LTE Uplink CoMP Trial in a HetNet Deployment

Low power remote radio units (RRU:s) are identified as one of the key components to increase the capacity of cellular networks in dense areas with high traffic demands. When the traffic is clustered in hotspots they are also feasible to, combined with high power macro RRU:s, form a heterogeneous network (HetNet). The inherited centralized architecture with RRU:s opens for advanced coordination features between sites. One such promising coordination feature is uplink CoMP (Co-ordinated Multi Point). This paper shows results from a recent full scale CoMP trial on release 8 3GPP Long Term Evolution (LTE). It is demonstrated that best uplink reception (in a micro node) can be decoupled from best downlink transmission (from a macro node), enabling improved uplink bitrate with maintained downlink bitrate. Furthermore, with joint reception a significant uplink reception macro diversity gain is achieved. In the tested scenario on a 10 MHz band the total improvement is in the order of 6 Mbps in the macro-micro transition area.