Combined User Pairing and Spectrum Allocation for Multiuser SC-FDMA Transmission

This paper proposes a strategy that combines user pairing and spectrum allocation for a virtual multiple-input multiple-output (V-MIMO) single-carrier frequency-division multiple access (SC-FDMA) transmission over intersymbol interference (ISI) channels. The users are equipped with a single antenna each, where always two users, composing one pair, transmit their data in the same time slot and frequency band. The receiver at the base station (BS) is assumed to have multiple antennas and separates the users of each pair with a multiuser equalizer. For this, linear minimum mean-squared error (MMSE) equalization and successive interference cancellation (SIC), respectively, are chosen. A solution for the combined optimization of user pairing and spectrum allocation is proposed and evaluated by simulations for a transmission in the uplink of E-UTRA Long Term Evolution (LTE). The simulation results show that the proposed algorithm yields significant gains compared to random user pairing and spectrum allocation. It is also shown that, despite its considerably lower complexity, the performance of the novel algorithm is very close to that of the optimum solution that can only be found by a very complex full search.