Intra-site CoMP in LTE-A systems: An antenna-selection-based solution

It is known that in cellular systems, the users in cell edge suffer from the interference from interfering cells. In LTE-A, coordinated multi-point (CoMP) processing was proposed to solve the problem. In CoMP, the transmitted/received signals of the users in neighbor cells can be jointly processed such that interference can be either avoided or estimated as desired signals. In the current CoMP operations, precoding is only conducted between individual base-stations and the served user. If we take all the base-stations and the served user into consideration, a network multiple-input-multiple-output (MIMO) system can be constructed. Precoding in such system will have better performance but require a high-dimension codebook which is not supported by current LTE-A systems. In this paper, we first propose a method to solve the problem. The idea is to use the antenna selection technique reducing the number of transmitted antennas such that the existing codebooks can still be used. Existing selection criteria for the maximum likelihood receivers often require sophisticated matrix operations such as QR-decomposition (QRD). Thus, the required computational complexity is high. We then propose some selection criteria without involving matrix operations. Simulations show that while the antenna-selection based precoding method can reduce the feedback overhead and at the same time improve the precoding performance. Also, the performance of the proposed low-complexity criteria is similar to that of the QRD-based criteria.