Modelado y evaluacion de estrategias de seguimiento de terminales moviles. Analisis de la carga de senalizacion en la Red de Acceso y en la Red Inteligente.

摘要

Mobility tracking operations in Personal Communication Services Networks (PCS) are signal-consuming. Several strategies have been proposed to reduce tracking costs in the:;1. Common air interface (CAI). First, a new hybrid Location Update (LU) strategy is studied combined with selective paging. A comparative analysis between classical GSM standard (one Location Area (LA) is used) and hybrid strategies (a dynamic group configured with 2 or 3 LAs) is made. To take advantage of the hysteresis of the dynamic LU strategy, it is shown that paging must be selective (2 steps or more); and so total cost in CAI is reduced in comparison with GSM cost. In this case, the best policy is the one with 3 LAs, followed by the one with 2 LAs, and finally GSM.;Later on, a movement-distance dynamic location management is proposed and compared to classical dynamic strategies (time, movement and distance). Favorable cases are shown where the use of such a strategy is suitable because performances close to distance costs can be obtained with a significant saving of memory per mobile terminal.;2. Fixed network (FN). In the first part, the impact of a decentralized data query strategy on the System DataBase (SDB) has been analyzed and compared to the classical GSM-MAP scheme. The querying order has been inverted (first a VLR, and then the HLR when necessary), so the Interrogation procedure is decentralized. As the number of users grows, calls are likely to be local, and the called parties may often be located by querying VLRs. Nowadays some systems are reaching this situation, and it has been shown a decentralized Interrogation is more suitable than a centralized query strategy.;In the last part, the impact of the hybrid strategy (proposed here) in a classical hierarchic SDB with 2 levels is evaluated. The LU algorithm is hybrid, so the signalling load at the CAI (and the VLRs) is reduced due to hysteresis. The VLRs absorb part of the RG load because they serve more than one LA. The Interrogation cost grows slightly because the mobile terminal is registered in 1, 2 or 3 VLRs. A decentralized Interrogation can be used in order to reduce this cost.