Browsing by Subject "transmit power control"

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    (2009) Kaybal, Fazlı
    In this thesis, we study the joint scheduling and routing problem in spatial reuse Time Division Multiple Access (STDMA) based multi-channel/multiradio/multi-rate wireless mesh networks (WMNs). The main objective of the joint scheduling and routing problem addressed in thesis is to reduce the number of required TDMA time slots to deliver all packets to their destinations. Since the optimum solution to the problem is NP-hard, we propose a greedy iterative solution methodology. The problem is formulated as an integer linear program (ILP) under the physical interference model. We consider two versions of the problem in order to investigate the factors affecting the capacity of WMNs. In the first one, we perform scheduling and routing when the number of channels and number of radios are varied for multi-rate WMNs where nodes are equipped with omni-directional antennas. This analysis is done for both single-class (best-effort traffic) and two-class (best-effort and delay sensitive classes) traffic models. We then extend this analysis by adding the power control scheme which allows transmitters to change the transmitting powers slot-by-slot. Finally, joint scheduling and routing problem is extended for WMNs where nodes are equipped with multiple sectored antennas. We show that the network performance is improved with more radio resources, e.g., using multiple orthogonal channels, multiple radios per node, transmit power control scheme, and directional antennas in terms of delay and total dissipated energy. The network throughput when using 3 channels and 3 radios is increased by up to 67.2% compared to single channel WMNs and the total dissipated energy is reduced by up to 45.5% with transmit power control scheme. Finally, when directional antennas with 6 sectors are used at both transmitters and receivers, the network throughput increases by up to 72.6% compared to omni-directional antenna case.