Experiments on Coordinated Multipoint Coherent Joint Transmission Using Remote Radio Heads in LTE-Advanced Downlink

This paper presents experimental results on coordinated multipoint (CoMP) coherent joint transmission (JT) using remote radio heads (RRHs) in the LTE-Advanced downlink. We investigate the gain of CoMP coherent JT compared to transmission point (TP) selection or non-CoMP in laboratory and field experiments considering the number of channel state information (CSI) feedback bits from a mobile station (MS), the moving speed of the MS, and the difference of path loss between TPs. Field experiments, which are conducted in a suburban area of Yokosuka city in Japan, show that the achievable user throughput employing adaptive modulation and coding and hybrid automatic repeat request at the cell boundary for CoMP coherent JT is 4.2 (3.9) and 1.5 (1.4) times greater than that for non-CoMP and TP selection, respectively, when the number of CSI feedback bits per subband is 5 bits and the moving speed of the MS is 3 (10) km/h.