1,720,969 research outputs found
Low-Delay Proportional Fair Rate Allocation for 802.11ac WLAN Downlink
No full textIn this paper we consider a next generation edge architecture where traffic is routed via a proxy located close to the network edge (e.g. within a cloudlet). This creates freedom to implement new transport layer behaviour over the wireless path between proxy and clients. We use this freedom to develop a novel approach to achieving high rate, low latency communication on the downlink. This works by adjusting the send rates to clients so as to regulate the aggregation level of transmitted frames which in turn robustly regulates the queueing delay at the AP. We derive the low-delay proportional fair rate allocation in the presence of aggregation and using this consider primal-dual and PI controller approaches for achieving the low-delay proportional fair rate allocation. We find that the primal-dual approach is fragile in the sense that it is sensitive to modelling errors, and in contrast the PI controller approach is much more robust. We present numerical simulation results evaluating the performance
Fair virtualization of 802.11 networks
No full textWe consider virtualization of network capacity in 802.11 WLANs and mesh networks. We show that allocating total airtime slices to ISPs is analogous to allocating a fraction of available time-slots in TDMA. We establish that the max-min fair flow rate allocation within an ISP airtime slice can be characterized independently of the rate allocation policy employed in other slices. Building on these observations, we present a lightweight, distributed algorithm for allocating airtime slices among ISP and max-min fair flow rates within each slice
Low-delay high-rate operation of 802.11ac WLAN downlink: Nonlinear controller analysis & design
No full textIn this paper we present a novel nonlinear control design for regulating the aggregation level in 802.11 WLANs so as to ensure robust low-delay operation at high data rates. The controller compensates for system nonlinearities and so can be used for the full range of WLAN operation. We develop an implementation of the nonlinear control design and use this to evaluate performance using both simulations and hardware measurements
Regulating Aggregation Level for Low Latency in 802.11ac
No full textIn this paper we consider transport layer approaches for achieving high rate, low delay communication over edge paths where the bottleneck is a modern 802.11ac WLAN which can aggregate multiple packets into each WLAN frame. We show that regulating send rate so as to maintain a target aggregation level can be used to avoid queue buildup at the WLAN AP. We present a prototype transport layer implementation of our low delay rate allocation approach and use this to evaluate performance under real radio conditions
Learning-Based Constraint Satisfaction With Sensing Restrictions
Full text linkIn this paper we consider graph-coloring problems, an important subset
of general constraint satisfaction problems that arise in wireless resource
allocation. We constructively establish the existence of fully decentralized
learning-based algorithms that are able to find a proper coloring
even in the presence of strong sensing restrictions, in particular sensing
asymmetry of the type encountered when hidden terminals are present.
Our main analytic contribution is to establish sufficient conditions on the
sensing behaviour to ensure that the solvers find satisfying assignments
with probability one. These conditions take the form of connectivity requirements
on the induced sensing graph. These requirements are mild,
and we demonstrate that they are commonly satisfied in wireless allocation
tasks. We argue that our results are of considerable practical importance
in view of the prevalence of both communication and sensing restrictions
in wireless resource allocation problems. The class of algorithms analysed
here requires no message-passing whatsoever between wireless devices,
and we show that they continue to perform well even when devices are
only able to carry out constrained sensing of the surrounding radio environment
Fast, responsive decentralized graph coloring
Full text linkGraph coloring problem arises in numerous networking applications. We solve it in a fully decentralized way (ı.e., with no message passing). We propose a novel algorithm that is automatically responsive to topology changes, and we prove that it converges to a proper coloring in O(NlogN) time with high probability for generic graphs, when the number of available colors is greater than Δ , the maximum degree of the graph, and in O(logN) time if Δ=O(1) . We believe the proof techniques used in this paper are of independent interest and provide new insight into the properties required to ensure fast convergence of decentralized algorithms
Updating Neighbour Cell List via Crowdsourced User Reports: A Framework for Measuring Time Performance
Full text linkIn modern wireless networks deployments, each serving node needs to keep its Neighbour Cell List (NCL) constantly up to date to
keep track of network changes. The time needed by each serving node to update its NCL is an important parameter of the network’s
reliability and performance. An adequate estimate of such parameter enables a significant improvement of self-configuration
functionalities. This paper focuses on the update time of NCLs when an approach of crowdsourced user reports is adopted. In
this setting, each user periodically reports to the serving node information about the set of nodes sensed by the user itself. We show
that, by mapping the local topological structure of the network onto states of increasing knowledge, a crisp mathematical framework
can be obtained, which allows in turn for the use of a variety of user mobility models. Further, using a simplified mobility model we
show how to obtain useful upper bounds on the expected time for a serving node to gain Full Knowledge of its local neighbourhood
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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