In this paper, we investigate joint optimal relay selection and resource allocation under bandwidth exchange (BE) enabled incentivized cooperative forwarding in wireless networks. We consider an autonomous network where N nodes transmit data in the uplink to an access point (AP) base station (BS). We consider the scenario where each node gets an initial amount (equal, optimal based on direct path or arbitrary) of bandwidth, and uses this bandwidth as a flexible incentive for two hop relaying. We focus on alpha-fair network utility maximization (NUM) and outage reduction in this environment. Our contribution is two-fold. First, we propose an incentivized forwarding based resource allocation algorithm which maximizes the global utility while preserving the initial utility of each cooperative node. Second, defining the link weight of each relay pair as the utility gain due to cooperation (over noncooperation), we show that the optimal relay selection in alpha-fair NUM reduces to the maximum weighted matching (MWM) problem in a non-bipartite graph. Numerical results show that the proposed algorithms provide 20- 25 gain in spectral efficiency and 90-98 reduction in outage probability.
Second, our proposed decode & forward (DF) BE enabled resource allocation maximizes the summation of the utilities while preserving the initial utilities of the individual nodes. Previously, the authors of @cite_13 considered BE from a simpler two hop relaying perspective. The authors of @cite_11 proposed a similar half duplex DF relaying approach. However, they considered a commercial relay network where the relay did not have its own data @cite_11 . To the best of our knowledge, our proposed BE based resource allocation algorithm has not been investigated before.
@cite_13 @cite_11
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We investigate an incentive mechanism called Bandwidth Exchange (BE) for cooperative forwarding where transmission bandwidth is used as a flexible resource. We focus on a network where two nodes, communicating with the base station (BS) access point (AP), initially get optimal amount of bandwidth based on direct path transmission and then use their individual bandwidths as flexible incentives for two hop relaying. In our proposed scenario, the forwarder node sends its own data along with the data of the sender in exchange for additional transmission bandwidth, provided by the sender. We compare the performance of the proposed mechanism with optimal bandwidth and power allocation based direct transmission. We use sum rate, max-min rate and min-max power as the evaluation criteria and prove the convex concave nature of the optimization problem formulations. Our numerical analysis shows that the BE based cooperative forwarding extends the coverage in wireless networks when the far node falls in outage under direct transmission. Further, BE significantly improves the max-min rate and min-max power performance of the network. In a multiple-antenna relay channel, the full-duplex cut-set capacity upper bound and decode-and-forward rate are formulated as convex optimization problems. For half-duplex relaying, bandwidth allocation and transmit signals are optimized jointly. Moreover, achievable rates based on the compress-and-forward strategy are presented using rate-distortion and Wyner-Ziv compression schemes.