494 research outputs found
A control theoretic approach to achieve proportional fairness in 802.11e EDCA WLANs
This paper considers proportional fairness amongst ACs in an EDCA WLAN for
provision of distinct QoS requirements and priority parameters. A detailed
theoretical analysis is provided to derive the optimal station attempt
probability which leads to a proportional fair allocation of station
throughputs. The desirable fairness can be achieved using a centralised
adaptive control approach. This approach is based on multivariable statespace
control theory and uses the Linear Quadratic Integral (LQI) controller to
periodically update CWmin till the optimal fair point of operation. Performance
evaluation demonstrates that the control approach has high accuracy performance
and fast convergence speed for general network scenarios. To our knowledge this
might be the first time that a closed-loop control system is designed for EDCA
WLANs to achieve proportional fairness
Rigorous and Practical Proportional-fair Allocation for Multi-rate Wi-Fi
Recent experimental studies confirm the prevalence of the widely known performance anomaly
problem in current Wi-Fi networks, and report on the severe network utility degradation caused by
this phenomenon. Although a large body of work addressed this issue, we attribute the refusal of
prior solutions to their poor implementation feasibility with off-the-shelf hardware and their impre-
cise modelling of the 802.11 protocol. Their applicability is further challenged today by very high
throughput enhancements (802.11n/ac) whereby link speeds can vary by two orders of magnitude.
Unlike earlier approaches, in this paper we introduce the first rigorous analytical model of 802.11
stations’ throughput and airtime in multi-rate settings, without sacrificing accuracy for tractability.
We use the proportional-fair allocation criterion to formulate network utility maximisation as a con-
vex optimisation problem for which we give a closed-form solution. We present a fully functional
light-weight implementation of our scheme on commodity access points and evaluate this extensively
via experiments in a real deployment, over a broad range of network conditions. Results demonstrate
that our proposal achieves up to 100% utility gains, can double video streaming goodput and reduces
TCP download times by 8x
Max-min Fairness in 802.11 Mesh Networks
In this paper we build upon the recent observation that the 802.11 rate
region is log-convex and, for the first time, characterise max-min fair rate
allocations for a large class of 802.11 wireless mesh networks. By exploiting
features of the 802.11e/n MAC, in particular TXOP packet bursting, we are able
to use this characterisation to establish a straightforward, practically
implementable approach for achieving max-min throughput fairness. We
demonstrate that this approach can be readily extended to encompass time-based
fairness in multi-rate 802.11 mesh networks
Running Multiple Instances of the Distributed Coordination Function for Air-time Fairness in Multi-Rate WLANs
Cataloged from PDF version of article.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. © 2013 IEEE
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