共查询到20条相似文献,搜索用时 11 毫秒
1.
Capacity has always been a major concern in wireless networks. This letter studies the impact of mobility on the overall system capacity in wireless cellular networks. In this letter, we present a simple system model which we developed to capture the inherent relationships among system capacity, new call blocking probability, handoff dropping probability, call terminating probability, and bandwidth utilization rate. We investigate the complex relationship between mobility and capacity‐related parameters. Through simulation, we demonstrate that mobility has a significant impact on capacity and is reversely proportional to the bandwidth reserved for handoff traffic. 相似文献
2.
In this paper new paging schemes are presented for locating mobile users in wireless networks. Paging costs and delay bounds are considered since paging costs are associated with bandwidth utilization and delay bounds influence call setup time. In general, location tracking schemes require intensive computation to search for a mobile terminal in current PCS networks. To reduce the paging costs, three new paging schemes, reverse, semi-reverse and uniform, are introduced to provide a simple way of partitioning the service areas and decrease the paging costs based on each mobile terminal's location probability distribution. Numerical results demonstrate that our approaches significantly reduce the paging costs for various probability distributions such as uniform, truncated discrete Gaussian, and irregular distributions. 相似文献
3.
位置管理是移动通信领域的一个具有挑战性的问题,涉及到位置更新和位置查找操作.在现行蜂窝系统的位置管理策略(简称"基本策略")中,一旦移动台越区,就需要进行位置更新.由于移动台的越区具有局部性,基本策略会造成系统资源的极大浪费.因此,降低位置管理的费用成为移动通信领域的一个研究热点.该文给出不需要进行位置更新的环状搜索位置管理策略(简称"环状策略"),并推导出搜索位置区平均层数的一个公式,然后利用这一公式对基本策略、指针推进策略与环状策略的费用进行了对比研究,得出:在一定条件下,环状策略的费用要比基本策略及基本指针推进策略小. 相似文献
4.
在移动IP网络中,层次移动IP协议可降低移动IP位置管理的信令消耗。该文研究支持寻呼的HMIPv6,提出了时延限制下的多步寻呼策略以及基于遗传算法的多步寻呼方案——根据移动节点的位置概率分布,采用遗传算法对寻呼区域内的所有子网进行分组,每步寻呼一个组,使平均寻呼信令开销达到或接近最优。此外,对HMIPv6、单步寻呼的HMIPv6以及基于遗传算法的多步HMIPv6寻呼方案的信令开销进行了比较分析,得出寻呼节省信令开销的必要条件。最后,给出一组数值结果以说明所提出的寻呼策略的有效性。 相似文献
5.
近年来,随着移动互联网的蓬勃发展和智能终端的快速普及,对无缝网络覆盖和高速数据传输要求日趋增强,超密集异构蜂窝无线网络通过减小小区半径,增加低功率节点数量进行超密集组网,提高无线资源利用率和频谱效率,因而引起了国内外研究学者的广泛关注。然而,超密集异构蜂窝无线网络中愈发密集的网络部署也带来了各种严峻的问题,包括超密集异构蜂窝无线网络中的系统干扰问题、无线信息的安全传输问题、以及网络运营的能量供给问题等。为此,本文首先简单介绍了超密集异构蜂窝无线网络架构,接着从干扰管理、物理层安全和能量效率等方面,深入分析了超密集异构蜂窝无线网络中的关键技术和当前挑战,最后,进一步展望了超密集异构蜂窝无线网络的未来发展。 相似文献
6.
王明松 《电信工程技术与标准化》2002,(3):50-52
随着通信技术飞速发展和通信领域竞争加剧,如何充分利用现有资源显得尤为重要。本评述了安徽联通无线寻呼和短消息之间的业务整合,分析了具体实现中的关键技术。 相似文献
7.
8.
A Combination of Optimal Partitioning and Location Prediction to Assist Paging in Mobile Cellular Networks 总被引:1,自引:0,他引:1
I. Z. Koukoutsidis M. E. Theologou 《International Journal of Wireless Information Networks》2004,11(3):123-129
The correlated both in space and time user mobility behavior can aid significantly in the localization of a moving terminal in the network coverage area. However, there is always some uncertainty in mobile user position and a network-wide search cannot be done. Therefore, a predictive paging scheme must always be combined with a location update strategy and a compatible algorithm to conduct the search. In this paper, we introduce a new strategy that combines an optimal partitioning of the location area (LA) with a model to predict user movements, based on the additional information of the cell where the last interaction between the network and the terminal took place. We study the performance of the strategy under delay bounds and different mobility and call arrival characteristics. It is found that the new scheme further minimizes signaling costs and enhances previous sequential paging algorithms. 相似文献
9.
Show-Shiow Tzeng 《Wireless Personal Communications》2007,42(4):527-536
Channel management aims to provide quality of service guarantees for mobile users while efficiently utilize limited radio
spectrum. With the increasing demand for diverse services in wireless networks, channel management for multi-service traffic
in wireless networks is important. To provide diverse broadband services in limited radio spectrum, previous literature has
presented adaptive services which provide mobile users with good quality of services. This study considers channel management
for multi-service traffic in wireless networks with adaptive services. A channel management scheme, namely, restricted sharing,
is devised to provide multi-class traffic with quality of service guarantees while increase channel utilization as much as
possible. An analysis is used to study the performance of the restricted sharing scheme. Three classes are considered in numerical
results. Numerical results show that the restricted sharing scheme guarantees quality of service and achieves high channel
utilization. 相似文献
10.
P-MIP: Paging Extensions for Mobile IP 总被引:12,自引:1,他引:12
Zhang Xiaowei Gomez Castellanos Javier Campbell Andrew T. 《Mobile Networks and Applications》2002,7(2):127-141
As the number of Mobile IP users grows, so will the signalling overhead associated with Internet mobility management in the core IP network. This presents a significant challenge to Mobile IP as the number of mobile devices scale-up. In cellular networks, registration and paging techniques are used to minimize the signalling overhead and optimize the mobility management performance. Currently, Mobile IP supports registration but not paging. In this paper, we argue that Mobile IP should be extended to support paging to improve the scalability of the protocol to handle large populations of mobile devices. To address this, we introduce P-MIP, a set of simple paging extensions for Mobile IP, and discuss the construction of paging areas, movement detection, registration, paging and data handling. We present analysis and simulation results for Mobile IP with and without paging extensions, and show that P-MIP can scale well supporting large numbers of mobile devices with reduced signalling under a wide variety of system conditions. 相似文献
11.
Robust Packet Scheduling in Wireless Cellular Networks 总被引:1,自引:0,他引:1
This paper addresses the following robust scheduling problem: Given that only coarse-grained channel state information (i.e., bounds on channel errors, but not the fine-grained error pattern) is available, how to design a robust scheduler that ensures worst-case optimal performance? To solve this problem, we consider two coarse-grained channel error models and take a zero-sum game theoretic approach, in which the scheduler and the channel error act as non-cooperative adversaries in the scheduling process. Our results show that in the heavy channel error case, the optimal scheduler adopts a threshold form. It does not schedule a flow if the price (the flow is willing to pay) is too small, in order to maximize the system revenue. Among the scheduled flows, the scheduler schedules a flow with a probability inversely proportional to the flow price such that the risk of being caught by the channel error adversary is minimized. We also show that in the mild channel error model, the robust scheduling policy exhibits a balanced trade-off between a greedy decision and a conservative policy. The scheduler is likely to take a greedy decision if it evaluates the risk of encountering the channel error adversary now to be small. Therefore, robust scheduling does not always imply conservative decision. The scheduler is willing to take “risks” to expect higher gain in some scenarios. Our solution also shows that probabilistic scheduling may lead to higher worst-case performance compared to traditional deterministic policies. Finally, the current efforts show the feasibility to explore a probabilistic approach to cope with dynamic channel error conditions. 相似文献
12.
Implied Costs for Multirate Wireless Networks 总被引:1,自引:0,他引:1
Implied costs for multirate wireless networks are calculated and their use is demonstrated for quantifying mobility, traffic load, call pricing, network optimization and for evaluating trade-offs between calls of different rates. User mobility is modeled by assigning call termination and call handoff probabilities. Fixed Channel Assignment (FCA) is used with priority for handoffs over new call arrivals by reserving a number of channels in all the cells. The performance measures used are new call blocking and handoff drop probabilities. The implied cost is calculated for the network net revenue, which considers the revenue generated by accepting a new call arrival into the network as well as the cost of a handoff drop in any cell. Simulation and numerical results are presented to show the accuracy of the model. The implied costs are used to suggest pricing techniques for different calls based on mobilities and bandwidth. Finally, a nonlinear constrained optimization problem is formulated to calculate the sum revenue for a given network by maximizing the net revenue using implied costs in a gradient descent algorithm. The implied cost analysis also shows that matching capacity distribution to not only exogenous traffic, but also to mobility can significantly increase revenue. 相似文献
13.
14.
The availability of variety of communication devices offers a choice among networks with vastly different characteristics. No single protocol or application can be expected to perform well over all these networks. A mobile host is likely to encounter these different networks and needs to adapt accordingly. The problem of adapting to a changing network environment is further complicated, because changes in network conditions are usually transparent to higher layers of the protocol stack. In order to allow automatic adaptation of applications and protocols, awareness of link conditions and network environment is necessary. In this paper, we present a uniform mechanism based on ICMP messages for providing information about the environment to the protocol stack. We also show how protocols can adapt to changes in the environment, and in particular, demonstrate dynamic fine tuning of some of the well known protocols such as UDP and TCP. Performance measurements demonstrate that our framework imposes little overheads and improves protocol performance under changing network conditions. 相似文献
15.
Maher A. Al-Sanabani Subramaniam K. Shamala Mohamed Othman Zuriati A. Zukarnain 《Wireless Personal Communications》2008,46(2):143-163
Next generation of wireless cellular networks aim at supporting a diverse range of multimedia services to Mobile Terminal
(MT) with guaranteed Quality of Service (QoS). The challenge is to maintain the playing continuity of multimedia streams during
handoff. In this paper, a bandwidth reservation scheme based on mobility prediction is proposed, to enable high accurate prediction
of next crossing cell (target cell) which a MT is going to, in order to avoid too early or over reservation resulting in a
waste of resources. The amount of bandwidth to be reserved is dynamically adjusted according to (a) the current position (location)
and the extrapolated direction of MT and; (b) the sector and zones of the cell. A Call Admission Control scheme (CAC) is also
considered to further guarantee the QoS of real time traffic. The performance of the system is evaluated through discrete
event simulation of the wireless cellular environment. Simulation results show that the proposed scheme as compared to several
existing schemes is able to reduce the Handoff Call Dropping Probability (HCDP) of real time traffic and the number of terminated
ongoing calls of non-real time traffic. In addition, it is efficient to reduce the number of cancelled reservation and subsequently
increase the system bandwidth utilization.
相似文献
Maher A. Al-SanabaniEmail: |
16.
17.
In wireless networks, mobile hosts must update the network with their current location in order to get packets delivered. Paging facilitates efficient power management at the mobile host by allowing the host to update the network less frequently at the cost of providing the network with only approximate location information. The network determines the exact location of a mobile host through paging before delivering packets destined to the mobile host. In this paper, we propose the concept of paging as an IP service. IP paging enables a common infrastructure and protocol to support the different wireless interfaces such as CDMA, GPRS, wireless LAN, avoiding the duplication of several application layer paging implementations and the inter-operability issues that exist today. We present the design, implementation, and detailed qualitative and quantitative evaluation, using measurements and simulation, of three IP-based paging protocols for mobile hosts. 相似文献
18.
Zohar Naor 《Wireless Communications and Mobile Computing》2005,5(7):733-748
The issue of providing a mobile virtual private network (MVPN) service by a cellular network is addressed in this study. The main focus of this study is on two aspects of MVPN handling: a multicast transmission, and location management of the MVPN members. Virtual private networks (VPNs) already exist in wired networks. The growing number of mobile users increases the demand for mobile services. It is expected that future wireless networks will have to provide wireless internet services, and in particular, to support MVPNs. In order to maintain an MVPN service offering, the system must support an efficient information delivery to the MVPN members. In order to achieve this goal, the physical locations of the MVPN members must be known to the system. In this study, we present methods to efficiently route and transmit information to the MVPN members, without affecting the quality of the personal service provided to each and every MVPN member. It is shown that the wireless MVPN bandwidth requirement is significantly less than the equivalent bandwidth required by a wired VPN. The offered bandwidth utilization is significantly better than the efficiency of IP‐based multicast transmission in the Internet, and the proposed IP‐based multicast transmission in cellular networks. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
19.
An effective paging strategy is essential for improving the utility of radio channels. This paper proposes a two‐step paging strategy which involves using base station paging agents to page a single cell at each paging. An analytical model is used to evaluate the performance of the proposed strategy. The proposed strategy is compared with the traditional simultaneous paging strategy and a recent proposal using the base station paging agents. The numerical results showed that the proposed strategy proficiently reduces paging cost on radio channels compared with other paging strategies. 相似文献