典型场景下WCDMA室内分布系统的设计

以中国联通WCDMA试验网测试为基础,分析了不同室内场景的结构特点和用户特征,分别从室内小区的划分、频点选择、切换区域的设置、HSPA的运用等方面对WCDMA室内分布系统进行设计,力求在保证用户体验的前提下尽量节约资源。     

TD-LTE同频异频切换性能研究

中国移动TD-LTE网络宏站覆盖有D频段和F频段两个频段,对应有同频切换和异频切换两种方式,两种切换过程基本相同。同频切换前SINR会比较差,切换后SINR提升比较明显,异频切换时由于有频率隔离,SINR值一直比较趋于稳定,切换后SINR值也会有所提升,但是会有异频测量GAP时间占用。两种切换方式都会提升速率,但从大量测试数据分析来看,异频切换速率提升幅度高于同频切换。     

第四代移动互联网切换算法

第四代移动通信网络是一个多网集成和重叠覆盖同一个区域的综合网络.为满足用户移动过程中,不同网络之间切换的需求,从提供用户快捷的数据传输服务和提高网络资源使用效率的角度出发,提出在不同的网络之间建立一个新的数据通道,从而给出了一种新的切换算法.仿真实验表明,使用新的切换算法不仅能获得高的数据传输速度,还能有效地提高载频的使用效率.     

Cooperative directional inter-cell handover scheme in high altitude platform communications systems

A novel Cooperative Directional inter-cell Handover Scheme (CDHS) for High Altitude Platform (HAP) communications systems is proposed, in which the handover target cell and the two cells adjacent to this handover target cell work cooperatively to exploit the traffic fluctuation to improve handover performance. Users in the overlap area of the overloaded handover target cell will be forced to handover directionally before their optimal handover boundary in order to free up resources for the handover calls which would otherwise be dropped due to the shortage of resources and queue time out. Simulation results show that the handover call dropping probability is greatly reduced (at least 60%) compared with the general queue handover scheme, with little performance reduction to the call blocking probability, and the Not in the Best Cell (NBC) average time is only increased moderately. Moreover, an optimal cell radius can be achieved for a specific platform speed by minimizing the unified system performance, which is the linear combination of the handover call dropping probability and the NBC average time.     

An Efficient Handover Mechanism Using the General Switch Management Protocol on a Multi‐Protocol Label Switching Network

Using the general switch management protocol on a multi‐protocol label switching network, we present an efficient method for handling handovers. The proposed method directly changes an established path into a new path for supporting a handover. Our investigation reveals the effects of the proposed scheme and demonstrates that this method significantly reduces signaling costs and delays.     

An efficient design and validation technique for secure handover between 3GPP LTE and WLANs systems

Future generations wireless systems, which integrate different wireless access networks together, will support a secured seamless mobility and a wide variety of applications and services with different quality of service (QoS) requirements. Most of the existing re-authentication protocols during vertical handover still have certain limitations such as man in the middle, eavesdropping and session hijacking attacks, and unacceptable delay for real time applications. In this article, we propose two re-authentication schemes to secure handover between 3GPP LTE and WLANs systems: Initial Handover Re-authentication Protocol, and Local Re-authentication Protocol. The second proposed protocol is executed locally in a WLAN network without contacting the authentication server of the home network for credentials verification. In fact, after a successful execution of the Initial Handover Re-authentication Protocol, the local key (LK) is shared between USIM and the authentication server of the WLAN. It is then used for securing handover and traffic in WLAN networks. Performance evaluation results obtained using simulation analysis show that the proposed re-authentication protocol enhances handover parameters such as handover latency, handover blocking rate and packet loss rate. Additionally, the proposed enhanced fast re-authentication protocol has been modeled and verified using the software AVISPA and is found to be safe.     

A model for the handover traffic in low earth-orbiting (LEO) satellite networks for personal communications

The spectacular growth of cellular telephone networks has demonstrated the demand for personal communications. Communication systems based on low earth orbit (LEO) constellations of satellites seem to be an adequate approach to achieve a world-wide network. When defining the capacity in terms of satellite circuits, the network designer has to take into account the handover traffic. Unfortunately, in a LEO communication network where handover is most often due to the network nodes motion, handover traffic models for terrestrial cellular networks cannot be used. Hence specific models must be developed. This paper proposes an analytical model for the handover in LEO satellite networks. This model is applied to different network configurations and compared to discrete-time simulations. Simulation results agree with those obtained from the analytical model.     

基于SPN的CTCS-3级列控系统RBC切换建模与分析

在CTCS-3级列控系统中,RBC切换是车载设备的关键功能之一,它严重影响着列车的行车效率。本文采用随机Petri网层次化建模思想,对基于一部车载电台RBC切换方式进行建模和分析。建立了GSM—R故障模型为最底层模型,之后建立了周期性消息模型和非周期性消息模型,在此之上建立了RBC切换模型。最后,利用建模仿真软件TimeNET进行了仿真实验,以基于一部车载电台的RBC切换为例进行了分析,得到在不同列车运行速度和不同消息重发时间间隔对RBC切换成功率和切换时间的影响。     

Multihomed SIP‐based network mobility for the scheduled public transit service

Network mobility (NEMO) enables a group of nodes to connect to the back‐end infrastructure during the movement. Because a vehicle must provide passengers good enough transmission quality, various access techniques, for example, 3 G/3.5 G, Wi‐Fi or dedicated short range communication, can be simultaneously equipped to aggregate bandwidth and tolerate link failure. This paper extends the Session Initiation Protocol (SIP)‐based NEMO framework to support multihoming. First, IEEE 802.21 Media Independent Handover (MIH) is integrated to manage multiple egress interfaces in an on‐board unit (OBU). Second, a dynamic synchronization mechanism using the SIP SUBSCRIBE and NOTIFY methods is proposed to manage multiple OBUs in a vehicle. Furthermore, the framework is applied to public transportation systems, for example, bus, train, or mass rapid transit. Passengers may need to transit several times during their journeys. The transit behavior must induce a flood of signaling messages for location update. In this paper, the SIP REFER method is exploited to reduce signaling messages while a group of passengers have scheduled their transit in advance. Copyright © 2011 John Wiley & Sons, Ltd.     

MG-HMIP协议模型的实现及应用

由于无线局域网(WLAN)IEEE802.11协议不能解决移动节点的三层漫游问题,介绍了WLAN与移动IP结合的解决方案。由于上述方案存在切换延时长、不支持微移动性等缺陷,研究了分层移动IP技术,并对分层移动IP进行了改进,提出了一个多GFA分层移动IP(MG-HMIP)模型,并详细介绍了MG-HMIP模型的注册机制和MN选择GFA的机制。最后,给出了MG-HMIP与WLAN结合的模型。这个改进的方案不仅解决了WLAN与传统的MobileIP结合所存在的切换延时长、频繁切换等问题,而且增强了分层移动IP的网络健壮性。