A precoded OFDMA system with user cooperation

We propose a two user OFDMA scheme with interblock precoding and user cooperation.We show that the proposed scheme can achieve maximum diversity of order twice the number of fading paths. A non-cooperative precoded OFDMA system that uses the same transmission energy per information block would require at least two transmit antennas to achieve the same diversity. In cases where there is a significant difference in SNR between each user/destination pair, the proposed scheme can improve the capacity of the weak user.