SEECS Colloquium

The rapid advancement in wireless communications and availability of powerful wireless devices are the main driving forces behind the emerging third generation (3G) wireless data networking technologies. Bringing the TCP applications from the Internet domain to the wireless devices is still a major challenge. Due to its inherent congestion control mechanism, the performance of TCP severely degrades when used in the wireless domain. Radio Link Protocol (RLP) is one scheme that shields the effect of the losses over wireless links from the TCP layer. However, the delay associated with RLP might not be small enough to sustain real-time communications with strict delay requirements. Retransmissions done at a lower layer, such as the medium access control (MAC), enhances the delay performance. A fast retransmission mechanism has been proposed for the 3G CDMA systems to deal with the recovery of dropped or corrupted packets. The proposed mechanism is integrated at the MAC layer and works hand-in-hand with the existing RLPs. Soft packet combining is considered at the receiver which effectively lowers the frame error rate. Analytical and simulation results demonstrate how retransmissions jointly offered by the MAC and the RLP on two CDMA protocols- cdma2000 and WCDMA can support TCP applications with strict delay requirements. (Joint work with Sajal K. Das and Giridhar D. Mandyam)

Mainak Chatterjee is a Ph.D. candidate in the Department of Computer Science and Engineering at the University of Texas at Arlington. He received his Masters from the Indian Institute of Science in 1998. His research interests include mobile computing, MAC layer protocols, CDMA data networking, multimedia communications and ad-hoc networks. He has published over a dozen research papers in these areas. He is a recipient of the Texas Telecommunication and Engineering Consortium (TxTEC) fellowship. He received the "Outstanding Research" award from the department of Computer Science and Engineering for his dissertation work on QoS Provisioning in Wireless Data Networks. He was also judged the Best Intern at Nokia Research Center in 2001. He is a a student member of IEEE.