TY - JOUR T1 - Spatial Interference Alignment in Relay-Assisted Multi-Cell Multi-User Networks TT - JF - ITRC JO - ITRC VL - 8 IS - 4 UR - http://ijict.itrc.ac.ir/article-1-50-en.html Y1 - 2016 SP - 1 EP - 10 KW - Cellular network KW - degrees of freedom KW - interference alignment KW - relay KW - sum rate N2 - In this paper, the spatial interference alignment (IA) is investigated in the downlink (DL) of a relay-assisted multi-cell multi-user network. The transmission from the base station (BS) to the mobile station (MS) takes place in two phases with the help of the selected relay station (RS). The closed-form IA algorithms are employed in both the BS to RS and RS to MS links. The performance of this cooperative scheme is analyzed in terms of the sum rate and the sum degrees of freedom (DoF) for the amplify-and-forward (AF) and decode-and-forward (DF) relaying schemes. The simulation results of the sum rate show that the DF scheme significantly outperforms the noncooperative minleakage and max-SINR iterative algorithms over the entire range of SNR, and the AF scheme performs very close to the min-leakage algorithm. Moreover, the DF scheme outperforms the noncooperative closed-form IA algorithm in the low and medium-SNR regimes. M3 ER -