School of Electrical and Computer Engineering

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Browsing School of Electrical and Computer Engineering by Author "Abate, Abi"

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    Shared Relay-Based Cooperative Communication with MIMO Detection
    (Addis Ababa University, 2013-02) Abate, Abi; Hailemaraim, Dereje (PhD)
    The wireless channel places fundamental limitation on the performance of wireless communication network. Fading, path loss and shadowing are some of the impairments caused by the wireless channel, which result in significant performance degradation. These wireless channel impairments can be compensated by various ways such as by increasing transmit power or bandwidth. Since these radio resources are scarce and expensive, future wireless systems should focus on new technologies that provide high spectral efficiency, high network coverage and improved link reliability. In this aspect, Multiple-Input Multiple- Output (MIMO) wireless communication system; where multiple antennas are equipped at the transceiver of the wireless link, has been considered as promising technology to meet these requirements. However, due to size, cost, and/or hardware limitations, a small handheld wireless device may not be able to support multiple antennas. As a remedy to this problem cooperative communication, where nodes cooperate to create multiple antennas virtually, has been proposed recently. Although cooperative communication provide high network coverage and improved link reliability, the available relay resources are not fully exploited due to lack of optimal signal detection scheme. To this end, this thesis presents a MIMO detection based cooperative wireless communication called multiple-access relay channel (MARC) and analyze the performance in the form of bit error rate (BER). It allows the receiver to jointly detect the source and relay transmissions, to provide better diversity gain. In MARC, multiple sources (two in our case) transmit to a common destination with the assistance of a single relay. In this scenario, a network containing two sources, a common destination and a relay is analyzed. Two cooperative communication schemes which include amplify and forward and decode and forward employing different MIMO detection techniques are investigated and results obtained from simulations with respect to variable relay positioning are presented. Keywords: Amplify-and-Forward, Bit-Error-Rate, MIMO Signal Detection, Cooperative Communications, Decode-and-Forward, Performance Analysis, Signalto- Noise-Ratio, Wireless Networks, Superposition Modulation.