tailieunhanh - Báo cáo hóa học: " Research Article A New Scheme to Improve Overall TCP Throughput with Vertical Handover between 3G Cellular Packet Networks and Wireless LANs"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article A New Scheme to Improve Overall TCP Throughput with Vertical Handover between 3G Cellular Packet Networks and Wireless LANs | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2009 Article ID 524960 12 pages doi 2009 524960 Research Article A New Scheme to Improve Overall TCP Throughput with Vertical Handover between 3G Cellular Packet Networks and Wireless LANs Chang Hyeon Lim1 and Ju Wook Jang2 1DMC R D Center Samsung Electronics Co. LTD. Dong Suwon . Box 105 Gyeonggi-do 443-742 South Korea 2 Department of Electronic Engineering Sogang University Seoul 121-742 South Korea Correspondence should be addressed to Ju Wook Jang jjang@ Received 20 December 2008 Revised 28 May 2009 Accepted 5 August 2009 Recommended by Ingrid Moerman One major difference between 3G cellular networks and Wireless LANs is in how packet losses are dealt with. 3G cellular networks employ selective repeat ARQ SR-ARQ which may result in packet-reordering due to local retransmissions. Wireless LANs employ stop-and-wait ARQ which may drop some packets in case the buffer overflows. While much work has been performed for TCP throughput enhancement with vertical handover between wired networks and wireless networks little attention is paid to the vertical handover between two different wireless networks. It is expected for majority of new mobile devices to be able to connect to both 3G cellular networks and wireless LANs by being equipped with multiple wireless interfaces. If this is the case on-going TCP transmission may move between 3G cellular networks and wireless LANs. In this paper we propose a scheme to improve TCP throughput with vertical handoff between 3G cellular networks and wireless LANs. For this we develop an algorithm which differentiates packet-reordering from packet losses and congestion losses from wireless losses. Simulation of our algorithm using ns-2 shows significant increase in throughput as large as 80 compared to TCP-SACK. The proposed scheme is able to respond to the change of loss pattern and then improve the TCP throughput .