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针对水平方向地电极电流场无线强穿透信息传输需求,研究了基于极低频水平双电极电流场信道传输特性。考虑到电极半径、电极入土深度、电极间距、发射信号频率和信号传输距离等参数对透地(Through-The-Earth, TTE)通信传输性能的影响,建立了地电极电流场TTE通信路径损耗模型,分析了各参数对路径损耗的影响,确定了信号传输最佳工作参数。根据选定参数搭建了极低频电流场TTE通信系统,在200 m和400 m通信距离下测试了3~10 Hz信号的路径损耗,通过试验数据与仿真结果对比分析验证了模型的准确性。 相似文献
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无线光通信系统适合大气随机信道传输,对该系统进行了模拟和数字信道的大气无线激光多媒体通信测试试验。该设计能够有效地补偿大气随机信道对传输信号的衰减损耗,提高系统的通信质量。 相似文献
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以高速铁路普遍采用的GSM-R通信系统理论为基础,以郑西客专、石武客专为实例及结合我国高铁发展现状,简要介绍了铁路客运专线无线通信设备建造的网络结构及设备特点,并阐述了GSM-R承载的铁路运行业务。通过分析这些铁路运行业务与信号专业列车控制系统的联动工作机理,比较明确地论述了GSM-R无线通信系统网络组织运行与信号列控系统CTCS-3如何协作控制动车行使的基本原理。能够将高铁列车自动控制信息的传输与无线系统接口服务器结合起来进行综合介绍,进一步展现了现代高速铁路在实现通信信号专业一体化方面的先进技术。 相似文献
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通过分析三网融合给电信运营商带来的机遇和挑战,结合电信运营商和广电企业等三网融合主体的优劣势,提出了三网融合背景下电信运营商业务、网络和产业链发展的策略。 相似文献
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运用华为软交换的失败码统计功能,分析研究各种失败情况下的产生原因,结合信令仪、设备自带跟踪工具等进行联合分析定位,解决了隐性网络问题,提高了华为软交换设备的网络质量。 相似文献
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本文将全面分析GSM移动通信系统中导致各类掉话的原因。在移动通信中,掉话可分为两种形式:一类是在SDCCH信道上的掉话,一类是在TCH信道上的掉话。掉话率作为反映网络性能的一项重要指标,一直是网络优化工作关注的重点。 相似文献
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TD-SCDMA网络处于逐步完善覆盖的时期,为了更好地提升用户使用感知,需要网优工程师及时发现网络中的问题,尤其是严重影响客户感知的掉话问题。针对TD-SCDMA网络中掉话率相关定时器、计数器设置过大导致的"网管统计信息不准确"的问题进行优化分析,并提出一种切实有效的优化方法。 相似文献
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Third-generation wireless communication faces the challenges of rapidly increasing mobile user demand against limited radio bandwidth. Splitting cells into smaller cells can reduce the frequency reuse distance to improve network capacity within a certain area. Other than increasing the cost of the fixed infrastructure, cell splitting also causes the problem of increasing handoff rate and event the handoff failure rate when high-speed users roam in the network. To solve this problem, larger cells are overlaid on these smaller cells, and different classes of users (usually classified by speed) are initially assigned to the proper types of cells (i.e., proper tiers). We call this kind of cellular network a hierarchical cellular network. In this study, we review the different design techniques in the hierarchical architecture and some analytical tools to study the performance of these designs. 相似文献
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The traffic performance of integrated 3G wide-band code division multiple access (WCDMA) and GSM/GPRS network is evaluated.
This type of network links two cellular radio systems which have different set of frequency bands and the same coverage size.
The base station of 3G WCDMA is installed on an existing GSM/GPRS site. Dual-mode mobile terminals use handoff to establish
calls on the better system. The soft handoff or inter-frequency hard handoff occurs when mobile terminals of 3G WCDMA or GSM/GPRS
move between two adjacent cells, respectively. The inter-system hard handoffs are used between 3G WCDMA and GSM/GPRS systems.
The data rate conversions between different systems, soft handoff region size, multiple data rate multimedia services, and
the effect of the mobile terminal mobility on the user mean dwell time in each system are considered in the study. The simulation
results demonstrate that a great traffic performance improvement on the complementary use of 3G WCDMA and GSM/GPRS cellular
radio networks compared with the use of GSM/GPRS cellular radio networks. When high-data rate transmission is chosen for low-mobility
subscribers, both the handoff failure probability, and carried traffic rates increase with the new call generation rate. However,
both rates decrease conversely with the increasing new call generation rate as soon as the new call generation rate exceeds
a critical value. This causes the integrated networks saturation. The higher mean speed for the mobile terminals produces
lower new call blocking probabilities and total carried traffic. The new call blocking probabilities and total carried traffic
increase with the size of the soft handoff region. 相似文献
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在GSM移动网中,由于智能新业务的不断增长,加之平等接入业务和就远入网路由原则的推广实施,呼叫接续的时间,尤其是主叫关口局至被叫端的接续过程会变得很长,超出等待ACM(AddressCompleteMessage)的时长,造成始发端因为后向接续超时而释放呼叫,导致呼叫失败。在ISUP中有early-ACM这样的机制,可以用来预防始发端因为后向接续超时而导致的呼叫被释放。可以在MTUP(MobileTelephoneUserPart)信令中引入early-ACM这样的机制来改善呼叫失败这样的情况。 相似文献