Co-primary inter-operator spectrum sharing using repeated games

Currently mobile network operators are allocated spectrum bands on an exclusive basis. While this approach facilitates interference control, it may also result in low spectrum utilization efficiency. Inter-operator spectrum sharing is a potential method to enhance spectrum utilization. In order to realize it, a protocol to coordinate the actions of operators is needed. In this paper, we propose a spectrum sharing protocol which is distributed in nature, does not require operator-specific information exchange, and incurs minimal communication overhead between the operators. Operators are free to decide whether they share spectrum or not as the protocol is based on a book keeping of spectrum usage favors asked and received by the operators. We show that operators can enhance their QoS in comparison with a scheme where no spectrum sharing is allowed while also maintaining reciprocity i.e. no operator benefits over the other in the long run. We demonstrate the usability of the proposed protocol in an indoor deployment scenario with frequent network load variations which are expected in small cell deployments.