Beamforming techniques for enabling spatial-reuse in MCCA 802.11s networks

Abstract

We address the problem of co-channel interference (CCI) in wireless mesh networks based on the IEEE802.11s extension. The carrier sensing mechanism deployed in those networks insufficiently addresses the CCI problem, causing the hidden and exposed node problems; consequently degrading the throughput and latency. In this paper, we show how beamforming techniques can be implemented on top of the IEEE802.11s medium access control protocol and, using the information readily available, cancel the interference to mitigate this inefficiency of carrier sense and improve the spatial-reuse gain. In addition, we propose the signal-to-jamming-noise ratio (SJNR) beamformer and show that it significantly improves the spatial-reuse gain compared to the simple zero-forcing (ZF) beamformer and the basic IEEE802.11s access scheme. We derive the ergodic capacity of the ZF beamformer and the basic IEEE802.11s access scheme and simulate the performance of the various schemes. We show that improvements of up to 85% are achieved as function of the scenario simulated and the beamforming technique used and that the SJNR scheme outperforms the standard ZF beamformer.

Empirical Performance Evaluation of Enhanced Throughput Schemes of IEEE802.11 Technology in Wireless Area Networks

“…[20] Investigated the efficiency of multi-cast beamforming optimization over IEEE802.11n WLAN. [21] Proposed the combination of advanced distributed beamforming techniques at physical layer for the improvement of the overall network capacity. Analytical modelling to evaluate the performance of ad hoc networks with M-element array was conducted by [22].…”

Investigation of Beam Forming Effectiveness in Ieee802.11AC Indoor Wireless Links

“…Matlab simulation was used [8] to investigate the efficiency of multi-cast beam forming optimization over IEEE802.11n WLAN. [9] proposed the combination of advanced distributed beam forming techniques at physical layer for the improvement of the overall network capacity. Analytical modelling to evaluate the performance of ad hoc networks with M-element array was conducted by [10].The upper and lower bounds on the transmission capacity in the multiple antenna ad hoc networks with multi-stream transmission and interference cancellation at the receiver were derived by [11] to increase system capacity through beam forming technique.…”

Solving hidden terminal problem in MU-MIMO WLANs with fairness and throughput-aware precoding and a degrees-of-freedom-based MAC design

“…In the multi-antenna wireless network scenario, the physical layer (PHY) technique such as zeroforcing (ZF) has been used to design a medium access control (MAC) protocol [12,13] and [14], where HT problem is briefly discussed. In [12], ZF beamforming technique for null steering similar to [13] was used in mesh networks.…”

“…The flip side of the scheme was the inefficient use of the spectrum because after every successful communication sessions, nodes were supposed to keep silent for a certain period of time specified in the field silent period in RTS and CTS so that they might not disturb neighbors' communications. Likewise, ZF beamforming technique enabling spatial reuse was presented in reference to IEEE802.11s in [14]. However, the scheme relies on optional mesh coordinated channel access (MCCA) for channel access which is challenging from synchronization aspects in such a decentralized mesh network.…”

“…The PHY design is supported by a degrees of freedom (DoF)-based MAC protocol. Unlike its precursors that used ZF null steering approach for MAC design [12][13][14] and other HT solutions [4,7,9,11], our design excels in twofolds. First, it maintains concurrent transmissions in the HT scenario (managed by our extended PCF).…”