Near-Optimal Linear Precoding for Multi-Point Cooperative Transmission with Frequency-Selective Channel

Using cyclic prefix (CP), the transmission schemes, Orthogonal frequency-division multiplexing (OFDM), Single carrier block transmission, and Time Reversal, can be unified as linear block precoding. Considering frequency-selective channel, this paper studies linear block precoding for CP-based multipoint transmission with individual antenna power constraints under capacity maximization criterion. We prove that, the optimal precoder can be of OFDM type (i.e., an inverse discrete fourier transformation (IDFT) matrix multiplying a complex diagonal matrix) but not necessarily. Further, we show that the capacity maximization problem with individual power constraints can be simplified as an unconstrained problems, which allows us to solve the problem using the simple gradient decent method. Simulation results show that the proposed precoding method achieves nearoptimal performance.