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1.
2.
In this paper, an analytical model is developed for the performance study of an IEEE 802.11n wireless local area network (WLAN)
supporting voice and video services, considering the new features of the medium access control (MAC) protocol proposed in
IEEE 802.11n, i.e., frame aggregation and bidirectional transmission. We show that these enhanced MAC mechanisms can effectively
improve the network capacity by not only reducing the protocol overheads, but also smoothing the AP-bottleneck effect in an
infrastructure-based WLAN. Voice and video capacity under various MAC mechanisms are compared as well.
相似文献
Lin CaiEmail: |
3.
A Novel Wireless Positioning System for Seamless Internet Connectivity based on the WLAN Infrastructure 总被引:2,自引:2,他引:0
Nowadays, several positioning systems are available for outdoor localization, such as the global positioning system (GPS),
assisted GPS (A-GPS), and other systems working on cellular networks, for example, time difference of arrival (TDOA), angle
of arrival (AOA) and enhanced observed time difference of arrival (E-OTD). However, with the increasing use of mobile computing
devices and an expansion of wireless local area networks (WLANs), there is a growing interest in indoor wireless positioning
systems based on the WLAN infrastructure. Wireless positioning systems (WPS) based on this infrastructure can be used for
indoor localization to determine the position of mobile users. In this paper, we present a novel wireless positioning system,
based on the IEEE 802.11b standard, using a novel access point (AP) with two transceivers to improve the performance of WPS
in terms of accuracy of the location estimation and to avoid service connectivity interruption. In our proposed system, the
novel AP uses the second transceiver to find information from neighboring mobile stations (STAs) in the transmission range
and then sends information in advance to associated APs, which estimate the location of the STA based on an internal database.
We also use a TDOA technique to estimate the location of the STA when there is not enough information in the database (in
this case, the STA moves into a new area where the system has not run the calibration phase). Using TDOA, the database can
be generated and updated automatically. The initial results from our simulations show that the proposed system provides higher
accuracy of location estimation than other related work and does not interrupt the Internet connection for end users in contrast
with other proposed schemes.
相似文献
Thavisak ManodhamEmail: |
4.
Thinh Nguyen Kien Nguyen Mario E. Magaña Linhai He 《Wireless Personal Communications》2008,47(2):171-191
Admission control algorithms have been widely researched for many years to guarantee the Quality of Service (QoS) for multimedia
applications over the wired Internet. With the recent surge of wireless home networks, it is increasingly important to employ the admission control mechanisms
in order to enhance the performance of the wireless multimedia applications. In this paper, we propose a framework for performing
distributed admission control in a collaborative wireless environment. In particular, a wireless device will not inject a
new flow into the wireless medium if it determines that by doing so, there is not enough resources to support all the existing
flows. Our contributions are threefold. First, we propose a modification to 802.11x based network in order to increase the
bandwidth efficiency. Specifically, doubling the contention window (CW) size after a collision is no longer necessary in the
proposed wireless network. Second, we provide a performance analysis for the modified 802.11x based wireless networks with
multiple flows having different throughput requirements. Third, using the theoretical analysis, we propose two distributed
admission control algorithms based on the transmission opportunity (TXOP) and the CW. Simulation results confirm our theoretical
predictions on the performance of the proposed admission control algorithms.
相似文献
Linhai HeEmail: |
5.
In this paper, we propose a new differentiated service model, referred to as Differentiated Service-EDCA (DS-EDCA), for the
Enhanced Distributed Channel Access (EDCA) of IEEE 802.11e wireless local area networks (WLANs). With DS-EDCA, both strict
priority and weighted fair service can be provided. The strict priority service is provided for high priority traffic through
carefully setting the EDCA parameter sets of lower priority traffic; the proportional fairness service is enabled by determining
the backoff intervals according to the distributed scheduling discipline (DFS). We also propose a hierarchical link sharing
model for IEEE 802.11e WLANs, in which AP and mobile stations are allocated different amounts of link resource. The performance
of DS-EDCA and EDCA is compared via ns-2 simulations. The results show that DS-EDCA outperforms the original EDCA in terms
of its support for both strict priority and weighted fair service. More importantly, DS-EDCA can be easily implemented, and
is compatible to the IEEE 802.11 Standard.
相似文献
Meng Chang ChenEmail: |
6.
To support distributive tracking of moving targets in a wireless sensor network, sensors that receive signal from the same
target must collaborate to facilitate collaborative, distributed target tracking. We present an efficient dynamic sensor self-organizing
algorithm that clusters sensors into groups without requiring a centralized control. Extensive simulations are conducted to
verify the performance improvement as well as the communication reduction for the proposed methods.
相似文献
Xiaohong ShengEmail: |
7.
Resource optimization in distributed biometric recognition using wireless sensor network 总被引:1,自引:1,他引:0
Rajani Muraleedharan Lisa Ann Osadciw Yanjun Yan 《Multidimensional Systems and Signal Processing》2009,20(2):165-182
Distributed, autonomous and energy efficient protocols are best suited for wireless sensor networks, where network needs and
events are dynamic. In this paper, a wireless face recognition system with limited resources such as energy, memory and bandwidth
is analyzed. The performance of the applications is influenced by the protocol adaptability and quality of information. Performance
comparisons are completed using 1. In-network image compression using Contourlet and Wavelet transforms versus raw image data
transmission, 2. longevity of sensors versus network throughput. Balancing resource constraints, maintaining network lifetime
and throughput is a non-deterministic polynomial computation time problem. Thus a meta-heuristic combinatorial algorithm,
based on swarm intelligence, forms the cognitive routing protocol. The network efficiency considers energy consumption, response
time, probability of correct acceptance, processing and computation time for wireless image transmission.
相似文献
Yanjun YanEmail: |
8.
Gwo-Jong Yu 《Wireless Personal Communications》2009,48(3):327-346
In wireless sensor networks, storage policies can be categorized into external storage, local storage and data centric storage.
Each storage police has its suitable network environments. If a correct storage policy is chosen for a given network condition,
unnecessary control messages can be significantly reduced. Then the network lifetime can be increased. In this paper, adaptive
data storage (ADS) policy which can dynamically choose suitable storage policy for wireless sensor network according to the
frequencies of user queries and events happening is proposed. Through collection and computation of user query and event rates,
the proposed algorithm switches between local storage and data centric storage policies adaptively. Simulations are given
to justify that the proposed adaptive storage policy indeed reduces the traffic in network and increases network lifetime.
相似文献
Gwo-Jong YuEmail: |
9.
To improve the capacity of wireless ad hoc networks by exploiting multiple available channels, we propose a distributed channel
assignment protocol that is based on a cross-layer approach. By combining channel assignment with routing protocols, the proposed
channel assignment protocol is shown to require fewer channels and exhibit lower communication, computation, and storage complexity
than existing channel assignment schemes. A multi-channel MAC (MC-MAC) protocol that works with the proposed channel assignment
protocol is also presented. We prove the correctness of the proposed channel assignment protocol. In addition, through a performance
study, we show that the proposed protocol can substantially increase throughput and reduce delay in wireless ad hoc networks,
compared to the IEEE 802.11 MAC protocol and an existing multi-channel scheme.
相似文献
Shiwen MaoEmail: |
10.
Wireless enabled portable devices must operate with the highest possible energy efficiency while still maintaining a minimum
level and quality of service to meet the user’s expectations. In this paper we analyse the performance of a new pointer-based
medium access control protocol that was designed to significantly improve the energy efficiency of user terminals in wireless
local area networks. The new protocol, pointer controlled slot allocation and resynchronisation (PCSAR) protocol is based
on the existing IEEE 802.11 point coordination function (PCF) standard. PCSAR reduces energy consumption by removing the need
for power saving stations to remain awake and listen to the channel. Using OPNET, simulations were performed to compare the
performance of PCSAR with the infrastructure power saving mode of IEEE 802.11, PCF-PS. The simulation results demonstrate
a significant improvement in energy efficiency without significant reduction in performance when using PCSAR. For a wireless
network consisting of an access point and eight stations in power saving mode, the energy saving was up to 28% while using
PCSAR instead of PCF-PS, depending upon frame error rate and channel loading. The results also show that PCSAR offers significantly
reduced uplink (UL) access delay over PCF-PS while modestly improving UL throughput.
相似文献
G. A. SafdarEmail: |
11.
A Survey on Wireless Position Estimation 总被引:7,自引:2,他引:5
Sinan Gezici 《Wireless Personal Communications》2008,44(3):263-282
In this paper, an overview of various algorithms for wireless position estimation is presented. Although the position of a
node in a wireless network can be estimated directly from the signals traveling between that node and a number of reference nodes, it is more practical to estimate a set of signal
parameters first, and then to obtain the final position estimation using those estimated parameters. In the first step of
such a two-step positioning algorithm, various signal parameters such as time of arrival, angle of arrival or signal strength
are estimated. In the second step, mapping, geometric or statistical approaches are commonly employed. In addition to various
positioning algorithms, theoretical limits on their estimation accuracy are also presented in terms of Cramer–Rao lower bounds.
相似文献
Sinan GeziciEmail: |
12.
For the transition from 3G communication systems to 4G communication systems, 3G-WLAN interworking systems can be a reference
model for 4G communication systems. In this paper, we identify challenging problems in 3G-WLAN interworking systems and propose
a loosely coupled architecture called SHARE. In SHARE, each WLAN hotspot access point (AP) is equipped with a 3G radio transmission module to generate radio signals
for control channels of 3G networks in addition to a WLAN radio module. Consequently, base stations of the 3G networks share their control channels with hotspot APs. By monitoring these channels, mobile nodes can easily detect available WLAN hotspots
without probe delay for handovers.
相似文献
Chong-Ho ChoiEmail: |
13.
Yaser Pourmohammadi Fallah Samer El-Housseini Hussein Alnuweiri 《Wireless Personal Communications》2008,47(2):235-245
The main service differentiation mechanism introduced by the IEEE 802.11e standard is described in terms of prioritized contention
access. Analyzing the performance and service differentiation ability of each of the priority features of the 802.11e standard
is an important task, and considerable research effort has recently been dedicated to this subject. In this article, we present
a generalized and comprehensive analysis of the prioritized access scheme of the 802.11e standard. Our model corrects and
extends the existing models and considers all priority features of the 802.11e Medium Access Control (MAC) protocol. We consider
an arbitrary number of priority levels, and provide a detailed parametric analysis of the MAC behavior for the main priority
parameters of inter frame spacing, contention window size, and transmission opportunity. We validate the accuracy of our analysis
with simulation experiments.
相似文献
Hussein AlnuweiriEmail: |
14.
Jan Van Ooteghem Bart Lannoo Koen Casier Sofie Verbrugge Emmeric Tanghe Wout Joseph Luc Martens Didier Colle Mario Pickavet Ingrid Moerman Piet Demeester 《Wireless Personal Communications》2009,49(3):391-414
Municipalities can form a driving force behind the deployment of new telecom infrastructure. While a telecom operator focuses
on direct (financial) profits, a municipality is mainly interested in the social benefits for its inhabitants. In this paper,
we evaluate a wireless municipality network from both a technical and an economic point of view. WiFi and WiMAX are considered
as the most suited technologies for this purpose. A detailed techno-economic study has been performed including forecasting
of the user adoption, dimensioning of the wireless network and modelling the related costs and revenues. The trade-off between
installing a high number of relatively cheap WiFi access points, and a smaller number of more expensive WiMAX base stations
for delivering full coverage is investigated in several scenarios.
相似文献
Piet DemeesterEmail: |
15.
Modeling Channel Access Delay and Jitter of IEEE 802.11 DCF 总被引:1,自引:0,他引:1
Yun Li Chonggang Wang Keping Long Weiliang Zhao 《Wireless Personal Communications》2008,47(3):417-440
With the ever-increasing requirement of WLAN to support real-time services, it is becoming important to study the delay properties
of WLAN protocols. This paper constructs a new model to analyze the channel access delay and delay jitter of IEEE 802.11 DCF
in saturation traffic condition. Based on this analytical model, average channel access delay and delay jitter are derived
for both basic access and RTS/CTS-based access scheme. The accuracy of the analytical model is validated by simulations and
furthermore we discuss the impact of initial contention window, maximal backoff stage, and packet size on channel access delay
and delay jitter of 802.11 DCF using the proposed model.
相似文献
Chonggang WangEmail: |
16.
The use of multibeam antennas (MBAs) in decentralized wireless networks significantly increases the throughput by improving
spatial reuse and extending coverage compared with single-beam antennas. The throughput performance may, however, degrade
in multipath environments due to the fact that multipath propagation increases the probability of collision among different
users. Based on the probability of collision, accurate analytical expressions are derived for the node throughput gain (NTG)
of a wireless network using MBAs in quasi-stationary multipath environments. The results show that a higher number of propagation
paths cause more frequent collisions and thus yield lower node throughput.
相似文献
Moeness G. AminEmail: |
17.
Mohamed Khalaf-Allah 《Wireless Personal Communications》2008,44(3):311-322
This paper investigates a Global Positioning system (GPS)-free positioning method for mobile units (MUs) in outdoor wireless
environments by using the Bayesian filtering formulation. The procedure utilizes simulated inertial measurements, cell-ID
of the serving base station, and pre-determined locations grouped according to cell antennas radio coverage in the experimentation
area. The developed algorithm makes no assumptions on the initial position of the MU. However, the algorithm takes some time
to converge. Experiments show the range of inertial measurement errors that would maintain reliable location information with
accuracy comparable to GPS positioning.
相似文献
Mohamed Khalaf-AllahEmail: |
18.
This article advocates a novel communication architecture and associated collaborative framework for future wireless communication
systems. In contrast to the dominating cellular architecture and the upcoming peer-to-peer architecture, the new approach
envisions a cellular controlled short-range communication network among cooperating mobile and wireless devices. The role
of the mobile device will change, from being an agnostic entity in respect to the surrounding world to a cognitive device.
This cognitive device is capable of being aware of the neighboring devices as well as on the possibility to establish cooperation
with them. The novel architecture together with several possible cooperative strategies will bring clear benefits for the
network and service providers, mobile device manufacturers and also end users.
相似文献
Qi ZhangEmail: |
19.
F. Angarita M. J. Canet T. Sansaloni A. Perez-Pascual J. Valls 《Journal of Signal Processing Systems》2008,52(2):181-191
In an orthogonal frequency division multiplexing-based wireless local area network receiver there are three operations that
can be performed by a unique coordinate rotation digital computer (CORDIC) processor since they are needed in different time
instants. These are the rotation of a vector, the computation of the angle of a vector and the computation of the reciprocal.
This paper proposes a common architecture of CORDIC algorithm suitable to implement the three operations with a reduced increase
of the hardware cost with respect to a single operation CORDIC. The proposed architecture has been validated on field programmable
gate-arrays devices and the results of the implementation show that area saving around 28% and throughput increment of 64%
are obtained.
相似文献
J. VallsEmail: |
20.
A Survey of Cryptographic Primitives and Implementations for Hardware-Constrained Sensor Network Nodes 总被引:1,自引:0,他引:1
In a wireless sensor network environment, a sensor node is extremely constrained in terms of hardware due to factors such
as maximizing lifetime and minimizing physical size and overall cost. Nevertheless, these nodes must be able to run cryptographic
operations based on primitives such as hash functions, symmetric encryption and public key cryptography in order to allow
the creation of secure services. Our objective in this paper is to survey how the existing research-based and commercial-based
sensor nodes are suitable for this purpose, analyzing how the hardware can influence the provision of the primitives and how
software implementations tackles the task of implementing instances of those primitives. As a result, it will be possible
to evaluate the influence of provision of security in the protocols and applications/scenarios where sensors can be used.
相似文献
Javier LopezEmail: |