Joseph S. M. Ho

Throughput and buffer analysis for GSM General Packet Radio Service (GPRS)

The Global System for Mobile Communications (GSM) Phase 2+ standard specifies a new type of packet data service called General Packet Radio Service (GPRS). GPRS allows the dynamic allocation of bandwidth resources. Wireless channels are allocated to a mobile terminal based on its traffic demands. This results in better resource utilization compared to the circuit-based data services. In general, packet-based communication has more bursty traffic and longer connection time compared to its circuit-based counterpart. A communication session may last for an extended period of time with intermittent packet transmissions. This traffic behavior coupled with flexible bandwidth allocation in a GPRS network results in multiplexing gain that is not available in circuit switched data networks. This paper evaluates the throughput and buffer utilization in a GPRS network under Internet traffic models, such as WWW and E-mail. The performance of GPRS is then compared with the circuit based GSM network to demonstrate the improvement due to multiplexing gain.

History-based location tracking for personal communications networks

A personal communication services (PCS) network consists of a fixed wireline network component and a number of mobile terminals. To conserve wireless bandwidth, mobile terminals are not permanently connected to the wireline network. A mobile terminal is completely detached from the network when it is idle and it is assigned a channel only if necessary. Therefore, a method is needed for locating the mobile terminal when an incoming call arrives. Current PCS networks rely on a paging scheme to locate a mobile terminal. However, when the network coverage area is large, the paging cost is high. To reduce the paging cost, a location update procedure is employed such that a mobile terminal periodically reports its location to the network. Location updates consume wireless bandwidth and impose additional overhead to the wireless network. However, the information obtained during location update allows the network to limit the size of the paging area and, thus, reduces the paging overhead. This paper describes a location update mechanism which reduces the cost for location update and paging based on the mobility history of the mobile terminal. Other system parameters such as the mobility and call arrival rates as well as the costs associated with location update and paging are also considered.