  A centralized coordinated multipoint downlink joint transmission in a
frequency division duplex system requires channel state information (CSI) to be
fed back from the cell-edge users to their serving BS, and aggregated at the
central coordination node for precoding, so that interference can be mitigated.
The control signals comprising of CSI and the precoding weights can easily
overwhelm the backhaul resources. Relative thresholding has been proposed to
alleviate the burden; however, this is at the cost of reduction in throughput.
In this paper, we propose utilizing the long term channel statistics comprising
of pathloss and shadow fading in the precoder design to model the statistical
interference for the unknown CSI. In this regard, a successive second order
cone programming (SSOCP) based precoder for maximizing the weighted sum rate is
proposed. The accuracy of the solution obtained is bounded with the branch and
bound technique. An alternative optimization framework via weighted mean square
error minimization is also derived. Both these approaches provide an efficient
solution close to the optimal, and also achieve efficient backhauling, in a
sense that the precoding weights are generated only for the active links. For
comparison, a stochastic approach based on particle swarm optimization is also
considered.
