Most of the existed works on the radio resource allocation (RRA) problem commonly assume the channel-state\ninformation (CSI) can be perfectly obtained by the transmission source. However, such assumption is not practical in\nthe realistic wireless systems. In this work, we consider the practical implementation issues of resource allocation in\northogonal frequency division multiple access (OFDMA) two-way relay networks: the inaccuracy of channel-state\ninformation (CSI) available to the source. Instead, only the estimated channel status is known by the source. In this\ncontext, a joint optimization of subcarrier pairing and allocation, relay selection, and transmit power allocation is\nformulated in OFDMA two-way amplify-and-forward relay networks. Moreover, the objective of this work is to\nminimize the energy consumption of the overall system. Further, to ensure the quality of service (QoS) or data rate\nrequirement, the energy consumption must be minimized without compromising the QoS. Therefore, by applying\nconvex optimization techniques, energy-efficient algorithms are developed with the objective to minimize the total\ntransmit power with guaranteeing the required data rates. Through simulation studies, energy consumption\nperformance of the systems under the proposed schemes is investigated. It can be observed that our proposed\nscheme can improve the energy consumption performance of the considered system.
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