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Performance Analysis and Design Optimization of Cooperative Relay Networks.


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Forghani, Amir Hossein (2014). Performance Analysis and Design Optimization of Cooperative Relay Networks. Thèse. Québec, Institut National de la Recherche Scientifique, Université du Québec, 129 p.

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In wireless communications, implementing multiple antennas to provide spatial diversity may not always be feasible in practice. Therefore, cooperative techniques which employ relays to assist communication have emerged as practical solutions to produce spatial diversity without the requirement of having multiple antennas at the transmitters and/or the receivers. In this thesis, cooperative relaying networks are investigated, where relays are employed to improve the communication reliability and coverage area. Two well-known transmission strategies are assumed for the relays in terms of processing their received signal: amplify-and-forward and decode-and-forward. The focus is on the performance evaluation and enhancement of multi-hop multi-branch relaying networks taking into account the practical issue of co-channel interference. With multi-hop transmission along a single branch between the source and the destination, it is possible to achieve higher coverage and decrease the effects of channel impairments. On the other hand, by leveraging different and independent branches instead of one branch, the diversity gain can be increased further. In this case, maximal ratio combining and selection combining are applied at the end receiver. Furthermore, different cooperative schemes are investigated in different scenarios. In particular, interferers affecting the relaying nodes in the network can be of equal power or have different powers. For improved network performance, variable-gain coefficient is used at the relaying nodes. Furthermore, optimal power allocation among the transmit nodes is developed. Also, a selection method, where only the relays which decode the signal correctly during the broadcast phase participate in the relaying phase, is investigated. For the latter case, dual-hop multi-branch relaying is studied. Later on, signal space diversity technique is studied as a mean to improve the performance in a particular relaying network with one relay. Based on the relaying strategy adopted, the network performance is evaluated in terms of several metrics such as the error probability, the outage probability and the Ergodic capacity. Statistics of the end-to-end signal-to-interference-plus-noise ratio, including cumulative density function, probability density function and moment generating function are used to in to conduct exact, approximate or lower-bound analysis. For instance, by employing approximate analysis to evaluate the system performance without resort to time-consuming simulation experiments, and determining the diversity order of the considered relaying networks. In particular, our result pertaining to the diversity order predicts that an error floor will appear when the ratio of the total transmit power to noise power is high, since the system performance is strictly interference-limited. The analyses conducted in this work allow the understanding of the impact of important system parameters, such as the interference and the number of branches and hops, on the performance of cooperative relaying networks, without resorting to time-consuming simulation experiments, and constitute the main task for providing guidelines as to the configuration to choose in practice.

Type de document: Thèse Thèse
Directeur de mémoire/thèse: Aïssa, Sonia
Mots-clés libres: réseaux de relais; MSMB; CCI; brouilleurs; performances ; optimisation ; conception
Centre: Centre Énergie Matériaux Télécommunications
Date de dépôt: 15 sept. 2021 17:32
Dernière modification: 01 oct. 2021 15:49
URI: https://espace.inrs.ca/id/eprint/2422

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