Date of Award

Spring 2006

Document Type

Thesis

Degree Name

Master of Science in Electrical Engineering - (M.S.)

Department

Electrical and Computer Engineering

First Advisor

Yeheskel Bar-Ness

Second Advisor

Alexander Haimovich

Third Advisor

Ali Abdi

Abstract

Impairments due to multipath signal propagation on the performance of wireless communications systems can be efficiently mitigated with time, frequency or spatial diversity. To exploit spatial diversity, multiple-antenna technology has been thoroughly investigated and emerged as one of the most mature communications areas. However, the need for smaller user terminals, which results in insufficient spacing for antenna collocation, tends to limit the practical implementation of this technology. Without compromising terminal dimensions, future wireless networks will therefore have to exploit their broadcast nature and rely on collaboration between single-antenna terminals for exploiting spatial diversity.

Among cooperative schemes, Collaborative ARQ transmission protocols, prescribing cooperation only when needed, i.e., upon erroneous decoding by the destination, emerge as an interesting solution in terms of achievable spectral efficiency. In this thesis, an information theoretical approach is presented for assessing the performance of Collaborative Hybrid-ARQ protocols based on Space-Time Block Coding. The expected number of retransmissions and the average throughput for Collaborative Hybrid-ARQ Type I and Chase Combining are derived in explicit form, while lower and upper bound are investigated for Collaborative Hybrid-ARQ Incremental Redundancy protocol, for any number of relays. Numerical results are presented to supplement the analysis and give insight into the performance of the considered scheme. Moreover, the issue of practical implementation of Space-Time Block Coding is investigated.

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