共查询到20条相似文献,搜索用时 343 毫秒
1.
Sheng-Wen Chang Prasan Kumar Sahoo Chih-Yung Chang 《Wireless Personal Communications》2008,47(4):541-566
Bluetooth is a most promising technology designed for the wireless personal area networks for the cable replacement. In this
paper, a location aware mobility based routing scheme for the Bluetooth scatternet is proposed that constructs the links dynamically.
Our proposed routing protocol requires location information of the nodes and constructs the route between any source and destination
and reduces the number of hops. Besides, the network routing problems are analyzed and role switch operations are proposed
to mitigate the problems. Moreover, the roles switch and route optimization operations are also proposed to improve route
performance. Rigorous simulation works are done to evaluate the performance of our protocol in terms of mobility speed and
number of mobile nodes and to compare our results with similar Bluetooth routing protocols. It is observed that our protocol
outperforms in terms of energy consumption and transmission packet overheads as compared to similar Bluetooth routing protocols.
相似文献
Chih-Yung ChangEmail: |
2.
When more than seven devices are connected in a Bluetooth scatternet, bridge devices are used to connect two piconets to the
scatternet. To deal with possible data transmissions between different piconets, the bridge device must frequently switch
to different masters. Suppose, however, that a bridge is serving a piconet and the master in another piconet is calling it
at the same time, the calling master has to wait until the bridge completes the previous service. Such transmission delay
may accumulate over a long period and the performance of the whole Bluetooth network will degrade significantly. In this work,
two new scheduling protocols, namely the static schedule and the hybrid schedule were implemented in an effort to smooth this
kind of transmission delay in Bluetooth networks. In this static schedule the rendezvous points between piconets are coordinated
by distributing them by using a graph edge coloring technique. In case of a heavy traffic load, the static schedule is expected
to perform well. On the other hand, in case of a light traffic load, the static schedule may cause long and unavoidable routing
delays even when there is no transmission between piconets; in this case a naive random round-robin (RR) schedule in each
piconet is more appropriate. Thus, in the hybrid schedule, each master initially runs a RR scheme in its piconet. When the
traffic load is heavier than a predefined threshold value, it runs the static schedule. Finally, simulations were conducted
by using an ns-2 simulator and Bluehoc to demonstrate the efficiency and effectiveness of the proposed scheduling protocols.
相似文献
Kun-Ming Yu (Corresponding author)Email: |
3.
Basagni Stefano Bruno Raffaele Mambrini Gabriele Petrioli Chiara 《Wireless Networks》2004,10(2):197-213
This paper describes the results of the first ns2-based comparative performance evaluation among four major solutions presented in the literature for forming multi-hop networks of Bluetooth devices (scatternet formation). The four protocols considered in this paper are BlueTrees [1], BlueStars [2], BlueNet [3] and the protocol presented in [4] which proposes geometric techniques for topology reduction combined with cluster-based scatternet formation. We implemented the operations of the four protocols from device discovery to scatternet formation. By means of a thorough performance evaluation we have identified protocol parameters and Bluetooth technology features that affect the duration of the formation process and the properties of the produced scatternet. We have investigated how possible modifications of the BT technology (e.g., backoff duration, possibility for a BT inquirer to identify itself) make device discovery more efficient for scatternet formation in multi-hop networks. We have then discussed implementation concerns for each of the selected protocols. Finally, we have analyzed the protocols overhead as well as the effect of the different protocols operations on key metrics of the generated scatternets, which includes the time needed for forming a scatternet, the number of its piconets, the number of slaves per piconet, the number of roles assumed by each node and the scatternet route lengths. 相似文献
4.
IP address autoconfiguration of mobile nodes is highly desirable in the practical usage of most mobile ad hoc networks (MANETs).
This paper proposes cluster-based autoconfiguration, a novel approach for the efficient address autoconfiguration of MANETs.
The cluster structure derived from clustering techniques is used to manage address assignment and conflict resolution. By
introducing the concept of virtual address agents (AAs), the proposed approach can be applicable to many existing clustering
protocols. Finally, analysis and simulation demonstrate that the proposed scheme outperforms the previous autoconfiguration
approaches.
相似文献
Longjiang LiEmail: |
5.
Expressions are given for the moment generating functions of the Rayleigh and generalized Rayleigh distributions.
相似文献
Saralees NadarajahEmail: |
6.
M. J. Moron R. Luque E. Casilari A. Diaz-Estrella 《Wireless Personal Communications》2009,50(2):161-180
Currently, Bluetooth is the most widely used technology for Wireless Personal Area Networks (WPAN). Quality-of-Service (QoS)
support is critical to ensure bandwidth maximization for mobile applications based on this WPAN technology. The overhead introduced
by the different layers of Bluetooth protocol may have a serious impact on WPAN performance. However, most studies of Bluetooth
performance neglect this overhead and assume that data are directly transmitted over L2CAP (Logical Link Control and Adaptation
Protocol) or even HCI (Host Controller Interface) layers. In fact, this option is not feasible in most Bluetooth applications,
as they integrate actual devices that implement a particular Bluetooth profile, usually SPP (Serial Port Profile). The use
of profiles cannot be disregarded as they guarantee the interoperability between devices from different vendors. The aim of
this paper is to characterise the performance of a Bluetooth WPAN (specifically the end-to-end delay and the throughput) when
profiles are utilised. This study takes into account the overhead added by the protocols taking part in the transmission of
user data. This paper also explores the effect of segmentation mismatch that may appear when the maximum size for data in
each layer of the architecture is different. The analysis has been focused on SPP and PAN (Personal Area Networks) profiles.
In the case of the PAN profile, the study concludes that the network performance decreases for user data sizes greater than
1,472 bytes, since the excessive overhead added by the network layer is increased by the IP (Internet Protocol) fragmentation.
In the case of SPP, an inappropriate choice of the maximum data unit at RFCOMM (Radio Frequency Communication for Serial Cable
Emulation Protocol based on ETSI TS 07.10) and L2CAP layers can also heavily affect the transmission delay.
相似文献
A. Diaz-EstrellaEmail: |
7.
In the wireless microsensor networks, both source and sink nodes can be changed or mobile. The movement of source and sink
may lead to the breakage of existing routes. In most routing protocols, query packets are broadcasted to correct a broken
route between source and sink, which causes significant communication overhead in terms of both energy and delay. In order
to support the sink mobility of conventional routing protocols, we propose a simple route maintaining algorithm which does
not use the flooding method. Since the proposed algorithm does not require the information on the geometric location of sensor
nodes, it can be easily adopted in most existing routing protocols including Ad Hoc On Demand Distance Vector (AODV) and Direct
Diffusion (DD). Experimental results show that the proposed algorithm drastically improves the conventional routing protocols
in terms of both energy and delay in case of mobile sinks.
相似文献
Sung-Jea KoEmail: |
8.
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: |
9.
Elliptic curve cryptography (ECC) is recognized as a fast cryptography system and has many applications in security systems.
In this paper, a novel sharing scheme is proposed to significantly reduce the number of field multiplications and the usage
of lookup tables, providing high speed operations for both hardware and software realizations.
相似文献
Brian KingEmail: |
10.
Saralees Nadarajah 《Wireless Personal Communications》2009,49(4):575-585
The quantization error for MIMO (multiple-input multiple-output) downlink channels is known to be the minimum of independent
and identically distributed beta random variables. In this note, an exact expression is derived for the average quantization
error. Computational issues relating to its correctness, usage and approximations are discussed.
相似文献
Saralees NadarajahEmail: |
11.
Grzegorz Mrugalski Janusz Rajski Chen Wang Artur Pogiel Jerzy Tyszer 《Journal of Electronic Testing》2007,23(1):35-45
This paper describes a non-recursive fault diagnosis technique for scan-based designs with convolutional test response compaction.
The proposed approach allows a time-efficient and accurate identification of failing scan cells using Gauss–Jordan elimination
method.
相似文献
Jerzy Tyszer (Corresponding author)Email: |
12.
More than 30 Million people in the world have diabetes type 1. People with diabetes type 1 need to take proper decisions 6–10
times a day to maintain balance between food, physical exercise and anti-diabetic treatment with the aim of keeping blood-glucose
level within thigh limits. These decisions are based on the diabetic’s own knowledge about diabetes as well as personal experience.
The requirements of taking proper decisions as well as the expectations from the end-users (the diabetics and their relatives)
have been included in the maXi project [See official website: ]. The maXi project develops Information and Communication Technology (ICT) support for personal chronic disease management
and verifies the solutions by end-users in a living lab. The end-users are represented by families where one or more family
member has diabetes.
相似文献
Niels BoyeEmail: |
13.
For applications requiring a large dynamic, real numbers may be represented either in floating-point, or in the logarithm
number system (LNS). Which system is best for a given application is difficult to know in advance, because the cost and performance
of LNS operators depend on the target accuracy in a highly non linear way. Therefore, a comparison of the pros and cons of
both number systems in terms of cost, performance and overall accuracy is only relevant on a per-application basis. To make
such a comparison possible, two concurrent libraries of parameterized arithmetic operators, targeting recent field-programmable
gate arrays, are presented. They are unbiased in the sense that they strive to reflect the state-of-the-art for both number
systems. These libraries are freely available at .
相似文献
Jérémie Detrey (Corresponding author)Email: |
Florent de DinechinEmail: |
14.
The paper summarizes the main results of one of the key panel session of the Workshop, focused on the investigation about
the possible translation of the “layerless communications” from a dreaming vision to reality.
相似文献
Juha SaarnioEmail: |
15.
We consider the problem of joint congestion control and resource allocation in spatial-TDMA wireless networks. The design
problem is posed as a utility maximization problem subject to link rate constraints which involve both transmission scheduling
and power allocation. Starting from the performance limitations of a centralized optimization based on global network information,
we proceed systematically in our development of two distributed and transparent protocols that rely on local information only.
In the process, we introduce a novel decomposition method for convex optimization, establish its convergence for the utility
maximization problem, and demonstrate how it suggests a distributed solution based on TCP/AQM and incremental updates of the
transmission schedule. We develop a two-step procedure for finding the schedule updates and suggest two schemes for distributed
link scheduling and power control under realistic interference models. Although the final protocols are suboptimal, we isolate
and quantify the performance losses incurred by each simplification and demonstrate strong performance in examples.
相似文献
Mikael JohanssonEmail: |
16.
Spyridon L. Tompros Christoforos D. Kavadias Dimitrios D. Vergados Nikolaos P. Mouratidis 《Wireless Personal Communications》2009,49(2):197-212
Heterogeneous networks are collections of communication platforms utilising different protocols. Heterogeneity was born by
the need of operators to offer within short time many different services on the market. As a result, nowadays users communicate
through collections of networks utilising different protocols, rendering service mapping from one network to another a complex
issue. With the emergence of IMS and the introduction of IP and SIP protocols as a means for achieving network homogeneity,
service interoperability has become even more important. With regard to this problem, the paper proposes a method for homogenising
IMS networks with regard to the utilised QoS settings and charging policy. The paper explains how the method can be applied
on real IMS networks for the preservation of QoS and charging records across the whole communication path and carries out
a comparative analysis with performance figures obtained in real networks.
相似文献
Dimitrios D. Vergados (Corresponding author)Email: |
17.
In the past years, several signaling protocols were proposed for OBS networks and the most popular one is the Just-Enough-Time
(JET) protocol. JET not only efficiently utilizes the network capacity, but also effectively reduces the end-to-end transmission
delay. However, the most critical defect of JET is its intrinsic deficiency: Fairness. The fairness problem is a traditional
problem common to various kinds of networks. It results in a phenomenon that bursts with a shorter number of hops are generally
favorized and hence deteriorates the network utilization as well. In this article, we investigate this problem and propose
a fair channel scheduling algorithm as a solution. Usually there is a tradeoff between fairness and blocking performance.
Accordingly, the objective of our scheme is to achieve a balance between the two conflicting metrics as much as possible.
In our scheme, each burst is associated with a dynamic priority which is defined by several characteristics of the burst.
When contention occurs, the proposed scheme picks the preferable burst and drops the other one according to their priorities.
From simulation results, we observed that the proposed scheme could improve fairness without causing significant reduction
in dropping performance. Furthermore, it increases the effective link utilization as well.
相似文献
Ching-Fang HsuEmail: |
18.
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: |
19.
Zygmunt J. Haas Rimon Barr 《International Journal of Wireless Information Networks》2007,14(2):93-105
We analyze the asymptotic cost of discovering a route within a flat ad hoc network and we show that one can discover a route
with cost that is proportional only to the area of the network, which is independent of the number of network nodes. Furthermore,
we show that this is optimal and that bordercasting (a query propagation protocol where a node retransmits a query to a set of nodes at some hop-distance away) possesses this
density-independence property. We present the design of bordercast and the associated maintenance protocols, and we evaluate
their performance. In particular, we highlight that the aggregation of local information by bordercasting at each network
node is a fundamental building block for the construction of scalable protocols in flat ad hoc networks.
相似文献
Zygmunt J. HaasEmail: URL: http://wnl.ece.cornell.edu |
20.
Xianyi Rui 《Wireless Personal Communications》2009,50(2):133-142
The effect of co-channel interference (CCI) is considered in multiple-input multiple-output (MIMO) systems employing maximal
ratio combining (MRC) under independent and identically distributed Rayleigh fading. Closed-form capacity and symbol error
rate expressions are presented to evaluate the performance without any numerical integrations or statistical simulations.
The analytical results are compared with Monte Carlo simulations and the good agreement is obtained.
相似文献
Xianyi RuiEmail: |