Statistical power allocation strategy for vector block-fading channels

The paper studies power control schemes for achieving the ergodic capacity of vector block-fading (BF) channels when the channel state information (CSI) is available to both transmitter and receiver sides. The optimal water-filling solution achieves the maximum ergodic capacity, but requires complicated calculations and frequent adjustment of the transmission powers. On the other hand, a single-target constant power (ST-CP) policy is easier to implement, but experiences large capacity loss compared to the optimal solution. A suboptimal policy is proposed which first groups the sub-channels within the frame of interest into multiple grouped channels, then allocates different constant powers to each grouped channel using a statistical water-filling (SWF) policy. The new scheme asymptotically achieves the maximum ergodic capacity. Simulations are given to evaluate the performance of the new scheme, and to compare it with the optimal power allocation scheme and the single-target constant power policy.