A divide-and-conquer approach to mitigate relay-to-relay interference

LTE-Advanced Type 1 inband relays support a two-hop decode-and-forward relaying mode where the relay link reception is time-division multiplexed with the access link transmission on different subframes. Thus, any misalignment in the subframe configurations of different relays may cause overlapped reception and transmission on both links generating a new type of interference, referred to as relay-to-relay interference. In this work, we propose a novel divide-and-conquer technique to mitigate such interference; the approach exploits the localized nature of the effect of the relay-to-relay interference and hence avoids the need to perform a network-wide subframe configuration. In particular, we propose a two-step scheme, namely grouping of RNs in exclusive groups and then aligning the subframe configurations within each group. Such an approach can be realized in a centralized manner by a proposed self-organizing network interference management entity within the Operation and Maintenance system. The proposed scheme is evaluated via comprehensive system-level simulations of relay deployments within the LTE-Advanced downlink framework. Results show that the divide-and-conquer approach can effectively mitigate relay-to-relay interference in all of the considered scenarios.