多波束天线下多层蜂窝小区切换性能分析

分析了一种基于多波束天线在垂直面发射形成的多层蜂窝移动通信小区结构的切换性能.在切换算法中引入了以移动台所接收有用信号功率与干扰信号功率之和作为切换发起的判断规则之一,讨论了在阴影衰落无线传播环境下,该多层小区的3种切换发起规则,并给出了相应的切换发起概率表示式.最后计算机模拟结果比较了不同切换发起规则下切换发起概率与小区区群数和基站天线俯仰角间的关系.     

An improved handover algorithm based on signal strength plus distance for interoperability in mobile cellular networks

In future generation mobile cellular systems, position location of mobile terminal is expected to be available. In this paper, we propose an initiation algorithm for intersystem handover based on the combination of position location of mobile terminal and the absolute signal strength thresholds. Global System for Mobile communication (GSM) and Universal Mobile Telecommunication Systems (UMTS) networks are considered for interworking. The proposed algorithm reduces the handover rate by around 50% and thus improves the network resource efficiency as compared to that based on signal strength thresholds only.     

Validation of an improved location-based handover algorithm using GSM measurement data

When a mobile station moves, the path loss and shadow fading contribute to the large-scale variation in the received signal strength. The variation of signal strength caused by shadow fadings is a random process, and handover decision mechanisms based on measurements of signal strength induce the "ping-pong effect." This paper proposes an improved handover algorithm, based on the estimates of location and velocity of the mobile station, to suppress the ping-pong effect in cellular systems. A practical approach based on GSM measurement data is used to estimate the location and velocity of mobile station to identify the correlation among shadowing components. The impact of location errors on handover performance was examined, and the proposed handover algorithm was applied to a real GSM system in urban Taipei city. The results indicate that the number of unnecessary handover can be reduced 18-26 percent by the proposed approach compared to the conventional method, while the signal outage probability remains similar. Besides, the computational complexity of the proposed algorithm is low, and the algorithm does not use a database or lookup table.     

Handover algorithm to counteract corner effects in microcellularmobile networks

A new handover algorithm suitable for implementation in modern cellular mobile radio systems, such as GSM or UMTS, is proposed and its performance assessed. The algorithm is based on the gradient of measured power values. Both the uplink and the downlink measurements are considered. The simulation results show a performance improvement with respect to traditional algorithms     

Research on the Handover of a Novel Cellular Architecture in Wireless Personal Communication Systems

1　IntroductionHandoverbetweencellsisplayinganimportantroleincellularcommunicationsystems[1～ 1 2 ] .Thehandoverprocedureanditseffectivenessareseriouslylimitedbythecellulararchitectureasaresultofmar ketplanning .Basedonthehexagonalcellulararchi tecture,manyhandoverprocedureshavebeendis cussedandevaluated ,andmostoftheimprovementproposedonthemleadstotheintroductionofsector ingcellularorlayeredcellularmodel.Otherwise ,abetterhandoverprocedureisessentialinmaintainingacallinprogressbutitreflectshi…     

WCDMA与GSM系统间切换浅析

本文介绍了WCDMA系统和GSM系统间切换和小区重选的操作过程,分析了压缩模式对网络质量的影响,并对提高切换成功率提出了几点建议.另外,本文对切换相关的GSM网络升级和测量控制参数的设置也进行了讨论.     

TD-SCDMA与GSM互操作中基于鉴权原因的切换失败问题分析及解决

随着TD-SCDMA网络的规模部署,TD-SCDMA和GSM间的互操作及切换将日益频繁,如何有效提高TD-SCDMA与GSM系统间的切换成功率对于TD-SCDMA的网络建设与优化至关重要。针对现阶段TD-SCDMA与GSM系统间由于鉴权原因引起的切换失败问题,通过对切换失败现象和3GPP技术规范的分析,定位了此类切换失败的原因所在,提出了GSM与TD-SCDMA之间因鉴权原因而造成的切换失败问题的解决方案,并以补丁程序的形式在现网中进行了应用测试,测试结果验证了本文所提方案的可行性。     

Interbeam handover in LEO satellite systems

This paper evaluates the performance of interbeam handover in LEO satellite systems. The evaluation is based on an analytical model that is specific for interbeam handover. There are three performance parameters concerned: handover probability, forced termination probability and time availability. From the results it can be seen that the interbeam handover probability depends strongly on the roll-off characteristics of the beam pattern. Forced termination and time availability depend on the quality of the received signal and the selected criterion. A comparison between the use of signal level and position as handover criteria is presented. © 1998 John Wiley & Sons, Ltd.     

Performance of received power and traffic-driven handover algorithms in urban cellular networks

This article presents an investigation of the handover algorithms suitable for implementation in urban mobile cellular networks based on TDMA. More precisely, the class of received power and traffic-driven handover algorithms, which are based on absolute and relative measured values of received power and on actual traffic load, is analyzed. The algorithms usually investigated in the literature (and often implemented in actual mobile networks) belong to this class. We show the performance of traditional algorithms, and also propose some new ones, in an effort to reduce the probability of dropout due to sudden changes of received power and to distribute the traffic load over several cells; they show performance improvements with respect to those previously known from the literature. The performance of the different handover algorithms is evaluated by means of a simulation tool that allows the consideration of complex scenarios, suitable mobility and propagation models, power control, cell sectorization, nonuniform user distribution, and so on. The metrics used for performance comparison are the outage, blocking, dropout, and satisfaction probabilities, whose different definitions are discussed in the article, and the average number of handovers per call. Several urban scenarios, characterized by uniform and nonuniform traffic distributions, are taken into account. Our results show that one of the proposed algorithms, based on traffic estimates, yields the best performance of all the considered scenarios.     

Combined handover algorithm for dynamic satellite constellations

A combined handover algorithm is proposed for a dynamic mobile satellite system. Handover decisions are based on user terminal (UT) position and signal strength measurement. The handover performances considered are handover position and call termination probability     

Adaptive Hysteresis Using Mobility Correlation for Fast Handover

The value of hysteresis has a significant effect on the handover performance measured in terms of the handover initiation delay and the number of handovers. To determine the hysteresis value effectively, a mobility correlation among users is utilized. In this letter, a grouping algorithm and an adaptive hysteresis algorithm based on the mobility correlation are proposed. It is shown that the proposed algorithms are very efficient in reducing both the handover initiation delay and the number of handovers.     

UMTS分组域与GSM/GPRS系统间切换过程中数据缓存与转移的实现与分析

首先介绍了UMTS中的几种切换类型,然后就UMTS分组域到GSM/GPRS系统间切换(SGSN间),GSM/GPRS到UMTS分组域系统间切换(SGSN间),UMTS分组域到GSM/GPRS系统间切换(SGSN内),GSM/GPRS到UMTS分组域系统间切换(SGSN内)这4种切换过程中的数据缓存与转移的实现过程进行了详细论述,并进行了进一步深入的分析与比较,最后指出其优缺点。     

A measurement-based prioritization scheme for handovers in mobilecellular networks

A method of improving the quality of service in mobile cellular systems based on prioritization of handover requests is presented. The objective is to improve perceived quality of cellular service by minimizing both the probability of forced termination of ongoing calls due to handover failures and the degradation in spectrum utilization. A model based on a multiple-priority nonpreemptive queuing discipline is developed. New calls are blocked if all channels are occupied. Handover requests are queued such that as soon as a channel is available, it is offered to the mobile subscriber with the measurement results closest to the minimum acceptable power level for communication. Service rate is given by channel occupancy time distribution and is assumed to be exponential. The performance of a cellular system employing the proposed handover policy is evaluated analytically and by simulation, and results are compared to those obtained when the cellular system employs nonprioritized call handling and first-in/first-out queuing discipline. This provides lower probability of forced termination and less call blocking, less reduction in traffic, and less delay     

GSM—R网络越区切换性能研究

GSM—R（GSM for Railway）是以GSM（全球移动通信系统）为平台,集列车公务通信和区间通信为一体的铁路专用移动通信系统,已经成为我国铁路通信技术的发展方向。越区切换是GSM—R系统的关键技术之一,由于列车速度的提升导致多普勒效应更严重、切换位置更靠后、越区切换更频繁,最终GSM—R的安全性和可靠性会严重降低,因此对越区切换的研究具有非常重要的意义。本文分析了GSM—R网络越区切换掉话的原因并提出了优化方案。     

Performance analysis of channel de-allocation schemes for dynamic resource allocation in GSM/GPRS networks

Channel de-allocation for GSM voice call (DASV) has been considered for dynamic resource allocation in GSM/GPRS networks. Two new de-allocation schemes are proposed: de-allocation for GPRS packet (DASP) and de-allocation for both GSM voice call and GPRS packet (DASVP). An analytic model with general GPRS data channel requirement is derived to evaluate the performance of the schemes in terms of GSM voice call incompletion probability, GPRS packet dropping probability, average GPRS packet transmission time and channel utilisation.     

Traffic performance analysis of handover in GMPCS systems

This paper presents an analysis of handover process and its effect on the traffic performance in global mobile personal communications by satellite (GMPCS) systems. With the nongeostationary satellite used for the system, the handover scheme needs to be applied to make calls completed without any interruption. An analytical model is developed for the analysis of the handover process. We derive the mean number of handovers and handover delay with various satellite antenna patterns and different settings of handover parameter. A suitable traffic model of the whole system is also derived after due considerations of the handover process. The system performance measures include new call blocking probability, call dropping probability, and mean number of handovers per call. A computer simulation is developed and used. We also analyze the system performance with a number of handover priority schemes applied. Based on the study results, the handover parameters are selected to maximize the traffic performance. It is shown that we can improve the overall traffic performance of GMPCS system by setting handover parameters properly and using the handover priority scheme     

A New Empirical Formula for Handover Rate in Microcellular Systems

In this paper, we propose a new empirical formula for handover rate as a function of base stations separation, standard deviation of shadow fading, path loss exponent, averaging distance, and correlation distance. The handover initiation algorithm is based on averaged signal strength measurements using relative signal strength with hysteresis margin approach. We generate the data through computer simulations for the average number of handovers referred to as handover rate, for the practical range of path loss exponent and standard deviation of shadow fading. The proposed formula provides for a practical design tool to optimize the handover initiation performance under varied propagation environments.     

Media-independent pre-authentication supporting secure interdomain handover optimization [architectures and protocols for mobility management in all-IP mobile networks]

Handovers may cause delays and packet losses that affect real-time communication performance. Mobility protocols at several layers are designed to support handover, but they need to be optimized to ensure high-quality application performance. Existing optimization techniques are not sufficient to take care of interdomain and intertechnology handovers involving different access technologies, such as Wi-Fi, GSM, CDMA, and WiMAX. We categorize several types of handover, describe handover delay components, and propose a handover optimization framework called media independent pre-authentication that can provide optimizations for interdomain and intertechnology handover in a manner that is transparent to mobility management protocols. In addition, we also present experimental results demonstrating that this framework can achieve a significant reduction in handover delays for both network-layer and application-layer mobility management protocols.     

基于测量统计的小区权重向量算法研究

在基于测量统计的GSM无线网络自动频率规划技术理论研究及工程实践的基础上,分析研究了根据无线网络的拓扑结构特点、话务承载分布特性等进一步提高频率方案性能的方法途径。提出了基于测量统计的小区权重向量算法,包括线性小区权重向量算法和改进的基于用户感知度的小区权重向量算法,以及关键切换路径权重向量算法等。给出了在运营中的GSM无线网络中应用改进的基于用户感知度的小区权重向量算法和关键路径权重算法,结合基于测量统计的频率规划技术进行的改频实验结果并对其进行分析。     

Performance between circuit allocation schemes for half- andfull-rate connections in GSM

This paper considers three circuit allocation schemes for half- and full-rate connections in the Global system for Mobile Communications (GSM): best fit, repacking, and fair repacking. Analytic numerical methods are used to investigate each scheme's blocking probability behavior. The analysis is based on a reduction of the state space to a manageable size. Fair repacking is found to be the fairest and most efficient. However, the best-fit scheme, while being somewhat less efficient and fair, is simpler to implement. The effect on quality of service (QoS) of voice dropouts related to intracell handover (repacking) was found to be negligible