Near-optimum transmit power allocation for space– time block encoded wireless communication systems

Space–time block codes (STBCs) allow the diversity provided by multiple-input– multiple-output (MIMO) communication channels to be utilised, thereby increasing the capacity over ergodic fading channels or decreasing the outage probability over non-ergodic fading channels. The authors consider the deployment of orthogonal STBCs in spatially distributed mesh networks where the potentially different average sub-channel gains from any transmit to any receive antenna are assumed to be known at the transmitting elements. To optimise performance in terms of capacity or outage probability, heavy signal processing is required at each transmit element as only numerical optimisation is known to yield the optimum performance. In the paper, explicit near-optimum transmit power allocation strategies for distributed STBCs operating over ergodic and non-ergodic frequency-flat Rayleigh fading channels are introduced which reduce the required signal processing considerably.