Cooperative implicit feedback generation in interfering heterogeneous LTE networks

Next generation long term evolution (LTE) systems evolve towards small cell transmission to enable the tremendous data growth. However, emerging interference is the dominant limiting factor achieving higher network capacities. In this paper we focus on cooperative implicit feedback generation in interfering heterogeneous networks (HetNets) to assist the cell edge user equipment (UE) suffering from dominant co-channel inter-cell interference. As a hand-over might be refused and conventional precoding matrix index (PMI) selection schemes limit reliable downlink (DL) transmission, the co-scheduled UEs delegate the PMI selection to that victim UE, trimming the codebook. We provide a practical implementation for the cooperative PMI selection, keeping computational complexity and feedback overhead low. With numerical results at the link level we show that the suggested cooperative PMI selection algorithm mitigates co-channel inter-cell interference and as a result enables reliable DL transmission at the victim UE.