Performance comparison of cooperative downlink transmission schemes in IEEE 802.11ac: Interference alignment vs. MU-MIMO with TDMA

Recently, demand for high data rate of wireless service is increased due to full high definition (HD) video transmission and cloud services and so on. To enhance the capacity, many APs are installed in various places. Because of multiple APs are deployed in unplanned situation, interference between basic service set (BSS) is increased. To reduce the overlapped BSS (OBSS) interference of IEEE 802.11ac interfering broadcasting network, we suggest two cooperative transmission schemes which are interference alignment (IA) and multi-user multi-input and multi-output (MU-MIMO) with time division multiple access (TDMA). We can simultaneously transmit the data in the same time and frequency with IA, however, the required overhead of transmission for IA is considerably high. However, MU-MIMO with TDMA scheme needs lower overhead than IA because only channel state information (CSI) feedback of a desired link from AP to STA and AP Poll transmission which decides the timely transmission order for MU-MIMO with TDMA. Even though there are a few feedback quantity for MU-MIMO with TDMA, the average throughput will be reduced because the data should be transmitted by dividing the time. Therefore, we have observed the average throughput between IA and MU-MIMO with TDMA in IEEE 802.11ac interfering downlink network. And we also compare the performance between two cooperative downlink transmission schemes.