31,001 research outputs found
Traffic eavesdropping based scheme to deliver time-sensitive data in sensor networks
Due to the broadcast nature of wireless channels, neighbouring sensor nodes may overhear packets transmissions from each other even if they are not the intended recipients of these transmissions. This redundant packet reception leads to unnecessary expenditure of battery energy of the recipients. Particularly in highly dense sensor networks, overhearing or eavesdropping overheads can constitute a significant fraction of the total energy consumption. Since overhearing of wireless traffic is unavoidable and sometimes essential, a new distributed energy efficient scheme is proposed in this paper. This new scheme exploits the inevitable overhearing effect as an effective approach in order to collect the required information to perform energy efficient delivery for data aggregation. Based on this approach, the proposed scheme achieves moderate energy consumption and high packet delivery rate notwithstanding the occurrence of high link failure rates. The performance of the proposed scheme is experimentally investigated a testbed of TelosB motes in addition to ns-2 simulations to validate the performed experiments on large-scale network
TCP Reno over Adaptive CSMA
An interesting distributed adaptive CSMA MAC protocol, called adaptive CSMA,
was proposed recently to schedule any strictly feasible achievable rates inside
the capacity region. Of particular interest is the fact that the adaptive CSMA
can achieve a system utility arbitrarily close to that is achievable under a
central scheduler. However, a specially designed transport-layer rate
controller is needed for this result. An outstanding question is whether the
widely-installed TCP Reno is compatible with adaptive CSMA and can achieve the
same result. The answer to this question will determine how close to practical
deployment adaptive CSMA is. Our answer is yes and no. First, we observe that
running TCP Reno directly over adaptive CSMA results in severe starvation
problems. Effectively, its performance is no better than that of TCP Reno over
legacy CSMA (IEEE 802.11), and the potentials of adaptive CSMA cannot be
realized. Fortunately, we find that multi-connection TCP Reno over adaptive
CSMA with active queue management can materialize the advantages of adaptive
CSMA. NS-2 simulations demonstrate that our solution can alleviate starvation
and achieve fair and efficient rate allocation. Multi-connection TCP can be
implemented at either application or transport layer. Application-layer
implementation requires no kernel modification, making the solution readily
deployable in networks running adaptive CSMA
Energy Aware, Scalable, K-Hop Based Cluster Formation In MANET
The study of Mobile Ad-hoc Network remains attractive due to the desire to
achieve better performance and scalability. MANETs are distributed systems
consisting of mobile hosts that are connected by multi-hop wireless links. Such
systems are self organized and facilitate communication in the network without
any centralized administration. MANETs exhibit battery power constraint and
suffer scalability issues therefore cluster formation is expensive. This is due
to the large number of messages passed during the process of cluster formation.
Clustering has evolved as an imperative research domain that enhances system
performance such as throughput and delay in Mobile Ad hoc Networks (MANETs) in
the presence of both mobility and a large number of mobile terminals.In this
thesis, we present a clustering scheme that minimizes message overhead and
congestion for cluster formation and maintenance. The algorithm is devised to
be independent of the MANET Routing algorithm. Depending upon the context, the
clustering algorithm may be implemented in the routing or in higher layers. The
dynamic formation of clusters helps reduce data packet overhead, node
complexity and power consumption, The simulation has been performed in ns-2.
The simulation shows that the number of clusters formed is in proportion with
the number of nodes in MANET
Robust Wireless Body Area Networks Coexistence: A Game Theoretic Approach to Time-Division MAC
The enabling of wireless body area networks (WBANs) coexistence by radio
interference mitigation is very important due to a rapid growth in potential
users, and a lack of a central coordinator among WBANs that are closely
located. In this paper, we propose a TDMA based MAC layer Scheme, with a
back-off mechanism that reduces packet collision probability; and estimate
performance using a Markov chain model. Based on the MAC layer scheme, a novel
non-cooperative game is proposed to jointly adjust sensor node's transmit power
and rate. In comparison with the state-of-art, simulation that includes
empirical data shows that the proposed approach leads to higher throughput and
longer node lifespan as WBAN wearers dynamically move into each other's
vicinity. Moreover, by adaptively tuning contention windows size an alternative
game is developed, which significantly reduces the latency. Both proposed games
provide robust transmission under strong inter-WBAN interferences, but are
demonstrated to be applicable to different scenarios. The uniqueness and
existence of Nash Equilibrium (NE), as well as close-to-optimum social
efficiency, is also proven for both games.Comment: 31 pages, 17 figures, submitted for possible publication on ACM
Transactions on Sensor Networks (TOSN
Markov Decision Processes with Applications in Wireless Sensor Networks: A Survey
Wireless sensor networks (WSNs) consist of autonomous and resource-limited
devices. The devices cooperate to monitor one or more physical phenomena within
an area of interest. WSNs operate as stochastic systems because of randomness
in the monitored environments. For long service time and low maintenance cost,
WSNs require adaptive and robust methods to address data exchange, topology
formulation, resource and power optimization, sensing coverage and object
detection, and security challenges. In these problems, sensor nodes are to make
optimized decisions from a set of accessible strategies to achieve design
goals. This survey reviews numerous applications of the Markov decision process
(MDP) framework, a powerful decision-making tool to develop adaptive algorithms
and protocols for WSNs. Furthermore, various solution methods are discussed and
compared to serve as a guide for using MDPs in WSNs
Towards Coordinated Bandwidth Adaptations for Hundred-Scale 3D Tele-Immersive Systems
3D tele-immersion improves the state of collaboration among geographically
distributed participants. Unlike the traditional 2D videos, a 3D tele-immersive
system employs multiple 3D cameras based in each physical site to cover a much
larger field of view, generating a very large amount of stream data. One of the
major challenges is how to efficiently transmit these bulky 3D streaming data
to bandwidth-constrained sites. In this paper, we study an adaptive Human
Visual System (HVS) -compliant bandwidth management framework for efficient
delivery of hundred-scale streams produced from distributed 3D tele-immersive
sites to a receiver site with limited bandwidth budget. Our adaptation
framework exploits the semantics link of HVS with multiple 3D streams in the 3D
tele-immersive environment. We developed TELEVIS, a visual simulation tool to
showcase a HVS-aware tele-immersive system for realistic cases. Our evaluation
results show that the proposed adaptation can improve the total quality per
unit of bandwidth used to deliver streams in 3D tele-immersive systems.Comment: Springer Multimedia Systems Journal, 14 pages, March 201
SDDV: scalable data dissemination in vehicular ad hoc networks
An important challenge in the domain of vehicular ad hoc networks (VANET) is the scalability of data dissemination. Under dense traffic conditions, the large number of communicating vehicles can easily result in a congested wireless channel. In that situation, delays and packet losses increase to a level where the VANET cannot be applied for road safety applications anymore. This paper introduces scalable data dissemination in vehicular ad hoc networks (SDDV), a holistic solution to this problem. It is composed of several techniques spread across the different layers of the protocol stack. Simulation results are presented that illustrate the severity of the scalability problem when applying common state-of-the-art techniques and parameters. Starting from such a baseline solution, optimization techniques are gradually added to SDDV until the scalability problem is entirely solved. Besides the performance evaluation based on simulations, the paper ends with an evaluation of the final SDDV configuration on real hardware. Experiments including 110 nodes are performed on the iMinds w-iLab.t wireless lab. The results of these experiments confirm the results obtained in the corresponding simulations
Scalability of broadcast performance in wireless network-on-chip
Networks-on-Chip (NoCs) are currently the paradigm of choice to interconnect the cores of a chip multiprocessor. However, conventional NoCs may not suffice to fulfill the on-chip communication requirements of processors with hundreds or thousands of cores. The main reason is that the performance of such networks drops as the number of cores grows, especially in the presence of multicast and broadcast traffic. This not only limits the scalability of current multiprocessor architectures, but also sets a performance wall that prevents the development of architectures that generate moderate-to-high levels of multicast. In this paper, a Wireless Network-on-Chip (WNoC) where all cores share a single broadband channel is presented. Such design is conceived to provide low latency and ordered delivery for multicast/broadcast traffic, in an attempt to complement a wireline NoC that will transport the rest of communication flows. To assess the feasibility of this approach, the network performance of WNoC is analyzed as a function of the system size and the channel capacity, and then compared to that of wireline NoCs with embedded multicast support. Based on this evaluation, preliminary results on the potential performance of the proposed hybrid scheme are provided, together with guidelines for the design of MAC protocols for WNoC.Peer ReviewedPostprint (published version
Adaptive Multicell 3D Beamforming in Multi-Antenna Cellular Networks
We consider a cellular network with multi-antenna base stations (BSs) and
single-antenna users, multicell cooperation, imperfect channel state
information, and directional antennas each with a vertically adjustable beam.
We investigate the impact of the elevation angle of the BS antenna pattern,
denoted as tilt, on the performance of the considered network when employing
either a conventional single-cell transmission or a fully cooperative multicell
transmission. Using the results of this investigation, we propose a novel
hybrid multicell cooperation technique in which the intercell interference is
controlled via either cooperative beamforming in the horizontal plane or
coordinated beamfroming in the vertical plane of the wireless channel, denoted
as adaptive multicell 3D beamforming. The main idea is to divide the coverage
area into two disjoint vertical regions and adapt the multicell cooperation
strategy at the BSs when serving each region. A fair scheduler is used to share
the time-slots between the vertical regions. It is shown that the proposed
technique can achieve performance comparable to that of a fully cooperative
transmission but with a significantly lower complexity and signaling
requirements. To make the performance analysis computationally efficient,
analytical expressions for the user ergodic rates under different beamforming
strategies are also derived.Comment: Accepted for publication in IEEE Transaction on Vehicular Technolog
Underwater Optical Wireless Communications, Networking, and Localization: A Survey
Underwater wireless communications can be carried out through acoustic, radio
frequency (RF), and optical waves. Compared to its bandwidth limited acoustic
and RF counterparts, underwater optical wireless communications (UOWCs) can
support higher data rates at low latency levels. However, severe aquatic
channel conditions (e.g., absorption, scattering, turbulence, etc.) pose great
challenges for UOWCs and significantly reduce the attainable communication
ranges, which necessitates efficient networking and localization solutions.
Therefore, we provide a comprehensive survey on the challenges, advances, and
prospects of underwater optical wireless networks (UOWNs) from a layer by layer
perspective which includes: 1) Potential network architectures; 2) Physical
layer issues including propagation characteristics, channel modeling, and
modulation techniques 3) Data link layer problems covering link configurations,
link budgets, performance metrics, and multiple access schemes; 4) Network
layer topics containing relaying techniques and potential routing algorithms;
5) Transport layer subjects such as connectivity, reliability, flow and
congestion control; 6) Application layer goals and state-of-the-art UOWN
applications, and 7) Localization and its impacts on UOWN layers. Finally, we
outline the open research challenges and point out the future directions for
underwater optical wireless communications, networking, and localization
research.Comment: This manuscript is submitted to IEEE Communication Surveys and
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