Investigation of power allocation of transmit antennas selected for limited power communication systems

Considering the multiple input and multiple output (MIMO) communication systems under both cases of limited and unlimited power per transmitted antenna, the paper proposes an algorithm of optimal transmit power, referred to as water-filling algorithm. The principle of power allocation under limited power systems and no limited power ones are discussed, respectively. The principle of power water-filling for the limited-power systems is introduced and examples also are provided. Following, the paper considers the performance of multiple transmit and single receive antenna (MISO) system employing orthogonal space-time block coding (STBC) and binary phase shift-keying (BPSK) modulation, and derives a Chernoff upper bound (CUB) theoretical expression of bit error rate (BER) for the multiple transmit antennas selection MISO systems. The numerical results show that appropriate power allocation for transmit antennas selected can effectively enhance system bit error performance. Meanwhile, the performance improvement is not obvious if total transmit power is filled to the best antenna selected. These conclusions have a guidance function in practical mobile communication systems.