Optimal clustering and rate allocation for uplink coordinated multi-point (CoMP) systems with delayed channel state information (CSI)

Abstract

Coordinated multi-point (CoMP) is a promising technology in next generation cellular networks to enhance the cell-edge performance under universal frequency reuse. In uplink CoMP, the transmitted signals from user equipments are cooperatively processed by multiple base stations assuming there is perfect channel state information (CSI) shared by those base stations. However, practical systems can only obtain imperfect CSI which suffers from quantization errors and especially delay introduced by channel estimation and signalling over backhaul networks. In this paper, we consider the optimal clustering and rate allocation problem in CoMP systems where the CSI feedback via backhaul is delayed. We model such system in the framework of networked Markov decision process (networked-MDP), which is equivalent to a partial observable Markov decision process (POMDP). We find out an optimal policy for such POMDP, which is computational inexpensive. Extensive simulations show promising performance gain of the proposed scheme over existing scheme which makes the decisions merely based on the current observation.