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OFDM技术在GSM语音信道中的应用 总被引:1,自引:0,他引:1
远距离数据传输以及数据传输的保密性向来是人们比较关注的问题,使用语音信道传输数据信息是一种可选的方案。利用GSM信道,结合OFDM技术,将电脑、手机、A/D、D/A组成一个系统,可以实现一种远距离数据传输平台。针对OFDM技术特点,实现了GSM语音信道OFDM调制解调系统,经过多次实验测试,平均误码率曲线表明设计达到了最初的设计要求,在话音保密数据通信及其他数据传输上有较好的应用前景。 相似文献
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A new multiaccess protocol is proposed for an integrated voice/data application. The protocol, which is a variation of virtual time CSMA (VT-CSMA), takes advantage of the periodicity of voice packets and possesses a number of important features. With this protocol, voice stations appear to have a dedicated time-division multiplexed (TDM) slot, and the delay of a voice packet is bounded by the length of a frame (defined to be the period between two consecutive voice packets from a voice station). Also, the amount of data added to the channel has little effect on the voice traffic. When silence detection is used, many more voice conversations can be supported without losing the dedicated-slot characteristic. This is in contrast to a movingboundary TDM system where the excessive bandwidth saved by silence detection can only be used for data. The protocol requires no global synchronization and is easy to implement. Simulation results are presented to evaluate its performance. 相似文献
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李继 《电信工程技术与标准化》2011,24(5):9-12
传统的话音业务仍是目前GSM网络业务收入的主要来源,通话质量也越来越为移动用户所关注,本文通过对GSM网络MOS话音质量评估标准及其影响因素的分析,重点给出提升GSM网络话音质量的方案。 相似文献
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Moe Rahnema 《International Journal of Wireless Information Networks》1996,3(3):181-185
This article presents first the generic structure and the formulation for the maximum likelihood detection of signals corrupted
by intersymbol interference. Then, simplifications are made for the application of the technique in the mobile communication
environment using the GSM specifications for which a channel memory length of 4 is used for equalizing over 4 bits.
This work was done while the author was with Motorola. 相似文献
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Abro Fauzia I. Rauf Farzana Mobeen-ur-Rehman Chowdhry B. S. Rajarajan Muttukrishnan 《Wireless Personal Communications》2019,108(3):1933-1955
Wireless Personal Communications - Global system for mobile communication (GSM) is widely used digital mobile service around the world. Although GSM was designed as a secure wireless system, it is... 相似文献
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讨论在当前发展的三种无线通信网GSM、GPRS和UMTS中,话音业务所承担的角色,介绍 GSM话音应用的未来。 相似文献
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目前,一些大、中城市的有线电视公司已经拥有庞大的有线电视宽带用户群,而基于HFC网的VoIP系统正是目前在有线电视宽带网条件下综合接入语音、数据和多媒体业务的最佳解决方案之一,其中语音业务可利用中继媒体网关设备完成媒体流转换,并通过标准的E1协议接入PSTN网络,以达到充分利用HFC及PSTN网络资源迅速开展话音业务的目的.同时,作为NGN(下一代网络)中的标准部件,VoIP是面向未来、可持续发展的解决方案之一,在有线电视宽带网所及之处,可以为商业和家庭用户提供质优价廉的IP语音服务. 相似文献
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吕宏滨 《电信工程技术与标准化》2007,20(4):85-88
3G到来的前夜,GSM网络的过度投资将大大增加成本风险,对网络资源配置进行评估和优化是目前工作的重点之一.既要提升网络服务能力,又要为今后降低经营成本提供有力条件.网络资源的利用率正在成为网络低成本运行的关键指标.本文就"GSM网络信道承载能力"问题进行一些分析. 相似文献
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Channel de-allocation schemes for GSM/GPRS networks 总被引:1,自引:0,他引:1
Jiang Tigang Fan Pingzhi Kam Yiu Lam 《电子科学学刊(英文版)》2005,22(6):581-585
Several channel de-allocation schemes for GSM/GPRS(General Packet Radio Service) networks are proposed in this paper. For DRA (Dynamical Resource Allocation) with de-allocation mechanism, if a new voice call arrives and finds that all the channels are busy, then one of the GPRS packets which occupy more than one channel for data transmission may release a channel for the new voice call. This paper presents 5 de-allocation mechanisms, i.e. DA-RANDOM, DA-RICHEST, DA-POOREST, DA-OLDEST and DA-YOUNGEST, to select the GPRS packet for releasing the appropriate channel. Simulation results show that DA-OLDEST achieves the best performance, especially in packets blocking probability, among all the de-allocation schemes. Although the performance of the proposed de-allocation schemes is not significantly different, they are all much better than that of the scheme without de-allocation. 相似文献
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GSM系统中话音加密技术的研究 总被引:3,自引:0,他引:3
无线传播的特性使得用户的保密性和利益容易受到影响。重点分析了GSM系统在安全性管理功能上的缺陷,提出了GSM系统中话音加密的技术路线。 相似文献
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本文论述了GSM无线系统话音质量问题的原因,并根据在日常监控中的实际维护经验分析了话音质量问题的多种原因和采取的处理方法。讨论了GSM数字移动通信无线系统网络话音质量问题;总结了一些常见的优化方法及经验。 相似文献
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Thakor Nitish V. Webster John G. Tompkins Willis J. 《IEEE transactions on bio-medical engineering》1982,(5):355-359
We present the design of a battery-powered digital modem for transmitting ECG signals. It operates from a 5-V battery supply, uses a coil or acoustic coupler for a telephone interface, and consumes only 30 mW during transmission. We show error rates comparable to regular stand-alone modems, well within the acceptable limit of 1 bit per 100 kbits transmitted at a transmission speed of 300 Bd. 相似文献
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This study considers the problem of transmitting generic (non-speech) data through compressed voice channels such as those
used in wireless communications networks. These networks employ voice codecs that are designed to efficiently encode and reproduce
the relatively slow-changing signals of human speech, which leads to communication channels that are nonlinear and have long-term
memory. A data modem is presented that utilizes finite alphabets of waveforms that are numerically optimized to be as separable
as possible after passing through the voice codec. The optimization of the finite alphabet is performed using a pattern search
algorithm. When used with the GSM Enhanced Full-Rate Voice Codec, this system demonstrated improved performance, in terms
of error rates, compared to previously reported results. Simulation results for four other voice codecs are also presented. 相似文献
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We develop a mathematical analysis for the steady state performance of a system where voice calls and data packets are transmitted over the same channel. The voice calls have priority over the data packets, in that the data packets are transmitted only when there are no voice calls present in the system or the voice conversation is in a long silent period. 相似文献