Jean C. Walrand

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Abstract — It is well known that head-of-line (HOL) blocking limits the throughput of an input-queued switch with FIFO queues. Under certain conditions, the throughput can be shown to be limited to approximately 58%. It is also known that if non-FIFO queueing policies are used, the throughput can be increased. However, it has not been previously shown that(More)
In multihop wireless networks, designing distributed scheduling algorithms to achieve the maximal throughput is a challenging problem because of the complex interference constraints among different links. Traditional maximal-weight scheduling (MWS), although throughput-optimal, is difficult to implement in distributed networks. On the other hand, a(More)
We propose some improvements of TCP Vegas and compare its performance characteristics with TCP Reno. We argue through analysis that TCP Vegas, with its better bandwidth estimation scheme, uses the network resources more efficiently and fairly than TCP Reno. Simulation results are given that support the results of the analysis. Keywords—TCP Reno, TCP Vegas,(More)
We consider the stability of Longest Queue First (LQF), a natural and low complexity scheduling policy, for a generalized switch model [1]. Contrary to common scheduling policies, the stability of LQF depends on the variance of the arrival processes in addition to their average intensities. We identify new sufficient conditions for LQF to be throughput(More)
This paper compares, through analysis and simulation, a number of multichannel MAC protocols for wireless networks. We first classify these protocols into 4 categories based on their principles of operation. We then examine the effects of the number of channels and devices, channel switching times, and traffic patterns on throughput and delay. Our study(More)
We show the existence of effective bandwidths for mtdticlass Markov fluids and other types of sources that are used to model ATM traffic. More precisely, we show that when such sources share a buffer with deterministic service rate, a constraint on the tail of the buffer occupancy distribution is a linear constraint on the number of sources. That is, for a(More)
Many multiple channel MAC protocols for wireless networks have been proposed to make efficient use of multiple channels where each node has a single radio which allows it to send or receive on one channel at a time. However, most of the proposed protocols are single rendezvous protocols that are subject to the congestion of the control channel. The paper(More)