WCDMA向GSM切换时压缩模式测量方案分析

本文分析了工作在WCDMA FDD模式下的双模用户设备(UE),利用压缩模式对GSM系统的载频校正信道(FCCH)和同步信道(SCH)进行测量的过程。并提出对压缩测量方案选择的原则,以提高压缩模式的使用效率,降低对系统容量的影响。     

GSM系统频率同步的实现

在GSM系统中提出一种简单的频率同步算法,利用系统频率校正信道(FCCH)的信号特征估计接收信号的频率偏移,并通过频率补偿实现系统频率同步.仿真结果表明,该算法丢包率低,信噪比为8 dB时就可完全检测到FCCH;频偏估计和补偿效果好,降低了系统误码率.与传统的基于频域FCCH检测算法和最大似然匹配检测算法相比,所提算法基于时域信号处理,不需进行频域分析,其性能好且简单实用.     

GSM多功能基站中同步设计及FPGA实现

GSM多功能基站对于军用侦察和通信对抗有着非常重要的作用。在复杂环境下,对实时数据进行同步,从而正确解调出系统消息是一个非常重要的课题。在GSM通信系统帧同步原理的基础上,针对下变频数据过大和码间干扰(ISI)的问题提出对A/D数据取符号化和短训练序列相结合的FPGA实现方案,并且在同步实现上进行了工程优化。以Xilinx FPGA 7K325T为硬件平台分别设计FCCH(频率校正信道)同步模块、解旋转模块和SCH(同步信道)同步模块,通过板级验证证明了设计的可行性。将设计模块加入GSM多功能基站中,对实时数据进行同步并将数据送入后续解调模块中,最后能成功解调出系统消息,完成GSM多功能基站的侦察工作。     

GSM公共信道中FCCH的同频分离与捕获

针对GSM侦察设备升空后，截获和分析GSM信号时存在的严重的同频干扰问题。首先分析了GSM系统公共信道中频率校正信道（FCCH）的结构，然后根据其特点，提出了几种捕获和克服同频FCCH的方法，并进行了仿真验证。结果表明提出的方法能够有效克服GSM空中FCCH同频干扰，并且可以准确地捕获FCCH。     

BCCH同频干扰对网络切换性能的影响

在GSM网络中,切换对于改善用户通话质量、避免掉话是十分重要的。由于切换发生在通话进行中,采用“偷帧”的方式在FACCH信道上进行,因此一旦发生切换失败,我们首先关注的是TCH信道所用频点的受干扰情况,而忽略了小区BCCH频点受干扰的情况。大量的测试实例表明,小区的BCCH频点如果受到干扰,则该小区的切入失败率往往是很高的。我们知道,在一个小区中,BCCH信道、FCCH信道、SCH信道所用的频点是同一个。BCCH信道用来广播系统消息;FCCH携带用于校正MS频率的消息,使MS可以定位并解调出同一小区的其他信息;SCH信道则包含了小区…     

基于最大似然匹配的FCCH侦察捕获算法研究

在介绍传统GSM系统频率校正信道（FCCH）侦察捕获算法的基础上，针对在受到强噪声干扰时传统算法的不适用性，提出了基于最大似然匹配的FCCH捕获算法，并进行了计算机仿真验证。结果表明文章提出的算法能够有效克服强噪声干扰，与传统算法相比可以更加准确地捕获FCCH。     

GSM无线定位技术

GSM定义了许多逻辑信道,每一个逻辑信道都有其特定的作用。其中主要有传送用户有效载荷的业务信道（TCH,Traffic CHannel）;协调基站与移动台的相关及专用控制信道（ADCCH,Associated and Dedicated Control CHannel）;建立链接的公用控制信道（CCCH,Common Control CHannel）;用于建立同步的同步信道（SCH,Synchronisation Channel）及传送系统参数的广播控制信道（BCCH,Broadcast Control CHannel）等。这些逻辑信道所包含的信息以一种突发的方式来占用时隙。GSM以不同的格式定义了许多突发类型。在通用突发结…     

基于GMR-1系统下行链路的π/4-CQPSK解调方法

针对GMR-1系统下行链路BCCH和TCH3信道的接收,分析了GMR-1下行信道的时隙结构和π/4-CQPSK调制特性,提出了一种基于GMR-1系统下行链路的π/4-CQPSK解调方法。通过FCCH信道实现频偏估计和时隙同步,利用独特字进行信道估计和内插,并对时隙边缘部分的信道估计值进行修正,从而实现对BCCH和TCH3信道π/4-CQPSK的解调。仿真结果表明,在信噪比大于7 d B的情况下,该算法可以实现对GMR-1系统下行链路π/4-CQPSK的正确解调。     

通信对抗2007年总目次

通信侦察技术未来发展方向探讨""""""""""""""""""""""""""""詹毅(1-3)基于重排方法的跳频信号分析研究""""""""""""""""田岩,苟彦新,池万红,卜卫东(1-8)GSM公共信道中SCH自适应均衡解调算法研究"""""""""""张浩,张硕,满涛,祁晓磊(1-13)一种新的OFDM系统定时同步算法""""""""""     

GSM公共信道中SCH自适应均衡解调算法研究

针对移动信道多径效应造成的严重的码间干扰(ISI)问题,研究了基于最大似然序列估计(MLSE)的GSM公共信道中SCH自适应均衡解调算法,并对这种自适应均衡解调算法在Jakes移动信道模型环境下的性能进行了分析和计算机仿真,仿真结果表明该自适应均衡解调算法能够很好地克服码间干扰(ISI)问题,性能良好。     

Performance analysis of channel de-allocation schemes for dynamic resource allocation in GSM/GPRS networks

Channel de-allocation for GSM voice call (DASV) has been considered for dynamic resource allocation in GSM/GPRS networks. Two new de-allocation schemes are proposed: de-allocation for GPRS packet (DASP) and de-allocation for both GSM voice call and GPRS packet (DASVP). An analytic model with general GPRS data channel requirement is derived to evaluate the performance of the schemes in terms of GSM voice call incompletion probability, GPRS packet dropping probability, average GPRS packet transmission time and channel utilisation.     

基于GSM基站信号的动目标探测方法

基于全球移动通信系统(GSM)蜂窝网信号的外辐射源系统,提出了一种利用GSM蜂窝网基站发射的信号实现对运动目标检测的外辐射源系统的方案。首先对GSM基站信号参数、信道特点、模糊函数进行了分析,然后给出了一个试验系统的组成及其处理方法,主要包括自适应直达波/杂波对消、相干检测及参数提取方法等,仿真分析了2种场景下的动目标检测及参数提取结果,验证了利用GSM信号进行目标探测体制的可行性。     

Simulation and performance of the pan-European land mobile radiosystem

The introduction of the European Telecommunications Standards Institute/Groupe Special Mobiles (ETSI/GSM) digital land mobile radio system has required the study and application of advanced transmission techniques, necessary to meet the quality objectives in very demanding environments. In particular, the authors consider the performance of the compact-spectrum constant-envelope modulation chosen by ETSI/GSM, together with concatenated block and convolutional coding, Viterbi adaptive equalization, and soft-decision Viterbi decoding to cope with the severe time- and frequency-selective distortions caused by propagation phenomena, properly modeled for computer simulation. Channel coding and adaptive equalization techniques, supported also by frequency hopping and diversity reception, are fundamental to operate the system with the required quality     

一种用于GSM系统的神经网络均衡器

在泛欧GSM移动通信系统中，由于存在码间干扰，必须采用信道均衡技术。常用的最大似然序列估计(MLSE)均衡器采用维特比算法(VA)，它只能用于具有较小时延扩展的信道。本文给出了一种适用于GSM系统的部分连接神经网络均衡器．其复杂度与信道的时延扩展成正比．特别适用于具有较大时延扩展的恶劣信道。为了消豫神经网络局部极小点引起的性能恶化．我们采用了均场退火技术。本文提出的均衡器既适于用模拟集成电路实现．又适于用数字集成电路实现。计算机仿真表明本文的方法具有比最常用的16状态和32状态VA更好的性能。     

无源雷达GSM信号模糊函数研究

以基于GSM的无源雷达系统为背景 ,研究了GSM信号的模糊函数 ,特别是针对GSM信号的调制特点 ,采用MSK代替GMSK调制的近似分析方法得到了一种时延和频移向模糊函数的解析表达式 ,为现有GSM信号作为雷达信号在目标检测、参数估计和杂波抑制等方面提供了一定的理论参考     

Hardware-Echtzeitsimulator für intelligente Antennen

As part of a joint research project a hardware real time simulator for smart antennas was developed. The simulator allows for the simulation and evaluation of smart antenua algorithms. Simulations are carried out in the baseband domain and consist of a transmitter (GSM signal generator), mobile transmission channels for multiple receiveing antennas (Geometry-based Stochastic Channel Model according to COST259), (GSM-) co-channel interferers, and a multi-channel mobile terminal receiver using smart antenna algorithms. Typical results are presented.     

Diversity embedded rate configurable GSM and a low complexity detection method

This paper presents an energy efficient transmission method that is suitable for emerging large scale MIMO scenario, by combining space time coding and spatial multiplexing with GSM. The proposed Diversity Embedded SM (DESM) provides required Quality of Service (QoS) for a high priority data and at the same time maintains a fair transmission rate by spatial multiplexing a low priority data. Only limited feedback is required and the system can be configured for different diversity/non-diversity stream rates, as per the required QoS. Utilizing some peculiarities of the channel matrix of the system, a QR decomposition based detection method that requires only four receiving antennas is shown to have good performance. The computational complexity of detection is less compared to the existing GSM detection schemes, for reasonable number of transmit and active antennas. The effect of incorporating diversity on the rate of the system is also analyzed.     

A simple low-complexity algorithm for generalized spatial modulation

Generalized spatial modulation (GSM) is an extension of spatial modulation which is significant for the next generation communication systems. Optimal detection process for the GSM is the maximum-likelihood (ML) detection which jointly detects the antenna combinations and transmitted symbols. However, the receiver is much more complicated than SM due to inter-antenna interference and/or increased number of combinations. Therefore, the computational complexity of the ML detection grows with the number of transmit antennas and the signal constellation size. In this letter, we introduce a novel and simple detection algorithm which uses sub-optimal method based on the least squares solution to detect likely antenna combinations. Once the antenna indices are detected, ML detection is utilized to identify the transmitted symbols. For obtaining near-ML performance while keeping lower complexity than ML detection, sphere decoding is applied. Our proposed algorithm reduces the search complexity while achieving a near optimum solution. Computer simulation results show that the proposed algorithm performs close to the optimal (ML) detection resulting in a significant reduction of computational complexity.