Interference Alignment (IA) and Coordinated Multi-Point (CoMP) Overheads and RF Impairments: Testbed Results

Abstract

Abstract-In this work we investigate the network MIMO techniques of interference alignment (IA) and joint transmission coordinated multipoint (CoMP) in an indoor very small cell environment. Our focus is on the overheads in a system with quantized channel state feedback from the receiver to the transmitter (based on the 802.11ac standard) and on the impact of non-ideal hardware. The indoor office scenario should be the most favorable case in terms of the required feedback rates due to the large coherence bandwidth and coherence time of the channel. The evaluations are done using a real-world wireless testbed with three BSs and three MSs all having two antennas. The signal to noise ratio in the measurements is very high, 35-60dB, due to the short transmission range. Under such conditions radio hardware impairments becomes a major limitation on the performance. We quantify the impact of these impairments. For a 23ms update interval the overhead is 2.5% and IA and CoMP improves the sum throughput 27% and 47% in average (over the reference schemes e.g. TDMA MIMO), under stationary conditions. When two people are walking in the measurement area the throughput improvements drops to 16% and 45%, respectively.

Second-Order Kalman Filtering Application to Fading Channels Supported by Real Data

“…There had been a great consideration and search in the area of measurements and modeling of the propagation effects in the indoor environments. However, such work only considered a specific environment explicitly stationary scenarios as reported in [15] [16], and thus the empirical results and modeling cannot represent a mobile device environment, where the wireless communication takes place while the mobile device is moving. In December of 2015, authors of [17] presented an alternative measurement technique that enabled us to conduct experiment where wireless devices are moving in more than one direction.…”

Performance evaluation of Joint Transmission Coordinated-Multipoint in dense Very High Throughput WLANs scenario

“…The throughput gain is considerable compared to that using CoMP in LTE, thanks to the collision decrease and transmission opportunity increase. [23] argues that the CSI of feedback scheme in MIMO network leads to a serious overhead problem mainly in outdoor deployment with mobility. So, it considers an indoor 802.11ac network and investigates, by simulation and measurement on a testbed, the CB/CS approach of CoMP and compares its performance to MIMO Interference Alignment (IA).…”