A novel scheme for improving good throughput performance in wireless local networks
ABSTRACT With the fast-paced deployment of wireless local networks, improving good throughput performance becomes more and more important to support various multimedia services. In this paper, we develop a novel scheme for such a purpose, which comprises two parts: a TCP quick-timeout (TCP-QT) algorithm and an adaptive frame size algorithm. The TCP-QT algorithm is to reduce the TCP timeout overhead, and the adaptive frame size algorithm is to reduce the number of retransmissions in the MAC layer. Using feedback from the MAC layer, the TCP layer can be made aware of the transmission history of a packet in the MAC layer. If a packet has been dropped by the MAC layer, a quick timeout in the TCP layer is triggered, resulting in a fast retransmission of the packet. Thus, the average good throughput observed in the application layer is greatly improved, while the current TCP semantics are largely unchanged. Then, we integrated an adaptive frame size algorithm into the TCP-QT algorithm for further performance improvement. Simulation results show that the proposed scheme can improve the energy efficiency by up to 5 times.
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ABSTRACT: In this paper, adaptive fragment algorithms for IEEE 802.11 wireless LAN are proposed and studied. This work is in- spired by studying end-to-end congestion control/avoidance methods used in transport layer. The throughput perfor- mance of proposed algorithms for IEEE 802.11 wireless LAN is simulated under different channel quality scenarios. Ac- cording to the simulation results, the adaptive algorithms designed by using the methods behind end-to-end conges- tion control/avoidanc e algorithms can improve the channel throughput and reduce the end-to-end delay, even the chan- nel is very noisy.Proceedings of the 2001 ACM Symposium on Applied Computing (SAC), March 11-14, 2001, Las Vegas, NV, USA; 01/2001
Conference Paper: Variable-rate variable-power MQAM for fading channels[Show abstract] [Hide abstract]
ABSTRACT: We propose a variable power and rate adaptive MQAM modulation scheme for high-speed data transmission on fading channels. We show that using just five or six different signal constellations achieves within 1-2 dB of the maximum spectral efficiency. We also obtain the exact efficiency loss for a smaller constellation set. In addition, we compare our technique with a fixed-rate scheme which inverts the channel fading. Assuming perfect power control, the fixed-rate scheme exhibits a 5-10 dB loss in spectral efficiency relative to our adaptive technique. We conclude by discussing performance degradation caused by channel measurement errorsVehicular Technology Conference, 1996. 'Mobile Technology for the Human Race'., IEEE 46th; 01/1996
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ABSTRACT: TCP is a reliable transport protocol tuned to perform well in traditional networks where congestion is the primary cause of packet loss. However, networks with wireless links and mobile hosts incur significant losses due to biterrors and handoff. This environment violates many of the assumptions made by TCP, causing degraded end-toend performance. In this paper, we describe the additions and modifications to the standard Internet protocol stack (TCP/IP) to improve end-to-end reliable transport performance in mobile environments. The protocol changes are made to network-layer software at the base station and mobile host, and preserve the end-to-end semantics of TCP. One part of the modifications, called the snoop module, caches packets at the base station and performs local retransmissions across the wireless link to alleviate the problems caused by high bit-error rates. The second part is a routing protocol that enables low-latency handoff to occur with negligible data loss. We have implemented this new protocol stack on a wireless testbed. Our experiments show that this system is significantly more robust at dealing with unreliable wireless links than normal TCP; we have achieved throughput speedups of up to 20 times over regular TCP and handoff latencies over 10 times shorter than other mobile routing protocols. 1.Wireless Networks 01/1995; 1:469-481. · 0.74 Impact Factor