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1.
A Simple and Robust Vertical Handoff Algorithm for Heterogeneous Wireless Mobile Networks 总被引:2,自引:0,他引:2
Daojing He Caixia Chi Sammy Chan Chun Chen Jiajun Bu Mingjian Yin 《Wireless Personal Communications》2011,59(2):361-373
Wireless networking is becoming an increasingly important and popular way of providing global information access to users
on the move. One of the main challenges for seamless mobility is the availability of simple and robust vertical handoff algorithms,
which allow a mobile node to roam among heterogeneous wireless networks. In this paper, motivated by the facts that vertical
handoff procedure is done on mobile nodes and battery power may be one crucial parameter for certain mobile nodes, a simple
and robust two-step vertical handoff decision algorithm is proposed for heterogeneous wireless mobile networks. To the best
of our knowledge, this is the first vertical handoff algorithm that takes the classification of mobile nodes into consideration,
one is resource-poor mobile nodes, and the other is resource-rich mobile nodes. This new feature makes it more applicable
in the real world. In addition, dynamic new call blocking probability is firstly introduced by this paper to make handoff
decision for wireless networks. The experiment results have shown that the proposed algorithm outperforms traditional algorithms
in bandwidth utilization, handoff dropping rate and handoff rate. 相似文献
2.
It is envisaged that next generation wireless networks (NGWN) will be heterogeneous, consisting of multiple radio access technologies (RATs) coexisting in the same geographical area. In these heterogeneous wireless networks, mobile terminals of different capabilities (heterogeneous terminals) will be used by subscribers to access network services. We investigate the effect of using heterogeneous mobile terminals (e.g. single-mode, dual-mode, triple-mode, etc.) on call blocking and call dropping probabilities in cooperative heterogeneous wireless networks. We develop analytical models for heterogeneous mobile terminals and joint radio resource management in heterogeneous wireless networks. Using a two-class three-RAT heterogeneous wireless network as an example, the effect of using heterogeneous terminals in the network is evaluated. Results show the overall call blocking/dropping probability experienced by subscribers in heterogeneous wireless networks depends on the capabilities of mobile terminals used by the subscribers. In the worst case scenario, when all subscribers use single-mode mobile terminals, each subscriber is confined to a single RAT and consequently, joint radio resource management in heterogeneous wireless network has no improvement on new call blocking and handoff call dropping probabilities. However, in the best case scenario, when all subscribers use three-mode terminals, new class-1 call blocking probability decreases from 0.37 (for 100% single-mode terminals) to 0.05, at the arrival rate of 6 calls per minute. New class-2 call blocking probability also decreases from 0.8 to 0.52. Similarly, handoff class-1 call dropping probability decreases from 0.14 to 0.003, and handoff class-2 call dropping probability decreases from 0.44 to 0.09. 相似文献
3.
Distributed call admission control in mobile/wireless networks 总被引:18,自引:0,他引:18
The major focus of this paper is distributed call admission control in mobile/wireless networks, the purpose of which is to limit the call handoff dropping probability in loss systems or the cell overload probability in lossless systems. Handoff dropping or cell overload are consequences of congestion in wireless networks. Our call admission control algorithm takes into consideration the number of calls in adjacent cells, in addition to the number of calls in the cell where a new call request is made, in order to make a call admission decision. This is done by every base station in a distributed manner without the involvement of the network call processor. The admission condition is simple enough that the admission decision can be made in real time. Furthermore, we show that our distributed call admission control scheme limits the handoff dropping or the cell overload probability to a predefined level almost independent of load conditions. This is an important requirement of future wireless/mobile networks with quality-of-service (QoS) provisioning 相似文献
4.
Prihandoko Habaebi M. H. Ali B. M. 《International Journal of Wireless Information Networks》2004,11(1):19-27
Multimedia traffic is expected to be included in the next generation of wireless networks. As in wireline networks, the wireless network must also be capable of providing guaranteed quality-of-service (QoS) over the lifetime of mobile connections. In this paper, a bandwidth reservation scheme incorporating a user mobility prediction is proposed to manage the QoS of the networks. The mobility prediction scheme is developed based on the aggregate history of mobile users. Based on the mobility prediction, bandwidth is reserved to guarantee the uninterrupted handoff process. Simulation results demonstrate that the proposed scheme can guarantee the required QoS requirements in terms of handoff call dropping probability and new call blocking probability while maintaining efficient bandwidth utilization. 相似文献
5.
In this paper, we propose the signal strength ratio (SSR) based vertical handoff (VHO) algorithms and the averaged received signal strength (ARSS) based VHO algorithms for integrated networks of wireless local area network (WLAN) and 3G network. The performance of our proposed VHO algorithms with hysteresis and dwell timer approaches has been investigated for two different topologies of integrated heterogeneous network. Two different network topologies consider two different types of radio cell arrangement. A mobile terminal (MT) is moving within the coverage area of WLAN and 3G with constant velocity. The received signal strength at the MT of interest is measured at different sampling instant. The received signal strength with other additional parameters is used to determine the condition of VHO. We evaluate the decision delay, and the number of vertical handoffs between WLAN and 3G network using the proposed VHO algorithms. We compare the performance of our proposed VHO algorithms with existing RSS based VHO algorithm. Our proposed SSR and ARSS based VHO algorithms provide less decision delay as compared to existing RSS based VHO algorithm. Further, ARSS with dwell timer based VHO algorithm provides better performance than other VHO algorithms. 相似文献
6.
异构分层无线网络中基于逗留时间的动态流量均衡算法研究 总被引:1,自引:1,他引:0
为使异构分层无线网络能服务更多的移动用户,提出了一种基于逗留时间的动态流量均衡算法.该算法首先根据用户移动模型计算其在小区内的逗留时间,然后基于小区呼叫到达率和重叠覆盖小区的流量状态来确定一个周期内呼叫转移的数量,最后依据逗留时间门限值将重负载小区中满足条件的呼叫转移到轻负载的重叠覆盖小区中.为降低切换呼叫掉线率,还对异构网间的呼叫切换策略做了改进.仿真实验结果表明,本算法在新呼叫阻塞率和切换呼叫掉线率等性能指标上比传统方法有显著的提高. 相似文献
7.
《Mobile Computing, IEEE Transactions on》2008,7(7):846-857
In heterogeneous wireless networks, handoff can be separated into two parts: horizontal handoff (HHO) and vertical handoff (VHO). VHO plays an important role to fulfill seamless data transfer when mobile nodes cross wireless access networks with different link layer technologies. Current VHO algorithms mainly focus on when to trigger VHO, but neglect the problem of how to synthetically consider all currently available networks (homogeneous or heterogeneous) and choose the optimal network for HHO or VHO from all the available candidates. In this paper, we present an analytical framework to evaluate VHO algorithms. Subsequently, we extend the traditional hysteresis based and dwelling-timer based algorithms to support both VHO and HHO decisions and apply them to complex heterogeneous wireless environments. We refer to these enhanced algorithms as E-HY and E-DW, respectively. Based on the proposed analytical model, we provide a formalization definition of the handoff conditions in E-HY and E-DW and analyze their performance. Subsequently, we propose a novel general handoff decision algorithm, GHO, to trigger HHO and VHO in heterogeneous wireless networks. Analysis shows that GHO can achieve better performance than E-HY and E-DW. Simulations validate the analytical results and verify that GHO outperforms traditional algorithms in terms of the matching ratio, TCP throughput and UDP throughput. 相似文献
8.
Yu Cheng Weihua Zhuang 《Communications Magazine, IEEE》2002,40(5):130-136
The next-generation wireless networks are evolving toward a versatile IP-based network that can provide various real-time multimedia services to mobile users. Two major challenges in establishing such a wireless mobile Internet are support of fast handoff and provision of quality of service (QoS) over IP-based wireless access networks. In this article, a DiffServ resource allocation architecture is proposed for the evolving wireless mobile Internet. The registration-domain-based scheme supports fast handoff by significantly reducing mobility management signaling. The registration domain is integrated with the DiffServ mechanism and provisions QoS guarantee for each service class by domain-based admission control. Furthermore, an adaptive assured service is presented for the stream class of traffic, where resource allocation is adjusted according to the network condition in order to minimize handoff call dropping and new call blocking probabilities 相似文献
9.
10.
Emerging mobile wireless networks are characterized by significant uncertainties in mobile user population and system resource state. Such networks require adaptive resource management that continuously monitor the system and dynamically adjust resource allocations for adherence to the desired system performance requirements. We propose adaptive resource management technique based on control theory. The controller dynamically solves resource allocation problem using feedback control laws. In the base algorithm, the number of guard channels is dynamically adjusted by feeding back the current handoff call dropping probability. The base algorithm is then enhanced in two ways: feeding back the instantaneous number of handoff calls and by probabilistically implementing a fractional number of guard channels. We study the effects of parameter choices on the performance of the proposed algorithms using discrete event simulation. Simulation results indicate that the feedback controllers can guarantee the predetermined call dropping probability under a variety of traffic conditions, and so can utilize the scarce wireless resource efficiently by accepting more new calls. 相似文献
11.
Wei Zhuang Bensaou B. Kee Chaing Chua 《Vehicular Technology, IEEE Transactions on》2000,49(2):494-505
For various advantages including better utilization of radio spectrum (through frequency reuse), lower mobile transmit power requirements, and smaller and cheaper base station equipment, future wireless mobile multimedia networks are likely to adopt micro/picocellular architectures. A consequence of using small cell sizes is the increased rate of call handoffs as mobiles move between cells during the holding times of calls. In a network supporting multimedia services, the increased rate of call handoffs not only increases the signaling load on the network, but makes it very difficult for the network to guarantee the quality of service (QoS) promised to a call at setup or admission time. This paper describes an adaptive QoS handoff priority scheme which reduces the probability of call handoff failures in a mobile multimedia network with a micro/picocellular architecture. The scheme exploits the ability of most multimedia traffic types to adapt and trade off QoS with changes in the amount of bandwidth used. In this way, calls can trade QoS received for fewer handoff failures. The call level and packet level performance of the handoff scheme are studied analytically for a homogeneous network supporting a mix of wide-band and narrow-band calls. Comparisons are made to the performance of the nonpriority handoff scheme and the well-known guard-channel handoff scheme 相似文献
12.
In heterogeneous wireless network environment, wireless local area network (WLAN) is usually deployed within the coverage of a cellular network to provide users with the convenience of seamless roaming among heterogeneous wireless access networks. Vertical handoffs between the WLAN and the cellular network maybe occur frequently. As for the vertical handoff performance, there is a critical requirement for developing algorithms for connection management and optimal resource allocation for seamless mobility. In this paper, we develop a mathematical model for vertical handoff decision problem, and propose a multi-objective optimization immune algorithm-based vertical handoff decision scheme. The proposed scheme can enable a wireless access network not only to balance the overall load among all base stations and access points but also maximize the collective battery lifetime of mobile terminals. Results based on a detailed performance evaluation study are also presented here to demonstrate the efficacy of the proposed scheme. 相似文献
13.
Handoff performance is a critical issue for mobile users in wireless cellular networks, such as GSM networks, 3G networks,
and next generation networks (NGNs). When ad hoc mode is introduced to cellular networks, multi-hop handoffs become inevitable,
which brings in new challenging issues to network designers, such as how to reduce the call dropping rate, how to simplify
the multi-hop handoff processes, and how to take more advantage of ad hoc mode for better resource management, and most of
these issues have not been well addressed as yet. In this paper, we will address some of the issues and propose a scheme,
Ad-hoc-Network–Embedded handoff Assisting Scheme (ANHOA), which utilizes the self-organizing feature of ad hoc networks to facilitate handoffs in cellular networks and provide an
auxiliary way for mobile users to handoff across different cells. Moreover, we also propose a scheme enabling each BS to find
the feasible minimum reservation for handoff calls based on the knowledge of adjacent cells’ traffic information. Due to the
use of multi-hop connections, our scheme can apparently alleviate the reservation requirement and lower the call blocking
rate while retaining higher spectrum efficiency. We further provide a framework for information exchange among adjacent cells,
which can dynamically balance the load among cells. Through this study, we demonstrate how we can utilize ad hoc mode in cellular
systems to significantly improve the handoff performance. 相似文献
14.
In cellular wireless networks, the choice of Call Admission Control scheme impacts the performance of the system, particularly as how calls are managed when a mobile user is handed off from one cell to another. Non-prioritized schemes treat handoff calls and new calls equally, while, prioritized schemes give higher priority to handoff calls. In this paper, some of the popular non-prioritized and prioritized Call Admission Control schemes were investigated and their behavior was simulated and analyzed. They are evaluated based on call dropping probability, call blocking probability and system utilization parameters. 相似文献
15.
Modeling and performance analysis for wireless mobile networks: a new analytical approach 总被引:1,自引:0,他引:1
Yuguang Fang 《Networking, IEEE/ACM Transactions on》2005,13(5):989-1002
In wireless mobile networks, quantities such as call blocking probability, call dropping probability, handoff probability, handoff rate, and the actual call holding times for both complete and incomplete calls are very important performance parameters in the network performance evaluation and design. In the past, their analytical computations are given only when the classical exponential assumptions for all involved time variables are imposed. In this paper, we relax the exponential assumptions for the involved time variables and, under independence assumption on the cell residence times, derive analytical formulae for these parameters using a novel unifying analytical approach. It turns out that the computation of many performance parameters is boiled down to computing a certain type of probability, and the obtained analytical results can be easily applied when the Laplace transform of probability density function of call holding time is a rational function. Thus, easily computable results can be obtained when the call holding time is distributed with the mixed-Erlang distribution, a distribution model having universal approximation capability. More importantly, this paper develops a new analytical approach to performance evaluation for wireless networks and mobile computing systems. 相似文献
16.
Sheng-Tzong Cheng Jian-Liang Lin 《Selected Areas in Communications, IEEE Journal on》2005,23(11):2093-2103
Many wireless access systems have been developed recently to support users mobility and ubiquitous communication. Nevertheless, these systems always work independently and cannot simultaneously serve users properly. In this paper, we aim to integrate IPv6-based wireless access systems and propose a coordinated call admission control mechanism to utilize the total bandwidth of these systems to minimize the call blocking probabilities, especially the handoff call dropping probabilities. First, we propose an integrated hierarchical wireless architecture over IPv6-based networks to combine the wireless access systems including cellular systems (second-generation, General Packet Radio Service, or third-generation), IEEE 802.11 a/b/g WLAN, and Bluetooth. In the proposed architecture, mobile user can request a call with quality-of-service (QoS) requirements by any wireless network interfaces that can be accessed. When the proposed coordinated call admission control (CCAC) mechanism receives a request, it takes the QoS requirements of the incoming call and the available and reserved bandwidth of this wireless system into consideration to accept or reject this request. Besides, the mechanism can coordinate with other wireless systems dynamically to adjust the bandwidth reserved for handoff calls at each wireless system in this architecture so as to reduce the call blocking probabilities. Once the call is admitted, the mobile user is able to access heterogeneous wireless access networks via multiple interfaces simultaneously. Finally, we evaluate this system to show that the CCAC on the proposed architecture outperforms other mechanisms proposed before. 相似文献
17.
Chung‐Ming Huang Meng‐Shu Chiang Chin‐Wei Lin 《Wireless Communications and Mobile Computing》2009,9(9):1194-1205
Mobile IP (MIP) defines a mobility management for mobile users to continuously access data when the currently attachment is changed to another network. However, when mobile node (MN) roams between network segments, the handoff latency results in packet losses and transmission delay. In this paper, we propose a multihomed fast handoff scheme (MFH‐MIP) to decrease the handoff cost. In the proposed MFH‐MIP scheme, each MN is implemeted with the link layer trigger and multihomed techniques. Based on the link layer trigger, MN can collect signal strengths of nearby access points (APs) and switch to a new link automatically when the old link becomes unsuitable to connect. Using the multihomed technique, MN can prepare for handoff using two (or more) interfaces, in which (i) one is connected with the old link to receive packets and (ii) the other one is used to access nearby APs and select the most suitable one as the new link, in parellel. In this way, MN can continuously transmit and receive packets during handoff. Based on the proposed method, MN can roam smoothly among different networks in the wireless environment. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
18.
XIE Sheng-dong WU Meng Communication Information Engineering Institute Nanjing University of Posts Telecommunications Nanjing China 《中国邮电高校学报(英文版)》2007,14(1):22-25
The integration of cellular network (CN) and wireless local area network (WLAN) is the trend of the next generation mobile communication systems, and nodes will handoff between the two kinds of networks. The received signal strength (RSS) is the dominant factor considered when handoff occurs. In order to improve the handoff efficiency, this study proposes an adaptive decision algorithm for vertical handoff on the basis of fast Fourier transform (FFT). The algorithm makes handoff decision after analyzing the signal strength fluctuation which is caused by slow fading through FFT. Simulations show that the algorithm reduces the number of handoff by 35%, shortens the areas influenced by slow fading, and enables the nodes to make full use of WLAN in communication compared with traditional algorithms. 相似文献
19.
VICTOR O.K. 《中国邮电高校学报(英文版)》2005,12(2)
1IntroductionWith the increasing demand for mobile access ,theInternet has to provide not only li mited mobility,suchas WLAN[1 ~3]access ,but also worldwide mobility,asexemplified by Mobile IP[4 ~7]to meet the user require-ments in terms of data rate and mobility.In particular ,it is desired that when a user stays in the hotspot cov-ered by WLAN, he can access the Internet throughWLAN,and when he goes out of the hotspot ,the on-going connection should not be dropped,but is insteadhanded … 相似文献
20.
Effective support of real‐time multimedia applications in wireless access networks, viz. cellular networks and wireless LANs, requires a dynamic bandwidth adaptation framework where the bandwidth of an ongoing call is continuously monitored and adjusted. Since bandwidth is a scarce resource in wireless networking, it needs to be carefully allocated amidst competing connections with different Quality of Service (QoS) requirements. In this paper, we propose a new framework called QoS‐adaptive multimedia wireless access (QoS‐AMWA) for supporting heterogeneous traffic with different QoS requirements in wireless cellular networks. The QoS‐AMWA framework combines the following components: (i) a threshold‐based bandwidth allocation policy that gives priority to handoff calls over new calls and prioritizes between different classes of handoff calls by assigning a threshold to each class, (ii) an efficient threshold‐type connection admission control algorithm, and (iii) a bandwidth adaptation algorithm that dynamically adjusts the bandwidth of an ongoing multimedia call to minimize the number of calls receiving lower bandwidth than the requested. The framework can be modeled as a multi‐dimensional Markov chain, and therefore, a product‐form solution is provided. The QoS metrics—new call blocking probability (NCBP), handoff call dropping probability (HCDB), and degradation probability (DP)—are derived. The analytical results are supported by simulation and show that this work improves the service quality by minimizing the handoff call dropping probability and maintaining the bandwidth utilization efficiently. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献