Abstract
Most of the existed works on the radio resource allocation (RRA) problem commonly assume the channel-state information (CSI) can be perfectly obtained by the transmission source. However, such assumption is not practical in the realistic wireless systems. In this work, we consider the practical implementation issues of resource allocation in orthogonal frequency division multiple access (OFDMA) two-way relay networks: the inaccuracy of channel-state information (CSI) available to the source. Instead, only the estimated channel status is known by the source. In this context, a joint optimization of subcarrier pairing and allocation, relay selection, and transmit power allocation is formulated in OFDMA two-way amplify-and-forward relay networks. Moreover, the objective of this work is to minimize the energy consumption of the overall system. Further, to ensure the quality of service (QoS) or data rate requirement, the energy consumption must be minimized without compromising the QoS. Therefore, by applying convex optimization techniques, energy-efficient algorithms are developed with the objective to minimize the total transmit power with guaranteeing the required data rates. Through simulation studies, energy consumption performance of the systems under the proposed schemes is investigated. It can be observed that our proposed scheme can improve the energy consumption performance of the considered system.
Highlights
The demand for high-speed data transmission has been significantly increased due to the fast-growing wireless multimedia service market in the last decade
Orthogonal frequency division multiple access (OFDMA) is known as an effective technique exploiting the features of OFDM in combating channel fading and multipath effects and providing high data rate
4.4 Algorithm description We have proposed an energy-efficient radio resource allocation scheme which jointly considers relay selection, subcarrier pairing, and power allocation problem in the OFDMA two-way (bidirectional) relay networks (TWRN)
Summary
The demand for high-speed data transmission has been significantly increased due to the fast-growing wireless multimedia service market in the last decade. Under the consideration of channel uncertainty, the relay selection and power allocation schemes are proposed to minimize the uplink transmit power of the network by taking each user’s target data rate as the quality of service (QoS) constraint in [10] Another recent work about RRA for OFDMA relay networks with imperfect CSI was introduced in [11], where only power allocation algorithm was introduced. The primer target of this work is to present an energyefficient resource allocation scheme which jointly address relay selection, subcarrier pairing, and power allocation in OFDMA TWRN with imperfect CSI. 2. When imperfect CSI is assumed, the closed-form expressions of optimal power allocation, relay selection, and subcarrier pairing are derived.
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