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TCP Unfairness in Ad Hoc Wireless Networks and a Neighborhood RED Solution


Signi¯cant TCP unfairness in ad hoc wireless networks has been reported during the past several years. This unfair- ness results from the nature of the shared wireless medium and location dependency. If we view a node and its in- terfering nodes to form a \neighborhood", the aggregate of local queues at these nodes represents the distributed queue for this neighborhood. However, this queue is not a FIFO queue. Flows sharing the queue have di®erent, dynamically changing priorities determined by the topology and traf- ¯c patterns. Thus, they get di®erent feedback in terms of packet loss rate and packet delay when congestion occurs. In wired networks, the Randomly Early Detection (RED) scheme was found to improve TCP fairness. In this paper, we show that the RED scheme does not work when running on individual queues in wireless nodes. We then propose a Neighborhood RED (NRED) scheme, which extends the RED concept to the distributed neighborhood queue. Sim- ulation studies con¯rm that the NRED scheme can improve TCP unfairness substantially in ad hoc networks. More- over, the NRED scheme acts at the network level, without MAC protocol modi¯cations. This considerably simpli¯es its deployment

Paper: PDF file of paper

Information & Date

WINET 2004, , January. 2004


Kaixin Xu
Mario Gerla
Lantao Qi
Yantai Shu