一种特殊的软交换局间低切换成功率故障分析

描述了一种特殊的软交换局间切换低成功率故障现象,分析了不同无线系统间切换的基本步骤和信令流程,以及影响切换成功率的主要因素,认为影响切换成功率的关键因素是无线网络规划及设备的参数设置。为了提高无线系统间的切换成功率,网络运营者尤其应适时关注源侧的无线网络规划和系统参数的调整。     

CDMA系统软切换预测分析

在简要叙述了CDMA系统软切换过程的基础上,讨论了CDMA系统软切换的参数设置对系统的影响,给出了参数设置的建议值,并借助模拟软件给出了不同参数设置下某实际业务区的软切换区域预测图.     

GSM/TD-SCDMA系统间切换场景划分的探讨

本文针对目前TD-SCDMA系统向GSM系统切换中存在的参数设置问题,对切换场景进行了分类,并通过路测、KPI指标对比等方法,给出了不同切换场景下的切换参数设置建议.     

基于MIPv6的异质无线网络的无缝切换策略

由于无线网络技术的多样性，用户在采用不同接入或存取技术的无线网络间的无缝切换是一个非常重要的课题，本提出一种新的基于MIPv6的WLAN与GPRS网络融合方案和在这种结构下的无缝切换机制。     

CDMA2000动态切换浅析

通过对CDMA2000动态切换机制的分析，对动态切换的使用、参数设置提出了具体解决方案并对其实际应用进行了介绍和分析。     

影响无线系统间切换成功率的关键因素分析

文章分析了无线系统间切换的基本步骤和影响切换成功率的各项因素,认为影响切换成功率的关键因素是无线网络规划。为了提高无线系统间的切换成功率,网络运营者尤其应关注源侧的无线网络规划。     

GSM-R网络越区切换分析及优化

GSM-R与GSM的差异，决定了两者在网络参数设置上也有差别。从分析越区切挟的流程出发，阐述了GSM-R越区切换异常的原因，包括移动台不能发起切换的问题、切换数据设置不合理以及由于设备故障、天馈线因素、外界干扰等引起的切换异常，并提出了相应的优化解决办法。     

第三代移动通信系统WCDMA中的软切换技术

WCDMA是第三代移动通信系统中的一种主流无线接入技术。论文介绍了WCDMA网络中软切换的分类，分析了软切换的执行策略和其中的重要参数，用系统级仿真的研究方法探讨了软切换门限和软切换比例，软切换门限和掉话率、阻塞率之间的关系，最后得出合适的软切换增加门限应该在3db～6db，软切换删除门限在5db～8db，为实际应用中进行参数设置提供了参考。     

异构无线网络融合切换算法研究

异构无线网络融合和泛在化是未来宽带无线通信发展的必然趋势。文章首先概述了移动性管理;然后对切换进行了分类,讨论了各种切换策略;最后讨论了混合网络垂直切换策略,不同网络间的快速无缝切换是未来异构无线网络的一个极大挑战。     

异构网络垂直切换技术

下一代无线网络(Next Generation Wireless Networks,NGWN)将融合多种不同的网络体系结构与无线技术,NGWN的异构性要求向用户提供无缝切换。为此文章引入了异构无线网络垂直切换策略,并深入论述了其中的关键细节——网络发现、切换判决和切换信息交互流程等。     

Characterization of soft handoff in CDMA systems

Many analytical approaches have been proposed for handoff analysis based on hard handoff in mobile communication systems. In code-division multiple-access (CDMA) systems with soft handoff, mobile stations (MSs) within a soft handoff region (SR) use multiple radio channels and receive their signals from multiple base stations (BSs) simultaneously. Therefore, the SRs should be considered for handoff analysis in CDMA systems. An analytical model for soft handoff in CDMA systems is developed by introducing an overlap region between adjacent cells and the handoff call attempt rate and the channel holding times are derived. Applying these results to a nonprioritized CDMA system, the effects of soft handoff and the mean cell residual time are investigated and compared with hard handoff     

CDMA2000中软切换的研究和实现

详细论述了CDMA2000系统中软切换技术的性能、依据及软切换实现的过程，并针对软切换会造成无线资源使用率降低的问题，分析了Is-95向CDMA2000过渡过程中所做的改进。     

CDMA软切换特性及其对系统性能的影响

本文对CDMA软切换增益、T-ADD和T-DROP等参数对软切换比例的影响等软切换特性进行了分析,在此基础上,分析了软切换对系统容量、覆盖范围等性能的影响情况,提出了软切换比例的合理取值范围.     

Radio resource management in multiple-chip-rate DS/CDMA systemssupporting multiclass services

This paper is concerned with radio resource management in multiple-chip-rate (MCR) DS/CDMA systems accommodating multiclass services with different information rates and quality requirements. Considering both power spectral density (PSD) over a radio frequency (RF) link and the effect of RF input filtering on the receiver in MCR-DS/CDMA systems, criteria for call admission are presented and the system performance is derived. The system performance in MCR-DS/CDMA systems is strongly affected by radio resource management. A minimum total-power-increment-based resource management scheme for an efficient resource management is proposed. The performance of this scheme is compared with that of a random-based resource management scheme in terms of the new call blocking probability, handoff call dropping probability, and normalized throughput. In addition, in order to reduce the handoff call dropping rate, reallocating subsystems assigned for communicating calls is proposed. The minimum total-power-increment-based resource management scheme yields better performance than the random-based resource management scheme for multiclass services     

CDMA soft handoff analysis in the presence of power control errorand shadowing correlation

Soft handoff has a special importance to power controlled code division multiple access (CDMA) systems. We introduce a new analytical model for CDMA soft handoff with emphasis on interference statistics at a system level. The relationship between soft handoff and power control is further explored by integrating power control error and shadowing correlation into the model. A new forward link model is also devised to study the effects of soft handoff on forward link performance. It is observed that the performance degradation due to power control error increases with increase in soft handoff region and higher shadowing correlation lowers the interference contribution from nonhandoff mobile stations (MS). It is also found that, unlike the reverse link, the forward performance depends on both given soft handoff setting and system load     

Adaptive and predictive downlink resource management in next-generation CDMA networks

Guard channels have been proposed to minimize handoff call dropping when mobile hosts move from one cell to another. Code-division multiple-access (CDMA) systems are power- and interference-limited. Therefore, guard capacity in CDMA networks is soft, that is, a given capacity corresponds to variable number of connections. Thus, it is essential to adjust the guard capacity in response to changes in traffic conditions and user mobility. We propose two schemes for managing downlink CDMA radio resources: guard capacity adaptation based on dropping (GAD), and guard capacity adaptation based on prediction and dropping (GAPD). In both schemes, the guard capacity of a cell is dynamically adjusted so as to maintain the handoff dropping rate at a target level. In the second scheme, there is an additional, frequent adjustment component where guard capacity is adjusted based on soft handoff prediction. We show through extensive simulations that GAD and GAPD control the handoff dropping rate effectively under varying traffic conditions and system parameters. We also find that GAPD is more robust than GAD to temporal traffic variations and changes in control parameters.     

CDMA增强型软切换探讨

文章介绍了增强型软切换算法,并通过引用相关文献和分析商用网实验结果,证实该算法能够有效控制软切换比例,最后给出的参数设置方法可作为工程人员实用参考.     

Locally optimal soft handoff algorithms

The design of soft handoff algorithms for cellular radio systems is considered. The design problem is posed as a tradeoff between three metrics: the rate of handoffs, the mean size of the active set, and the link quality. It is argued that the algorithm that optimizes the tradeoff among these metrics is impractical. Hence, a locally optimal (LO) handoff algorithm is derived as a practical approximation to the optimal handoff algorithm. The LO algorithm is shown to yield a significantly better tradeoff than the static threshold handoff algorithm used in second-generation code-division multiple-access (CDMA) systems. It is also shown that the dynamic threshold algorithm, which is an ad hoc algorithm proposed for third-generation CDMA systems, achieves nearly the same performance as the LO algorithm. Thus, an analytical justification is developed for the dynamic threshold algorithm. Further, the handoff algorithm design is separated into independent design problems on the forward and reverse links. The forward link LO algorithm is shown to be computationally intensive but is also shown to be closely approximated by the simpler reverse link LO algorithm.     

A novel dynamic cell configuration scheme in next-generation situation-aware CDMA networks

To balance the time-varying traffic load between cells, caused by user mobility and diverse applications, it is crucial for next-generation code-division multiple-access (CDMA) cellular networks to configure cell coverage and capacity dynamically. In this paper, we show that pilot power allocation is highly coupled to other facets of radio resource management. We propose a novel dynamic cell configuration scheme for multimedia CDMA cellular networks, based on reinforcement-learning, which takes into account pilot, soft handoff, and maximum link power allocations, as well as call admission control mechanisms. Simulation results demonstrate the effectiveness of the proposed scheme in situation-aware CDMA networks.     

Optimal Joint Session Admission Control in Integrated WLAN and CDMA Cellular Networks with Vertical Handoff

This paper considers optimizing the utilization of radio resources in a heterogeneous integrated system consisting of two different networks: a wireless local area network (WLAN) and a wideband code division multiple access (CDMA) network. We propose a joint session admission control scheme for multimedia traffic that maximizes overall network revenue with quality of service (QoS) constraints over both the WLAN and the CDMA cellular networks. The WLAN operates under the IEEE 802.11e medium access control (MAC) protocol, which supports QoS for multimedia traffic. A novel concept of effective bandwidth is used in the CDMA network to derive the unified radio resource usage, taking into account both physical layer linear minimum mean square error (LMMSE) receivers and characteristics of the packet traffic. Numerical examples illustrate that the network revenue earned in the proposed joint admission control scheme is significantly larger than that when the individual networks are optimized independently with no vertical handoff between them. The revenue gain is also significant over the scheme in which vertical handoff is supported, but admission control is not done jointly. Furthermore, we show that the optimal joint admission control policy is a randomized policy, i.e., sessions are admitted to the system with probabilities in some states