On Wireless Link Scheduling and Flow Control

This thesis focuses on link scheduling in wireless mesh networks by taking into account physical layer characteristics. The assumption made throughout is that a packet is received successfully only if the Signal to Interference and Noise Ratio (SINR) at the receiver exceeds a certain threshold, termed as communication threshold. The thesis also discusses the complementary problem of flow control. First, we consider various problems on centralized link scheduling in Spatial Time Division Multiple Access (STDMA) wireless mesh networks. We motivate the use of spatial reuse as performance metric and provide an explicit characterization of spatial reuse. We propose link scheduling algorithms based on certain graph models (communication graph, SINR graph) of the network. Our algorithms achieve higher spatial reuse than that of existing algorithms, with only a slight increase in computational complexity. Next, we investigate a related scenario involving link scheduling, namely random access algorithms in wireless networks. We assume that the receiver is capable of powerbased capture and propose a splitting algorithm that varies transmission powers of users on the basis of quaternary channel feedback. We model the algorithm dynamics by a Discrete Time Markov Chain and consequently show that its maximum stable throughput is 0.5518. Our algorithm achieves higher maximum stable throughput and significantly lower delay than the First Come First Serve (FCFS) splitting algorithm with uniform transmission power. Finally, we consider the complementary problem of flow control in packet networks from an information-theoretic perspective. We derive the maximum entropy of a flow which conforms to traffic constraints imposed by a generalized token bucket regulator, by taking into account the covert information present in the randomness of packet lengths. Our results demonstrate that the optimal generalized token bucket regulator has a near uniform bucket depth sequence and a decreasing token increment sequence.