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Presenter: Xue Dong
Supervisor: Dr. Xiaodai Dong

Date: Tue, June 21, 2011
Time: 10:00:00 - 11:00:00
Place: EOW 230

ABSTRACT

Abstract:

Transmitted reference pulse cluster (TRPC) was recently proposed for ultrawideband (UWB) communications attributing to its robust performance, higher data rate, enhanced reliability and lower implementation complexity compared with the conventional transmitted reference technique. This thesis investigates the TRPC UWB relay strategies between two nodes lack of direct link. Two novel channel quality indicators are first proposed for the TRPC UWB system, which can detect the channel condition and the relay decoding quality in the bit level without requiring estimating the channel state information. Five relay strategies based on these indicators (Relay Combining (RC), Weighted Relay Combining (WRC), Outage based Relay Selection (ORS), Maximum Product Relay Selection (MP-RS) and Minimax Relay Selection (MinMax-RS)) are proposed for the cooperative network to extend the network coverage and improve the system performance. The efficiency and effectiveness of the proposed cooperative strategies are examined under different channel environments through simulations, among which the MinMax-RS strategy based on the Log Likelihood Ratio (LLR) channel quality indicator is testified to yield the best performance under the typical indoor line of sight (LOS) environment. Moreover, in order to reduce the relay overhead, a multipath channel based relay selection strategy (MC-RS) is proposed, where the channel quality is detected once for each channel realization and the noise variation in each bit is reasonably neglected. And base on both the channel and bit level selection, a joint relay selection (JRS) strategy is investigated to gain a balance between the channel condition and the bit-by-bit decoding quality at relays. At last, for the two-way-relay system prototype, the power allocation strategies are further investigated to minimize the system outage probability, under the limit of the total transmit power. Simulations in this thesis are executed under various channel environments following the IEEE 802.15.4a standard, and numerical results validate the effectiveness of the proposed strategies.