Optimal Resource Sharing and Network Beamforming in Multi-Carrier Bidirectional Relay Networks

Considering a bidirectional collaborative scheme, we study the problem of resource sharing between two transceiver pairs in a multi-carrier scenario. One pair, referred to as the primary pair, is considered to be the owner of the spectral resources, meaning that the rates of its users must be guaranteed to be greater than a predefined threshold. It is assumed that the other pair, called the secondary pair, owns the relay infrastructure. Considering no direct link between the transceivers in each pair, the primary network allows the secondary pair to use the spectral resources in order to establish a bidirectional communication between its transceivers. In exchange for this cooperation, the primary pair utilizes the relay infrastructure, thereby enabling a two-way communication between its transceivers. Assuming amplify-and-forward relaying scheme in each subchannel, the relays collectively build two network beamformers each of which enables communication between one pair of transceivers. Aiming to optimally calculate the parameters of the two networks, we study two different approaches. The first approach relies on maximizing the secondary network average sum-rate subject to two spectral power masks for the two networks, while providing a minimum sum-rate to the primary pair in a multi-relay scenario. In the second approach, we consider a constraint on the total power consumed in each network over all subchannels, while maximizing the sum-rate of the secondary transceivers. In this approach, we provide two iterative convex search solutions, one for a single-relay case and one for a multi-relay scenario.