Nortel Networks Corporation

Joseph S M Ho

Jim Xu

Nhut Nguyen

Hakan Ernam

Julie Y C Liu

Hector Maturino

A wireless communication system constructed according to the present invention assigns each serviced mobile unit to a serving mobile switching center to minimize mobility management overhead and to equalize loading among a plurality of mobile switching centers. The wireless communication system includes the plurality of mobile switching centers and a base station system which includes a plurality of base station controllers, each of which couples to a plurality of base stations. A plurality of mobile units served by the system are assigned to the mobile switching centers so that loading is equalized. In one particular construction of the wireless communication system, a dispatching switch couples the base station system to the plurality of mobile switching centers and performs the assignments of the mobile units. In an example of operation, upon attachment of a mobile unit, the dispatching switch determines loading of each of the mobile switching centers. Then, based upon the loading, the dispatching switch assigns the mobile unit to one of the mobile switching centers, the &ldquo;serving&rdquo; mobile switching center.

Distributed signaling message routing in a scalable wireless communication system

A method and system for improving overall system capacity in GSM networks by reducing the number of visitor location register queries is disclosed. The method and system determines if subsequent calls for a mobile terminal which has been detached by its subscriber from the GSM network should require querying of its visiting mobile switching center and HLR based on the call arrival characteristics of the subscriber. A &ldquo;call-arrival-after detach&rdquo; counter is created at the home location register and visitor location register for tracking the number of incoming calls that occur during the interval when the subscriber has detached. The value of this counter is compared for every incoming call to a threshold level value for determining if the call is to be forwarded. The threshold level value is determined on the past call arrival characteristics of the subscriber. The method and system of the present invention makes it unnecessary to query the VLR when a land-to-mobile call arrives for a subscriber and the subscriber has detached from the network thereby increasing network capacity while reducing processing load.

Method and system for reducing call setup processing cost by determining when to forward calls to detached subscribers

A method and system for improving overall system capacity in GSM networks by reducing the number of home location register and visitor location register queries is disclosed. The method and system allows the reuse of the MSRN by allocating the MSRN to a mobile terminal and using it for future calls. The method of the present invention allows the GMSC to cache the MSRN for a called mobile terminal. During a first call setup, an entry is recorded at a cache register that maps the Mobile Subscriber ISDN Number (MSISDN) of the mobile terminal to a previously allocated MSRN. Additionally, the Bearer Capability (BC) associated with this MSRN is also recorded in the cache register. When the next call arrives, the GMSC first checks if a MSRN for that called mobile terminal already exists in its cache register. If a cached MSRN is available and the BC associated with the cached MSRN matches the BC requested by the current call, then the GMSC uses the cached MSRN to route the call to the VMSC. The method and system of the present invention makes it unnecessary to query the HLR and VLR when a land-to-mobile call arrives thereby increasing network capacity while reducing processing load.

Method and system for reducing call setup by roaming number caching

A method is illustrated for reducing the call setup time of high priority calls such as voice or high speed user generated data without unduly wasting RF frequency resources on non priority calls such as short message calls. This is accomplished by ascertaining the call priority at the base station controller (BSC) level in a GSM system soon after call initiation and immediately changing the channel assignment for use by the remaining signalling type messages to a different operational speed where appropriate. The concept is further extended by supplying the call priority data to a called party's BSC such that all signalling messages after initial contact can be at the operational speed appropriate to the priority of the call.

Method and apparatus for enhanced call setup

A method for ordering subscriber records in a location database stored in at least one of a Visitor Location Register (VLR) or a Home Location Register (HLR) of a wireless communications network by ordering the subscriber records in subsets according to the access rates of the records. Records within the respective subsets are then ordered in a middle-rootage order based on the subscriber ID of each subscriber record. The subscriber records are then inserted into a binary tree in subset order beginning with the subset containing subscriber records having the highest access rate. This method enables subscriber records to be more economically stored and used than is possible using conventional binary trees and, thereby, increases network capacity.

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Dallas, TX, United States of America

Joseph S M Ho