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Please use this identifier to cite or link to this item: http://hdl.handle.net/1860/2921

Title: Cross-layer design for cooperative wireless networks
Authors: Dong, Lun
Keywords: Electric engineering;Wireless communication systems;Signal processing -- Digital techniques
Issue Date: 4-Dec-2008
Abstract: Cooperation and cross-layer design are two emerging techniques for wireless networks. In this dissertation, novel cooperative cross-layer techniques are proposed in three areas of wireless networks: cooperative beamforming, wireless security and collision resolution. First, we propose a cross-layer cooperative beamforming (CB) approach that enables long-distance communications in an energy and bandwidth efficient fashion. This is a two stage scheme. In the first stage, source nodes share their information with their neighbors via low-power communications. In the second stage, cooperating nodes, by appropriately weighting and forwarding the signal that they received in the first stage, act as a distributed antenna array and beamform the source signals to destinations. We propose system design based on various criteria, such as we allow for the desired signals to combine coherently at the destination(s), maximize the received signal-to-noise ratio (SNR), or maximize the signal-to-interference-plus-noise ratio (SINR). We also analyze the system performance in term of average beampattern, SNR/SINR, symbol error probability, spectral efficiency and packet delays. Second, we propose a novel cross-layer cooperative approach to wireless security. Cooperation of network nodes allows us to overcome the limitations of previous physical (PHY) layer based security approaches posed by the wireless channel. We consider system design that maximizes the secrecy capacity, or minimizes the transmit power in the presence of one and multiple eavesdroppers, respectively. Finally, we present a multichannel extension of ALLIANCES - a cross-layer cooperative protocol for collision resolution in broadband wireless networks. At the PHY layer, the proposed approach is based on orthogonal frequency division multiplexing (OFDM), which effectively handles frequency selective fading. At the medium access control (MAC) layer, we propose various schemes of OFDM subchannel allocation for wireless traffic with diverse quality of service (QoS) requirements. We also conduct error analysis to study how the maximal achievable diversity is effectively by network parameters.
URI: http://hdl.handle.net/1860/2921
Appears in Collections:Drexel Theses and Dissertations

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