Bandwidth efficient cooperative diversity scheme based on relaying superposition symbols

A bandwidth efficient three-user cooperative diversity scheme based on relaying superposition symbols is proposed. Each user has two partners and each partner relays superposition symbols of the other two users instead of repetition. Thus, the bandwidth efficiency is improved compared to the baseline decode-and-forward cooperative diversity scheme in which each user retransmits its partner¿s information by employing repetition coding. The proposed scheme can also offer diversity order of two. Then, a new constellation labeling for the superposition 8PSK modulation to exploit the symbol mapping diversity is designed and it is a simple way to obtain a gain of about 2 dB.