Collision-Aware Rate Adaptation Research Articles

CARA-OHT: Collision-Aware Rate Adaptation for Optimal High-Throughput in IEEE 802.11s Wireless Mesh Networks

The wireless mesh network (WMN) is a future network technology that develops single-hop wireless local area networks (WLANs) into multi-hop wireless mesh networks, based on the IEEE 802.11s standard. However, this development still presents many challenges, such as determining the best route between sources and destinations, especially taking into account the use of the medium access control (MAC) and physical (PHY) layers of IEEE 802.11n/ac. Some papers have proposed rate adaptation algorithms particularly for single-hop networks; however, these only focused on mechanisms to find data rates suitable for channel conditions. In IEEE 802.11s WMNs, the design of the rate adaptation algorithm is more challenging. Besides considering the problem of channel quality and optimal throughput, it is necessary to also consider the problem of collision and the best route. It is important to take collision into account because the collision probability in multi-hop mesh networks is higher than that in single-hop networks and can lead to a lower throughput. Rate adaptation algorithms for IEEE 802.11s WMNs have been proposed in other papers, but they also do not consider the use of the MAC and PHY layers of IEEE 802.11n/ac. In this paper, we propose the collision-aware rate adaptation for optimal high-throughput (CARA-OHT) algorithm for WMN IEEE 802.11s. An evaluation through the extensive use of a network NS-3 simulator shows that the proposed algorithm exhibits a higher throughput than previously developed algorithms.

Throughput analysis of IEEE 802.11 multirate WLANs with collision aware rate adaptation algorithm

This paper presents a mathematical model that analyzes the throughput of the IEEE 802.11b distributed coordination function (DCF) with the collision aware rate adaptation (CARA) algorithm. IEEE 802.11 WLANs provide multiple transmission rates to improve system throughput by adapting the transmission rate to the current channel conditions. The system throughput is determined by some stations using low transmission rates due to bad channel conditions. CARA algorithm does not disturb the existing IEEE 802.11b formats and it can be easily incorporated into the commercial wireless local area networks (WLAN) devices. Finally, we verify our findings with simulation.

Collision-Aware Rate Adaptation in multi-rate WLANs: Design and implementation

Many rate adaptation algorithms have been proposed for IEEE 802.11 Wireless LAN devices and most of them operate in an open-loop manner, i.e., the transmitter adapts its transmission rate without using the feedback from the receiver. A key problem with such transmitter-based rate adaptation schemes is that they do not consider the collision effect. Accordingly, they often result in severe throughput degradation when many transmission failures are due to frame collisions. In this paper, we present a transmitter-based rate adaptation scheme, called CARA (Collision-Aware Rate Adaptation), and its MadWifi-based implementation. The key idea of CARA is that the transmitter combines adaptively the RTS/CTS (Request-to-Send/Clear-to-Send) exchange with the CCA (Clear Channel Assessment) functionality in order to differentiate frame collisions from transmission failures due to channel errors. The effectiveness of CARA schemes is evaluated via extensive ns-2 simulations and testbed experimentations.