Robust and Efficient Multi-Cell Cooperation under Imperfect CSI and Limited Backhaul

Future cellular networks need to harvest existing spectral resources more efficiently. Hence, networks will be deployed at a higher density in order to increase the spatial reuse. This will require advanced interference mitigation techniques that allow to cope with the increased interference level. In this paper, the two-way interference channel is analyzed as a model for a typical inter-cell interference scenario. Based on this model, a new inter-cell interference mitigation approach is derived. This new approach reshapes interference by asymmetrically assigning uplink and downlink to communication pairs, i.e., one communication pair operates in uplink while an adjacent communication pair is in downlink. In addition, backhaul resources are taken into account, which are used to exchange support information between radio access points and to support the interference mitigation process. The introduced approach is compared to cooperative multi-point techniques which employ joint transmission and reception algorithms. The evaluation is done under consideration of limited backhaul resources and imperfect channel state information. It shows that assigning uplink and downlink asymmetrically is able to outperform cooperative multi-point techniques for terminals close to the cell border with gains of up to about 20 % compared to noncooperative transmission and 10 % compared to CoMP.