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1996 | Buch

Principles of Mobile Communication

verfasst von: Gordon L. Stüber

Verlag: Springer US

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Principles of Mobile Communication provides an authoritative treatment of the fundamentals of mobile communications, one of the fastest growing areas of the modern telecommunications industry. The book stresses the fundamentals of mobile communications engineering that are important for the design of any mobile system. Less emphasis is placed on the description of existing and proposed wireless standards. This focus on fundamental issues should be of benefit not only to students taking formal instruction but also to practising engineers who are likely to already have a detailed familiarity with the standards and are seeking to deepen their knowledge of this important field. The book stresses mathematical modeling and analysis, rather than providing a qualitative overview. It has been specifically developed as a textbook for graduate level instruction and a reference book for practising engineers and those seeking to pursue research in the area. The book contains sufficient background material for the novice, yet enough advanced material for a sequence of graduate level courses.
Principles of Mobile Communication treats a variety of contemporary issues, many of which have been treated before only in the journals. Some material in the book has never appeared before in the literature. The book provides an up-to-date treatment of the subject area at a level of detail that is not available in other books. Also, the book is unique in that the whole range of topics covered is not presently available in any other book. Throughout the book, detailed derivations are provided and extensive references to the literature are made. This is of value to the reader wishing to gain detailed knowledge of a particular topic.

Inhaltsverzeichnis

Frontmatter
1. Introduction
Abstract
The basic technological components of a cellular telephone system are radio transmission technology and computer technology. A cellular telephone system has two basic functions; it must locate and track the mobile stations (MSs), and it must always attempt to connect the MSs to the best available base station(s) (BS(s)). The latter task requires the continuous evaluation of the radio link quality with the serving BS(s), and the radio link quality with alternate BSs. This monitoring is performed by a computer system that uses knowledge of the link quality evaluations, in addition to the system topology and traffic flow, to decide upon the best BS(s) to serve a particular MS.
Gordon L. Stüber
2. Propagation Modeling
Abstract
A typical cellular radio system consists of a collection of base stations (BSs) that are relatively free from local scatterers. The BS antenna height and placement affects the proximity of local scatterers. In a macrocellular environment, the BS antennas are usually well elevated above the local terrain. No direct line-of-sight (LOS) path exists between the BS and mobile station (MS) antennas, because of the natural and man-made objects that are in the immediate vicinity of the MS. As a consequence of reflections, scattering and diffraction, multiple plane waves arrive at a MS from many different directions and with different delays, as shown in Fig. 2.1. This property is called multipath propagation. The multiple plane waves combine vectorially at the receiver antenna to produce a composite received signal.
Gordon L. Stüber
3. Co-Channel Interference
Abstract
For cellular radio systems the radio link performance is usually limited by interference rather than noise and, therefore, the probability of co-channel interference (CCI), is of primary concern. The definition of the probability of CCI depends on the the assumptions made about the radio receiver and propagation environment. At higher velocities, the radio receiver can usually average over the fast envelope variations by using coding and interleaving techniques. In this case, the transmission quality will be acceptable provided that the average received carrier-to-interference ratio, Λ, exceeds a receiver threshold Λth. The receiver threshold Λth is determined by the performance of the radio link in the presence of envelope fading. Once Λth has been determined, the variations in Λ due to path loss and shadowing will determine the probability of CCI. At lower velocities, the radio receiver cannot average over the fast envelope variations due to the delay constraints imposed by voice traffic. In this case, the transmission quality will be acceptable provided that the instantaneous received carrier-to-interference ratio, λ, exceeds another receiver threshold λth 1. Once λth has been specified, variations in λ due to path loss, shadowing, and envelope fading, will determine the probability of CCI.
Gordon L. Stüber
4. Modulated Signals and Their Power Spectral Densities
Abstract
Modulation is a process where the message information is embedded into the radio carrier. Message information can be transmitted in the amplitude, frequency, or phase of the carrier, or a combination of these, in either analog or digital form. For mobile radio applications it is desirable to use bandwidth and power resources most efficiently. The primary objective of bandwidth and power efficient modulation is to maximize the bandwidth efficiency, measured in bits/s/Hz, while achieving a prescribed bit error probability with a minimum expenditure of power resources. Good bit error rate performance must be achieved in the presence of a variety of channel impairments including fading, Doppler spread, intersymbol interference, adjacent and co-channel interference, and thermal noise. Furthermore, portable and mobile radio transmitters normally use power efficient nonlinear amplifiers to conserve battery resources. Because of the amplifier nonlinearities, modulation techniques with a relatively constant envelope are often used. All first generation cellular systems used analog FM. However, the pressing need for greater bandwidth efficiency has lead to the use of digital modulation techniques in second generation digital cellular standards. The North American IS-54 and Japanese PDC systems use π/4-DQPSK, the European GSM system uses Gaussian minimum shift keying (GSMK), and the Motorola Integrated Radio System (MIRS) uses orthogonal frequency division multiplexing (OFDM).
Gordon L. Stüber
5. Digital Signaling on Flat Fading Channels
Abstract
The performance of a digital modulation scheme is degraded by many transmission impairments including fading, delay spread, Doppler spread, co-channel and adjacent channel interference, and noise. Fading causes a very low instantaneous received signal-to-noise ratio (SNR) or carrier-to-noise ratio (CNR) when the channel exhibits a deep fade, delay spread causes intersymbol interference (ISI) between the transmitted symbols, and a large Doppler spread is indicative of rapid channel variation and necessitates a receiver with a fast convergent algorithm. Co-channel interference, adjacent channel interference, and noise, are all additive distortions that degrade the bit error rate performance by reducing the CNR or SNR.
Gordon L. Stüber
6. Digital Signaling on ISI Channels
Abstract
Land mobile radio channels are modeled as fading dispersive channels, because of the multipath propagation and the randomly changing medium characteristics. Many types of impairments are observed on these channels such as multipath spread (or delay spread), fading, Doppler spread, nonlinear distortion, frequency offset, phase jitter, impulse noise, thermal noise, and co-channel and adjacent channel interference arising from spectrum sharing. This chapter concentrates on the effects of delay spread, fading, Doppler spread, thermal noise, and co-channel interference. Delay spread causes interference between adjacent symbols, known as intersymbol interference (ISI), a large Doppler spread indicates rapid channel variations and necessitates a fast convergent algorithm when an adaptive receiver is employed, and fading results in a very low received signal-to-noise ratio or signal-to-interference ratio when the channel exhibits a deep fade.
Gordon L. Stüber
7. Bandwidth Efficient Coding
Abstract
Channel coding and interleaving techniques have long been recognized as an effective technique for combating the deleterious effects of noise, interference, jamming, fading, and other channel impairments. The basic idea of channel coding is to introduce controlled redundancy into the transmitted signals that is exploited at the receiver to correct channel induced errors by means of forward error correction. Channel coding can also be used for error detection in schemes that employ automatic repeat request (ARQ) strategies. ARQ strategies must have a feedback channel to relay the retransmission requests from the receiver back to the transmitter when errors are detected. ARQ schemes require buffering at the transmitter and/or receiver and, therefore, are suitable for data applications but are not suitable for delay sensitive voice applications. Hybrid ARQ schemes use both error correction and error detection; the code is used to correct the most likely error patterns, and to detect the more infrequently occurring error patterns. Upon detection of errors a retransmission is requested. Although ARQ schemes are essential for data transmission over wireless channels they nevertheless employ error correction codes. Therefore, the emphasis in this chapter is on error correction coding.
Gordon L. Stüber
8. Code Division Multiple Access
Abstract
Spread spectrum systems were originally developed for military applications, to provide antijam and low probability of intercept communications by spreading a signal over a large frequency band and transmitting it with a low power per unit bandwidth [73], [247], [286]. Recently, code division multiple access (CDMA) based on spread spectrum technology has been recognized as a viable alternative to both frequency division multiple access (FDMA) and time division multiple access (TDMA) for cellular systems. During the late 1980s and early 1990s, Qualcomm, Inc.’s efforts, along with those of many other organizations such as Motorola and AT&T, have lead to the North American IS-95 cellular standard [79]. A detailed description of the IS-95 CDMA cellular approach can be found in a number of papers, including those by Lee [181] and Gilhousen et al. [118]. The book by Viterbi [324] provides a good coverage of the spread spectrum concepts that form the foundation of the IS-95 CDMA cellular system.
Gordon L. Stüber
9. Cellular Coverage Planning
Abstract
Many current cellular systems employ fixed channel assignment (FCA) schemes, where the cells are permanently assigned a subset of the available channels according to a frequency reuse plan. This chapter discusses the issues associated with radio coverage planning for cellular systems. Several schemes are suggested for improving the spectral efficiency in a cellular system including cell sectoring, cell splitting, reuse partitioning, switched beam smart antenna systems, selective base station (BS) diversity, and overlay/underlay schemes. Although the concepts are developed for systems that employ FCA, they will in many cases apply to those that use dynamic channel assignment (DCA).
Gordon L. Stüber
10. Link Quality Measurement and Handoff Initiation
Abstract
Cellular systems must have the ability to maintain a call while a mobile station (MS) moves throughout a cellular service area. This is accomplished by performing a handoff to an alternate base station (BS) whenever the link quality with the serving BS becomes unacceptable. A variety of parameters such as bit error rate (BER) [54], carrier-to-interference ratio (C/I) [103], distance [209], [85], traffic load, signal strength [209], [130], [132], [225], [41], [319], and various combinations of these fundamental schemes have been suggested for evaluating the link quality and deciding when a handoff should be performed. Of these, temporal averaging signal strength based handoff algorithms that measure the received carrier plus interference power (C+I) have received the most attention due to their simplicity and good performance in macrocellular systems. As a reflection of this trend, much of this chapter will be devoted to these types of handoff algorithms. However, spectrally efficient cellular systems are interference limited and a large C+I does not necessary imply a large C/I. Since radio link quality is more closely related to C/I than to C+I, it is apparent that C/I based handoff algorithms are highly desirable for microcellular systems with their characteristically erratic propagation environments. Unfortunately, C/I measurements can be quite difficult to obtain in practice [180], [348] and, hence, practical resource allocation algorithms often resort to received (C+I) measurements as a quality measure. Nevertheless, some discussion of C/I measurement techniques will be presented in this chapter.
Gordon L. Stüber
11. Channel Assignment Techniques
Abstract
First generation macrocellular systems typically use fixed channel assignment (FCA), where disjoint subsets of the available channels are permanently allocated to the cells in advance according to their estimated traffic loads. The cells are arranged in tessellating reuse clusters whose size is determined by the co-channel reuse constraint. For example, the North American AMPS system typically uses a 7-cell reuse cluster with 120° sectoring. The 12.5 MHz bandwidth allocation for AMPS can support a total of 416 two-way channels, 21 of which are control channels (one for each sector in a cluster), leaving a total of 395 traffic channels. This yields an allocation of 56 channels/cell with uniform FCA.
Gordon L. Stüber
Backmatter
Metadaten
Titel
Principles of Mobile Communication
verfasst von
Gordon L. Stüber
Copyright-Jahr
1996
Verlag
Springer US
Electronic ISBN
978-1-4757-6268-6
Print ISBN
978-1-4757-6270-9
DOI
https://doi.org/10.1007/978-1-4757-6268-6