The renaissance of privately-licensed shortwave broadcast stationsin the United States

The status of privately licensed shortwave broadcast stations in the US is reviewed. The stations are identified, and their reasons for broadcasting are examined. The laws, rules, and regulations which permit these stations to operate in a world of government-funded stations are discussed, along with the technical standards that they are required to meet, and the particular technical problems that they face     

A New System Synchronization Technique for the Switching Satellite

A new technique for achieving system synchronization to the switching satellite is described; this technique requires only three earth stations, designated as control stations, to transmit synchronization signals. The three signals are used to measure the three space delays from the control stations to the satellite. The control stations broadcast the space delays to all other stations in the system. Thus, any other earth station can obtain synchronization passively by calculating its own space delay.     

基于基站密度和业务负载的异构蜂窝网络能效优化

该文在两层异构网络架构下,采用泊松分布(PPP)建立基站分布模型,构建基于基站密度和业务负载的网络能效模型。分析基站密度对网络能效的影响,并根据网络业务流量的到达率对宏基站和小基站的密度进行联合优化,得到宏基站和小基站的最优联合密度,在保证网络服务质量的同时,使能效达到最优。仿真结果表明,在不同的网络业务需求下,通过基站密度的优化,在保证网络服务质量的同时,合理部署宏基站和小基站的数量,可使能效大幅度提高。     

室外集中直流远供系统在街道站的应用探讨

传统的街道站供电方案不论是室外小型-48 V开关电源还是220 V电源供电,都存在许多的弊端,给后期维护带来很大的压力。文中提出一种新的街道站后备电源保障方案,即采用室外280 V高压直流远供给街道站提供后备电源保障。     

An Algorithm for the Design of a Cost-Optimized Topology for the Fixed Part of a GSM Network

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On the performance effects of station locations and access protocolparameters in Ethernet networks

A simulation study is presented in several distributions of stations on a linear-bus Ethernet. Aggregate performance is shown to depend on the distribution of stations. Individual station performance varies with the location of the station. Unbalanced distributions can lead to large performance differences between individual stations, with isolated stations achieving relatively poor performance compared to the average. The effects of access protocol parameters such as the number of buffers per station and the retransmission algorithm are examined. A modification of the standard retransmission algorithm is presented that enables a higher throughput to be achieved at high load. The results are compared to the predictions of theoretical models, and the applicability of the models to finite-population Ethernets is examined     

Determining the target coordinates in forward-scattering radar systems with mobile stations

The maximum-likelihood method is applied to determination of the target coordinates in forward-scattering radar systems with mobile stations. Estimates of the potential accuracy of measurement are obtained. It is shown that forward-scattering radars with mobile stations can ensure almost the same accuracy of measurement of the target coordinates as radar systems with stationary stations.     

移动通信基站巡查中路线回放功能的设计与实现

基站天线的工程参数影响着基站的覆盖范围,是网络优化的关键参数。对基站进行定期巡查是维护基站工程参数正常的必要举措,但从代维公司反馈的作业计划中发现有存在谎报巡查站点的情况。针对这一问题,本文基于Android系统,利用智能手机终端,在基站天线工程参数测量系统中,设计和实现了当前GPS定位信息展示,行走方位角度指示,巡查位置坐标实时记录,以及利用地图进行巡查路线回放等功能。在方便巡查人员出行的同时,管理人员可以通过路线回放来判断代维巡查人员是否到站,从而可以有效避免谎报巡查站点的行为。该功能经测试效果良好,为基站天线维护工作提供了有力的帮助。     

A study of alternative broadcasting technologies for the extensionof DTV coverage in Taiwan

In Taiwan, there are six major NTSC terrestrial broadcasting stations and 129 relay stations, which cover about 98% of Taiwan's population. This paper addresses the planning of DTV broadcasting in Taiwan. DTV signals will be broadcast from the same six major transmitting sites and are expected to provide similar coverage. To extend DTV coverage beyond the major transmitting sites, only the existing 9 NTSC relay stations with over 100 W transmitting power would relay DTV signals. Residences living beyond the above coverage areas could rely on CATV or DTH to receive terrestrial DTV programs     

Local Base Station Cooperation Via Finite-Capacity Links for the Uplink of Linear Cellular Networks

Cooperative decoding at the base stations (or access points) of an infrastructure wireless network is currently well recognized as a promising approach for intercell interference mitigation, thus enabling high frequency reuse. Deployment of cooperative multicell decoding depends critically on the tolopology and quality of the available backhaul links connecting the base stations. This work studies a scenario where base stations are connected only if in adjacent cells, and via finite-capacity links. Relying on a linear Wyner-type cellular model with no fading, achievable rates are derived for the two scenarios where base stations are endowed only with the codebooks of local (in-cell) mobile stations, or also with the codebooks used in adjacent cells. Moreover, both uni- and bidirectional backhaul links are considered. The analysis sheds light on the impact of codebook information, decoding delay, and network planning (frequency reuse) on the performance of multicell decoding as enabled by local and finite-capacity backhaul links. Analysis in the high-signal-to-noise ratio (SNR) regime and numerical results validate the main conclusions.      

浅析通信基站电源设备安全运行防护原理与解决办法

通过对通信基站电源设备防护原理的介绍,系统地分析了当前通信基站普遍存在的季节性电源设备大量毁损的原因,同时,结合维护实践提出新的技术解决方案。     

融媒体时代电视台编导发展战略研究

在当前信息全球化大背景下,融媒体时代的来临使得传统电视媒体功能单一性和发展模式滞后性逐渐体现,因此为确保电视台后续运维发展的高效性和稳定性,电视台编导专业人员必须结合融媒体特征制定合理的电视台发展战略,明确各分项落实重点才能使现今我国电视台逐渐形成可持续发展的模式。而融媒体所表现出的将传统视听媒体以及平面媒体等均可直接借助网络进行全方位内容传播特性,使得传统媒体与新媒体形成相互融合发展的形态,虽然近年来大部分电视台从节目制作、传播等方面逐渐体现出多功能性的融媒体特征,但综合来看大部分电视台在借助融媒体进行制播改革编导期间,无论是技术创新还是目标设置,都缺乏较为系统的战略指导方案支撑。因此做好融媒体时代电视台编导发展战略研究工作便显得极为必要。     

基于GPS的公交自动报站算法研究

为了提高公交自动报站的准确性,让乘客有一个愉快的行车体验,文中讨论了两种基于GPS的公交自动报站算法,分别从线路站点信息的采集、车辆上下行方向的判断、进站的判定方法、出站的判定方法四个关键问题进行了充分阐述,并对两种方案各自的优缺进行了比较,第一种算法线路采集简单,算法复杂,准确性低,第二种算法线路采集复杂,算法简单,准确性高。在实际产品中采用了第二种算法,取得了良好效果。     

Relay Selection Strategy in the Secure Cooperative Communications System

With the low cost and low hardware complex considerations, cooperative systems are a tendency in the future communications. This work considers the secure cooperative communications systems. For a practical situation in the system, the scenario includes multiple source stations, multiple relay stations, multiple destination stations, and eavesdroppers. To analyze the optimal relay selection in the system, we begin with the performance analysis for a single source station and a single destination station. By applying two cooperative models, the amplify-and-forward (AF) mode and decode-and-forward (DF) mode, the secrecy capacity is derived. Then, we apply the derived results to the considered environment to find the optimal relay assignment. By the way, the relay selection can be obtained by the exhaustive search algorithm. However, there are a lot of steps needed if the number of source stations is large. Hence, applying the characters of the cooperative modes in the relay selection, the pre-selection step is proposed with a mathematical derivation. It could be used for the practical situation without a long-time calculation.     

提高电台供电质量的方法

本文分析了一些广播电台、电视台的电能质量差的原因,提出了解决的具体措施对新工程建设和老电台改进供电系统的设计有一定参考意义。     

On the distribution of cumulated interference power in Rayleigh fading channels

This paper deals with the distribution of cumulated instantaneous interference power in a Rayleigh fading channel for an infinite number of interfering stations, where each station transmits with a certain probability, independently of all others. If all distances are known, a necessary and sufficient condition is given for the corresponding distribution to be nondefective. Explicit formulae of density and distribution functions are obtained in the interesting special case that interfering stations are located on a linear grid. Moreover, the Laplace transform of cumulated power is investigated when the positions of stations follow a one- or two-dimensional Poisson process. It turns out that the corresponding distribution is defective for the two-dimensional models.This work was supported by the Deutsche Forschungsgemeinschaft under grant no. Ma 1184/2-3.     

Relayed communication via parallel redundancy

A communication is described where relay stations are moving in groups of k stations. If all k stations of a group fail, then all groups of k stations ahead of the failed k stations as well as the k failed stations are lost. The objective is to have one station reach the destination with all groups having at least one station in good condition. It is shown that this second communication system requires fewer stations on the average than the system of D.T. Chiang and R.-F. Chiang (1986). The probability distribution of the numbers of stations required in the Chiang-Chiang communication system is also examined     

浅谈基础科研院所驻外站点信息化建设的现状及思考

基础科研院所驻外站点“小”而分散,因为资金、地域及功能定位等历史原因信息化建设不受重视,针对目前站点现状进行剖析,提出信息化建设一体化思路及对未来发展的影响。     

短信在基站监控的应用

针对通信基站监控系统的长期运行中所存在的问题,结合公司出品的短信监控系统的三年实践,提出基站监控信息自动分配到目标用户的办法,使监控值班中心从信息传递链中撤出,实现通信基站从“无人值守”到“无人值班”的跨越。     

Techniques for the Management of Frequency Bands Shared Between Terrestrial Stations and Mobile or Transportable Earth Stations

The allocation of frequency bands on a shared basis to different radiocommunications services has created requirements for specialized spectrum management techniques. Techniques used in the management of frequency bands shared between terrestrial stations and mobile or transportable Earth stations are presented.