User pairing and power allocation for energy efficient SC-FDMA transmission with QoS requirements

In this paper we consider joint user pairing, frequency resource and power allocation with Quality of Service (QoS) requirements for a single-carrier frequency-division multiple-access (SC-FDMA) uplink transmission. The optimum solution to this problem is derived for a zero-forcing (ZF) and a minimum mean-squared error (MMSE) equalizer, respectively. It is shown that the required powers for a given data rate can be analytically determined for the ZF equalizer, whereas a numerical solution is provided for MMSE equalization. The optimum approach to the joint optimization problem requires far too much computational complexity for an actual implementation and therefore two suboptimal algorithms with reduced complexity are proposed. Numerical results are presented that show that the reduced-complexity algorithms perform close to the optimum scheme.