The Two-Way Interference Channel: Towards a Redesign of Mobile Communication Systems

Full spatial reuse of spectral resources (frequency reuse of 1) is an inevitable consequence of the demanding requirements on mobile communication networks. A prerequisite to obtain full reuse is to either cancel or mitigate inter-cell interference as it otherwise limits the achievable performance. In order to derive new strategies for cellular interference-mitigation, this paper introduces the two-way interference channel and analyzes the achievable uplink-downlink data rates for different inter-cell interference scenarios. Of particular interest is an asymmetric protocol that exploits cross-uplink-downlink interference, i. e. two adjacent cells do not operate simultaneously in uplink or downlink but only one of both is active in uplink and one is active in downlink. Using analytical results, it is shown that under specific conditions this approach provides performance gains over conventional approaches and close to multi-cell MIMO. Although this approach is not able to improve the performance under all channel conditions, it provides a new degree of freedom which might be exploited if inter-cell interference significantly impairs the performance.