Spectrum and Infrastructure Sharing in Wireless Networks: A Case Study with Relay-Assisted Communications

Physical resource sharing between wireless operators and service providers can be used to support efficient, competitive, and innovative wireless com- munication markets. By sharing resources, which are usually exclusively allocated such as spectrum or infrastructure, interference is create d on the physical layer. Han- dling this new type of interference poses a significant and no vel challenge to the design of suitable transmission techniques. In this paper, we inve stigate the example of two- way relaying with amplify and forward relays as a case study. Here, two operators physically share their spectrum and the relay (infrastruct ure). We demonstrate that both operators can serve their users by using multiple antennas at the relay via a naive scheme inspired by the block diagonalization method. Numerical results verify that already this simple approach results in significant gains in terms of the sum data rates as compared to an exclusive (orthogonal) assignment of the resources. This shows that cooperation leads to a more efficient use of the shared re sources.