CDMA与ETACS共基站干扰的解决方法

目前，全国各地长城公司的ＣＤＭＡ移动电话系统正在建设，由于ＣＤＭＡ系统的基站发射频率与邮电模拟ＥＴＡＣＳ系统的基站接收频率非常靠近，很容易造成ＣＤＭＡ对ＥＴＡＣＳ基站的干扰，尤其在ＣＤＭＡ和ＥＴＡＣＳ系统进行共站建设时，这种干扰会特别严重。所以在Ｃ...     

摩托罗拉900 MHz CDMA试验网

ＣＤＭＡ(码分多址)移动通信技术的频谱利用率较高,具有诱人的发展前景。在该技术的发源地美国,ＣＤＭＡ已超过ＧＳＭ,成为个人通信的主流技术。在我国,长城移动通信分司正在积极开展800ＭＨｚＣＤＭＡ蜂窝区移动通信系统的试验。另外,900ＭＨｚＣＤＭＡ蜂窝区移动通信系统能否较好地改善我国现有的模拟ＴＡＣＳ网,也同样值得一试。在此背景下,1997年7月,摩托罗拉公司在我国福建省莆田市开通了900ＭＨｚＣＤＭＡ试验网。该试验网包括一个ＥＭＸ2500Ｇ交换机、一个集中基站控制器(ＣＢＳＣ)、一个无线操作维护中心(ＯＭＣＲ)、两个全向ＳＣ24…     

中兴通讯推出全套CDMA移动通信系统

１９９９年５月,中兴通讯成功开发出ＣＤＭＡ移动交换系统,通过了信息产业部组织的测试,并进入商用。２０００年７月,中兴通讯推出基于ＩＳ—９５Ａ／Ｂ、ｃｄｍａ２００１Ｘ标准的ＺＸＣ１０—ＢＳＳ（包括ＢＳＣ和ＢＴＳ）ＣＤＭＡ数字蜂窝移动通信基站系统。届时,中国将拥有自主开发的、达到世界领先水平的全套ＣＤＭＡ移动通信技术和产品。此外,中兴通讯还积极参与了国家关于ＣＤＭＡ移动通信技术标准的制定工作,与信息产业部电信传输研究所共同起草了《８００ＭＨｚＣＤＭＡ数字蜂窝移动通信网设备总测试规范：基站部分》、《８…     

浅析移动电话切换技术

介绍了ＴＡＣＳ，ＧＳＭ，ＣＤＭＡ蜂窝移动通信系统的无线切换技术，并简要介绍了ＥＭＸ２５００系统的切换过程。     

浅析移动电话切换技术

介绍了ＴＡＣＳ，ＧＳＭ，ＣＤＭＡ蜂窝移动通信系统的无线切换技术，并简要介绍了ＥＭＸ２５００系统的切换过程。     

CDMA基站对ETACS基站干扰拉生和解决方法

ＤＭＡ基站与ＥＴＡＣＳ基站间的干扰是实现两者共站时一个首要解决的难题。文章从干扰的产生干扰的产生及基站对干扰的保护要求入手介绍解决这一问题的方法     

测试精品廊

ＡｇｉｌｅｎｔＥ７４９５Ａ基站测试仪安捷伦科技的便携式基站测试仪ＡｇｉｌｅｎｔＥ７４９５Ａ(如图１所示 ) ,提供ＣＤＭＡ、ＧＳＭ、ＴＤＭＡ及ＵＭＴＳ等无线通信系统基站关键测试。结合所有最常用的ＢＴＳ测量 :功率表、ＣＷ及ＣＤＭＡ反向链路信号发生器、ＣＤＭＡ空中接口测试工具、天馈线故障分析仪、频谱分析仪、Ｔ１／Ｅ１测试仪、ＣＤＭＡ／ＵＭＴＳ／ＴＤＭＡ／ＧＳＭ的ＴＸＲＦ测试、ＣＤＭＡ／ＵＭＴＳ的ＴＸＲＦ调制分析、内置ＧＰＳ接收机。该基站测试仪具有以下特点 :·使用简便 :单一的硬键／软键接口设计和内置式辅助…     

CDMA基站及其新技术发展

一、ＣＤＭＡ系统结构 ＣＤＭＡ数字蜂窝移动通信系统的结构如图１所示： ＣＤＭＡ 数字蜂窝移动通信系统主要由交换子系统和基站子系统两大部分组成。连接两大子系统的接口（也就是连接ＢＳＣ和ＭＳＣ的接口）称之为Ａ接口,Ａ接口是ＣＤＭＡ数字蜂窝移动通信系统中一个非常重要的接口。在我国规定Ａ接口必须是一个开放的接口,它必须遵从我国相关规范的要求。只有在Ａ接口标准化之后,不同厂商的交换子系统才可以和其它厂商的基站子系统相连接。交换子系统主要由移动交换机ＭＳＣ、鉴权中心ＡＵＣ、短消息中心ＭＣ、归属位置寄存器ＨＬＲ…     

产品之窗

产品之窗室内光纤／电缆覆盖系统由亚伦电信下属意大利ＴＥＫ－ＭＡＲ公司生产的ＢＲＩＴＥＣＥＬＬ室内光纤覆盖系统适用于ＧＳＭ、ＤＣＳ１８００、ＴＡＣＳ及集群通信系统。其工作原理是：将主单元模块接收基站的射频信号（下行信号）转换为光信号后通过光纤传输到分布...     

SKY'S综合无线数据通信系统

ＳＫＹ'Ｓ综合无线数据通信系统依托ＡＭＰＳ及ＴＡＣＳ基站上的成熟技术,确保整个系统运行良好。频分双工,收发间隔１０ＭＨｚ～４５ＭＨｚ,可用频段３５０Ｍ～９００ＭＨｚ。双工无线ＭＯＤＥＭ具有ＡＴ＆ＴＥＴＣ增强功能可确保通信链络畅通可靠。ＴＡＣＳ制式（２５Ｋ带宽）ＭＯＤＥＭ最高速率１４．４ｋｂ／ｓ。ＡＭＰＳ制式（３０ＫＨｚ带宽）最高速率２８．８ｋｂ／ｓ。美国Ｒｏｃｋｗｅｌｌ公司的专用无线ＭＯＤＥＭ芯片组,确保无线通信可靠。硬件及软件的双层加密体系,有效解决了安全性问题。一个基站控制器可带１～１６个基…     

A 3-V monolithic SiGe HBT power amplifier for dual-mode (CDMA/AMPS)cellular handset applications

A dual-mode (CDMA/AMPS) power amplifier has been successfully implemented by using a monolithic SiGe/Si heterojunction bipolar transistor (HBT) foundry process for cellular handset (824-849 MHz) applications. The designed two-stage power amplifier satisfies both CDMA and AMPS requirements in output power, linearity, and efficiency. At V _cc=3 V,the power amplifier shows an excellent linearity (first ACPR<-44.1 dBc and second ACPR<-57.1 dBc) up to 28 dBm of output power for CDMA applications. Under the same bias condition, the power amplifier also meets AMPS handset requirements in output power (up to 31 dBm) and linearity (with second and third harmonic to fundamental ratios lower than -37 dBc and -55 dBc, respectively). At the maximum output power level, the worst power-added efficiencies (PAEs) are measured to be 36% for CDMA and 49% for AMPS operations. The power amplifier also tolerates severe output mismatch (VSWR>12:1) up to V _cc=4 V, with spurs measured to be <-22 dBc in CDMA outputs at two specific tuning angles, but with no spur in AMPS outputs at any tuning angle     

470～510MHz频段无线抄表系统干扰共存

现行射频规范限制470～510MHz频段无线抄表系统不能适应电力网络新的通信速率和覆盖范围需求.如何调整相关射频规范,在保障邻频先用通信业务不受干扰的前提下,有效提升无线抄表系统的通信能力成为目前亟待解决的问题之一.针对该问题,首先分析国内450～566MHz频段频谱划分情况.随后根据国家电网3种无线抄表系统的射频参数,通过确定性计算和射线追踪仿真的方法,研究所述无线抄表系统和邻频广播电视系统、CDMA450系统、铁路列调系统、FDD LTE系统之间的干扰共存情况.最后给出相关射频规范的修改建议.     

Potentials of smart antennas in CDMA systems and uplinkimprovements

An overview of the application of smart antennas in DS-CDMA systems, including IS-95 and IS-2000, is presented. Since CDMA systems are interference-limited, adaptive antenna arrays have great potential for improving the performance of such systems in terms of capacity, coverage, and quality of service, In this paper, we study the multiple-access interference that affects a CDMA system, and we describe how smart antennas can be implemented in an IS-2000-based mobile communications system. When smart antennas are used at the base station to transmit in narrow beams, the interference on the downlink is reduced, and C/I is improved. This, in turn, increases the system capacity on the downlink or, alternatively, the quality of service is improved. Such gains will prove very beneficial for asymmetric high-speed data applications, requiring much higher bit rates on the downlink than on the uplink. By reducing the base-station receiver's sensitivity, smart antennas can boost the capacity of the reverse link. Results are presented that outline how this reduction can be employed by the system designer on the uplink to increase capacity, reduce the mobile transmit power, or effect a tradeoff between capacity improvement and coverage or range extension under different system-loading scenarios     

CDMA cellular engineering issues

The frequency reuse efficiency for the proposed code division multiple access (CDMA) cellular system is analytically derived, and it is shown that the cell capacity of a fully loaded multiple cell system is about 75% of what would be available for a single cell system. In addition, an engineering issue in transitioning from analog advanced mobile phone system (AMPS) to CDMA system is discussed. Calculating excessive interference power due to a CDMA channel, it is shown that when a CDMA channel is introduced in a cell, there should be at least one ring of buffer cells, in which the analog channels falling into the CDMA band are not reused     

A highly integrated dual-band triple-mode transmit IC for cellular CDMA2000 applications

A highly integrated transmit integrated circuit intended for dual-band (CELL/PCS) and triple-mode (CDMA/TDMA/AMPS) cellular mobile stations is presented. It features a linear-in-dB gain-control range of 90 dB and provides a high output power of 9 dBm (PCS band) while meeting linearity requirements (-53-dBc ACPR) and achieving the receive-band noise floor of -133 dBm/Hz. It consumes only 130-mA current (3-V supply) in the PCS band. A dynamic-biasing feature results in additional power savings at lower signal levels. The circuit is fabricated in a 30-GHz f/sub T/ BiCMOS technology.     

Overlay of cellular CDMA on AMPS forward and reverse link analysis

The forward and reverse link capacities of code division multiple access (CDMA) and analog cellular system in North America (AMPS) are derived when they are overlaid. Formulas that describe the relationship between the number of CDMA and AMPS users for a given carrier to interference ratio (C/I) of each are presented. A nonlinear system that reduces the power of narrow-band interference is introduced. Simulation results are presented for one narrow-band interferer     

A CDMA2000 zero-IF receiver with low-leakage integrated front-end

This paper describes a highly integrated CDMA 2000 US-CEL band (880-MHz) receiver. The single-chip zero-IF design incorporates all receiver signal-path functions including the low-noise amplifier (LNA) on a single die. The complete receiver design exceeds the stringent linearity and local oscillator (LO) leakage requirements for this standard arising from the coexistence with narrow-band FM signals. The integrated LNA achieves 1.0-dB noise figure with +9-dBm IIP3 at high gain, and by maintaining LO leakage to the antenna port well below -80 dBm at all gain settings, no external LNA is required. The receiver is fabricated in a 0.25-/spl mu/m 40-GHz f/sub t/ BICMOS technology, and occupies 3 mm/sup 2/.     

Using RF filtering to reduce competitor-induced interference

This paper examines the success of RF filtering on mitigating interference that occurs between two wireless multiple-access systems operating within the same geographic area. Such interference is referred to as "competitor-induced interference" and can significantly degrade system capacity and performance. Three dual-system scenarios are considered: a dual code-division multiple-access (CDMA) (IS-95) system, a CDMA mobile in an FM (AMPS) cell, and an FM mobile in a CDMA cell     

A CDMA-distributed antenna system for in-building personalcommunications services

To investigate applications of spread spectrum code division multiple access (CDMA) technology to in-building personal communications services (PCS), comprehensive studies have been conducted for a CDMA PCS distributed antenna system in the 1.8 GHz band. The CDMA PCS distributed antenna system was set up with three nodes, each having two time-delayed elements, in a Qualcomm two story office building in San Diego. This paper presents measurement and modeling results on coverage, voice quality (frame error rate), reduction of transmit power, and path diversity for the in-building CDMA PCS distributed antenna system. Wideband CDMA signal coverage was predicted by using a ray tracing tool to find optimum placement of the distributed antennas. Using three nodes mounted in the ceiling space between the first and second floors, with each active element transmitting at -5 dBm in the system, the ray-tracing prediction shows good signal coverage in both floors of the building. The prediction results are confirmed by measurements at numerous discrete points with a standard deviation of 3.3 dB. Measurements using various combinations of number of nodes and delay elements showed significant time and path diversity advantages for the CDMA-distributed antenna system in indoor radio environments. Trade-offs between diversity gain and self-interference due to uncaptured finger energy in fringe areas are discussed     

一种电调Doherty功率放大器

提出了一种全新的电调Doherty移动基站功率放大器。该Doherty放大器的载波放大器和峰值放大器的驱动功率分配比及输出合成相位实现了电可调,从而保证了Doherty功率放大器的最佳驱动功率分配比,以及最佳的输出合成相位,同时结合内部线性化技术以实现Doherty功率放大器的最优性能。为保证功率放大器性能的稳定,设计了一种用于Doherty功率放大器的恒静态偏置电路,在-25℃～+50℃的高低温实验中使放大器偏置电流的波动小于5%。功放的工作频率为870～890MHz,增益大于58dB。在CDMA2000信号测试下,输出功率为50.06dBm时,其ACLR(邻道泄漏功率比)小于-47.5dBc,整机效率达42.3%(含驱动级)。