Repeated spectrum sharing games in multi-operator heterogeneous networks

When femto cells of different network operators do not generate harmful interference to each other, they may agree to aggregate their spectral resources and share spectrum. While this approach would enhance the femto cell performance of both operators, it may introduce harmful inter-operator cross-tier interference, for instance, between the femto cells of one operator and the micro or the macro cells of the other. In this paper, we design a scheme in which two operators construct a spectrum pool and coordinate spectrum sharing in the downlink using repeated games between femto cells and micro cells of different network operators. The scheme does not require operator-specific information exchange. It is based on book keeping of asking and receiving spectrum usage favors. When the micro cells of an operator are exposed to high inter-operator interference, they ask for spectrum usage favors from the femto cells of the opponent operator. A spectrum usage favor is exchanged if the micro cells of an operator ask for the permission to use some of the resources of the spectrum pool exclusively, and the femto cells of the opponent operator allow it. Micro cells with a high load may take spectrum usage favors from femto cells that have few users to serve. We illustrate that two heterogeneous network operators can exploit varying network traffic and interference profiles in space and time and both achieves benefits from spectrum sharing.