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.     

Modeling and performance evaluation of a cellular mobile network

An analytic model of cellular mobile communications networks with instantaneous movement is investigated in this paper. This cellular mobile network is showed to be equivalent to a queueing network and furthermore the equilibrium distribution of this cellular mobile network is proved to have a product form. The explicit expressions for handoff rates of calls from one cell to another, the blocking probability of new calls and handoff calls are then obtained. Actual call connection time (ACCT) of a call in this cellular mobile network is characterized in detail, which is the total time a mobile user engages in communications over the network during a call connection and can be used to design appropriate charging schemes. The average ACCT for both complete call and incomplete call, as well as the probability for a call to be incomplete or complete, are derived. Our numerical results show how the above measures depend on the new call arrival process for some specific reserved channels numbers in each cell. The results presented in this paper are expected to be useful for the cost analysis for updating location and paging in cellular mobile network.     

Concurrently searching for mobile users in cellular networks

In today's systems, upon arrival of calls to mobile users, the system attempts to locate the users sequentially (one by one) through a paging operation. In this letter, we propose to concurrently search for a number of mobile users in a mobile network, significantly reducing the cost of locating mobile users. The reduction in the paging costs due to such a concurrent search can be quite substantial, depending on the knowledge of the probabilities of the users' locations, the number of cells in the network, and the number of mobiles to be located. Additionally, we propose a low-complexity heuristic that reduces the average paging cost by 25%, in the case of no knowledge of probabilities of the mobiles' locations. With such knowledge, further reduction in the average paging costs of up to 90% can be achieved.     

关于TMSI寻呼与IMSI寻呼性能分析

随着移动用户的持续增长和手机新业务的不断推广,移动通信系统的寻呼负荷日益加重。以移动用户漫游被叫时的呼叫流程为例,分析IMSI寻呼和TMSI寻呼的原理,对比两种寻呼方式对网络性能影响,提出一种评估寻呼方式的量化计算方法。通过对寻呼容量较为紧张网元的试验证明,该方法可以科学指导寻呼方式的优化工作,提高移动通信网络的系统寻呼容量,改善移动通信系统寻呼性能。     

Method for efficient location area planning in mobile telecommunications

Location area dimensioning is based on the tradeoff between the amount of signalling generated due to paging and location updating. The authors present a new approach which compares the frequency of location updates per mobile terminal with the frequency of mobile terminating calls. This leads to the concept of useless location updating, when location updating occurs but this information is not subsequently used.<>     

A novel sectional paging strategy for location tracking in cellular networks

In this letter, we propose a new paging technique, sectional paging, that reduces the paging cost while complying with the delay constraint for mobiles roaming with traceable patterns. Without having to install much additional complexity, the developed scheme predicts the likelihood of residence and assigns optimal paging boundaries. Thus while complying with the required delay constraints, quality-of-service (QoS) measures will not need to be sacrificed as a result of increasing the update threshold. Under the same network conditions and mobile characteristics, simulation results reveal that the usage of sectional paging is most suitable when the roaming pattern is either traceable or can be predicted with reasonable precision.     

Information-Theory Based Optimal Location Management Schemes for Integrated Multi-System Wireless Networks

In a multisystem environment where a mobile node can utilize multiple interfaces and simultaneously connect to multiple providers, new opportunities exist for efficient location management strategies spanning heterogeneous cellular wireless networks. In this paper, an integrated framework is developed for location management in such a multi-system, fourth generation (4 G) wireless networks. This information-theoretic framework allows each individual sub-system to operate fairly independently, and does not require the knowledge of individual sub-network topologies. An efficient location management in such a loosely coupled network is designed by having a mobile node view its movement as a vector-valued sequence, and then transmit this sequence in an entropy coded form to the network. We demonstrate how an intelligent, integrated paging strategy must consider the joint residence probability distribution of a mobile node in multiple sub-networks. We prove that the determination of an optimal paging sequence is NP-complete, and also propose an efficient greedy heuristic to compute the paging sequence, both without and with bounds on the paging delay. Three different location tracking strategies are proposed and evaluated; they differ in their degrees of centralized control and provide tradeoff between the location update and paging costs. Simulation experiments demonstrate that our proposed schemes can result in more than 50% savings in both update and paging costs, in comparison with the basic movement-based, multi-system location management strategy.     

Concurrent search of mobile users in cellular networks

In this paper, we propose to concurrently search for a number of mobile users in a wireless cellular network based on the probabilistic information about the locations of mobile users. The concurrent search approach guarantees that all k mobile users will be located within k time slots. It is shown that even in the worst case when mobile users appear equally in all the cells of the network, the concurrent search approach is able to reduce the average paging cost by 25%. More importantly, this is achieved without an increase in the worst case paging delay or in the worst case paging cost. Depending on the total number of mobile users to be located, total number of cells in the network, and the probabilistic information about the locations of mobile users, the reduction of the average paging cost due to the usage of the concurrent search approach ranges from 25% to 88%. The case in which perfect probabilistic information is unavailable is also studied.     

SIP Paging and Tracking of Wireless LAN Hosts for VoIP

This paper introduces a new paging technique to track and wake up a mobile node (MN) attached to an access point (AP) in a wireless LAN network after a session initiation protocol (SIP) INVITE message is initiated by a caller. A tracking agent (TA) keeps track of the mobiles' handoffs between the APs. A paging agent (PA) triggers the TA to page the mobile when a SIP INVITE is received for one of its users. The context transfer feature of our paging protocol allows the paging messages to deliver the station context in order to enable faster session reestablishment. The AP then does onlink paging in a wireless link. SIP extensions are needed to trigger the PA to start paging MNs to notify their dormant status using an extended SIP REGISTER method. Tracking protocol is analyzed to compare soft- and hard-state approaches for state inconsistency ratio, message rate, and the overall cost. The simulation model we developed enables us to evaluate the traffic introduced by the tracking protocol and the cache (state) size. Paging protocol is analyzed for CPU processing times and the transmission delays in the SIP session setup with paging. Simulation of the paging with context transfer is used to show the gains in reauthentication.     

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.     

An analysis of location record checkpointing interval for mobility database in PCS networks

Mobility database that stores the users’ location records is very important to connect calls to mobile users on personal communication networks. If the mobility database fails, calls to mobile users may not be set up in time. This paper studies failure restoration of mobility database. We study per-user location record checkpointing schemes that checkpoint a user’s record into a non-volatile storage from time to time on a per-user basis. When the mobility database fails, the user location records can be restored from the backup storage. Numeric analysis has been used to choose the optimum checkpointing interval so that the overall cost is minimized. The cost function that we consider includes the cost of checkpointing a user’s location record and the cost of paging a user due to an invalid location record. Our results indicate that when user registration intervals are exponentially distributed, the user record should never be checkpointed if checkpointing costs more than paging. Otherwise, if paging costs more, the user record should be always checkpointed when a user registers.     

CDMA网络移动交换机系统间短消息寻呼技术研究及应用

研究并提出了CDMA网络移动交换机系统间短消息寻呼的技术要求,主要描述了CDMA网络移动交换机系统间短消息寻呼对服务交换机、相邻交换机技术的要求、呼叫流程等,并对该技术在现网的实际应用效果进行了评估。本文所述的CDMA网络短消息系统间寻呼技术能明显改善CDMA网络MT短消息的首发寻呼成功率。     

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.     

双向寻呼和个人移动信息系统的近期发展

本文作者通过多年来对双向寻呼和个人移动信息系统的跟踪研究，及对美国几家系统供应商和网络经营商的实地考察，从网络结构，组网方式，通信过程及应用等方面，详细介绍了目前美国的两种双向寻呼系统，即与现有单向寻呼网兼容的系统和采用９００ＭＨｚ频段的系统。     

An adaptive location management scheme for mobile broadband cellular systems

This paper presents an adaptive location management strategy that considers both location updating and paging by evaluating realistic mobility patterns. It proposes the design of an adaptive macro-location area based on multi-registration adapted to the terminals’ trajectory to reduce location updates. The solution includes an estimation of residence probabilities in the areas of the multi-registered list. This facilitates the design of a sequential paging scheme that reduces the average paging cost. Results show the capability of the solution to adapt to mobility patterns and traffic conditions in the network to minimize the overall location cost. Furthermore, the multi-registration approach and the reduced complexity in both network infrastructure and mobile terminals make the solution suitable for new packet-based broadband cellular systems.     

A crossing-tier location update/paging scheme in hierarchical cellular networks

Location update/paging strategies have been widely studied in the traditional single-tier cellular networks. We propose and evaluate a novel crossing-tier location update/paging scheme that can be used in a hierarchical macrocell/microcell cellular network. Location update is proceeded only in the macrocell tier, where a location area (LA) is made up by larger macrocells. A mobile user will stay in such a LA for longer time. Therefore, the cost on location update can be reduced due to the decreased frequency of location update. To reduce the paging delay, the paged mobile user will be searched in the macrocell tier only when the paging load is not high. Otherwise, it will be searched in the microcell tier, where a sequential searching method is applied. The operation for the scheme is simple, as the macrocell/microcell cellular network has the advantage because a mobile user can receive a signal from both a microcell and the overlaid macrocell. Analytical models have been built for cost and delay evaluation. Numerical results show that, at relatively low cost, the crossing-tier scheme also achieves low paging delay.     

Intelligent paging strategies for third generation mobiletelecommunication systems

Location management procedures, in conjunction with the millions of users expected to subscribe to third generation mobile telecommunication systems, will generate a huge signaling load. In this paper, we propose a method which aims at the reduction of signaling overhead on the radio link produced by the paging procedure. The key idea is the application of a multiple step paging strategy which operates as follows: at the instance of a call terminating to a mobile user who roams within a certain location area, paging is initially performed in a portion of the location area (the paging area) that the so-called “paging related information” indicates. On no paging response, the mobile user is paged in the complementary portion of the location area-this phase can be completed in more than one (paging) step. Various “paging related information” elements (e.g. recent interaction information, high mobility flag, etc.) can be used and several “intelligent” paging strategies can be defined. Representative paging strategies are analyzed in terms of network performance and quality of service (paging signaling, paging delay, processing power requirements), via a simulation tool which models a realistic city area environment     

移动GSM网络寻呼成功率参数优化

移动通信的网络质量越来越受到关注,运营商对网络性能指标的稳定性要求越来越高,尤其是涉及到用户感知的指标,例如寻呼成功率、接通率、掉话率等,都提出了很高的要求。文章对影响用户感知的重要指标寻呼成功率进行了分析。从分析影响GSM网络寻呼成功率的原因人手,找到寻呼成功率的参数优化方法。通过无线寻呼参数的优化,使寻呼成功率明显提高,达到预期的目的,提高用户感知。     

Ensemble polling strategies for increased paging capacity in mobile communication networks

The process of finding a unit in a mobile communications system is called paging and requires the use of limited network resources. Although it is understood how to minimize the use of network resources and satisfy delay constraints when paging a single unit, optimal policies for paging multiple units are difficult to derive. Here we adapt single unit polling methods to obtain simple ensemble polling schemes for use with multiple units which can greatly increase the rate at which page requests can be processed while maintaining acceptable average delay. This revised version was published online in July 2006 with corrections to the Cover Date.     

Terminal detach scenarios in future mobile telecommunications

In mobile telecommunications the network should monitor the terminal status, i.e.,switched on, switched off, busy. Once a mobile terminal is switched on, it automatically informs the network about its status (attachment action). However, regarding the way that the network can identify that a terminal is switched off (detachment), there are three alternatives: (a)Periodic detachment scenario. The terminal (when switched on) periodically informs the network about its state. If the network detects that there is no contact with the terminal for more than the agreed time period, it detaches the terminal, (b)Detach on unsuccessful paging. At the instance of a call terminating to a mobile terminal and after a number of unanswered paging messages, the terminal is detached. (c)Detachment action scenario. The moment that the mobile terminal is switched off, it informs the network about its status. Scenarios (a) and (c) claim that paging signaling savings can be achieved when the network is early informed that a mobile terminal is switched off. However, these scenarios require access to the network database, which is expected to be a bottleneck. On the other hand, scenario (b) requires no access to the database but does not guarantee paging signaling savings. In this paper we model the behavior of a terminal so as to compare the above scenarios in terms of performance. Note that paging signaling and database transactions are not the same cost.This paper was partially funded by the CEC through the RACE 2066 project MObile NETwork (MONET). The paper does not present the views of the project as a whole but those of the authors.