A new ATM adaptation layer for TCP/IP over wireless ATM networks

This paper describes the design and performance of a new ATM adaptation lay er protocol (AAL-T) for improving TCP performance over wireless ATM network s. The wireless links are characterized by higher error rates and burstier error patterns in comparison with the fiber links for which ATM was introdu ced in the beginning. Since the low performance of TCP over wireless ATM ne tworks is mainly due to the fact that TCP always responds to all packet los ses 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-T is based on a novel and reliable ARQ mechani sm to support quality-critical TCP traffic over wireless ATM networks. The proposed AAL protocol has been validated using the OPNET tool with the simu lated wireless ATM network. The simulation results show that the AAL-T prov ides higher throughput for TCP over wireless ATM networks compared to the e xisting approach of TCP with AAL 5.