Power Allocation for Discrete-Input Non-Ergodic Block-Fading Channels

摘要

We consider power allocation algorithms for fixed-rate transmission overNakagami-m non-ergodic block-fading channels with perfect transmitter andreceiver channel state information and discrete input signal constellationsunder both short- and long-term power constraints. Optimal power allocationschemes are shown to be direct applications of previous results in theliterature. We show that the SNR exponent of the optimal short-term scheme isgiven by the Singleton bound. We also illustrate the significant gainsavailable by employing long-term power constraints. Due to the nature of theexpressions involved, the complexity of optimal schemes may be prohibitive forsystem implementation. We propose simple sub-optimal power allocation schemeswhose outage probability performance is very close to the minimum outageprobability obtained by optimal schemes.