Adaptive Distributed Precoding Scheme Based on Gradient Iteration for CoMP Systems

An adaptive distributed precoding scheme is proposed for coordinated multi-point transmission systems. The precoding vector used by coordinated base station (BS) is determined by adaptive gradient iteration according to the perturbation vector and adjustment factor. The user equipment only feeds one quantized adjustment factor back to each coordinated BS. The adjustment factor is selected based on the precoding vector of the coordinated BS in the previous frame and the perturbation vector predefined in this frame. The proposed scheme takes advantage of the spatial non-correlation and temporal correlation of the distributed MIMO channel. The design of the perturbation vector set is given. Simulation results show that the proposed scheme has a good trade-off between system performance and the system control feedback overhead.