Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W28/00—Network traffic management; Network resource management
  • H04W28/02—Traffic management, e.g. flow control or congestion control
  • H04W28/06—Optimizing the usage of the radio link, e.g. header compression, information sizing, discarding information
  • H04W28/065—Optimizing the usage of the radio link, e.g. header compression, information sizing, discarding information using assembly or disassembly of packets
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q11/00—Selecting arrangements for multiplex systems
  • H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
  • H04Q11/0428—Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
  • H04Q11/0478—Provisions for broadband connections
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/54—Store-and-forward switching systems 
  • H04L12/56—Packet switching systems
  • H04L12/5601—Transfer mode dependent, e.g. ATM
  • H04L2012/5603—Access techniques
  • H04L2012/5604—Medium of transmission, e.g. fibre, cable, radio
  • H04L2012/5607—Radio
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/54—Store-and-forward switching systems 
  • H04L12/56—Packet switching systems
  • H04L12/5601—Transfer mode dependent, e.g. ATM
  • H04L2012/5638—Services, e.g. multimedia, GOS, QOS
  • H04L2012/5646—Cell characteristics, e.g. loss, delay, jitter, sequence integrity
  • H04L2012/5652—Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/54—Store-and-forward switching systems 
  • H04L12/56—Packet switching systems
  • H04L12/5601—Transfer mode dependent, e.g. ATM
  • H04L2012/5672—Multiplexing, e.g. coding, scrambling

Definitions

• the present invention relates to a method according to claim 1 for transmitting data over the air interface in a telecommunication system which comprises at least one air interface and a packet network.
• the radio connection used in conventional digital mobile communication systems is circuit-switched, which means that the radio resources allocated to a subscriber are kept allocated to the connection for the entire duration of the call.
• a new service planned for digital mobile communication systems is referred to as a packet radio service.
• the packet radio service planned for the GSM system namely GPRS (General Packet Radio Service), is described in the ETSI recommendations TC-TR-GSM 02.60 and 03.60.
• the packet radio service in the D-AMPS system, used in the United States, is referred to as CDPD.
• the data to be transmitted are assembled into fixed length packets. (The last packet in a message is usually shorter than the other ones.) Once such a packet has been sent over the air interface Um, and the transmitting party has no packets to be sent immediately thereafter, the radio resource may be released for use by other subscribers.
• Figure 1 shows the parts essential to the present invention in the telecommunication system, and the protocols required i.e. practices for transmitting data packets as in prior art over the air interface Um of the radio network in a GPRS system.
• the invention is not, however, restricted to the GPRS packet radio system operating in conjunction with the GSM network.
• An applications program of a computer PC establishes a connection according to, for example, the Internet Protocol IP.
• a PPP Point to Point Protocol
• a GLP GPRS Link Protocol
• MAC Medium Access Control
• ATM Asynchronous Transfer Mode
• data are transferred in fixed-length packets consisting of 53 bytes, referred to as ATM cells.
• the cell header takes up five bytes while the remaining 48 bytes are payload, i.e. actual information.
• ATM cells are specified in the CCITT Recommendation 1.361 and CCITT Draft Recommendation 1.150.
• the user information to be transferred is cut into fixed-length bit strings, and each bit string is inserted into the information field of the ATM cell. The number of bit strings in a time unit indicates the transfer capacity required by the user.
• a header is added to the information field, whereby a fixed length ATM cell having 53 bytes is created.
• the cell is an independent data carrying unit as it indirectly comprises information on the receiving party's address on the basis of which the receiving party may be found in the network.
• service criteria include response time, bit error ratio, and the probability of packet loss.
• the ATM is a connection oriented packet network, which means that connections are set up and terminated according to standardized protocols.
• a connection between two parties via an ATM network is referred to as an ATM Virtual Channel.
• the advantages of ATM include, to mention but one, flexible providing of different services. All the bandwidths, for example, in the ATM network are equally natural within the capacity of the physical layer (with modern technology, between 1.5 - 622 Mbps).
• All the bandwidths, for example, in the ATM network are equally natural within the capacity of the physical layer (with modern technology, between 1.5 - 622 Mbps).
• Jouni Mikkonen published in Mobile Communication International, February 1996, pp. 59 - 61
• the aforementioned article does not directly take a stand as to how the ATM cells should be transported over the air interface.
• each ATM cell is carried over the air interface as an individual radio packet.
• AAL ATM Adaptation Layer
• SAAL Synignalling ATM Adaptation Layer
• the SAAL is preceded by an adaptation layer according to the ITU protocol Q.2931.
• the Q.2931 is an ITU signalling protocol. Among other things, it establishes and releases connections by transmitting Setup and Release messages.
• Packing ATC cells as such in packets of a packet radio network reduces the available bandwidth as each of the protocol layers inserts their own headers to the packets.
• D Data
• H Header
• R Radio
• the efficiency of bandwidth use is impaired by the fact that the lengths of packets used on the various layers are not multiples of each other, which means that all the packets cannot be filled up.
• ATM cells are not well suited for transmission units in a packet network because it would be uneconomical to allocate and release radio resources for each 53-byte-long ATM cell.
• Another problem may also be seen in that present-day packet radio networks are not capable of offering isochronous ATM connections.
• the method should be as flexible as possible. This means that the method may be taken in use in present-day systems with few changes, but on the other hand it is to allow flexible expansion with the packet radio systems of the next generation in mind.
• the invention is based on assembling ATM cells, or advantageously only their payloads, into larger transmission units for transmission over the air interface. With this arrangement, it is possible to optimize the transmission capacity of the air interface, a bottleneck in the transfer, and to facilitate repacking the ATM cells for transmission in a wired network.
• Figure 1 shows the parts essential to the present invention, and the protocols required for transmitting data packets as in prior art over the air interface Um of the radio network in a GPRS system;
• Figure 2 shows a system according to Figure 1 and the protocols required when the ATM network is extended to a mobile station;
• Figure 3 illustrates sending packets over the air interface by ATM technique as in prior art;
• Figure 4 illustrates the technique of the present invention for extending an ATM network to a mobile station
• FIG. 5 illustrates sending packet over the air interface by ATM technique according to the invention.
• a protocol stack is according to the invention supplemented with an adaptation layer below the ATM layer (closer to the physical layer), the function of such an adaptation layer being to form Radio Packets (RP) from the Transport Packets (TP) so that several transport packets TP or at least parts thereof are incorporated in at least some of the radio packets RP.
• the transport packets are ATM cells.
• the radio packets are GPRS packets having the approximate length of 300 bytes.
• the ATM cells produced by a communication program of a computer are assembled for the radio path into a larger Transmission Packet (XP), whose size is chosen so that the maximum allocation time of the radio path will not be exceeded.
• XP Transmission Packet
• the optimum size of a packet transferred on the radio path might be approximately 3000 bytes, which corresponds to the payload of approximately 60 ATM cells.
• the radio resource is allocated for as long a time as possible on the radio path in question. With this method, the net bandwidth is considerably better than if every ATM cell were to be transferred over the air interface as an individual radio packet.
• the ATM cell headers are not transmitted on the radio path, but only the payloads of the cells. This alternative is based on the notion that most of the information in the ATM cell header may be regenerated after transmission over the air interface. More specifically, the ATM cell header in the User Network Interface (UNI) consists of the following bits:
• VPI virtual path indicator
• VCI virtual channel indicator
• payload type 3 bits cell loss priority
• cell loss priority 1 bit header check sequence 8 bits total 40 bits
• the check sequence of the header changes.
• the information elements that change in headers of each ATM cell may be sent over the radio path and the unchanged information elements are generated at the receiving side.
• the information that originates from the payload of the ATM cells may be packed separately by some algorithm that removes redundancy, e.g. by Lempel-Ziv algorithm.
• the packing algorithms work the better the more data they have at their disposal at a time. Packing one ATM cell at a time does not provide a good packing result.
• the data at least partly consist of information entered by the user.
• time supervision which takes care that the transmission packets XP are transmitted at the latest when a predetermined time T has elapsed from incorporating the first transfer packet TP in the transmission packet XP in question.
• the time T is chosen so that the O 97/48211 PC ⁇ YFI97/00344
• a suitable time might be within 0.1 - 0.5 s, advantageously 0.2 s.

Landscapes

• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Data Exchanges In Wide-Area Networks (AREA)
• Mobile Radio Communication Systems (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (2)

Family

ID=8546163

Family Applications (1)

Country Status (4)

Cited By (8)

Citations (5)

• 1996
  • 1996-06-07 FI FI962382A patent/FI101921B/fi active
• 1997
  • 1997-06-03 AU AU29655/97A patent/AU2965597A/en not_active Abandoned
  • 1997-06-03 EP EP97924059A patent/EP0898824A2/en not_active Withdrawn
  • 1997-06-03 WO PCT/FI1997/000344 patent/WO1997048211A2/en not_active Application Discontinuation

Patent Citations (5)

Also Published As

Similar Documents

Legal Events