Abstract: A joint optimization algorithm of relay beamforming and user power allocation is proposed for cooperative single-carrier frequency-division multiple access (SC-FDMA) systems with signal-to-interference-plus-noise ratio (SINR) constraint. The proposed algorithm can minimize the transmit powers for the relay and user while maintaining the output SINR at the base station above a pre-specified SINR threshold. The optimal solution for the optimization problem is derived and analyzed by employing Rayleigh quotient and the alternative optimization theory. Simulation results and analysis show that the proposed beamforming algorithm can save more transmit powers for the relay and user compared with the algorithm used in orthogonal frequency division multiplexing systems. Moreover, in order to reduce the computational complexity and feedback overhead, equal power allocation for the user and the corresponding relay beamforming algorithm are also proposed.

Key words: relay beamforming, single-carrier frequency-division multiple access (SC-FDMA), cooperative communications, power allocation