Abstract
The potential of multiantenna interference cancellation receiver algorithms for increasing the uplink throughput in WLAN systems such as 802.11 is investigated. The medium access control (MAC) in such systems is based on carrier sensing multiple-access with collision avoidance (CSMA/CA), which itself is a powerful tool for the mitigation of intrasystem interference. However, due to the spatial dependence of received signal strengths, it is possible for the collision avoidance mechanism to fail, resulting in packet collisions at the receiver and a reduction in system throughput. The CSMA/CA MAC protocol can be complemented in such scenarios by interference cancellation (IC) algorithms at the physical (PHY) layer. The corresponding gains in throughput are a result of the complex interplay between the PHY and MAC layers. It is shown that semiblind interference cancellation techniques are essential for mitigating the impact of interference bursts, in particular since these are typically asynchronous with respect to the desired signal burst. Semiblind IC algorithms based on second- and higher-order statistics are compared to the conventional no-IC and training-based IC techniques in an open access network (OAN) scenario involving home and visiting users. It is found that the semiblind IC algorithms significantly outperform the other techniques due to the bursty and asynchronous nature of the interference caused by the MAC interference avoidance scheme.
Highlights
Interference at the radio receiver is a key source of degradation in quality of service (QoS) as experienced in wireless communication systems
This is the case for the IEEE 802.11 family of wireless local area network (WLAN) systems [4], where the carrier sensing multiple-access with collision avoidance (CSMA/CA) medium access control (MAC) protocol is itself designed to eliminate the possibility of interference at the receiver from other users of the same system
The potential gains provided by multiantenna interference cancellation receiver algorithms, in the context of WLAN systems employing CSMA/CA protocols, were evaluated in this paper
Summary
Interference at the radio receiver is a key source of degradation in quality of service (QoS) as experienced in wireless communication systems. It is clear that any gains at the system level are highly dependent on the nature of cross-layer interactions, if multiple layers are designed to contribute to the interference mitigation process This is the case for the IEEE 802.11 family of wireless local area network (WLAN) systems [4], where the carrier sensing multiple-access with collision avoidance (CSMA/CA) MAC protocol is itself designed to eliminate the possibility of interference at the receiver from other users of the same system. The regularized semiblind algorithms can be applied independently or as an initialization for higher-order algorithms that exploit the finite alphabet (FA) or constant modulus (CM) properties of communication signals The efficiency of these algorithms has been compared to the conventional LS solution [1] by means of PHY simulations.
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