Two-mode limited feedback block-fading adaptive transmission with minimum guaranteed rate in MIMO channel

This paper develops an adaptive scheme relying on a part-time availability of the channel state information and supplying the constant minimum rate achievable for an arbitrary fading realization. The two-mode transmission is investigated with the instantaneous perfect channel state information being known at the transmitter in the limited portion of time. We derived a general procedure for a suitable probabilistic description of the channel under such a scheme. The first mode is without any feedback and it uses a simple uniform symbol energy assignment. The second one is the emergency mode with the perfect instantaneous channel state information. It is implemented by the channel inversion (or eigenmode sub-space channel inversion) guaranteeing the minimum required rate regardless of the channel observation. The parameters of the transmission are the total available transmitted symbol energy, the portion of time the perfect feedback channel is used, the minimum required rate, and the average symbol energy transmitted in the first and the second mode. For these cases, we have found very essential trade-off among the system parameters and also we have derived a general procedure how to evaluate long-term performance. Copyright © 2010 John Wiley & Sons, Ltd.