Fading Broadcast Channels with One-Sided Feedback

In this paper, we study the fading broadcast channel with perfect CSIR and one-sided feedback. One important scenario for multiuser wireless communications is the broadcast channel (BC) where a single transmitter sends independent information to many receivers, for example in the downlink of a cellular system. The capacity region of a fading BC with perfect channel state information at the transmitter (CSIT) and the receivers (CSIR) along with the capacity-achieving transmission strategy was found. However, knowing the channel perfectly at the transmitter requires 1) perfect channel measurements at the receiver and 2) a perfect feedback link to send the estimates to the transmitter. The second requirement is usually harder to meet than the former in a practical system, especially for all the users in the system. For the two-user broadcast channel, this means that only one user may be able to feedback its channel values instantaneously to the transmitter and so the feedback is one-sided. We find achievable rate regions for the fading BC with one-sided feedback for three possible broadcast transmission strategies-1) super-position coding (SPC), 2) dirty-paper coding (DPC) and 3) time-division multiplexing (TDM).