Performance of LLC and TCP on GPRS Uplink with RLC Slot Level Retransmission

In this paper, we evaluate the performance of the logical link control (LLC) layer and the Transmission control protocol (TCP) layer in General Packet Radio Service (GPRS) networks. We evaluate the uplink throughput and delay performance of GPRS-LLC protocol with radio link control (RLC) layer using block level retransmission (BLR), as defined in the current GPRS standards, and compare it with that of using slot level retransmission (SLR) at the RLC. We investigate the optimum choice of parameters (e.g., number of retransmission attempts) for the ARQ schemes at the RLC and the LLC layers. Our results show that it is more beneficial to do the error recovery by allowing more retransmissions at the RLC layer than at the LLC layer. We show that SLR performs better than BLR. We also study the impact of SLR on the TCP performance.