A cooperative channel estimation approach for coordinated multipoint transmission networks

This paper considers the problem of coordinated multi-point transmission from transmitter devices that acquire noisy and partial channel state information (CSI) estimates from local feedback links. As cooperative multi-antenna transmission often relies on the availability of global channel estimates, we propose a novel decentralized algorithm that produces MMSEoptimal channel estimates on the basis of combining local feedback and inter-transmitter communications. To this end, we assume the devices are equipped with rate-limited bi-directional communication links over which they exchange a finite number of CSI-related bits. We propose a low-complexity cooperative channel estimation algorithm which exploits the local communications near-optimally and is robust to arbitrary feedback noise statistics. The proposed method has application in future decentralized CoMP scenarios, where we show clear advantages over the conventional channel state information exchange mechanisms.