Precode and quantize channel state information sharing for cloud radio access networks

Joint transmission by a cluster of smart remote radio heads is an important technique for enhancing network throughout in future cellular networks. This transmission requires global channel state information at the processing unit which optimizes the joint precoder. To this end, a large amount of channel state information must be shared between the smart remote radio heads and that unit. In this paper, we present a new channel state information sharing scheme, which drastically reduces the large overhead in acquiring global channel state information for joint transmission. The idea is that each smart remote radio head applies a local precoding matrix, whose objective is to create equivalent channels which can be quantized more accurately with fewer bits, thereby to reduce the overhead of sharing channel state information. The proposed scheme facilitate joint transmission in a cluster in which the smart remote radio heads are interconnected by limited-rate link.