OFDM transmission diversity scheme for MMAC systems

OFDM (orthogonal frequency division multiplexing) is used in the MMAC (multimedia mobile access communication) systems using 5 GHz band systems as an effective solution under a multipass fading environment. Transmission space diversity techniques for OFDM have been reported. In order to improve the performance better, it is proposed to control the gain of each sub-carrier at the transmitter side using transmission space diversity. Then the receiver gets a constant received level at each sub-carrier. Using this scheme, the receiver improves the performance better. Moreover, concerning peak power reduction, it is proposed to control the bound of the maximum gain according to number of sub-carriers in each branch