Browsing by Subject "Performance anomaly"

Now showing 1 - 3 of 3

Open Access
A distributed air-time fair MAC for multi-rate IEEE 80211 networks using multiple distributed coordination functions
(2010) Karataş, Fırat
In a multi-rate IEEE 802.11 network, the conventional Distributed Coordination Function (DCF) Medium Access Control (MAC) aims to ensure max-min throughput fairness and equal channel access in scenarios with multiple nodes, while failing to satisfy air-time fairness. Consequently, nodes that have relatively poor channels or longer packets to transmit invade the channel substantially more than others, hence decreasing the throughput of nodes which have better channels or shorter packets. This phenomenon is known as the performance anomaly problem in the existing literature. In this thesis, we propose a novel distributed air-time fair algorithm to cope with the performance anomaly problem without having to change the conventional IEEE 802.11 DCF MAC. In the proposed algorithm, each node in the system runs multiple instances of the conventional IEEE 802.11 DCF back-off algorithm where the number of instances for the particular node is calculated independently from other nodes using only local information such as packet lengths and transmission rates. Both analytical and simulationbased results are provided to validate the effectiveness of the distributed air-time fair algorithm we propose.
Open Access
A distributed solution for air-time fairness in multi-rate WLANs
(IEEE, 2013) Yazıcı, Mehmet Akif; Akar, Nail
WLANs employing IEEE802.11 standards suffer from a performance anomaly that drags down the fast nodes in the WLAN due to the slow nodes. Air time fairness has been proposed to battle this anomaly. We propose a novel distributed method to achieve air time fairness in this study. © 2013 IEEE.
Open Access
Running multiple instances of the distributed coordination function for air-time fairness in multi-rate WLANs
(IEEE, 2013) Yazici, M. A.; Akar, N.
Conventional multi-rate IEEE 802.11 Wireless LANs (WLANs) are associated with the so-called performance anomaly to describe the phenomenon of high bit rate nodes being dragged down by slower nodes. This anomaly is known to be an impediment to obtaining high cumulative throughputs despite the employment of effective link adaptation mechanisms. To cope with the performance anomaly, air-time fairness has been proposed as an alternative to throughput fairness, the latter being a main characteristic of the IEEE 802.11 Distributed Coordination Function (DCF). In this paper, we propose a novel distributed air-time fair MAC (Medium Access Control) without having to change the operation of the conventional DCF. In the proposed MAC, each node in the system runs multiple instances of the conventional DCF back-off algorithm where the number of DCF instances for the nodes can be chosen in a distributed manner. Both analytical and simulation-based results are provided to validate the effectiveness of the proposed air-time fair MAC.