Colloquium Speaker

Speaker: Sandeep K.S. Gupta
Computer Science Department
Colorado State University
Topic:Dynamically Adapting Registration Areas to User Mobility and Call
Patterns for Efficient Location Management in PCS Networks
Date:Tuesday, September 5, 2000
Time:11:00 AM
Place:Gould-Simpson, Room 701

Refreshments will be served in the 7th-floor lobby of Gould-Simpson at 10:45 AM


Location management is an essential service in mobile networks. It provides mechanisms for recording and querying location of mobile units in the network. This is needed for establishing calls or delivering messages to mobile units. In personal communication service (PCS) networks, location management protocols such as IS-41 and GSM use statically defined Registration Areas (RAs). Each RA consists of all the communication cells in its geographical area. Associated with each RA is a database called Location Registrar. Further, each mobile unit has a pre-assigned Home Location Registrar (HLR). A mobile unit informs its location (location update operation) whenever it moves from one communication cell to another. When the move results in move from one registration area to another updates are made to home location registrar. In order to locate a mobile unit the initiator of the call or (sender of the message) first contacts the HLR of the destination mobile unit to know its current location (registration area). Location Management based on statically defined registration areas is unable to adapt to changing mobility and call patterns of the users.

In this talk, we present an extension to PCS location management protocol which uses dynamically overlapped registration areas. Overlapping of registration areas helps in reducing the number of location updates for a fixed mobility pattern. Further, dynamically changing the registration area is used to adapt to changes in aggregate mobility and call pattern. This reduces and balances the signaling and database access load on the mobile services stations (MSS). In order to study the adaptiveness of the proposed scheme, we have simulated our scheme under various mobility and call patterns. Our simulation results show that by dynamically adapting the registration areas to aggregate mobility and call pattern of the mobile units is useful when the mobility pattern exhibit locality. For such mobility and call patterns, the proposed scheme can greatly reduce the average signaling and database access load on MSSs. Further, the cost of adapting the registration areas is shown to be low in terms of memory and communication requirements.