Combined Frequency and Spatial Domains Power Distribution for MIMO-OFDM Transmission

In this paper, we propose to adapt simultaneously the transmit power both in the spatial and frequency domains using a heuristic expression of the bit error rate (BER) for each sub- carrier and transmit antenna. The proposed method consists of grouping a certain number of subcarriers and performing local power adaptation in each subcarrier group and transmit antenna. The subcarrier grouping is performed in such a way that equalizes the average channel condition of each subcarrier group. The grouping and the local power adaptation allow us to take advantage of the channel variations and to reduce the computational complexity of the proposed power distribution scheme. With the simplicity of the heuristic BER expression, we can obtain a closed form expression of the transmit power to be allocated. Simulation results show significant performance gain in term of BER compared to the equal power distribution.