Performance of link adaptation in GPRS networks

In GPRS four coding schemes have been defined with different degrees of data protection. The selection of a fixed one for a certain packet transmission would lead to a throughput loss if the channel quality conditions vary during the connection, therefore, a link adaptation algorithm based on a block error rate (BLER) estimation is proposed and analyzed. The BLER is calculated from the acknowledgement messages reported by the receiver; so the acknowledgement frequency impacts the link adaptation, and therefore, is studied in the present article. The resulting link adaptation algorithm has been analyzed with a dynamic network simulator, under different frequency reuse patterns and frequency hopping strategies. Furthermore, the mean user throughput for the fixed coding schemes and for link adaptation has been estimated from GSM network reported measurements, and a network operator planning tool.