Recent work has shown that the usage of multiple antennas at the transmitter and receiver in a flat fading environment results in a linear increase in channel capacity. But increasing the number of antennas induces the higher hardware costs and computational burden. To overcome those problems, it is effective to select antennas appropriately among all available ones. In this paper, a new antenna selection method is proposed. The transmit antennas are selected so as to maximize the channel capacity using the genetic algorithm (GA) which is the one of the general random search algorithm. The results show that the proposed GA achieves almost the same performance as the optimal selection method with less computational amount.

Adaptive transmission methods improve the performance of wireless communication system by adjusting parameters like modulation, code-rate, and power depending on the channel state adaptively. In this letter, we consider the adaptive code-rate OFDM system in which code-rate of each subcarrier is adapted optimally. RCPC code is used to obtain different code-rate for each subcarrier. Performance analysis shows that 3-6 dB SNR gain or up to 30-50% data rate increase is achieved at bit error rate 10-6.