Improving GPRS/EDGE end-to-end performance by optimization of the RLC protocol and parameters

The end-to-end performance in both GPRS and EDGE is strongly related to the efficiency of the RLC/MAC protocol. In this paper, we focus on the optimization of several parameters like RLC polling period, RLC roundtrip time and RLC window size. Furthermore, we discuss specific implementation options as well as control mechanisms provided by the standard. The optimum settings of these parameters and their mutual interaction evaluated by simulations have been confirmed by PING and application throughput measurements in a real system. In addition, different architectural aspects such as PCU embedded either in the BSC or in the BTS and 64 kbps vs. 16 kbps based Abis interface have been discussed. The new concept of "RLC frequent retransmission prevention" on the sender side allows fast polling by simultaneously avoiding retransmission of RLC blocks with pending acknowledgement status. The novel fast polling strategy provides about 3 dB to 4 dB link level gain as well as user throughput enhancement in the order of 20% for GPRS and 30% for EDGE.