Highly mobile users and paging: optimal polling strategies

We consider the problem of minimizing average paging cost subject to delay constraints in a wireless system. Previous work assumed the unit to be found did not move during the paging process whereas here the unit may change location during polling events. We show that the conditionally most probable locations, given that the unit has not yet been found, should be searched first. We find the optimal sequential paging strategies for given maximum delay constraints and compute both paging and delay costs as a function of the time between polling events. The results show that sequential paging strategies are beneficial in all but the extremely high-mobility cases where polling failures provide little information about the unit location. It is observed that optimal sequential paging strategies substantially lower the paging cost compared to the classical blanket polling at the expense of a small degradation in the average delay performance     

Optimal Sequential Paging in Cellular Wireless Networks

In a high-capacity cellular network with limited spectral resources, it is desirable to minimize the radio bandwidth costs associated with paging when locating mobile users. Sequential paging, in which cells in the coverage area are partitioned into groups and paged in a non-increasing order of user location probabilities, permits a reduction in the average radio costs of paging at the expense of greater delay in locating the users. We present a polynomial time algorithm for minimizing paging cost under the average delay constraint, a problem that has previously been considered intractable. We show the conditions under which cluster paging, a simple heuristic technique proposed for use with dynamic location update schemes, is optimal. We also present analytical results on the average delay and paging cost obtained with sequential paging, including tight bounds.     

Minimizing the average cost of paging under delay constraints

Efficient paging procedures help minimize the amount of bandwidth expended in locating a mobile unit. Given a probability distribution on user location, it is shown that the optimal paging strategy which minimizes the expected number of locations polledE[L] is to query each location sequentially in order of decreasing probability. However, since sequential search over many locations may impose unacceptable polling delay,D, optimal paging subject to delay constraints is considered. It is shown that substantial reductions inE[L] can be had even after moderate constraints are imposed on acceptableD (i.e.,D<-3).Since all methods of mobility management eventually reduce to considering a time-varying probability distribution on user location, this work should be applicable to a wide range of problems in the area. most notably those with additive cost structures.     

On hierarchical pipeline paging in multi-tier overlaid hierarchical cellular networks

We propose a hierarchical pipeline paging (HPP) for multi-tier hierarchical cellular networks, in which different tiers overlay with one another to provide overlapped coverage of cellular service, and each mobile terminal can be paged in any tier of a network. Paging requests (PRs) are queued in different waiting queues, and multiple PRs in each waiting queue are served in a pipeline manner. We study HPP, hierarchical sequential paging (HSP), and hierarchical blanket paging (HBP) schemes analytically in terms of discovery rate, total delay, paging delay, and cost. It is shown that HPP scheme outperforms both HBP and HSP schemes in terms of discovery rate while maintaining the same cost as HSP scheme. The HPP scheme outperforms HSP scheme in terms of total delay and has a lower total delay than HBP scheme when traffic load is high.     

Analysis of an identifier splitting algorithm combined with polling(ISAP) for contention resolution in a wireless access network

A contention resolution scheme for an uplink contention channel in a wireless access network is presented. The scheme consists of a tree algorithm, namely the identifier splitting algorithm (ISA), combined with a polling scheme. Initially, ISA is used, but at a certain level of the tree, the scheme switches to polling of the stations. This scheme is further enhanced by skipping a few levels in the tree when starting the algorithm (both in a static and a dynamic way) and by allowing multiple instants simultaneously. An analytical model of the system and its variants leads to the evaluation of its performance, by means of the delay density function and the throughput characteristics. This model is used to investigate the influence of the packet arrival rate, the instant at which the ISA scheme switches to polling, the starting level of the ISA scheme, and the use of multiple instances on the mean delay, the delay quantiles, and the throughput     

Dynamic multi-step paging scheme in PMIPv6-based wireless networks

In Proxy Mobile IP (PMIPv6) networks, proxy-registrations are performed even for idle MNs, resulting in unnecessary signaling traffic. Although there have been many IP paging techniques aimed at reducing the unnecessary location update, they focus only on Mobile IP (MIP) since they had been developed before PMIPv6 was proposed. Thus, adopting existing IP paging support is not sufficient to support mobility in PMIPv6 networks. For more efficient support, we propose a dynamic multi-step paging scheme that pages an MN in multiple incremental steps instead of flooding paging messages to a whole paging area to significantly reduce the signaling traffic caused by the proxy location updates in the PMIPv6 networks. In addition, to improve the paging delay performance that may be deteriorated by the multi-step paging, the proposed scheme configures paging area dynamically to raise the efficiency of locating MNs. The size of a paging area is designed to be determined based on the speed of an MN. We also develop a thorough analytical model for evaluating the performance of the proposed scheme compared with a static paging scheme in terms of the signaling cost and the paging delay. Thorough analysis and simulation demonstrate that in the PMIPv6 network, our paging scheme can significantly reduce the signaling cost for IP paging, achieving a shorter paging delay, compared to that of a paging scheme with a fixed paging area.     

Packet Delay Analysis of Symmetric Gated Polling System for DBA Scheme in an EPON

In this paper, we analyze the mean packet delay of a dynamic bandwidth allocation (DBA) scheme in an Ethernet passive optical network (EPON). We propose the interleaved polling system with a gated service discipline and a two-stage queue in order to investigate the delay performance of DBA scheme in an EPON. We assume that input packets arrive at an optical network unit (ONU) according to a Poisson process from several types of users. We use a continuous time queueing model in order to find the mean packet delay and the mean cycle time of an arbitrary packet. We obtain the closed form solution for the mean packet delay of the proposed gated polling system with a two-stage queue. We obtain another result on the mean packet delay by solving a system of linear equations derived from the moments of the queue length distribution. We give some numerical results to investigate the delay performances for the symmetric polling system with statistically identical stations. In addition, we compare numerical results on the closed form solution with numerical results on a system of linear equations.     

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Ad HOc网络中的公平按需多址接入协议

基于快速、有效竞争预约接入、无冲突轮询传输的思想和带冲突预防的冲突分解策略,本文提出了适于移动Ad Hoc网络的公平按需多址接入(FODA)协议.该协议在分群结构的基础上,利用公平冲突预防算法预约信道资源获得轮询服务,从而完全消除了载波侦听方式下多跳无线网络业务传输中的隐藏终端和暴露终端问题.另外,公平冲突预防算法解决了节点竞争接入时的冲突问题和不公平现象.最后,仿真结果表明,与带冲突避免的载波侦听多址接入(CSMA/CA)和轮询协议相比,FODA协议可以提供较高的信道吞吐量、较低的平均消息丢弃率和平均消息时延.     

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.     

Inter‐ONU Bandwidth Scheduling by Using Threshold Reporting and Adaptive Polling for QoS in EPONs

I dynamic bandwidth allocation (DBA) scheme, an inter–optical network unit (ONU) bandwidth scheduling, is presented to provide quality of service (QoS) to different classes of packets in Ethernet passive optical networks (EPONs). This scheme, referred to as TADBA, is based on efficient threshold reporting from, and adaptive polling order rearranging of, ONUs. It has been shown that the network resources are efficiently allocated among the three traffic classes by guaranteeing the requested QoS, adaptively rearranging the polling orders, and avoiding nearly all fragmentation losses. Simulation results using an OPNET network simulator show that TADBA performs well in comparison to the available allocation scheme for the given parameters, such as packet delay and channel utilization.     

Activity polling and activity contention in media access controlprotocols

This paper compares activity polling mechanisms occurring in a class of media access control (MAC) protocols for passive tree or star networks. An analytical model is developed which explains the function of polling mechanisms in MAC protocols for the single source case, i.e., with one on-off source present in the whole system. Results from this model are compared to simulation results for the single source case and for multiple source cases. It is shown that these analytical results can furthermore explain the main effects seen under normal load, and the analysis is extended to a contention based mechanism, leading to a fair parametric comparison between activity polling and activity contention under comparable conditions. The final result quantifies the range of parameters (round-trip time and fraction of active stations) where a contention mechanism can give better delay quantile performance than a polling mechanism     

IPACT With Grant Estimation (IPACT-GE) Scheme for Ethernet Passive Optical Networks

Dynamic bandwidth allocation (DBA) is an open and hot topic in the Ethernet passive optical network (EPON), which is regarded as one of the best choices for next-generation access networks. This paper proposes an estimation-based scheme, interleaved polling with adaptive cycle time with grant estimation (IPACT-GE), for effective upstream channel sharing among multiple optical network units (ONUs) in EPONs. By estimating the amount of new packets arriving between two consecutive pollings and granting ONUs with extra estimated amount, the proposed IPACT-GE scheme can achieve shorter waiting delay and less buffer occupancy at the light load than IPACT, a significant DBA scheme in EPONs. Moreover, when combined with the strict priority queue (SPQ) mechanism to provide differentiated services, IPACT-GE can greatly mitigate the light load penalty that is obvious in the IPACT solution combined with SPQ.      

Analysis of a polling system for telephony traffic with application to wireless LANs

Recently, polling has been included as a resource sharing mechanism in the medium access control (MAC) protocol of several communication systems, such as the IEEE 802.11 wireless local area network, primarily to support real-time traffic. Furthermore, to allow these communication systems to support multimedia traffic, the polling scheme often coexists with other MAC schemes such as random access. Motivated by these systems, we develop a model for a polling system with vacations, where the vacations represent the time periods in which the resource sharing mechanism used is a non-polling mode. The real-time traffic served by the polling mode in our study is telephony. We use an on-off Markov modulated fluid (MMF) model to characterize telephony sources. Our analytical study and a counterpart validating simulation study show the following. Since voice codec rates are much smaller than link transmission rates, the queueing delay that arises from waiting for a poll dominates the total delay experienced by a voice packet. To keep delays low, the number of telephone calls that can be admitted must be chosen carefully according to delay tolerance, loss tolerance, codec rates, protocol overheads and the amount of bandwidth allocated to the polling mode. The effect of statistical multiplexing gain obtained by exploiting the on-off characteristics of telephony traffic is more noticeable when the impact of polling overhead is small.     

Performance of Double-Tier Access-Control Schemes Using a Polling Backbone for Metropolitan and Interconnected Communication Networks

We consider a double-tier communication network architecture for metropolitan area and packet radio networks for controlling the access of network terminals into a single shared broadcast channel. Terminals are organized into local groups in accordance with their geographical proximity or other criteria. Each local group can be associated with a primary station. The latter can serve as an unbuffered repeater for terminal transmissions unto the multiple-access channel. A polling policy is used by the primary stations to gain access into the shared communications backbone. Once a primary station is provided access into the channel, it initiates a local access control procedure. Message delay performance results and bounds are obtained for general reservation local-access procedures. In particular, we analyze and present performance results for a polling/tree-random-access procedure which can be effectively used for many packet radio and cellular digital radio networks, as well as for a polling/positionalpriority scheme for CATV and fiber-optic based networks.     

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.     

GSM系统寻呼容量评估

本文比较详细地阐述了GSM系统寻呼能力的计算方法及优化原则,以便使网络资源达到最佳配置,发挥最大的经济效益.在论述中提出3种方法供大家参考.     

A parallel shuffled paging strategy under delay bounds in wireless systems

In sequential paging schemes, the paging process is considered on per user basis. When an incoming call arrives to a mobile terminal (MT), the associated location area is divided into several paging areas (PAs) and PAs are paged one by one until the MT is found. Even though sequential paging algorithms can reduce the paging cost compared to the blanket-paging scheme, they introduce extra and unnecessary delay due to the fact that, during each paging cycle, unpaged cells are idle and unused in terms of paging. In this letter, a simple parallel shuffled paging strategy is proposed to reduce delay and improve performance. In the proposed scheme, multiple MTs can be paged in difference PAs in parallel. Our study shows that the proposed scheme outperforms both the sequential paging and the blanket paging in terms of discovery rate and queueing delay.     

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.     

Effective paging procedure for the optical feeder microcellular system

The paper considers a paging problem in the optical feeder microcellular system where group simulcasting and dynamic channel allocation technologies are incorporated. The objective is to propose an effective paging procedure whose performance is measured in terms of paging load, average paging delay, and paging success probability. In the paging procedure, paging signals are transmitted via group simulcasting, for which the control channel is allocated dynamically. The performance of the procedure is analyzed in an approximate queueing network model. The proposed procedure is then compared in performance with a simulation approach, from which the procedure is found to outperform any previous methods in the literature.