Effective Paging Schemes with Delay Bounds as QoS Constraints in Wireless Systems

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.     

移动IP网络中基于遗传算法的多步寻呼策略及性能分析

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。     

无线寻呼和移动短消息的整合

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。     

A Combination of Optimal Partitioning and Location Prediction to Assist Paging in Mobile Cellular Networks

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.     

Channel Management for Multi-Service Traffic in Cellular Wireless Networks

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.     

P-MIP: Paging Extensions for Mobile IP

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.     

Robust Packet Scheduling in Wireless Cellular Networks

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.     

Implied Costs for Multirate Wireless Networks

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.     

具有无线寻呼通信接口的关联式交通信号控制机的设计

分析了交通控制系统目前的现状及不足,并提出了一种科学且经济实用的解决方法。     

On Providing Support for Protocol Adaptation in Mobile Wireless Networks

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.     

Multi-class Bandwidth Reservation Scheme Based on Mobility Prediction for Handoff in Multimedia Wireless/Mobile Cellular Networks

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.

全国邮电无线寻呼联网

本文介绍了全国邮电无线寻呼联网的网络结构，各部分的功能以及能够提供的业务。     

IP Paging Service for Mobile Hosts

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.     

An Efficient Two‐Step Paging Strategy Using Base Station Paging Agents in Mobile Communication Networks

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.     

LEO卫星网络基于动态位置区的寻呼策略

针对LEO卫星网络中具有自主定位能力的用户终端,采用基于地理位置的动态位置区划分方案,根据用户移动速度设置位置区的大小。在动态位置区的基础上,对高速移动用户提出了一种基于时延限制的分组寻呼策略。仿真结果表明,对于低速移动用户,二次寻呼策略的时延和开销性能最佳;对于高速移动用户,基于时延限制的分组寻呼策略最佳。     

Mobility Management for Hierarchical Wireless Networks

In this paper, we consider the mobility management in large, hierarchically organized multihop wireless networks. The examples of such networks range from battlefield networks, emergency disaster relief and law enforcement etc. We present a novel network addressing architecture to accommodate mobility using a Home Agent concept akin to mobile IP. We distinguish between the physical routing hierarchy (dictated by geographical relationships between nodes) and logical hierarchy of subnets in which the members move as a group (e.g., company, brigade, battalion in the battlefield). The performance of the mobility management scheme is investigated through simulation.     

On the Design Problem of Cellular Wireless Networks

In this paper, we deal with the problem of how to design cellular networks in a cost-effective way. We first propose an optimization model that deals with selecting the location of the base station controllers (BSCs) and mobile service switching centers (MSCs), selecting their types, designing the network topology and selecting the link types. In order to find a “good” solution, we propose a tabu search algorithm. Numerical results show that the tabu search algorithm produces solutions close to a proposed lower bound.Steven Chamberland received the Electrical Engineering degree from the École Polytechnique de Montréal in 1994 and the Ph.D. degree in Operations Research in 1998 also from the École Polytechnique. From 1998 to 1999, he was with the network architecture group of Bell Canada and from 1999 to 2001, he was a professor at the École de technologie supérieure. Since 2001, he has been an assistant professor of Computer Engineering at the École Polytechnique de Montréal. His research interests include telecommunication network planning and design and network architecture. Dr. Chamberland is a member of IEEE and ACM. E-mail: steven.chamberland@polymtl.caSamuel Pierre received the B.Eng. degree in Civil Engineering in 1981 from the École Polytechnique de Montréal, the B.Sc. and M.Sc. degrees in mathematics and computer science in 1984 and 1985, respectively, from the Université du Québec, the M.Sc. degree in economics in 1987 from the Université de Montréal and, the Ph.D. degree in Electrical Engineering in 1991 from the École Polytechnique de Montréal. He is currently a professor of Computer Engineering at the École Polytechnique de Montréal where he is Director of the Mobile Computing and Networking Research Laboratory and the NSERC/Ericsson Industrial Research Chair in Next- Generation Mobile Networking Systems.Dr. Pierre is the author of four books, co-author of two books and six book chapters, as well as over 200 other technical publications including journal and proceedings papers. He received the Best Paper Award of the Ninth International Workshop in Expert Systems & their Applications (France, 1989), a Distinguished Paper Award from OPNETWORK’2003 (Washington, USA). One of these co-authored books, Télécommunications et transmission de données (Eyrolles, 1992), received special mention from Telecoms Magazine (France, 1994). His research interests include wireline and wireless networks, mobile computing, performance evaluation, artificial intelligence, and electronic learning. He is a Fellow of Engineering Institute of Canada, senior member of IEEE, a member of ACM and IEEE Communications Society. He is an Associate Editor of IEEE Communications Letters and IEEE Canadian Review. He also serves on the editorial board of Telematics and Informatics published by Elsevier Science. E-mail: samuel.pierre@polymtl.ca     

Secure Multicast in Wireless Networks of Mobile Hosts: Protocols and Issues

Multicast services and wireless interconnection networks are among the emerging technologies of the last decade. A significant amount of research has been separately performed in the areas of secure multicast and wireless interconnection networks. In this paper we investigate the issues of designing secure multicast services in wireless mobile environments for dynamic groups and propose protocols for key management for a variety of scenarios. Our solution decouples mobility management from group dynamics management, by taking into account the level of trust in the support stations. In particular, we show that protocol efficiency on the mobile host side can be traded-off with the level of trust in the support stations.     

无线传感器网络中恶意软件传播研究

从平面无线传感器网络的拓扑结构、无线共享通信及安全机制等固有特征出发,对无线传感器网络上的恶意软件传播动力学进行研究。首先,使用随机几何图建立平面无线传感器网络模型;然后,基于元胞自动机理论建立恶意软件SI（Susceptible—Infected）传播模型,该模型充分考虑无线传感器网络固有特征和传播特征,模型建立引入MAC机制和随机密钥预分布方案。分析和仿真表明,无线传感器网络的空间局域化结构特征、无线信道共享机制和安全管理应用主导了传播增长效果,限制了恶意软件传播速度,降低了在无线传感器网络中大规模流行恶意软件的风险。文中提出的模型能够描述无线传感器网络中恶意软件传播行为,为建立无线传感器网络安全防御机制提供了基础。     

Handoffs in Cellular Wireless Networks: The Daedalus Implementation and Experience

Network protocols in cellular wireless data networks must update routes as a mobile host moves between cells. These routing updates combined with some associated state changes are called handoffs. Most current handoff schemes in wireless networks result in data loss or large variations in packet delivery times. Unfortunately, many applications, such as real-time multimedia applications and reliable transport protocols, adapt to long term estimates of end-to-end delay and loss. Violations and rapid fluctuations of these estimates caused by handoff processing often result in degraded performance. For example, loss during handoff adversely affects TCP performance [4], and high packet loss and variable delays result in poor real-time multimedia performance. In this paper, we describe a multicast-based protocol that eliminates data loss and incurs negligible delays during a handoff. The basic technique of the algorithm is to anticipate a handoff using wireless network information in the form of received signal strengths and to multicast data destined for the mobile host to nearby base stations in advance. This routing, combined with intelligent buffering techniques at the base stations, enables very rapid routing updates and eliminates data loss without the use of explicit data forwarding. We have implemented this protocol using IP Multicast and Mobile IP-like routing. In our implementation, handoffs typically take between 8 and 15 ms to complete and result in no data loss.