TCP performance improvement over wireless ATM networks through a new AAL protocol

This paper describes the design and simulation of a new AAL protocol (AAL-X) for improving TCP performance over wireless ATM networks. The wireless links are characterized by higher error rates and burstier error patterns in comparison with the fiber-based links for which ATM was designed. Since the poor performance of TCP over wireless ATM networks is mainly due to the fact that TCP always responds to all packet losses by congestion control, the key idea in the design is to push the error control portion of TCP to the AAL layer so that TCP is only responsible for congestion control. The AAL-X is based on a novel and reliable ARQ mechanism to support quality-critical TCP traffic over wireless ATM networks. The proposed AAL protocol has been validated using the OPNET tool on the simulated wireless ATM network. The simulation results show that the AAL-X provides higher throughput for TCP over wireless ATM networks compared to the existing approach of TCP with AAL 5.