Keyvan Yasami

Date of Award

2011

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Electrical and Computer Engineering

Advisor

Ali Abedi

Second Committee Member

Donald M. Hummels

Third Committee Member

Nuri Emanetoglu

Abstract

Cooperative relaying can improve the overall throughput of a network in various communication scenarios in which a terminal acts as a traffic relay for other users. Examples of these scenarios can be found in home and consumer communication networks, different applications of wireless sensor network to improve energy consumption and prolong network lifetime, such as environmental monitoring, target tracking, etc. Wireless network coding has received an increasing attention since network coding was introduced by Ahlswede. This increasing interest is due to considerable gains that are foreseen in application of network coding in cooperative relaying scenarios with two-way or multi-way traffic. Most prior works reported in the literature have made simplified and idealistic assumptions. Specifically, channel state is assumed to be perfectly known. This thesis investigates the effect of erroneous channel estimation on performance of physical layer network coding over fading channels. In this scenario, the relay maps the superimposed noisy modulated data, received from the two end terminals, to network coded combination of the source packets. We consider channel estimation error to be Gaussian distributed and formulate the network coding error by the distance between real and estimated points in the channel coefficients plane. Using this model, a statistical lower bound on variance of estimation error is presented that can be tolerated by the relay terminal without imposing a network coding error on the system. This study can determine the required channel estimation accuracy in design of practical relaying systems, which use physical layer network coding.

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