Design of a telemedicine system using a mobile telephone

This paper describes the design of a prototype integrated mobile telemedicine system that is compatible with existing mobile telecommunications networks and upgradable for use with third-generation networks. The system, when fully developed, will enable a doctor to monitor remotely a patient who is free to move around for sports medicine and for emergency situations     

A UHF mobile telephone system using digital modulation: Preliminary study

A UHF mobile telephone system using digital modulation is described. The system uses on-off keying of an 836-MHz carrier, the code being supplied by an adaptive delta coder with a clock frequency of 50 kHz. The maximum audio baseband signal-to-noise ratio is approximately 30 dB. The mobile receiver employs space diversity in a maximal-ratio combiner. Due to the use of amplitude modulation of the carrier rather than exponential modulation, the diversity receiver is very simple. The system was tested in the laboratory and in the field. Field tests were made in suburban and urban areas. For the four-branch system, threshold occurred at an average IF signal-to-noise ratio of approximately 12 dB.     

Digital multiplex telephone transmission system using statistical properties of speech

A digital multiplex telephone transmission system is proposed, which should achieve a smaller bandwidth than conventional pulse-code modulation by using the statistical properties of speech waveforms. Each frame of transmitted pulses only contains a coded sample for a channel if the sample differs from the previous one from that channel. The frame can thus contain fewer time slots than there are channels, if there is a high probability of baseband signals changing by less than one quantising level during the frame period.     

A secure mobile healthcare system using trust-based multicast scheme

Due to the introduction of telecommunication technologies in telemedicine services, the expeditious development of wireless and mobile networks has stimulated wide applications of mobile electronic healthcare systems. However, security is an essential system requirement since many patients have privacy concerns when it comes to releasing their personal information over the open wireless channels. For this reason, this study discusses the characteristics and security issues with wireless and pervasive data communications for a ubiquitous and mobile healthcare system which consists of a number of mobile devices and sensors attached to a patient. These devices form a mobile ad hoc sensor network and collect data that are sent to a hospital or healthcare center for monitoring. Subsequently, this paper discusses the innovation and design of a novel trust evaluation model. We then propose a secure multicast strategy that employs trust in order to evaluate the behavior of each node, so that only trustworthy nodes are allowed to participate in communications, while the misbehavior of malicious nodes is effectively prevented. We analyze the security properties of our multicast scheme and evaluate its performance based on simulation experiments. Our experimental results demonstrate that our scheme not only achieves the necessary data transmission in mobile environments, but also provides more security with reasonably little additional overhead.     

数字蜂窝式移动电话系统现状与发展

目前在世界上许多国家运营的蜂窝式移动电话系统如北欧四国的 NMT、美国的AMPS、联邦德图的 C 网、英国的 TACS、日本的 NAMTS,我国在北京、上海和广州运营的 TACS 和爱立克森系统都属第一代模拟式移动电话系统。为了满足更多用户的要求,建立符合统一技术标准的系统,欧州许多国家在移动通信专业组(GSM)组织协调下,提出了多种系统方案,即第二代数字蜂窝式移动电话系统试验系统方案。本文对这几种系统,重点对 CD900、S900D,作了全面介绍。并从多址技术、信道编码、语音编码、调制技术以及经济性等方面进行了分析和评估。     

多通道数字电话的设计方案

给出了一种基于DSP技术实现的模数兼容的多通道数字电话的系统设计方案，设计中采用了DSP、低比特率语音压缩编解码、信道复用、快闪存储、串口和调制解调器通信等技术。在通用调制解调器构成的点对点通信平台上实现了两种语音的复用、传输及交换。     

Switching plan for a cellular mobile telephone system

Federal Communication Commission Docket 18 262 allocated a 75-MHz band to the common carriers to implement high capacity mobile telephone systems. The Bell System has proposed a cellular arrangement of low-power transmitters/receivers that permits frequency reuse in a coverage area. This method of achieving spectrum efficiency will require extensive centralized coordination and control to properly administer channel assignments and to interconnect the mobiles with each other and with the direct distance dialing (DDD) network. This can be accomplished by means of an electronic switching system (ESS) with special data terminals and trunking arrangements, and a unique program. In the proposed plan the radio sites (base stations) act effectively as remote concentrators in the frequency domain under the control of ESS, which in turn acts primarily as a trunk-to-trunk switcher. In addition to the usual switching, signaling, and supervising functions, the switching office must also perform numerous special functions including paging of mobiles, location of mobiles (signal strength and ranging data analysis), channel reassignment of mobiles, and reswitching of mobiles to various base stations-these last three occurring while customers ate talking.     

Frequency allocation for a mobile radio telephone system

Several ways of allocating frequencies efficiently are suggested that are based on the use of Latin squares. A Latin square of order n is a square array of n rows and n columns, and involving n symbols each of which occurs n times within the square in such a way that all the different symbols occur once in each row and once in each column. This approach provides two alternative ways of arranging the transmitters for a mobile radio telephone system, one rectangular and the other close-packed hexagonal. In both cases optimal patterns for frequency allocation result. A solution using the least-possible number of frequencies for each case is given, as well as one that is ideal in the sense that all the transmitters that surround any particular one are provided with distinct frequencies     

CDMA/GSM手机在线功能测试

本文提供了一种利用无线测试工具包对CDMA／GSM手机进行功能测试的方法,此工具包是VI Servicee Network开发的产品。手机功能测试包括了很多参数的测量。本文中以CDMA手机的校验测试和GSM手机各特征参数测试为例,验证了我们手机测试系统的有效性和准确性。在CDMA手机的校验测试中,我们主要根据发射器／接收器功率与手机内部寄存器的初值是否一致来判断校验结果的正确性。在GSM手机测试中,我们通过时域、频域和调制域各种参数的测量验证了本手机测试系统的准确性。最后我们介绍了信威公司使用本系统在生产线测试的实例,进一步证明了我们的手机测试系统在大规模生产测试方面广阔的应用前景。     

A flat energy density antenna system for mobile telephone

The notch array designed as a crossed slot antenna for receiving the magnetic field components is replaced by the disk of a ring patch antenna. Since the electric field components are received by the ring patch antenna, this combination provides an energy density reception antenna. A prototype of the flat energy density antenna has been built and tested: and the measured results of the input impedance characteristics and the radiation patterns are presented. Indoor field measurements with this antenna also verified the energy density reception     

数字集群移动通信系统体制

1.范围 本标准规定了采用TDMA制的数字集群移动通信系统的频段、网络结构、业务、空中接口、同步、安全性、编号、接口要求和设备的基本技术要求.     

IMS中骚扰电话拦截系统的设计方案

骚扰电话拦截系统是一个可以对骚扰号码进行主叫骚扰拦截、被叫骚扰拦截和二次运营拦截的系统,并提供并发控制、白名单和报表等监视和管控功能。对减少骚扰号码,提高IMS电话用户的使用体验和减少运营商的经济损失有着很重要的意义。本文首先给出了骚扰电话拦截系统的系统架构,然后重点介绍了决策分析子系统的工作机理、基于规则和滑动窗口统计形式的骚扰号码识别流程,最后给出了骚扰号码拦截流程。     

A pilot-based dynamic channel assignment scheme for wireless access TDMA/FDMA systems

We propose a control architecture for implementing a dynamic channel assignment (DCA) algorithm which optimizes two-way channel quality in a TDMA portable radio system. Computer simulations are used to evaluate the performance of this DCA method. A common control frequency, which is frame-synchronized among base stations, provides (1) beacons for portables to locate base stations and obtain DCA information, (2) broadcast channels for system and alerting information, and (3) pilot signals to permit portables to evaluate downlink interference. This allows low-complexity radio ports and portables to mutually select channels to avoid interference and avoid creating excessive interference. Results from computer simulations demonstrate the good spectrum efficiency of this method and its potential for handling nonuniform traffic demand. This work is targeted toward understanding the implications to local exchange networks of wireless system alternatives that could provide access to those networks.A preliminary work with the same title was presented at the Second International Conference on Universal Personal Communications, October 12–15, 1993, Ottawa, Canada.     

高速公路移动通信系统设计方案研究

高速公路移动通信系统是实现智能高速公路系统的基础,是现代高速公路系统的重要组成部分。为了解决现有的覆盖区域性的高速公路移动通信系统中部分路段存在"死区"的问题,建立能覆盖全国范围的高速公路移动通信系统,利用GSM-R技术,结合高速公路的实际特点,设计了基于GSM-R技术的高速公路移动通信系统,并对高速公路移动通信系统的设计方案进行了具体分析。     

CDMA versus FDMA channel capacity in mobile satellite communication

At present a major effort is under way to define the most efficient modulation/multiple access system in mobile satellite communication. Where the emphasis is on digital voice modulation, the proposed multiple access methods almost always imply frequency division multiple access (FDMA). This analysis presents a comparison between FDMA and code division multiple access (CDMA), for the operation of both multiple access methods in the mobile satellite communication environment. The mobile satellites under consideration use multiple-beam or scan-beam antennas and employ frequency reuse of the allocated L-band frequency spectrum. As CDMA is better at absorbing Doppler and multipath effects, and permits higher rate coding, in general (practical considerations aside) it appears to be the more capable system.     

Satellite repeater arrangement in a new maritime mobile telephone system

A new maritime mobile radio telephone system adopted by Nippon Telegraph and Telephone Public Corporation (NTT), is described. An outline of the technical features of the entire system and the satellite repeater arrangement, adopted to reduce service-dead areas, is given.     

User Capacity of a Demand-Assigned Satellite Communication System with a Hybrid TD/FDMA Up-Link and a TDM Down-Link

The advent of processing satellites which perform demodulation and remodulation of received signals has made it practical to consider satellite communication systems in which the up-link and down-link multiplexing/multiple-access schemes are different. This paper considers a satellite communication system in which channels are demand-assigned, and in which a hybrid time-division/frequencydivision multiple-access approach is employed for the up-link and pure time-division multiplexing is employed for the down-link. This scheme has significant advantage for systems which may be subject to electronic jamming. The user capacity is analyzed in general, and numerical results are given for some specific parameters of interest. Depending on the number of ground terminals in the network, it is found that the user capacity of the system can be limited by either the terminal's or the satellite's channel capacity.