Mobile radio channel

Xem 1-20 trên 28 kết quả Mobile radio channel
  • Parametrization – a Technique for SDR Implementation Friedrich Jondral University of Karlsruhe Mobile communications is mainly a service driven business. But there are important marginal conditions from physics and technology that may not be ignored when developing a mobile communications system; the frequency spectrum is a scarce resource. Therefore terminals, mobile as well as base station transceivers, have to work efficiently with respect to spectrum. Mobile radio channels are complicated due to multipath propagation, reflections, scattering, time, or frequency dispersion, etc. ...

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  • Our first chapter puts LTE into its historical context, and lays out its requirements and key technical features. We begin by reviewing the architectures of UMTS and GSM, and by introducing some of the terminology that the two systems use. We then summarize the history of mobile telecommunication systems, discuss the issues that have driven the development of LTE, and show how UMTS has evolved first into LTE and then into an enhanced version known as LTE-Advanced. The chapter closes by reviewing the standardization process for LTE....

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  • The third generation (3G) mobile communication system is the next big thing in the world of mobile telecommunications. The first generation included analog mobile phones [e.g., Total Access Communications Systems (TACS), Nordic Mobile Telephone (NMT), and Advanced Mobile Phone Service (AMPS)], and the second generation (2G) included digital mobile phones [e.g., global system for mobile communications (GSM), personal digital cellular (PDC), and digital AMPS (D-AMPS)].

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  • The Mobile Radio Propagation Channel. Second Edition. J. D. Parsons Copyright & 2000 John Wiley & Sons Ltd Print ISBN 0-471-98857-X Online ISBN 0-470-84152-4 The Mobile Radio Propagation Channel The Mobile Radio Propagation Channel. Second Edition. J. D. Parsons Copyright & 2000 John Wiley & Sons Ltd Print ISBN 0-471-98857-X Online ISBN 0-470-84152-4 The Mobile Radio Propagation Channel Second Edition J. D.

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  • Sounding, Sampling and Simulation In the earlier chapters we discussed the characteristics of mobile radio channels in some detail. It emerged that there are certain parameters which provide an adequate description of the channel and it remains now to describe measuring equipment (channel sounders) that can be used to obtain experimental data from which these parameters can be derived.

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  • Other Mobile Radio Channels A great deal of attention has been given to propagation in built-up areas, in particular to the situation where the mobile is located in the streets, i.e. when it is outside the buildings. It is apparent, however, that other important scenarios exist. For example, hand-portable equipment can be taken inside buildings, and in recent years there has been a substantial increase in the use of this type of equipment.

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  • GSM (Global System for Mobile Communications, originally Groupe Spécial Mobile), is a standard set developed by the European Telecommunications Standards Institute (ETSI) to describe technologies for second generation (2G) digital cellular networks. Developed as a replacement for first generation (1G) analog cellular networks, the GSM standard originally described a digital, circuit switched network optimized for full duplex voice telephony.

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  • Hard to fathom, but it really wasn't all that long ago that even a plain old telephone was a luxury item. But, as we all know, technology's only constant is change. In this day and age, many folks need to be accessible everywhere, whether they're at work or play, in the office or at home. To meet this demand, the GSM standard (Global System for Mobile Communications) for mobile telephony was introduced in the mid- 1980s. Today, GSM is the most popular mobile radio standard in the world. A boom is underway, such that many GSM users find life without their phone practically inconceivable....

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  • This book explains the basic components, technologies used, and operation of IS-95 CDMA systems. You will discover why mobile telephone service providers have upgraded from 1st generation analog systems to more efficient and feature rich 2nd generation system. You will also discover how 2nd generation systems are gradually evolving into 3rd generation broadband multimedia systems. This book starts with the system components and basic services that the IS-95 CDMA system can provide.

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  • The history of mobile radio goes back almost to the origins of radio communication itself. The very early work of Hertz in the 1880s showed that electromagnetic wave propagation was possible in free space and hence demonstrated the practicality of radio communications. In 1892, less than ®ve years later, a paper written by the British scientist Sir William Crookes [1] predicted telegraphic communication over long distances using tuned receiving and transmitting apparatus.

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  • Mobile Satellite Communication∗ In principle communications satellites provide the same connectivity as terrestrial (wireless and wireline) networks. The advantages of satellites, such as fast wide-area coverage, flexible transmission parameters and cost independence due to distance, are compared with the disadvantages, such as restricted channel capacity because of the frequencies available, orbital positions, need for line-of-sight connectivity and high initial investment besides relatively long signal propagation times.

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  • The mobile radio propagation environment clearly places fundamental limitations on the performance of radio communication systems. Signals arrive at a receiver via a scattering mechanism, and the existence of multiple propagation paths (multipath) with di€erent time delays, attenuations and phases gives rise to a highly complex, time-varying transmission channel. In order for systems engineers to determine optimum methods of mitigating the impairments caused by multipath propagation, it is essential that the transmission channel be properly characterised. ...

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  • Fundamentals of VHF and UHF Propagation Having established the suitability of the VHF and UHF bands for mobile communications and the need to characterise the radio channel, we can now develop some fundamental relationships between the transmitted and received power, distance (range) and carrier frequency. We begin with a few relevant de®nitions. At frequencies below 1 GHz, antennas normally consist of a wire or wires of a suitable length coupled to the transmitter via a transmission line.

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  • Propagation over Irregular Terrain Land mobile radio systems are used in a wide variety of scenarios. At one extreme, county police and other emergency services operate over fairly large areas using frequencies in the lower part of the VHF band. The service area may be large enough to require several transmitters, operating in a quasi-synchronous mode, and is likely to include rural, suburban and urban areas.

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  • Many measures, functions and protocols in digital mobile radio networks are based on the properties of the radio channel and its speci®c qualities in contrast to information transmission through guided media. For the understanding of digital mobile radio networks it is therefore absolutely necessary to know a few related basic principles. For this reason, the most important fundamentals of the radio channel and of cellular and transmission technology will be presented and brie¯y explained in the following. For a more detailed treatment, see the extensive literature [4,42,50,64]. ...

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  • As argued throughout the previous chapters the book, mobile propagation channels exhibit of time-variant propagation properties [ 131. Although apart from simple cordless telephone schemes most mobile radio systems employ power control for mitigating the effects of received power fluctuations, rapid channel quality fluctuations cannot be compensated by practical, finite reaction-time power control schemes.

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  • As the growing demand formobile communications is constantly increasing, the need for better coverage, improved capacity and higher transmission quality rises. Thus, a more efficient use of the radio spectrum is required. Smart antenna systems are capable of efficiently utilizing the radio spectrum and, thus, is a promise for an effective solution to the present wireless systems’ problems while achieving reliable and robust high-speed high-data-rate transmission. The purpose of this book is to provide the reader a broad viewof the systemaspects of smart antennas.

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  • So, given PT and G it is possible to calculate the power density at any point in the far ®eld that lies in the direction of maximum radiation. A knowledge of the radiation pattern is necessary to determine the power density at other points. The power gain is unity for an isotropic antenna, i.e. one which radiates uniformly in all directions, and an alternative de®nition of power gain is therefore the ratio of power density, from the speci®ed antenna, at a given distance in the direction of maximum radiation, to the power density at the same point, from an isotropic...

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  • Propagation in Built-up Areas Having looked at how irregular terrain a€ects VHF and UHF radio wave propagation and the e€ects of multipath, we are now in a position to discuss propagation in built-up areas. This chapter will deal principally with propagation between base stations and mobiles located at street level; propagation into buildings and totally within buildings will be discussed later. Although losses due to buildings and other man-made obstacles are of major concern, terrain variations also play an important role in many cases.

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  • Enable many mobile users to share simultaneously radio spectrum. Provide for the sharing of channel capacity between a number of transmitters at different locations. Aim to share a channel between two or more signals in such way that each signal can be received without interference from another.

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