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Title: OFDM-based relay systems for next generation networks
Author: Dang, Shuping
ISNI:       0000 0004 7229 4191
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2017
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The performance of four newly proposed orthogonal frequency-division multiplexing (OFDM)-based relay systems with different application scenarios are analyzed in this thesis. The first scenario that is studied relates to the bulk and per-subcarrier relay selections, which can be regarded as two extremes of the performance-complexity trade-off in multi-carrier relay selection. Specifically, the outage performance yielded by these two selection schemes is analyzed in spatially random networks where relays are randomly distributed. Subsequently, a novel selection scheme for OFDM-based relay systems is proposed by combining conventional bulk and per-subcarrier selections. The asymptotic outage performance of the combined selection scheme in the high signal-to-noise (SNR) region is analyzed, and it is found that the combined selection can achieve the optimal outage probability without using the full set of available relays for selection. Hence, a satisfactory solution to the performance-complexity trade-off can be obtained. Apart from conventional application scenarios, OFDM-based relay systems with relay selections are also analyzed in more practical scenarios, e.g., device-to-device (D2D) communications. However, due to the adoption of underlay D2D communication protocol, power control mechanisms are thereby necessary to be applied to mitigate the interference to conventional cellular communications, which lead to a series of new analytical challenges. Meanwhile, to incorporate with new modulation techniques, OFDM-based relay systems are also combined with index modulation (IM). Then, an adaptive OFDM-IM is proposed for two-hop relay networks to enhance the system reliability when there is only one relay, and relay selection is thereby infeasible. Specifically, in this proposed adaptive OFDM-IM, the mapping schemes between a bit stream and indices of active subcarriers are adaptively selected by a certain criterion. All these analyses for a variety of cases given in this thesis constitute a comprehensive analytical framework for OFDM-based relay systems in next generation networks.
Supervisor: Coon, Justin P. ; O'Brien, Dominic Sponsor: China Scholarship Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available