Measured performance of GSM, HSCSD and GPRS

In this paper we present results of measurements on the performance of GSM HSCSD and GPRS data transmission. We used a measurement tool that we have developed to study the performance of various wireless links as perceived by nomadic applications using TCP. The results show that in stationary connections the throughput and response time are stable and, in general, close to the theoretical values. However, the throughput and response time vary a lot when connections are used in motion. One of the reasons is that TCP is not capable to adapt itself properly to the variability of QoS of HSCSD and GPRS, and therefore, it does a lot of unnecessary retransmissions causing performance slowdown. The performance of HSCSD is better than the performance of GPRS. Reliability is adequate in stationary connections, but in moving connections there are unwanted disconnections or long pauses in data transfer.