TD-SCDMA覆盖分析

首先对无线传播模型进行了归纳；然后对TD-SCDMA的上／下行链路预算和基站覆盖半径进行了计算，并分析了覆盖受限方向；最后讨论了3G混合业务下的基站覆盖半径以及与WCDMA覆盖方面的差异。     

一种用于网络优化覆盖的GSM准基站构建方案

针对目前GSM网络优化覆盖存在的问题, 提出了用于网络优化覆盖的GSM准基站构建 方案。对GSM准基站构建方案的产生背景、系统组成、覆盖功能进行了深入讨论,分析了GSM 准基站网络优化覆盖的工程应用场景及解决的问题。     

全向小区与定向小区共站解决覆盖断点

针对目前一些全向基站信号覆盖不理想问题，提出了有效解决办法：在全向基站增加一定向小区，专门覆盖该盲区，解决覆盖断点问题。     

LTE无线网络中微基站应用研究

提出从容量和覆盖两方面采用微基站解决LTE网络深度覆盖问题方案,介绍微基站特点及按照功率进行分类,对微基站产品LampSite、ATOM(原子级基站)、AAU(有源天线单元)进行对比分析,给出微基站产品在解决无法获取站址、局部小范围覆盖弱区、楼宇内深度覆盖等问题的场景中的应用。最后总结出"宏站为主、微基站为辅"的建设原则,微基站定位于局部小范围补盲、难以获取站址区域及室内深度覆盖等场景的补充手段。指出基于微基站的定位方法及特点,在进行微基站建设时,配套建设应相匹配,避免超配。除根据需求使用PoE(以太网供电)远供外,原则上微基站不进行电源保证配置。     

基站越区覆盖的控制

对基站越区覆盖对移动通信网络的影响进行了分析,研究了如何通过各种工具来分析评估基站的越区覆盖,并提出控制基站越区覆盖的方法.     

面向空天应急通信系统的空地连续覆盖技术研究与应用

摘 要：为了解决大型固定翼无人机应急基站覆盖范围小、覆盖不连续的问题，提出一种无人机应急基站连续覆盖的设计方案。通过对机载基站单天线覆盖能力的分析，提出内侧天线加边缘天线的多幅天线覆盖方案，并结合无人机飞行的滚转角、俯仰角等参数，设计保证连续覆盖的多天线挂装的安装方案。根据 3GPP 传播损耗模型进行链路预算，根据连续覆盖面积需求，规划无人机飞行方案。仿真和飞行测试结果表明，所提方案能在不使用云台智能控制天线角度的情况下，实现空中移动基站对地面50 km²面积的连续覆盖。     

移动通讯基站覆盖问题的研究

在对小圆覆盖大圆问题的研究中,提出了实用的圆覆盖的等腰三角法。并将其与移动通信发射基站的建立进行了有效的结合,对其可行性及优势作了较为详细的阐述。同时,根据本文提出的方法,我们与现在普遍运用在移动基站建设中的正六边形覆盖法作了比较。     

室内无线覆盖系统浅析

针对PHS室外基站对大型建筑室内覆盖不足的问题，介绍了利用分布式天、馈线系统解决室内和电梯覆盖的几种常用方式，并从频率干扰、传播差异和兼容性方面分析了与WLAN共用系统的可能性。     

大下倾角天线抑制现网高站过远覆盖问题的分析研究

本文对基站过远覆盖形成的原因以及对网络和用户使用感知带来的负面影响进行了详细阐述。针对此问题,创新性地提出采用大下倾角天线来抑制现网超高基站过远覆盖问题的新思路,并结合现网情况进行了实际应用。分析结果表明,大下倾角天线的波瓣抑制能力能够较好的控制超高基站信号的覆盖距离,为网络优化工作中经常出现并难以解决的过远覆盖、导频污染等问题提供了新的、有效的控制手段。     

无线基站用于海域覆盖时出现的问题及其解决方法

首先提出了用GSM900无线基站在做近海海域覆盖时会出现的一些问题，并阐述了其原因：随后给出了处理这些问题的解决方案，最后提供了一个在实际工程中对某海域覆盖型基站的测试实例。     

On the Doppler power spectrum at the mobile unit employing adirectional antenna

The effects of directional antennas at the mobile unit on the Doppler power spectrum are investigated. The Doppler power spectral density (PSD) functions at the mobile unit employing a directional antenna have been derived and presented. These Doppler PSD functions were derived for both the omnidirectional and directional antenna cases at the base station     

Effect of employing directional antennas on mobile OFDM system with time-varying channel

In this letter, we analyze the inter-carrier-interference (ICI) caused by Doppler spreading in an orthogonal frequency-division multiplexing system when the angle-of-arrival (AOA) of the received signal is not uniformly distributed. An expression of the ICI power is derived by taking into account the probability density function of the AOA. We also present examples using directional antennas at the base station, at the mobile or at both mobile and base station. The ICI power changes marginally when a directional antenna is placed at the base station. Finally, we show that the ICI power can be reduced substantially when a directional antenna, along with frequency tracking, is employed at the mobile.     

Antenna selection in a multisector packet radio system

To improve performance on the inbound (mobile-to-base-station) channel of a packet radio system consisting of a base station and a number of mobile users, the area around the base station is divided into M sectors. Signals originating from users in different sectors are received by different directional antennas at the base station. It is shown that, if the number of receivers at the base station is less than M, the selection of the antennas to be connected to the receivers becomes an issue. A number of antenna selection schemes are compared for three different channel models, assuming an ideal antenna pattern. It is found that the scheme that selects the antennas with the largest received signal powers is nearly optimum. The effects of a more practical nonideal antenna pattern are discussed     

上层站在移动通信的应用

随着现代化城市的快速发展,高层建筑的发展在我国大城市中已经成为一种趋势。高层建筑一般是指楼层在10层及以上或其高度大于28m的建筑物。在现有的GSM网络中,一般基站天线挂高在30m左右,再加上天线的下倾,通常可以覆盖到附近楼宇的10层及其以下部分,10层以上楼宇区域的覆盖成为了急需解决的问题。本文将从上层站覆盖方式的角度来进行分析解决这个问题。     

Performance evaluation of a cellular base station multibeam antenna

Experimental test results are used to determine the performance that can be achieved from a multibeam antenna array, with fixed-beam azimuths, relative to a traditional dual-diversity three-sector antenna configuration. The performance tradeoffs between the hysterisis level, switching time, and gain improvement for a multibeam antenna are also examined. The multibeam antenna uses selection combining to switch the signals from the two strongest directional beams to the base station's main and diversity receivers. To assess the impact of beamwidth on overall system performance, the following two multibeam antennas were tested: a 12-beam 30° beamwidth array and a 24-beam 15° beamwidth array. Both multibeam antennas were field-tested in typical cellular base station sites located in heavy urban and light urban environments. Altogether, the system performance is evaluated by investigating three fundamental aspects of multibeam antenna behavior. First, the relative powers of the signals measured in each directional beam of the multibeam antenna are characterized. Then, beam separation statistics for the strongest two signals are examined. Gain improvements achievable with a multibeam antenna compared to the traditional sector configuration are determined in the second phase of the analysis. Results indicate that in excess of 5 dB of gain enhancement can be achieved with a 24-beam base station antenna in a cellular mobile radio environment. Finally, the effects of hysterisis level and switching time are characterized based on gain reductions relative to a reference case with no hysterisis and a 0.5-s switching decision time. Useful approximations are developed for the gain effects associated with varying hysterisis levels and switching times. The resulting design curves and empirical rules allow engineers to quantify multibeam antenna performance while making appropriate tradeoffs for parameter selection     

基于紧耦合结构的宽带基站天线设计

随着5G移动通信频段的公布,传统基站天线已不足以覆盖其工作频段。文章以紧耦合阵列天线理论为基础,提出了一种基于紧耦合结构的交叉偶极子宽带基站天线。该天线由两对正交的领结状偶极子天线构成,通过两对交叉偶极子之间的耦合效应,有效地展宽了天线的阻抗带宽。同时,通过在天线和金属反射板之间加载电阻型频率选择表面,吸收由反射板引入的谐振反射波,改善天线高频端辐射性能。仿真及测试结果表明:该天线在1.7-3.6 GHz 频率范围内,可以满足基站天线的设计指标,两端口驻波比均小于1.5,两端口之间隔离度大于55 dB,半功率波束宽度满足65°±5°范围,且整个频段内增益均大于8.5 dBi。     

基于方向性天线的中继蜂窝网络资源复用方案

针对传统的蜂窝的缺点,中继蜂窝网络通过在基站和移动台之间引入若干中继节点,缩短了收发节点之间的通信距离,降低了传输衰落,提高了链路通信质量。基于方向性天线的中继蜂窝网络采用合理的区域划分以及资源分配方案,提高了资源的利用率,减少了系统同频干扰;系用过对系统干扰进行理论分析和仿真实验,证明了该方案的可行性。     

人体受到电磁辐射的仿真研究

基于可变网络的时域有限差分法,仿真了暴露于900MHz移动通信基站天线远区场中的人体和移动电话天线近区场中的人体头部电磁模型中产生的比吸收率分布,分析了基站天线和手机天线辐射对人体的影响。以理想点源天线作为基站天线,在人体正前方入射频率为900MHz的正弦平面波,仿真结果显示,人体在基站天线照射下的平均SAR值符合国际卫生部标准;以900MHz单频PIAF天线作为手机天线置于高仿真人体头部1cm处,仿真结果与环保标准比较,人体头部受到的照射剂量远低于安全标准。     

Redundancy concepts to increase transmission reliability in wireless industrial LANs

Wireless LANs are an attractive networking technology for industrial applications. A major obstacle toward the fulfillment of hard real-time requirements is the error-prone behavior of wireless channels. A common approach to increase the probability of a message being transmitted successfully before a prescribed deadline is to use feedback from the receiver and subsequent retransmissions (automatic repeat request-ARQ-protocols). In this paper, three modifications to an ARQ protocol are investigated. As one of these modifications a specific transmit diversity scheme, called antenna redundancy, is introduced. The other modifications are error-correcting codes and the transmission of multiple copies of the same packet. In antenna redundancy the base station/access point has several antennas. The base station transmits on one antenna at a time, but whenever a retransmission is needed, the base station switches to another antenna. The relative benefits of using FEC versus adding antennas versus sending multiple copies are investigated under different error conditions. One important result is that for independent Gilbert-Elliot channels between the base station antennas and the wireless station the antenna redundancy scheme effectively decreases the probability of missing a deadline, in a numerical example approximately an order of magnitude per additional antenna can be observed. As a second benefit, antenna redundancy decreases the number of transmission trials needed to transmit a message successfully, thus saving bandwidth.     

Selective Mobile Communication in Socially Sensitive Environments

In certain environments, the use of mobile phones must be curtailed for the sake of security or out of respect for others. We present a novel method for selectively controlling mobile phone services in such areas using a base station controller and a sequence of detection steps to identify when the mobile device is within the coverage area. A prototype for the method has been developed using commercial off-the-shelf and custom designed hardware and software subsystems. Key components in the prototype system are two directional antennas located at the entry to the controlled area with one antenna facing outwards and the other inwards. By using the proposed detection method, the base station controller is able to detect when a mobile station enters or leaves the controlled area. Experiments using a variety of detection sequences by the two directional antennas and associated white- and blacklists of allowable and disallowed devices, respectively, confirm that the prototype system is able to effectively control the use of mobile devices within the coverage area.