Downlink multicell distributed beamforming with intra-cell local channel state informations

In this paper, a distributed beamforming algorithm is proposed for downlink multicell network when the intra-cell local channel state informations (CSIs) are available at each base station (BS). The proposed algorithm includes three parts, firstly, an algorithm is proposed to estimate the direction vectors of the inter-cell local channels. The algorithm above utilizes a set of random orthogonal bases and the known training formula to get all basis vectors of orthogonal complement space of the inter-cell local channel vector. Secondly, a proposition based on singular value decomposition of all local channel vectors is presented for the distributed beamforming causing minimum intra-cell interference (InCI) and inter-cell interference (ICI) toward other users. Thirdly, with only intra-cell local CSIs at BS, a training algorithm is proposed to obtain the amplitudes of the whole local channel vectors. This training algorithm exploits the unit matrix and unit transmit power to perform fixed steps of training process, and the amplitude of inter-cell local channel vector is estimated by the observations of BS or user. Finally, simulation results demonstrate that the proposed algorithm can achieve higher user rate while offering more advantages to suppress InCI and ICI than the traditional ones.