Interference alignment aided by non-regenerative relays for multiuser wireless networks

Interference alignment is a promising technique to handle the interference in wireless networks. For a time-invariant channel, interference alignment for a scenario consisting of several pairs of nodes can be achieved using a number of single antenna relays. In the present work, a two time-slot transmission scheme which can be considered as a virtual MIMO interference channel is introduced. At the first time slot, every relay stores the received signal. During the second time-slot, it retransmits the received signal after a proper adjustment on both the amplitude and the phase of the signal. For a priori known transmit and receive filters, a closed form solution for the relays´ scaling factors is obtained. The required number of relays can be reduced by adapting the transmit and receive filters to the channel. Also the transmit energies of the relays are analyzed. The performance of the proposed scheme is investigated using numerical simulations. The results show that the proposed schemes outperform the conventional schemes, e.g., in terms of the achieved sum rates at high SNRs.