On MAC Layer Throughput Enhancements in LTE-A by Downlink Macro Diversity

Coordinated transmission between base stations is one of the techniques under investigation to further improve the system performance of E-UTRA. In general, such a coordination, sometimes also called network MIMO, requires a large amount of signaling between cells. A relatively simple scheme for cell coordination is macro diversity. In this paper we consider macro diversity for the downlink direction of LTE-Advanced as a means to improve cell edge user throughput. We investigate the frequency-selectivity gains offered by over the air combining for different radio channels at link level. The impact on cell throughput as well as on user throughput for mobiles operated in macro diversity mode and for legacy mobile stations is investigated by means of system level simulations. Additionally, open issues related to network coordination are identified for future work.