344,842 research outputs found
Experimental Study of Transport Layer Protocols for Wireless Networked Control Systems
In Wireless Networked Control Systems (WNCSs), the feedback control loops are
closed over a wireless communication network. The proliferation of WNCSs
requires efficient network resource management mechanisms since the control
performance is significantly affected by the impairments caused by network
limitations. In conventional communication networks, the amount of transmitted
data is one of the key performance indicators. In contrast, in WNCSs, the
efficiency of the network is measured by its ability to facilitate control
applications, and the data transmission rate should be limited to avoid network
congestion. In this work, we consider an experimental setup where multiple
control loops share a wireless communication network. Our testbed comprises up
to five control loops that include Zolertia Re-Mote devices implementing IEEE
802.15.4 standard. We propose a novel relevance- and network-aware transport
layer (TL) scheme for WNCSs. The proposed scheme admits the most important
measurements for the control process into the network while taking current
network conditions into account. Moreover, we propose a mechanism for the
scheme parameters adaptation in dynamic scenarios with unknown network
statistics. Unlike the conventional TL mechanisms failing to provide adequate
control performance due to either congestion in the network or inefficient
utilization of available resources, our method prevents network congestion
while keeping the control performance high. We argue that relevance- and
network-awareness are critical components of network protocol design to avoid
control performance degradation in practice.Comment: 10 pages, 11 figure
A Network Congestion control Protocol (NCP)
The transmission control protocol (TCP) which is the dominant
congestion control protocol at the transport layer is proved to have
many performance problems with the growth of the Internet. TCP for
instance results in throughput degradation for high bandwidth delay
product networks and is unfair for flows with high round trip delays.
There have been many patches and modifications to TCP all of which
inherit the problems of TCP in spite of some performance improve-
ments.
On the other hand there are clean-slate design approaches of the
Internet. The eXplicit Congestion control Protocol (XCP) and the
Rate Control Protocol (RCP) are the prominent clean slate congestion
control protocols. Nonetheless, the XCP protocol is also proved to
have its own performance problems some of which are its unfairness
to long flows (flows with high round trip delay), and many per-packet
computations at the router. As shown in this paper RCP also makes
gross approximation to its important component that it may only give
the performance reports shown in the literature for specific choices of
its parameter values and traffic patterns.
In this paper we present a new congestion control protocol called
Network congestion Control Protocol (NCP). We show that NCP can
outperform both TCP, XCP and RCP in terms of among other things
fairness and file download times.unpublishe
Internal Model Hop-by-hop Congestion Control for High-Speed Networks
This paper presents a hop-by-hop congestion control for highspeed networks. The control policy relies on the data exchange between adjacent nodes of the network (nearest-neighbour interaction). The novelty of this paper consists in the extensive use of Internal Model Control (IMC) to set the rates of the traffic flows. As a result, the proposed congestion control provides upper-bounds of the queue lengths in all the network buffers (overflow avoidance), avoids wasting the assigned capacity (full link utilisation) and guarantees the congestion recovery. Numerical simulations prove the effectiveness of the scheme
ABC: A Simple Explicit Congestion Controller for Wireless Networks
We propose Accel-Brake Control (ABC), a simple and deployable explicit
congestion control protocol for network paths with time-varying wireless links.
ABC routers mark each packet with an "accelerate" or "brake", which causes
senders to slightly increase or decrease their congestion windows. Routers use
this feedback to quickly guide senders towards a desired target rate. ABC
requires no changes to header formats or user devices, but achieves better
performance than XCP. ABC is also incrementally deployable; it operates
correctly when the bottleneck is a non-ABC router, and can coexist with non-ABC
traffic sharing the same bottleneck link. We evaluate ABC using a Wi-Fi
implementation and trace-driven emulation of cellular links. ABC achieves
30-40% higher throughput than Cubic+Codel for similar delays, and 2.2X lower
delays than BBR on a Wi-Fi path. On cellular network paths, ABC achieves 50%
higher throughput than Cubic+Codel
The Practical Challenges of Interference Alignment
Interference alignment (IA) is a revolutionary wireless transmission strategy
that reduces the impact of interference. The idea of interference alignment is
to coordinate multiple transmitters so that their mutual interference aligns at
the receivers, facilitating simple interference cancellation techniques. Since
IA's inception, researchers have investigated its performance and proposed
improvements, verifying IA's ability to achieve the maximum degrees of freedom
(an approximation of sum capacity) in a variety of settings, developing
algorithms for determining alignment solutions, and generalizing transmission
strategies that relax the need for perfect alignment but yield better
performance. This article provides an overview of the concept of interference
alignment as well as an assessment of practical issues including performance in
realistic propagation environments, the role of channel state information at
the transmitter, and the practicality of interference alignment in large
networks.Comment: submitted to IEEE Wireless Communications Magazin
Separation Framework: An Enabler for Cooperative and D2D Communication for Future 5G Networks
Soaring capacity and coverage demands dictate that future cellular networks
need to soon migrate towards ultra-dense networks. However, network
densification comes with a host of challenges that include compromised energy
efficiency, complex interference management, cumbersome mobility management,
burdensome signaling overheads and higher backhaul costs. Interestingly, most
of the problems, that beleaguer network densification, stem from legacy
networks' one common feature i.e., tight coupling between the control and data
planes regardless of their degree of heterogeneity and cell density.
Consequently, in wake of 5G, control and data planes separation architecture
(SARC) has recently been conceived as a promising paradigm that has potential
to address most of aforementioned challenges. In this article, we review
various proposals that have been presented in literature so far to enable SARC.
More specifically, we analyze how and to what degree various SARC proposals
address the four main challenges in network densification namely: energy
efficiency, system level capacity maximization, interference management and
mobility management. We then focus on two salient features of future cellular
networks that have not yet been adapted in legacy networks at wide scale and
thus remain a hallmark of 5G, i.e., coordinated multipoint (CoMP), and
device-to-device (D2D) communications. After providing necessary background on
CoMP and D2D, we analyze how SARC can particularly act as a major enabler for
CoMP and D2D in context of 5G. This article thus serves as both a tutorial as
well as an up to date survey on SARC, CoMP and D2D. Most importantly, the
article provides an extensive outlook of challenges and opportunities that lie
at the crossroads of these three mutually entangled emerging technologies.Comment: 28 pages, 11 figures, IEEE Communications Surveys & Tutorials 201
Approaches for Future Internet architecture design and Quality of Experience (QoE) Control
Researching a Future Internet capable of overcoming the current Internet limitations is a strategic
investment. In this respect, this paper presents some concepts that can contribute to provide some guidelines to
overcome the above-mentioned limitations. In the authors' vision, a key Future Internet target is to allow
applications to transparently, efficiently and flexibly exploit the available network resources with the aim to
match the users' expectations. Such expectations could be expressed in terms of a properly defined Quality of
Experience (QoE). In this respect, this paper provides some approaches for coping with the QoE provision
problem
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