3,070 research outputs found
Proportional Fair Coding for Wireless Mesh Networks
We consider multi–hop wireless networks carrying
unicast flows for multiple users. Each flow has a specified
delay deadline, and the lossy wireless links are modelled as
binary symmetric channels (BSCs). Since transmission time, also
called airtime, on the links is shared amongst flows, increasing
the airtime for one flow comes at the cost of reducing the
airtime available to other flows sharing the same link. We
derive the joint allocation of flow airtimes and coding rates that
achieves the proportionally fair throughput allocation. This utility
optimisation problem is non–convex, and one of the technical
contributions of this paper is to show that the proportional
fair utility optimisation can nevertheless be decomposed into
a sequence of convex optimisation problems. The solution to
this sequence of convex problems is the unique solution to the
original non–convex optimisation. Surprisingly, this solution can
be written in an explicit form that yields considerable insight
into the nature of the proportional fair joint airtime/coding rate
allocation. To our knowledge, this is the first time that the utility
fair joint allocation of airtime/coding rate has been analysed,
and also, one of the first times that utility fairness with delay
deadlines has been considered
Cross-layer design of multi-hop wireless networks
MULTI -hop wireless networks are usually defined as a collection of nodes
equipped with radio transmitters, which not only have the capability to
communicate each other in a multi-hop fashion, but also to route each others’ data
packets. The distributed nature of such networks makes them suitable for a variety of
applications where there are no assumed reliable central entities, or controllers, and
may significantly improve the scalability issues of conventional single-hop wireless
networks.
This Ph.D. dissertation mainly investigates two aspects of the research issues
related to the efficient multi-hop wireless networks design, namely: (a) network
protocols and (b) network management, both in cross-layer design paradigms to
ensure the notion of service quality, such as quality of service (QoS) in wireless mesh
networks (WMNs) for backhaul applications and quality of information (QoI) in
wireless sensor networks (WSNs) for sensing tasks. Throughout the presentation of
this Ph.D. dissertation, different network settings are used as illustrative examples,
however the proposed algorithms, methodologies, protocols, and models are not
restricted in the considered networks, but rather have wide applicability.
First, this dissertation proposes a cross-layer design framework integrating
a distributed proportional-fair scheduler and a QoS routing algorithm, while using
WMNs as an illustrative example. The proposed approach has significant performance
gain compared with other network protocols. Second, this dissertation proposes
a generic admission control methodology for any packet network, wired and
wireless, by modeling the network as a black box, and using a generic mathematical
0. Abstract 3
function and Taylor expansion to capture the admission impact. Third, this dissertation
further enhances the previous designs by proposing a negotiation process,
to bridge the applications’ service quality demands and the resource management,
while using WSNs as an illustrative example. This approach allows the negotiation
among different service classes and WSN resource allocations to reach the optimal
operational status. Finally, the guarantees of the service quality are extended to
the environment of multiple, disconnected, mobile subnetworks, where the question
of how to maintain communications using dynamically controlled, unmanned data
ferries is investigated
Utility Optimal Coding for Packet Transmission over Wireless Networks - Part II: Networks of Packet Erasure Channels
We define a class of multi--hop erasure networks that approximates a wireless
multi--hop network. The network carries unicast flows for multiple users, and
each information packet within a flow is required to be decoded at the flow
destination within a specified delay deadline. The allocation of coding rates
amongst flows/users is constrained by network capacity. We propose a
proportional fair transmission scheme that maximises the sum utility of flow
throughputs. This is achieved by {\em jointly optimising the packet coding
rates and the allocation of bits of coded packets across transmission slots.}Comment: Submitted to the Forty-Ninth Annual Allerton Conference on
Communication, Control, and Computing, Monticello, Illinois, US
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
Applications of Repeated Games in Wireless Networks: A Survey
A repeated game is an effective tool to model interactions and conflicts for
players aiming to achieve their objectives in a long-term basis. Contrary to
static noncooperative games that model an interaction among players in only one
period, in repeated games, interactions of players repeat for multiple periods;
and thus the players become aware of other players' past behaviors and their
future benefits, and will adapt their behavior accordingly. In wireless
networks, conflicts among wireless nodes can lead to selfish behaviors,
resulting in poor network performances and detrimental individual payoffs. In
this paper, we survey the applications of repeated games in different wireless
networks. The main goal is to demonstrate the use of repeated games to
encourage wireless nodes to cooperate, thereby improving network performances
and avoiding network disruption due to selfish behaviors. Furthermore, various
problems in wireless networks and variations of repeated game models together
with the corresponding solutions are discussed in this survey. Finally, we
outline some open issues and future research directions.Comment: 32 pages, 15 figures, 5 tables, 168 reference
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
Proportional Fair MU-MIMO in 802.11 WLANs
We consider the proportional fair rate allocation in an 802.11 WLAN that
supports multi-user MIMO (MU-MIMO) transmission by one or more stations. We
characterise, for the first time, the proportional fair allocation of MU-MIMO
spatial streams and station transmission opportunities. While a number of
features carry over from the case without MU-MIMO, in general neither flows nor
stations need to be allocated equal airtime when MU-MIMO is available
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