Date Added: May 2012
High spectral efficiency can be achieved in the downlink of multi-antenna coordinated multi-point systems provided that the multi-user interference is appropriately managed at the transmitter side. For this sake, down-link channel information needs to be sent back by the users, thus reducing the rate available at the up-link channel. The amount and type of feedback information required has been extensively studied and many limited feedback schemes have been proposed lately. A common pattern to all of them is that achieving low rates of feedback information is possible at the cost of increasing complexity at the user side and, sometimes, assuming that some statistics of the channel are known.