Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
1998-09-18
2003-10-14
Nguyen, Steven (Department: 2663)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C455S436000
Reexamination Certificate
active
06633555
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is related to capturing messages in a signaling network, and more particularly, to capturing and correlating messages from an A interface in a GSM network.
BACKGROUND OF THE INVENTION
The Global System for Mobile Communications (GSM) is the standard for a second generation cellular system. Although it was initially developed as a common mobile communications system in Europe, GSM systems are now deployed world-wide. The GSM standards, which specify network level architectures and services, are set by the European Technical Standards Institute (ETSI). In a GSM system, Mobile Stations (MS) communicate with a Base Station Subsystem (BSS) via a radio interface or air interface “Um”. BSSs are connected to Mobile Switching Centers (MSC) through an “A” interface, which may be embodied as dedicated or leased wirelines or a microwave link.
The GSM BSSs are comprised of a number of Base Transceiver Stations (BTS) each coupled to a single Base Station Controller (BSC). The Um air interface exists between the BTSs and the individual MSs. The interface between a BTS and the BSC is designated the Abis interface. The BSS is responsible for channel allocation, power control, signaling, handover initiation and other functions. The MSC functions include handover control, MS location updating and paging. MSCs also provide a gateway to other networks, such as the Public Switched Telephone Network (PSTN), Integrated Services Digital Network (ISDN) and packet data networks.
The A interface has a well defined protocol in the GSM system so that service providers and network operators can connect BSSs and MSCs from different manufacturers for use in the same system. The A interface uses the Signaling System No. 7 (SS
7
) Signaling Correction Control Part (SCCP) protocol to support communication between the MSC and the BSs and between the MSC and the MSs. The signaling protocol on the A interface consists of three layers. The first layer, or the Physical Layer, is a digital trunk. The digital trunk is coupled to a traffic channel on the Um air interface to convey speech and data between the MSC and MS. The Data Link Layer (Layer
2
) consists of the Message Transfer Part Level
2
(MTP
2
) of SS
7
. MTP
2
provides reliable transfer of signaling messages between the MSC and BS. The Message Layer (Layer
3
) consists of the Base Station Subsystem Application Part (BSSAP).
BSSAP uses the SCCP protocol and consists of two parts: the Direct Transfer Application Part (DTAP) and the BSS Management Application Process (BSSMAP). At a BSS, DTAP transparently transfers Mobility Management (MM) messages and Connection Management (CM) messages between the MSC and MSs. The DTAP messages are not processed by the BSS. MM messages support MS location updating and authentication. CM messages support Call Control, Supplementary Services and Short Message Service (SMS). The Call Control sublayer contains messages for the set-up and release of connections to the MS. SMS allows users to send short text messages to the MS for display to the subscriber. BSSMAP messages relate to communications between the MSC and the BSC, such as Radio Resource management (RR) messages. The BSSMAP messages support all of the procedures between the MSC and the BSS, such as resource allocation, paging, handover, and release.
The GSM mobiles, or Mobile Stations (MSs), consist of two parts: the Mobile Equipment (ME) and the Subscriber Identify Module (SIM). The ME comprises the transmitter, receiver, keypad, microphone, speaker, etc. The SIM is a smart card that stores information about the ME user. The SIM can be used with any ME and the ME is operable only when the SIM is inserted. An MS is uniquely identified by its International Mobile Station Identity (IMSI). The IMSI identifies both a Public Land Mobile Network (PLMN) selected by the user for mobile service and a specific MS within the PLMN. The IMSI is assigned by the PLMN service provider and is stored in permanent memory on the SIM. MSs are also identified by a Temporary Mobile Station Identity (TMSI). A TMSI uniquely identifies the MS within a location area of a PLMN using a 32-bit binary number. Location areas consist of a number of adjacent cells in a PLMN. The TMSI is stored in temporary memory on the SIM. TMSIs provide protection against fraudulent use of MS identities because an intercepted TMSI does not identify the MS after it has left a location area. Most messages identify the MS by a TSMI and a Location Area Identity (LAI).
Related, co-pending application Ser. No. 09/092,771, filed Jun. 5, 1998, which issued as U.S. Pat. No. 6,411,604 on Jun. 25, 2002, entitled SYSTEM AND METHOD FOR CORRELATING TRANSACTION MESSAGES IN A COMMUNICATIONS NETWORK, discloses a monitoring system for capturing and correlating all of the messages for a single transaction in a communication or signaling network, such as an SS
7
network. Other applications, including application Ser. No. 09/057,940, entitled SYSTEM AND METHOD FOR MONITORING PERFORMANCE STATISTICS IN A COMMUNICATION NETWORK, filed Apr. 9, 1998, which was issued as U.S. Pat. No. 6,028,914 on Feb. 22, 2000; application Ser. No. 09/092,699 entitled SYSTEM AND METHOD FOR SIGNAL UNIT DATA STORAGE AND POST CAPTURE CALL TRACE IN A COMMUNICATIONS NETWORK, filed Jun. 5, 1998; application Ser. No. 09/093,824 entitled TRANSACTION CONTROL APPLICATION PART (TCAP) CALL DETAIL RECORD GENERATION IN A COMMUNICATION NETWORK, filed Jun. 8, 1998, which issued as U.S. Pat. No. 6,249,572 on Jun. 19, 2001; and application Ser. No. 09/093,955 entitled SYSTEM AND METHOD FOR MONITORING SERVICE QUALITY IN A COMMUNICATION NETWORK, filed Jun. 8, 1998, which issued as U.S. Pat. No. 6,381,306 on Apr. 30, 2002, also disclose systems and methods for capturing and correlating call and transaction messages in a communication network. These applications are commonly assigned and hereby incorporated by reference herein.
It is known in the prior art for monitoring systems to be coupled to the communication links in a wireline network. The monitoring systems disclosed in the prior art capture the Signaling Units (SU) and messages that pass across the communication link. The systems then correlate the call and transaction messages captured from various links into call and transaction records. System operators can access these records to monitor calls or transactions for particular subscribers or to troubleshoot network problems. The call and transaction records can also be used to generate network and performance statistics. However, the prior art does not teach a system or method for capturing and correlating messages from the links between components in a wireless network. In the case of a wireless network, such as a GSM network, the prior art methods of correlating call or transaction messages will not work because a MS may change BTSs, BSCs, and even MSCs during the course of a single call as the MS moves from one cell to another. Accordingly, there is a need in the art for a system and method in which all of the messages that are related to a single GSM call can be captured and correlated into a single record.
It is an object of the present invention to capture all of the signaling units from the A interfaces for an MSC and to correlate messages that belong to a single mobile call into a call record.
It is a further object of the present invention to correlate messages for a single call as the call is handed over among two or more BSCs served by the MSC.
It is another object of the present invention to correlate mobile call messages captured from A interface links with related call and transaction messages that are captured on other communication links.
It is another object of the present invention to correlate messages based on SCCP connections.
SUMMARY OF THE INVENTION
These and other objects, features and technical advantages are achieved by a system and method which correlates signaling units captured from A interface links in a GSM network so that all messages for a particular call, including messages on diffe
Lin Lisan
Lu Xingchen
Miao Xin
Venkataraman Vijayakumar
Duong Duc
Fulbright & Jaworski LLP
Inet Technologies, Inc.
Nguyen Steven
LandOfFree
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