Reviewed by
Norm Violette,
Associate Editor
Author: Reinaldo Perez
Spacecraft Design
Jet Propulsion Laboratory
California Institute of Technology
Academic Press, San Diego, CA 1998
This book is the second volume of a three-volume handbook series by the author titled: Wireless Communications Design Handbook. This five-chapter, 184-page Volume 2 is titled and addresses Terrestrial and Mobile Interference. Volume 1 of this series was reviewed in the EMC Society Newsletter, Summer 1999, Issue 182.
Mutual interference in today’s telecommunication systems is considered directly related to the ITU frequency allocation. Types of potential mutual interference described among frequency sharing systems include: (1) interference between terrestrial stations; (2) interference between satellite-earth links; and (3) interference between terrestrial stations and earth stations.
Included among the factors that are linked to these interference situations are frequency spectra and planning, ground terminal location and positioning, transmitted signal power levels, antenna types (radiation patterns, gain, polarization, and orientation), satellite orbit utilization (such as low earth or geosynchronous orbit), propagation paths and spacing, and sharing of frequency bands. Technical means for protecting radio channels from interference are described. These techniques include means of interference cancellation.
Pager concepts, including pager loop antenna models and design techniques, are presented.
Basic cellular phone operation is described. Standards applicable to guide the design of cellular phones are identified and basic design techniques are described. The requirements for audio-to-cellular interface are presented. Analog and digital phone signal composition and processing, including basic TDMA architecture, are illustrated. Other topics addressed include coding and decoding, modulation techniques, filtering requirements, the effects of multipath phenomena, DSP applications, AD and DA conversions. Several illustrative figures are provided.
Antenna performance parameters and characterization for ground stations are described. The basic antenna parameter relationships between radiation patterns, gain, effective area, beamwidth, directivity, impedance, polarization, and beam area are summarized. Antennas considered suitable for use in wireless system base stations are described as falling into three basic groups: resonant, aperture, and phase array. The features of each group are described, including the parameters involved in antenna-to-antenna interference. Environmental factors in antenna selection are described. The performance of dipole arrays is analyzed and applications described.
Passive repeater technology for PCS systems is described. The objective is to provide adequate coverage in cell-based systems in handling the great number of new subscribers. The author describes how a passive repeater design could be placed in a covered zone to modify and shape the radiation pattern to reduce the losses due to multipath, diffraction, and shadow regions. The basic design, construction, and application of a device called a space lattice passive repeater (SLPR) are described and illustrated. The use of RF coaxial and optical distribution systems is also described.
The use of smart antennas is described to increase the coverage and capacity as well as signal quality. Basically, two kinds of smart antennas are described: switched beam and adaptive array systems. The capabilities and advantages of smart antennas over omnidirectional antennas are described including coverage of larger areas, lower transmitting power, and interference reduction such as reducing co-channel interference. Smart antennas are used in CDMA applications.
Propagation models are provided for simulating interference. The physical medium between antennas, referred to as the propagation channel, includes the different kinds of obstacles that could influence the propagation of electromagnetic waves such as mechanisms that can cause reflections, diffractions, and scattering. Models described include multipath interference, envelope fading, Doppler spread, time delay spread, path loss, co-channel and adjacent channel interference. The application of Rayleigh fading principles is presented.
The natural radio noise environment for frequencies up to 300 GHz is described including such noise sources as lightning, extraterrestrial sources, and atmospheric thermal emissions. Quantum noise and the effects of the ground on antenna temperature are considered. The concept of noise factor is defined. Relationships are presented tying noise power flux density, electric field strength, and effective antenna area.
The effects of temperature are discussed including defined distinctions between antenna temperature, sky noise temperature, and brightness temperature. Blackbody thermal radiation is briefly described. The characteristics are presented of natural noise at the Earth’s surface, atmospherics, and extraterrestrial noise.
The effects of the interaction of ions in the ionosphere and geomagnetic field lines are discussed. This section describes the variations of the quiet and disturbed plasmasphere and the impact on VLF whistlers and other wave propagation. Also, space storms, including solar activity (solar wind and sunspots), are described along with their effects on satellites.
This Chapter provides detailed developments of the concepts of the applications of deterministic and stochastic waveforms as applied to receiver modeling. The details discuss waveform parameters of total energy, peak current (and voltage), and rise time. The discussion is in terms of the electromagnetic interference (EMI) margin for each of these parameters that preserve the important features of the average power margin. Interference models are developed for deterministic and stochastic waveforms.
Detailed mathematical derivations are provided of several nonlinear models. The basis of these derivations is the modified nonlinear transfer function, which is discussed in great detail, with particular emphasis on its derivation from an approach based on the more general Volterra series. The mathematical theory of functionals and functional expansion (proposed by Vito Volterra in 1930) is presented in detail and used to develop the modified nonlinear transfer function approach. Limitations of the approach are discussed, and the response of a weakly nonlinear system is developed for sinusoidal steady-state and two-tone sinusoidal inputs.
Receiver desensitization, gain compression and expansion, intermodulation, cross modulation, and spurious responses, are described. Included is a discussion of transmitter intermodulation products.
This chapter describes interference problems that can arise between terrestrial systems, between terrestrial and space systems, and between space systems. Potential interference situations are described. The signal-to-noise and signal-to-interference ratios are defined and described. Commu- nications over long distances and transhorizon propagation related to interference are presented, including the troposcatter propagation technique. The effects of ducting and rain scatter are discussed.
The analysis of the problem of interference to or from an earth station is described based on determining a coordination area surrounding the earth station. This approach is described in detail based on great circle propagation and for scattering by rain. Interference between space and surface stations is described and detailed procedures for interference analysis are presented.
A discussion is presented on the permissible level of interfering emissions. Other topics include link communications systems design (digital and analog systems), allocations of noise and signal-to-noise ratio, and diversity reception.
The end of the book includes a comprehensive list of references and an index.