarkson packet drivers.
  • NDIS Network Driver Interface Specification
  • ODI Open Data-Link Interface
  • Clarkson packet drivers such as but not limited to, NDIS (Network Driver Interface Specification), ODI (Open Data-Link Interface), and/or the Clarkson packet drivers.
  • FIG. 11 further expands cable transmission physical layer 1075 (and the associated physical layer transceiver) into SMD sublayer 1166, PCS sublayer 1167, IMS sublayer 1168, and frame management sublayer 1169.
  • FMS Frame Management Sublayer
  • FIG. 12 shows a system diagram using the physical layer of the preferred embodiment of the present invention for communication between a transport modem termination system and a client transport.
  • the four sublayers FMS 1202, IMS 1204,
  • PCS 1206, and SMD 1208) are shown within dashed boxes.
  • the upper portion of FIG. 12 shows downstream communication from a TMTS to a cTM, while the lower portion of FIG. 12 shows upstream communication from a cTM to a TMTS.
  • downstream communication ethemet/802 packets ingress into a cable transmission physical layer of the preferred embodiments of the present invention at ethernet/802 ingress 1212, which performs a conversion from ethemet/802 packets to FMS frames.
  • FMS frames are then communicated to downstream multiplexer 1214 which converts the octets in FMS frames to octets in MPEG frames.
  • MPEG headers and MPEG forward error correction (FEC) coding which generally is a Reed-Solomon code, generally are added for communication to downstream modulator(s) 1216.
  • the output of downstream modulator(s) 1216 is passed through radio frequency (RF) transmitter (TX) 1218, which generates the electrical and/or optical signals in the proper frequencies.
  • RF radio frequency
  • TX radio frequency
  • MPEG frames are then passed to downstream inverse multiplexer 1226, which extracts the proper octets from MPEG frames to recover frame management sublayer (FMS) frames.
  • the FMS frames then are converted back to ethemet/802 frames and complete downstream conveyance at ethemet/802 egress 1228.
  • the FMS frames are converted into blocks of data in preparation for forward error correction coding in upstream multiplexer 1246.
  • upstream blocks of data may carry the octets of ethemet/802 frames over multiple carrier frequencies.
  • a turbo product code forward error correction technique is utilized on the upstream blocks of data.
  • Upstream modulator 1244 modulates the information of the forward error correction blocks and passes the resulting modulating information to RF transmitter 1242, which generates the electrical and/or optical signals in the proper frequency ranges for communication over cable transmission network 1220.
  • the upstream electrical and/or optical signals are received in RF receiver 1238.
  • Upstream demodulator 1236 then handles recovering the forward error correction blocks of data.
  • upstream demodulator 1236 converts the forward error correction blocks back to the original blocks of data that were prepared in upstream multiplexer 1246.
  • the octets of the data blocks are placed back into the proper FMS frames in upstream inverse multiplexer 1234.
  • These FMS frames are then further converted back to ethemet/802 frames and leave the physical layer at ethemet/802 egress 1232.
  • FIG. 13 shows a more detailed diagram of the frame management sublayer (FMS).
  • 802.3/ethemet media 1302 is connected across media independent interface (Mil) and/or gigabit media independent interface (GMII) 1304 to frame management sublayer (FMS) 1306, which is further connected to inverse multiplex sublayer (IMS) 1308.
  • the connections of FMS 1306 to 802.3/ethemet media 1302 are known as uplink ports 1 through N (1312, 1314, 1316, and 1318). While the connections of FMS 1306 leading to IMS 1308 generally are known as attachment ports 1 through N (1322, 1324, 1326, and 1328).
  • Each attachment port (1322, 1324, 1326, and 1328) is connected to its own set of at least one frame buffer (1332, 1334, 1336, and 1338, respectively) that provides at least part of the interface between FMS 1306 and IMS 1308.
  • Frame buffer(s)
  • each active FMS data flow of a frame management sublayer in one device is associated one-to-one with an active data flow of a peer entity frame management sublayer in another device.
  • each FMS data flow provides bi-directional connection-oriented communication between frame management sublayer peer entities in the associated devices.
  • an FMS data flow generally provides bi-directional point- to-point connectivity between a pair of FMS peer entities.
  • FIG. 13 further shows various control functions 1352, which comprise 802.3/ethemet medium access control (MAC) interface 1354, cable transmission physical layer control 1356, and system control 1358.
  • CT PHY 1356 generally handles control of the cable transmission physical layer, which includes the sublayers of FMS 1306 and IMS 1308 that are shown in FIG. 13.
  • System control 1358 includes many of the network management, software download, and/or configuration setting file download and/or upload capabilities that generally utilize protocols from the TCP/IP suite for administering network devices.
  • the frame management layer (FMS) 1306 is responsible for framing ethernet data into the proper frames for communications using the preferred embodiments of the present invention. Furthermore, control flows are communicated between cable transmission physical control 1356 and a corresponding peer entity cable transmission physical control in another device. These control flows are not part of the user data, and thus are not communicated through FMS 1306 to the uplink ports (1312, 1314, 1316, and 1318) that carry information to 802.3/ethemet media 1302.
  • the control frames of control flows may be multiplexed with data frames by utilizing different start frame delimiters to indicate ethernet data frames and control frames.
  • FIG. 14 shows a general format for an 802.3/ethernet frame as is known by one of ordinary skill in the art.
  • an ethernet frame comprises a preamble 1402 that is used to synchronize the transmitter and receiver in 802.3/ethemet media. After the preamble, start frame delimiter 1404 is used to indicate the beginning of the preamble.
  • 802.3/ethernet frame In IEEE 802.3 and ethernet, this start frame delimiter is the one octet value of OxAB (in hexadecimal). Following the start frame delimiter (SFD) 1402, 802.3/ethernet frames generally have a header 1406 that includes six octets of destination address, six octets of source address, and other information depending on whether the frame type is IEEE 802.3 raw, ethernet l, IEEE 802.3 with an 802.2 LLC, or IEEE 802.3 with an 802.2 LLC and a Sub-Network Access Protocol (SNAP).
  • SFD start frame delimiter
  • 802.3/ethernet frames generally have a header 1406 that includes six octets of destination address, six octets of source address, and other information depending on whether the frame type is IEEE 802.3 raw, ethernet l, IEEE 802.3 with an 802.2 LLC, or IEEE 802.3 with an 802.2 LLC and a Sub-Network Access Protocol (SNAP).
  • SNAP
  • FCS frame check sum
  • CRC cyclic redundancy check
  • the start frame delimiter is used as a field for multiplexing control frames with ethernet/802.3 data frames.
  • ethernet/802.3 frames do not use the start frame delimiter (SFD) field 1404 for multiplexing because the SFD octet is responsible for providing proper frame alignment in ethemet/802.3 networks.
  • FIG. 15 shows the frame format for control frames in the preferred embodiment of the present invention.
  • control frames are similar to ethernet II and 802.3 raw frames with a preamble 1502, a start frame delimiter (SFD) 1504, a six octet destination address 1505, a six octet source address 1506, a two octet length and/or type field 1507, a variable length payload 1508 for carrying control information, and a four octet frame check sequence (FCS) or cyclic redundancy code (CRC) 1510.
  • SFD start frame delimiter
  • FCS octet destination address
  • CRC cyclic redundancy code
  • the start frame delimiter fields 1404 and 1504 are different.
  • the start frame delimiter has a value of OxAB in hexadecimal
  • the start frame delimiter has a value of OxAE in hexadecimal.
  • This difference in the octet of the start frame delimiter (SFD) allows data frames and control frames to be multiplexed together without affecting the transparency of the communication system to all types of ethemet/802.3 frame variations.
  • Control frames transmitted by cable transmission physical control are multiplexed with the data of an FMS data flow (such as 1342, 1344, 1346, and/or 1348) that is destined for the same location as the data of that FMS data flow.
  • FIG. 16 shows the FMS frames 1602 communicated between FMS peer entities in a system utilizing the preferred embodiments of the present invention.
  • bits may be continuously transmitted to maintain synchronization.
  • the system continuously communicates an octet of 0x7E hexadecimal, which functions similarly to the continuous communication of HDLC (High-level Data-Link Control) flags in many point-to-point synchronous connections.
  • HDLC High-level Data-Link Control
  • the delimiter 1604 for an FMS frame 1602 is one octet of 0x00 followed by six octets of 0x7E hexadecimal 1605.
  • the frame delimiter of an FMS frame 1602 is followed by a one octet start frame delimiter (SFD) 1606 that contains the value OxAB hexadecimal for ethernet/802.3 data frames and that contains the value OxAE hexadecimal for control frames as shown in FIG. 15.
  • FMS frame 1602 generally has a frame trailer 1608 and a payload 1610.
  • the payload 1610 of an FMS frame 1602 generally may carry an ethemet/802.3 frame or a control frame beginning with the SFD octets of OxAB and OxAE, respectively, and continuing through the frame check sequence (FCS) 1410 or 1510.
  • FCS frame check sequence
  • an octet stuffing technique is used to ensure that the information in an FMS frame payload 1610 is communicated transparently and that the FMS frame 1602 boundaries can be detected by a starting FMS delimiter 1604 and an FMS trailer 1608 (i.e., a trailing FMS delimiter).
  • the FMS sublayer handles this process of framing ethernet and control frames using the FMS frame delimiters of one octet of 0x00 followed by six octets of 0x7E.
  • byte or octet stuffing allows a payload containing octet or byte values that might cause misinterpretations of starting delimiter 1604 or trailing delimiter 1608 to be communicated transparently.
  • Various techniques for byte, octet, and/or character stuffing in byte-oriented protocols as well as bit stuffing in bit-oriented protocols are known by one of ordinary skill in the art, and one technique is described in Andrew S.
  • octet stuffing involves adding additional octets to a frame whenever a pattern in the frame might cause an ambiguity in a receiver trying to dete ⁇ nine frame boundaries.
  • six payload octets of 0x7E at 1612 in FIG. 16 could have an extra octet of 0x00 added as a stuffed octet 1614.
  • the additional stuffed octets generally increase the size of the payload.
  • FIG. 17 shows the relationships of inverse multiplex sublayer 1308 to frame management sublayer 1306 and physical coding sublayer 1710.
  • FMS data flows 1 through N 1 through N (1342, 1344, 1346, and 1348).
  • the frame buffers between FMS 1306 and IMS 1308 have been omitted for simplicity of the discussion of FIG. 17.
  • Physical coding sublayer 1710 varies depending on whether client transport modem modulation 1712 or transport modem termination system modulation 1722 is being used.
  • Client transport modem modulation comprises a downstream demodulator 1714 that provides input into IMS 1308 and further comprises upstream modulator 1716 that receives the output of an inverse multiplex sublayer 1308.
  • the TMTS modulation 1722 comprises upstream demodulator 1724 that provides input to an IMS 1308 and further comprises downstream modulator 1726 that receives input from IMS 1308.
  • the IMS 1308 performs different multiplexing/demultiplexing functions depending on • whether the direction of communication is upstream or downstream.
  • the downstream modulator 1726 of a transport modem termination system may include integrated QAM modulators.
  • the downstream MPEG packets and/or frames may be communicated over an optional asynchronous serial interface (ASI) 1732 to an external QAM modulator.
  • ASI asynchronous serial interface
  • Tl stratum reference clock source 1736 or another clock source commonly used for various N x 64 and/or N x 56 digital telephone company services that may involve plesiochronous digital hierarchy (PDH) or synchronous digital hierarchy (SDH) multiplexing.
  • PDH plesiochronous digital hierarchy
  • SDH synchronous digital hierarchy
  • Tl stratum reference clock source 1736 (or another clock source as would be known by someone of ordinary skill in the art) generally is an input to IMS 1308 in a TMTS.
  • Tl stratum reference clock source 1736 or another clock source as would be known by someone of ordinary skill in the art
  • Tl stratum reference clock source 1736 generally is an output that is driven by the IMS 1308 in a cTM.
  • FIG. 18 shows the layout of an MPEG frame that is known to one of skill in the art and is described in ITU-T H.222.0 entitled “Audiovisual and Multimedia Systems” and ITU-T J.83 entitled “Transmission of Television, Sound Program and Other Multimedia Signals", which are both incorporated by reference in their entirety herein.
  • Synchronization Byte (SB) 1812 contains the eight bit value 0x47 hexadecimal.
  • the transport error indicator (TEI) 1822 is set in a communication system using the preferred embodiments of the present invention to indicate frame decoding errors of MPEG packets to an 802.3 Mil interface connected to a frame management sublayer.
  • the cable transmission physical layer including the four sublayers of FMS, IMS, PCS, and SMD) in a communication system utilizing the preferred embodiments of the present invention generally does not utilize payload start indicator (PSI) 1824, transport priority (TP) bit
  • the cable transmission physical (CT PHY) layer of a communication system utilizing the preferred embodiments of the present invention does utilize the thirteen bit packet identifier (PID) field to specify various streams of MPEG packets.
  • PID packet identifier
  • the PID numbers 0x0000 through OxOOOF are not used to carry the cable transmission physical (CT PHY) layer communications in a system operating with the preferred embodiments of the present invention.
  • These PIDs of 0x0000 through OxOOOF are utilized for other MPEG functions such as but not, limited to, program association table (PAT), conditional access table (CAT), and transport stream description table that are known to one of skill in the art.
  • PAT program association table
  • CAT conditional access table
  • transport stream description table transport stream description table
  • the preferred embodiments of the present invention do not utilize the PIDs of OxlFFF, which indicates the null packet, and OxlFFE, which indicates DOCSIS downstream communications.
  • PIDs in the range of 0x0010 through O lFFD are utilized to carry the cable transmission physical layer (CT PHY) information in a communication system using the preferred embodiments of the present invention.
  • CT PHY cable transmission physical layer
  • the PIDs are allocated for carrying the information of FMS data flows by starting at OxlFFD and working downward.
  • the four bits of the continuity counter (CC) 1846 increment sequentially for each packet that belongs to the same PID.
  • the IMS downstream communication of MPEG packets are generated contemporaneously in parallel with the same value for the continuity counter (CC) 1846 across all the parallel packets.
  • the continuity counter 1846 is incremented in unison across all the MPEG stream to help ensure that inverse multiplexing operations across multiple MPEG streams are performed utilizing the correctly aligned set of packet payloads.
  • the two bits of the adaptation field control (AFC) 1844 specifies whether the payload contains a packet payload only, an adaptation field only, or a packet payload and an adaptation field.
  • the 184 octets of an MPEG packet or frame after the four octet header may contain an adaptation field and/or a packet payload 1852, and is padded to the fixed size of 184 octets with pad 1854.
  • the preferred embodiments of the present invention do not generate MPEG packets containing both adaptation fields and other payload information.
  • one skilled in the art will be aware that other implementations are possible using various combinations of adaptation fields and payload information in MPEG packets.
  • FIG. 19 further shows an MPEG adaptation field that has been slightly modified from the standard MPEG adaptation field known to one of ordinary skill in the art.
  • the cable transmission physical layer (CT PHY) of a communication system using the preferred embodiments of the present invention generally does not utilize the MPEG adaptation field bits of the discontinuity indicator (Dl) 1921, the random access indicator (RAI) 1922, the elementary stream priority indicator (ESPI) 1923, the original program clock reference flag (OPCRF) 1925, the splice point flag (SPF) 1926, the transport private data flag (TPDF) 1927, and the adaptation field extension flag (AFEF) 1928.
  • Dl discontinuity indicator
  • RAI random access indicator
  • ESPI elementary stream priority indicator
  • OCRF original program clock reference flag
  • SPF splice point flag
  • TPDF transport private data flag
  • AFEF adaptation field extension flag
  • the adaptation field length 1912 comprises eight bits that specify the number of octets in an adaptation field after the adaptation field length itself.
  • the adaptation field length (AFL) 1912 may range from 0 to 182 octets (with the count starting at the first octet after the AFL octet 1912).
  • the MPEG packets generated by the preferred embodiments of the present invention that carry an adaptation field generally have the program clock reference flag (PCRF) set to 1 to indicate that a program clock reference is carried in the adaptation field.
  • PCRF program clock reference flag
  • the thirty-three bit program clock reference (PCR) 1932 and the nine bit program clock reference extension (PCRE) 1982 are concatenated into a forty-two bit counter with the PCRE being the least significant bits of the counter.
  • the forty-two bit counter generally is used to indicate the intended time of arrival of the octet containing the last bit of the program clock reference (PCR) at the input to an inverse multiplex sublayer (IMS) of a client transport modem (cTM).
  • IMS inverse multiplex sublayer
  • cTM client transport modem
  • reserved bits 1972 are not utilized in the preferred embodiments of the present invention.
  • the maintenance channel PID (MC PID) 1992 is used to allow a client transport modem (cTM) to startup and establish communications with a transport modem termination system (TMTS) to begin a registration process.
  • the cTM listens to at least one low bandwidth maintenance channel established by the TMTS.
  • the TMTS continuously broadcasts maintenance-oriented information on at least one low bandwidth maintenance channel that is specified by at least one MC PID 1992.
  • the maintenance information includes multiplexing maps as well as other registration information.
  • the client transport modem determines the maintenance channel PID 1992 by listening to downstream MPEG packets containing the adaptation field. Based on the value of the MC PID 1992, the client transport modem will know which downstream MPEG packets contain maintenance channel information.
  • Each bit in the MC-MAP represents one octet in the 184 octet MPEG payload of the MPEG packets with a PID value equal to MC-PID.
  • This map of bits (MC-MAP) and the PID value (MC- PID) allow a client transport modem to select and inverse multiplex through the IMS sublayer the information of the low bandwidth downstream maintenance channel.
  • the preferred embodiments of the present invention also allow communication of circuit emulation services (CES) that generally are associated with the N x 56 and N x 64 interfaces of telephone company service providers.
  • CES circuit emulation services
  • N x 56 and N x 64 equipment such as, but not limited to, a PBX (private branch exchange) with a Tl interface usually expects the Tl line from the service provider to supply the necessary network clocking.
  • PBX private branch exchange
  • the preferred embodiments of the present invention generally should also be able to supply the necessary network clocking to customer premises equipment (CPE) such as a PBX.
  • CPE customer premises equipment
  • FIG. 20 shows a way of delivering the proper clocking to customer premises equipment using a transport modem termination system and a client transport modem.
  • Dashed line 2002 generally divides FIG. 20 between TMTS 2004 and cTM 2006. Both TMTS 2004 and cTM 2006 are connected into cable transmission network 2008.
  • TMTS 2004 comprises various potential clock inputs including, but not limited to, downstream Tl input 2012, 8 kHz input clock 2014, as well as 27 MHz MPEG input clock 2016. These clock inputs are expected to be commonly found in the headend and/or distribution hub of cable service providers.
  • the 8 kHz clock 2014 is related to the N x 56 kbps and N x 64 kbps services. 8 kHz is the Nyquist sampling rate to be able to properly sample a 0 to 4 kHz analog POTS (Plain Old Telephone Service) voice frequency channel.
  • an 8 kHz clock with a 1 / 8 kHz or 125 microsecond period is commonly available at N x 56/64 interfaces to the public switched telephone network (PSTN).
  • PSTN public switched telephone network
  • Downstream Tl input 2012 generally also has a corresponding upstream Tl clock and data 2018 because Tl services are bi-directional.
  • the service provider (or in this case downstream) clock generally is considered to be the master reference.
  • Customer equipment clocking generally is derived from reference clocking of service provider or downstream services.
  • the downstream Tl input 2012 and upstream Tl clock and data 2018 generally are connected in the TMTS to a Tl physical layer and fra er (2022).
  • Tl framing including various framing issues such as extended superframe (ESF) and D4 framing, synchronization based on the 193 rd bit, as well as various physical layer technologies such as, but not limited to, alternate mark inversion (AMI) and 2B1Q of HDSL (High bit rate Digital Subscriber Line) for carrying the 1.536 Mbps (or 1.544 Mbps) Tl service.
  • ESF extended superframe
  • D4 framing synchronization based on the 193 rd bit
  • various physical layer technologies such as, but not limited to, alternate mark inversion (AMI) and 2B1Q of HDSL (High bit rate Digital Subscriber Line) for carrying the 1.536 Mbps (or 1.544 Mbps) Tl service.
  • AMI alternate mark inversion
  • Tl physical (PHY) layer interface and framer 2022 comprises an 8 kHz clock source.
  • a 27 MHz MPEG input clock 2016 is expected to be available based on the ubiquitous deployment of MPEG in digital cable television (CATV) networks.
  • An 8 kHz reference clock may be derived from the 27 MHz clock by dividing by 3375 at item 2024.
  • the 27 MHz MPEG clock which generally is used for digital movies, turns out to be an exact multiple of 3375 times the 8 kHz clock, which generally is used for N x 56/64 services associated with the PSTN.
  • the three input clocks from MPEG, Tl, and an 8 kHz reference are converted to 8 kHz clocks.
  • Reference clock selection 2026 may be a switch that selects among the various 8 kHz reference clocks. As would be known by one of skill in the art, this clock selection switching could be implemented by mechanisms such as, but not limited to, software controlled switches, manual physical switches, and/or jumpers.
  • phase locked loop 2030, which further comprises phase detector 2032, loop filter 2034, a 162 MHz voltage controlled crystal oscillator (VCXO) of TMTS master clock 2036.
  • the 162 MHz output of TMTS master clock 2036 is divided by 20,250 at item 2038 and fed back into phase detector 2032.
  • phase locked loop provides a loop that is used for locking the relative phases of the 8 kHz clock relative to the 162 MHz TMTS master clock 2036.
  • Phase locked loops are known to one of skill in the art.
  • the 162 MHz master clock 2036 is divided by 6 at item 2040 to generate a 27 MHz clock before being input into a 42-bit counter and MPEG framer 2046 that performs the function of inserting the program clock reference into MPEG frames.
  • Interval counter 2042 generates a 0.1 Hz interval clock 2044 that generally determines that rate at which snapshots of the 42 bit counter are sent downstream as the program clock reference (PCR) in the adaptation field of MPEG packets.
  • the MPEG frames are communicated downstream to client transport modem 2006 using QAM modulator(s) 2048, which may be integrated into TMTS 2004 or could be external to TMTS 2004.
  • the client transport modem (cTM) 2006 includes the hardware and/or software to properly extract the MPEG frames and interpret the fields. These functions might be performed in cTM downstream front end to extract MPEG 2052 and program clock reference parser 2054. Based on the PCR value extracted from MPEG adaptation fields, the client transport modem 2006 determines how much the cTM master clock has drifted relative to the TMTS master clock. Counter and loop control 2062 determines the amount and direction of the relative clock drifts between the cTM and the TMTS and sends control signals to the cTM oscillator to correct the relative clock drift.
  • the counter and loop control 2062 regulates the cTM clock to ensure the proper relationship relative the TMTS master clock 2036.
  • the cTM utilizes a 162 MHz voltage controlled crystal oscillator (VCXO) 2064 that operates based on a 162 MHz crystal (XTAL) 2066.
  • VXO voltage controlled crystal oscillator
  • XTAL 162 MHz crystal
  • the 162 MHz clock is divided by 6 at item 2068 to result in a 27
  • the 8 kHz clock is an input into Tl physical layer interface and framer 2076 which provide downstream Tl output 2082 that can be used as a network service provider clock by other CPE (such as but not limited to a PBX).
  • CPE such as but not limited to a PBX
  • the upstream Tl clock and data from CPE such as, but not limited to a
  • PBX provides the bi-directional communication generally associated with Tl.
  • the clock associated with upstream Tl clock and data 2088 from a PBX or other CPE generally is not a master clock, but a derived clock based on the downstream Tl output 2082, that is based on the master clock of a service provider.
  • the downstream delivery of MPEG packets with PCR information is used as a network clock distribution mechanism to clock transfers of information in the opposite direction to distribution of the clock.
  • MPEG PCR information in downstream MPEG packets is used to clock downstream flows of audio/visual information.
  • the downstream delivery of MPEG PCR clock information is used to provide a stratum clock to lock the upstream transmissions of circuit emulation services (CES) or N x 56 / N x 64 services to the downstream network clock normally provided by service providers.
  • the downstream distribution of MPEG packet containing PCR information is used to synchronoize the upstream transmissions over multiple tones from a plurality of cTMs to a TMTS.
  • the PCR information contained in MPEG packets is used to provide network clocking for communication that is in the opposite direction from the direction that MPEG packets are propagated.
  • the timing diagram includes an 8 kHz reference clock 2102 that generally is associated with N x 56/64 kbps services.
  • An 8 kHz reference clock 2102 has a 125 microsecond period 2104.
  • MPEG has a 27 MHz clock 2112 that has a period 2122 of approximately 37.037 nanoseconds.
  • the 8 kHz reference clock 2102 and the 27 MHz reference clock 2112 will have an arbitrary relative phase difference 2106.
  • a 27 MHz MPEG clock generally will complete approximately 1069 clock ticks in the 39.6 microseconds needed to transmit an MPEG packet of 188 octets at 38 Mbps on a 6 MHz frequency channel ((188 octets X 8 bits / octet) / 38 Mbps ) / (1 / 27 MHz clock rate)).
  • 27 MHz / 8 kHz 3375 clock ticks of the MPEG 27 MHz clock 2112 occur in one clock tick of an 8 kHz clock 2102 with a 125 microsecond period
  • the four MPEG packets (or MPEG transport stream (TS) packets) shown in FIG. 21 are labeled as 2132, 2134, 2136, and 2128. Although all the MPEG packets have headers (HDR) only some of the MPEG packets (namely MPEG packet 2132 and the MPEG packet following MPEG packet 2138) contain program clock reference (PCR) values.
  • HDR headers
  • PCR program clock reference
  • the time distance between MPEG packets containing PCR values generally is arbitrary as shown at item 2142.
  • Item 2144 in FIG. 21 shows the counter values that are recovered from the MPEG PCR information received at a client transport modem (cTM). Because some of the MPEG packets received by a cTM generally will not contain PCR values (e.g., MPEG packets 2134, 2136, and 2138), a cTM generally will not recover a clock counter value from those MPEG packets.
  • cTM client transport modem
  • MPEG PCR values 2144 can be used in the client transport modem (cTM) to compare and adjust the client transport modem clock 2152 using a voltage controlled crystal oscillator (VCXO) to keep it in sync with the transport modem termination system (TMTS) clock 2112.
  • VCXO voltage controlled crystal oscillator
  • TMTS transport modem termination system
  • the counter values recovered from the PCR 2144 are compared with client transport modem (cTM) counter values 2154 to allow adjustment of the cTM clock 2152.
  • the 27 MHz client transport modem (cTM) clock 2152 can then be used to generate a recovered 8 kHz stratum clock 2162 by dividing by 3375.
  • the recovered 8 kHz clock 2162 at a cTM will have the same frequency as the 8 kHz reference clock 2102 at the TMTS.
  • the TMTS clock counter 2114 may start at an arbitrary phase difference 2106 from a reference 8 kHz clock 2102 at the TMTS, the 8 kHz clock 2162 recovered at a cTM will have an arbitrary (but generally fixed) phase difference 2106 from the 8 kHz reference clock 2102 at a TMTS.
  • the 8 kHz clock 2162 recovered at any cTM generally will have an arbitrary (but basically fixed) phase difference 2106 from the 8 kHz reference clock 2102 of the TMTS and an arbitrary (but basically fixed) phase difference 2106 from each of the other 8 kHz recovered clocks 2162 at the other cTMs.
  • the recovered 8 kHz clock 2162 at a cTM will have an arbitrary phase difference 2106 from the 8 kHz input reference clock 2102 of the TMTS, this clock phase difference 2106 is not a problem.
  • the phase of a reference clock at a telephone company central office is different from the phase of the clock delivered to customer premises equipment due at least to the propagation delays in the transmission lines between the service provider and the customer premises.
  • the recovered 8 kHz clock 2162 at the cTM is frequency-locked to the 8 kHz reference stratum clock 2102 at the TMTS (i.e., the clocks do not significantly drift relative to each other).
  • each cTM clock By frequency-locking each cTM clock to the TMTS clock, frequency stability of the poorly regulated cTM clocks is ensured.
  • the multi-tone upstream frequency division multiplexing receiver in the TMTS generally performs optimally when the frequency error of the transmissions of different cTMs is small.
  • Significant frequency differences in cTM clocks as well as the TMTS clock may create problems in selecting the correct carrier frequency of the upstream multi-tone frequency-division multiplexing.
  • the downstream delivery of PCR information allows a plurality of client transport modems to properly set their respective oscillation clocks that are used in generating the frequency carrier signals. In this way each cTM can ensure that it is accurately transmitting in the right upstream frequency range for a tone instead of slightly interfering with an adjacent tone.

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  • Engineering & Computer Science (AREA)
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  • Computer Networks & Wireless Communication (AREA)
  • Time-Division Multiplex Systems (AREA)
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Abstract

L'invention concerne une architecture pour assurer un accès rapide sur des canaux multiplexés par répartition en fréquence. Cette architecture assure la transmission de données sur un réseau de transmission par câble. Les paquets aval supportant les signaux d'horloge du réseau peuvent utiliser le format de paquet MPEG et l'horloge peut être une référence d'horloge de programme MPEG. A la différence de l'utilisation traditionnelle de la référence d'horloge de programme MPEG permettant de synchroniser les données s'écoulant dans le même sens que les informations d'horloge, l'utilisation de la référence d'horloge du programme MPEG permet également de synchroniser des données circulant dans un sens opposé par rapport aux informations d'horloge. En outre, les informations d'horloge permettent d'aligner avec précision l'utilisation de canaux de fréquence des dispositifs clients (295, 296) ou à distance. Etant donné que plusieurs dispositifs clients (295, 296) ou à distance peuvent utiliser un multiplexage par répartition en fréquence, une référence de fréquence précise provenant d'une horloge de réseau permet d'assurer que les transmissions des divers dispositifs clients (295, 296) ne se chevauchent pas en fréquences.
PCT/US2002/029585 2001-09-18 2002-09-18 Fourniture de reference d'horloge de programme mpeg pour supporter des horloges de reseau precises WO2003026177A1 (fr)

Applications Claiming Priority (11)

Application Number Priority Date Filing Date Title
US32296601P 2001-09-18 2001-09-18
US60/322,966 2001-09-18
US33886801P 2001-11-13 2001-11-13
US60/338,868 2001-11-13
US84262701P 2001-12-20 2001-12-20
US60/842,627 2001-12-20
US39798702P 2002-07-23 2002-07-23
US60/397,987 2002-07-23
US10/245,032 US7729379B2 (en) 2001-09-18 2002-09-17 Mapping of bit streams into MPEG frames
US10/245,050 2002-09-17
US10/245,250 US20030058890A1 (en) 2001-09-18 2002-09-17 MPEG program clock reference (PCR) delivery for support of accurate network clocks

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WO2003026177A1 true WO2003026177A1 (fr) 2003-03-27
WO2003026177A8 WO2003026177A8 (fr) 2004-04-22

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US5963557A (en) * 1997-04-11 1999-10-05 Eng; John W. High capacity reservation multiple access network with multiple shared unidirectional paths
US6477204B1 (en) * 1997-12-19 2002-11-05 Kabushiki Kaisha Toshiba Video image decoding method and apparatus
US6493832B1 (en) * 1999-03-17 2002-12-10 Sony Corporation Communication apparatus which handles a time stamp
US6501743B1 (en) * 1998-12-11 2002-12-31 Electronics And Telecommunications Research Institute Apparatus and method of network synchronization in asymmetric two-way satellite communication system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5963557A (en) * 1997-04-11 1999-10-05 Eng; John W. High capacity reservation multiple access network with multiple shared unidirectional paths
US6477204B1 (en) * 1997-12-19 2002-11-05 Kabushiki Kaisha Toshiba Video image decoding method and apparatus
US6501743B1 (en) * 1998-12-11 2002-12-31 Electronics And Telecommunications Research Institute Apparatus and method of network synchronization in asymmetric two-way satellite communication system
US6493832B1 (en) * 1999-03-17 2002-12-10 Sony Corporation Communication apparatus which handles a time stamp

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