Joint Scheduling, Routing and Power Control for Single-Channel Wireless Mesh Networks

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Title: Joint Scheduling, Routing and Power Control for Single-Channel Wireless Mesh Networks
Author: Gupta, Divya
Advisors: Dr. Mihail Sichitiu, Committee Member
Dr. Harry Perros, Committee Member
Dr. Rudra Dutta, Committee Chair
Abstract: Mesh networks is a class of wireless networks consisting of a set of backbone nodes and some client nodes. In this work, we look at the problems of routing, scheduling and power control in such networks, with the ultimate goal of increasing the throughput while satisfying all the traffic requirements. Increasing the throughput of the network implies the ability to send more data between as many source and destination nodes as possible, in shorter periods of time. To achieve this, we need intelligent scheduling schemes that take advantage of the spatial reuse that is possible. We outline two heuristic scheduling algorithms that look at various ways of ordering the links and choosing the ones that might reduce the schedule length, which is a measure of the throughput of the network. The simpler algorithm works at the candidate node level for each slot, while the more complex independent sets based algorithm works with individual links. Different options have been outlined for choosing the first and subsequent links of every slot in the schedule. This includes the interference score of the link, the magnitude of traffic requirement, the specific interfering links, etc. We also study in detail how the links in the network affect the schedule length. When certain links are scheduled, the spatial reuse factor is reduced to zero, implying that no other links can be active at the same time as these links. Hence it is of interest to us to study more about these "loner" links as they add to the schedule length. We characterize these links for topologies in square and circular areas. Using simple geometric arguments, we show that links of length 0.579k and 0.485d in a square area of side k and circular area of diameter d respectively, will always be loners. We also outline a method to analytically find the number of loner links in a given network. This number gives a lower bound on the schedule length. With the understanding gained from the study of scheduling heuristics, we present a routing algorithm that performs topology control by removing loner links. The traffic on these links is routed using other links in the network. Although this routing scheme does not perform well, it leads to a more intelligent joint routing and scheduling mechanism that succeeds in reducing schedule lengths. The joint mechanism does routing in parallel with 2 the scheduling, by calculating routes over links that fit completely into the current schedule. The power control mechanism for both these schemes is to use the minimum power level needed for communication.
Date: 2006-08-29
Degree: MS
Discipline: Computer Networking

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