Broadcast channel: Degrees of freedom with no CSIR

We analyze a broadcast channel with no initial assumption of channel state information neither at the base station (BS) nor at the users' side. For the case when there is no possibility of feedback to the BS and it remains oblivious of the channel state information throughout the transmission, it is shown that the capacity region is bounded by the capacity of a point-to-point MISO link and hence the pre-log of the sum rate is (1 - 1/
T
) for a block fading channel of coherence length
T
. When the BS is allowed to acquire channel knowledge, operating under time-division duplex (TDD) mode, we give a very simple scheme through which BS and all users get necessary channel state information and the high SNR sum rate shows significant multiplexing gain or degrees of freedom (DOF).