Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W24/00—Supervisory, monitoring or testing arrangements

Definitions

• the present invention relates generally to radiocommunication systems wherein signals are transmitted over an air interface and, more specifically, to providing terminal-related information to a management system within such radiocommunication systems.
• radiocommunication systems As part of the evolution of radiocommunication systems, network operators continue to look for better ways to manage and optimize the operation of their systems. This need is highlighted by the fact that the management of radiocommunication systems includes tracking many variables which have a time- varying nature, e.g. , as subscribers move around while communicating or as new buildings are added to a city, so too does the load on the system change. To address these needs, various tools have been considered to help network operators adjust the operation of their networks.
• Figure 1 provides an example of such a conventional, counter-based system.
• the exchange level or network level switch 105 contains a number of event counters 0...n.
• the human operator 115 must define a measuring program. This involves entering the appropriate commands into the switch 105, through the network operator workstation 120, which in turn, instructs the corresponding counter (or counters) to count the occurrence of a particular event over a period of time also defined by the human operator 115. Then, each time that event occurs, the switch 105 increments the corresponding counter.
• the type of events that can be tracked using the event counters 0...n include, for example, attempted handovers into a particular cell, successful handovers into a cell, attempted handovers from a cell into a neighboring cell, and successful handovers from a cell into a neighboring cell.
• the switch 105 outputs the value stored in the corresponding counter to a post-processing application being executed in the external workstation 120.
• the post-processing application then converts the event information into a user-friendly format, such as a report or graph, for the human operator 115.
• the human operator 115 may then alter or update the configuration of the switch 105 based on the information provided by the post-processing application.
• the MTR function can record the different radio messages that are sent during a call, for a certain subscriber.
• the CTR function can record the different radio messages that are sent during each, e.g., 100th call in a cell.
• some measurements are also performed by the mobile terminal and reported to the system. For example, in digital cellular systems signal strength measurements can be made on the downlink, i.e. on transmissions from the base station to the user, to assist in performing handoff. These measurements are commonly referred to as mobile-assisted handoff (MAHO) measurements and provide the system with information regarding which channel(s) are preferable handover candidates.
• MAHO mobile-assisted handoff
• SACCH Slow Associated Control Channel
• RF physical
• the SACCH occupies one timeslot out of every 96 timeslots associated with a traffic channel as represented conceptually in Figure 2(a).
• the physical channel occupies timeslot #1 in each frame of eight timeslots. For the first eleven frames, the timeslot is used to carry traffic information and then, in the twelfth frame, the timeslot is used for SACCH.
• Systems designed in accordance with other standards provide for transmitting SACCH information along with traffic or payload data in each timeslot assigned to a mobile terminal's channel, e.g., as shown in the uplink traffic channel timeslot format of Figure 2(b) for a system operating in conformance with ANSI-136.
• MACA mobile assisted channel allocation
• MACA involves employing idle mobile terminals, i.e., those which are powered on, but currently not connected to the system via a traffic channel, as measurement probes to aid the system in quantifying localized interference situations.
• idle mobile terminals may be requested to make measurements on certain traffic channels so that the system can determine which traffic channel to allocate to another mobile terminal that needs a traffic channel assignment. Since these measurements are made by idle mobile terminals, they are reported to the system on the uplink of a broadcast control channel.
• mobile terminals provide measurement reports to the system regarding signal strength and/or quality measurements
• today network operators do not have access to complete information regarding the mobile terminal's interaction with the network in order to provide proper management of their services and network. Instead, the conventional MAHO and MACA techniques described above only provide limited information from the mobile terminal, which information is used by the system for traffic purposes.
• All other mobile terminal information which might be useful e.g., information which would help a network operator discriminate between dropped calls caused by events which could potentially be compensated for by the network operator (e.g., heavy, localized loading) and dropped calls caused by events which could not (e.g., detachment of the battery from the mobile phone), is not readily available to the network operators. Accordingly, it would be desirable to provide a mechanism for making this type of mobile terminal information readily available to network operators to assist in efficient network management, as well as to provide a mechanism to distribute management functions for the network and services to mobile terrninals.
• a management signaling channel is established between the mobile terminal and the management system for the purpose of exchanging management information.
• the termination points of this management signaling channel are in the mobile terminal and in the management system.
• management information available in the terminal can be transported in a resource efficient way and in a manner intended to result in a minimal impact from a user's point of view (e.g., by transmitting the management signaling channel with a lower priority than a user's payload data).
• the radio interface is not available for transmission of mobile terminal related management information (e.g., out of coverage, terminal switched off, etc.)
• the mobile terminal management information can be stored in a non-volatile memory for later delivery to the network.
• Similar management information can be logged at the system side of the air interface, e.g., by the base station, and reported to a management processing node. At the management processing node, this information can be used to identify the source of problems and take corrective action for example by comparing information received from the system side and the terminal side. Information available from the MS channel can also be used for other purposes, and provides the capability of epitomizing the performance of services, as well as service and network configurations based on what happens in the mobile terminal.
• the MS channel according to the present invention also provides a mechanism which permits the network to query the mobile terminal regarding its service characteristics, for example, what services are implemented, their version and their status (e.g., activated, passive, etc.).
• Other mobile terminal characteristics can also be reported, e.g., service influencing characteristics the mobile terminal has with respect to bearer capabilities, display characteristics (what display characteristics it has used, as those can be changed by for instance plugging in a mobile terminal to a computer using a PCMCIA-card) etc.
• Another objective of the present invention is to introduce the capability of providing management information on a per customer basis, which will increase the network operator's customer-care capabilities and hence it's competitiveness in the marketplace.
• Yet another object of the present invention is to introduce the capability of correlating faults on the mobile teirriinal side of the system (e.g. problems with a mobile terminal that has an outdated version of the service software) with events that occur on the network side of the system.
• Still another object of the present invention is to provide a mechanism for monitoring a quality of service (QoS) agreed to by the system versus the QoS actually experienced at the terminal.
• QoS quality of service
• the present invention provides terminal and base station information that can be used by a management system to improve the perceived quality of service to the end user.
• Figure 1 is an exemplary block diagram of a conventional network management system associated with the collection of information from the system's perspective;
• Figure 2(a) illustrates SACCH information transmission in an exemplary GSM system
• Figure 2(b) illustrates SACCH information transmission in an exemplary ANSI- 136 system
• Figure 3 provides a conceptual representation of a management signaling channel according to the present invention
• Figure 4(a) depicts one exemplary technique by which an MS channel according to the present invention can be allocated air interface resources
• Figure 4(b) depicts another exemplary technique by which an MS channel according to the present invention can be allocated air interface resources
• Figure 4(c) depicts a spread spectrum technique by which an MS channel according to the present invention can be allocated air interface resources
• Figure 5 is a flowchart depicting an exemplary method for communicating and using management information via an MS channel according to the present invention.
• TDMA time division multiple access
• CDMA code division multiple access
• exemplary embodiments contemplate providing this and other information to the system by creating a management signaling (MS) channel between the mobile terminal and the entity (node) in the network which provides network management information to the operator.
• MS management signaling
• this entity is the Operations Support System (OSS) 300 and the MS channel is shown conceptually by way of the dotted lines between the mobile terminal 310 and the OSS 300, as well as between the computer 320 having a wireless modem (not shown) and the OSS 300.
• the OSS is a node in GSM systems which is responsible for operations and network maintenance functions, subscriber maintenance, and mobile equipment maintenance.
• FIG. 3 In addition to the MS channel according to the present invention, existing (conventional) interfaces are also illustrated in Figure 3.
• the zig-zag lines emanating from mobile terminal 310 and computer 320 represent the air interface between these devices and a base station (part of base station subsystem (BSS) 330).
• BSS base station subsystem
• interfaces also exist between the BSS 330, the core network switching system 340 and the OSS 300, which interfaces are well known to those skilled in the art and, therefore, are not further described herein.
• the MS channel can be implemented in a number of different ways, but is preferably a dedicated channel (i.e., a point-to-point channel, rather than point-to- multipoint (broadcast) channel) which has termination points at the remote terminal, e.g., mobile terminal 310 or computer 320 in Figure 3, and the management system responsible for generating information based on data received from the remote terminals, e.g., the OSS 300 in Figure 3.
• Termination points for the MS channel refer to the nodes in which the payload information is available in an uncoded form, as compared with the state of the information as it passes through intervening nodes, e.g., BSS 330.
• the conventional SACCH terminates in the BSS 330.
• the mobile terminal 310 may also encode the information to be sent on the MS channel in a manner which will be recognized by the other terminating node, e.g., OSS 300.
• the OSS is connected to the rest of the system with a Common Object Request Broker Architecture (i.e., CORBA) interface 350, then mobile terminal 310 will also encode or format MS channel information in accordance with this specification.
• CORBA Common Object Request Broker Architecture
• a management system (OSS) using CORBA will be able to incorporate management functions in the terminal related to the transfer and processing of management information from the terminal to the management system over the MS channel as described herein.
• the management system can be connected to the rest of the system using any technology, architecture or protocol, e.g.. Ethernet, radio link, El, Tl, SDH, TCP/IP, SNMP.
• the same application protocol(s) that the management system uses to communicate with the network elements can be used between the management system and the mobile terminal.
• the management system communicates with the different functions (nodes) using different application protocols (which can be carried on IP or ATM etc.).
• this protocol might be HOP, for the IP router might use SNMP etc. Since the information from the MS channel is associated with the information from the Radio Network Controller, it is advantageous to use the same application protocol for the MS channel as for the interface between the management system and the RNC.
• these inventive channels can be distinguished from conventional channels, e.g., SACCH or traffic channels, based upon the manner in which they are allocated throughput resources on the air interface.
• the MS channel can be implemented by "stealing" another timeslot (e.g., in addition to SACCH) from the traffic channel as shown by comparing frame 14 of Figure 2(a), with frame 14 of Figure 4(a).
• space within each timeslot can be dedicated to sending MS channel information, as exemplified by comparing Figure 2(b) with Figure 4(b).
• Yet another alternative is to time multiplex the SACCH and the MS channel, e.g. , by alternatingly sending SACCH information and MS channel information in every other timeslot.
• the manner in which the MS channel is allocated resources can vary depending upon the type of access methodology employed in the radiocommunication system.
• the MS channel could be implemented by providing different spreading codes for the MS channel and the traffic channel (including the SACCH) as shown in Figure 4(c) .
• a portion of a direct sequence (DS) CDMA system is illustrated, wherein symbol stream to be transmitted (i.e., a symbol stream which has undergone JO- channel coding, interleaving, etc. at block 400) is impressed upon a much higher rate data stream known as a signature sequence or spreading code A.
• the signature sequence data (commonly referred to as "chips") are binary or quaternary, providing a chip stream which is generated at a rate which is commonly referred to as the "chip rate" .
• PN pseudo-noise
• the symbol stream and the signature sequence stream can be combined by multiplying the two streams together at multiplier 420. This combination of the signature sequence stream with the symbol stream is called spreading the symbol stream signal.
• Each symbol stream or channel is typically allocated a unique spreading code.
• the data stream to be processed is initially split into two portions, the MS channel information and the remaining information (e.g., traffic, SACCH, etc.), with the MS channel information being fed into a parallel branch which performs, e.g., channel coding and interleaving, at processing unit 430, prior to spreading the MS information at block 440 with a different spreading code B.
• the information can then be summed at block 450, prior to modulation and transmission.
• the MS information can be distinguished from the traffic/SACCH information and extracted from the composite signal by correlating the composite signal with both spreading codes A and B.
• the mobile terminal 310 (or computer 320) logs and timestamps information which can be used by the system to understand the mobile terminal's view of the system's operation.
• the mobile terminal 310 can log predetermined terminal -related events which will be of interest to the network operator including, e.g., terminal power level drops below a threshold, terminal unable to connect to the system, dropped calls, terminal's operating temperature, effective received bit rate, coverage, interference levels, congestion, sent and received signal strength, number of retransmissions of messages, Bit Error Rate (BER), C/I, Eb/IO for CDMA systems, call procedures started on the radio interface that are interrupted by the end user, etc.
• BER Bit Error Rate
• C/I Bit Error Rate
• Eb/IO Call procedures started on the radio interface that are interrupted by the end user, etc.
• Other examples of possible types of MS information e.g., related to usage patterns associated with the terminal, are provided below, however those skilled in the art will appreciate that the enumerated information types are not intended to be exhaustive.
• the terminal saves an identifier associated with the event in memory along with an indication of the time at which the event took place.
• the BSS 330 logs and time stamps its own MS information.
• This MS information may include, for example, failure to receive information from a mobile terminal on an active connection, system loading (e.g., relative to geographic areas), registration of a terminal, sent and received signal strength, interference levels, number of re-sending of messages, BER, C/I, and Eb/IO. If the sent and received signal strengths from the base station and the sent and received signal strengths from the mobile station are provided, the real attenuation can be calculated by the management system.
• the MS information (including a terminal identification or a call identifier) is then transmitted from the mobile terminal 310 to the OSS 300 at step 530 over the MS channel.
• the mobile terminal 310 will add to this information any encoding or formatting needed for compatibility with the OSS interface 350 and can use separate air interface resources to segregate the MS channel from other channels, such that the MS channel terminates in the mobile terminal 310 and the OSS 300.
• the BSS 330 will also forward its logged MS information (including a BSS identifier or a call identifier) to the OSS 300, albeit without using the air interface portion of this channel.
• the management system operating within OSS 300 can then store and process the MS information received from both the mobile terminal(s) and BSSs to make decisions based on these two sets of information at step 550. Such decisions can automatically generate changes in the operation of the radiocommunication system or can simply be used to inform the network operator who can then selectively make changes in system operating parameters.
• Logging of the power level in the mobile terminal 310 may be performed, for active calls, by logging the power level of the battery regularly, e.g. once a second. This time and power level information can be stored in the mobile terminal 310's memory (not shown).
• the log (which can also include other parameters of interest from the mobile's point of view regarding the abnormally disconnected call) is transferred to the OSS 300 over the MS channel the next time that the mobile terminal 310 is in contact with the radiocommunication system, e.g. at Call Setup, Location Registration or an analogous message.
• the BSS 330 will also record and time stamp the abnormal disconnection between the mobile terminal 310 and the BSS 330.
• the BSS can log any other information of interest to the network operator from the system's point of view which may be useful in determining what caused the abnormal disconnection, e.g., congestion, location of the mobile terminal 310, a sudden increase in bitrate demands associated with variable bitrate users, etc. This information is then also forwarded to the OSS 300.
• the OSS 300 uses the time stamp information, as well as the terminal and BSS identifiers, to compare and correlate information received over the MS channel from the mobile terminal 310 and the BSS 330.
• a unique call ID could be used (in lieu of, or together with, the terminal and BSS identifiers) by both the terminal and BSS which would render correlation of MS information more straight forward in the management system.
• the OSS 300 can attempt to identify the underlying cause of the abnormal disconnection by evaluating the MS information transmitted from the terminal 310 at a particular time (or range of time stamps) in conjunction with correspondingly time stamped MS information received from the BSS 330.
• the OSS 300 may categorize this particular problem as something that was not attributable to the system's operation and may not include it in data or reports that are generated in relation to potential adjustments of system operations.
• the mobile terminal 310 reports no problems in its log at the time of the abnormal disconnection (other than the disconnection itself) and the BSS 330 logs a sudden increase in transmit power levels of other existing CDMA transmissions at that time, then the OSS 300 may conclude that the interference caused by these other users increased the bit error rate of the received uplink signal at the BSS 330 to such a level that the call was dropped. In this case, the OSS 300 could categorize and report this problem in conjunction with others that might suggest the desirability of network operating parameter adaptation.
• the present invention provides the network operator with the possibility to obtain information regarding the mobile terminal's point of view as to how the radio access network works and how, more specifically, the various services provided by the network are operating. Many other usages are envisioned for radiocommunication systems which incorporate an MS channel according to the present invention some of which are described below.
• the present invention introduces the capability to control services in the mobile terminal remotely, i.e. from the management system. For example, non- conforming services can be turned off by changing the configuration data of the service, i.e., what information should be monitored and logged and how old the logged data is allowed to be before it should be discarded in the mobile terminal if contact with the network is not made.
• Non-conforming service that can be turned off is a service (e.g., a video conference service) that has upgraded its software so that an old software version (which the service provider has attempted to get the terminal user to upgrade) still residing in the terminal is incompatible.
• a service can be expressly disabled in the mobile terminal (e.g., the old video coding is not supported anymore for the video conference service) using the MS channel.
• the present invention also introduces the capability of remotely loading software into the mobile terminal, e.g., service logic or patches, as well as testing the service logic remotely.
• This type of software upgrade or test can be delivered or controlled via the downlink of the MS channel, for example.
• the present invention introduces the capability of monitoring service and network performance in the mobile terminal remotely. This provides the best opportunity for the network operator to measure customer perceived quality.
• Examples of service and network performance related parameters and events to monitor in the mobile terminal 310 include: user interaction/behavior with respect to the network and selection of and access to specific services (e.g., SMS service, video services, call forwarding, conference calling, channel throughput selection, etc.), radio interface performance (from the mobile terminal 's perspective) with the respect to whether the radio interface is preventing access to a service or in any other way interfering with the execution of a service, determination of when call attempts were unsuccessful due to congestion in the radio interface, etc.
• specific services e.g., SMS service, video services, call forwarding, conference calling, channel throughput selection, etc.
• radio interface performance from the mobile terminal 's perspective
• the present invention also provides tools which can be used to gauge the manner in which various services interact in the mobile terminal, and/or interfere with other active services which have been invoked by the mobile terminal.
• Such a situation might occur, e.g, when all active services require a cumulative bandwidth which exceeds that available on the radio interface, one or several services have to reduce their bandwidth demands or be terminated.
• An example of this situation might be, for example, if during a video conference call (which might need 1 Mbit/s bandwidth) the end user decides that a real time MPEG2 (which uses 2 Mbit/s bandwidth) video stream should be sent.
• the radiocommunication system only supports connections having a maximum of, e.g., 2 Mbit/s, then the terminal could log this event for reporting to the management system. This type of information can be useful to the network operator, e.g., for plarining purposes.
• terminal events can be recorded and forwarded to the management system using the MS channel according to the present invention.
• Such events include, for example, removing the battery without turning the mobile terminal off, removing the battery while a call is ongoing, interrupting an ongoing signaling procedure, tampering with the mobile terminal, etc. If a dropped call event has occurred, but battery power level is high, BER low and signal strength high, the management system could make the conclusion that the battery was removed.
• the event associated with user tampering with the hardware in the mobile terminal could be detected by having micro switches installed in the bolts of the terminal's case detecting if the case has been taken apart.

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