Cellular Radio: Analog and Digital Systems [Book Reviews]

Abstract

Understanding cellular radio technology requires an understanding of the engineering issues in the complex mobile radio environment as well as the higher-level issues necessary to build a complete system. The author has simultaneously released two books. The first covers the underlying technology related to the radio environment [l]. The second, reviewed here, covers cellular concepts, traffic engineering, existing standards, and base stationlintersystem networking for a cellular system. The book is based on information from many journal articles, technical reports, and government documents. The author draws on his years of industrial and academic communication systems experience. For interested readers desiring more information, each chapter has many references. There a re problem sets at the end of each chapter, so this is a suitable textbook for a senior or graduate course in cellular principles. The book has nine chapters and several appendices with traffic tables and formulas. The first four chapters treat analog cellular with a focus on the venerable American analog Advanced Mobile Phone System (AMPS). Chapter 1 quickly sketches the cellular environment along with some historical perspective. From here it dives into the main topic. Chapter 2 introduces the cellular concept, including cellular geometry, cell splitting, and signal-to-interference ratios. It then goes on to cover important details of the AMPS air interface standard such as cellular phone numbering schemes and how they fit into the North American numbering plan, control channel features, and extensive coverage of call setup, handoff, and terminat ion sequences. It f inishes with design considerations unique to rural service areas. This chapter is the heart of the book. Once through this chapter, the reader can pick and choose as desired from the remaining chapters. Chapter 3 introduces traffic analysis with a good example of utilizing marketing and census data to generate percell traffic loads. I t also breaks down users into types and analyzes the traffic demands of each. Based on this analysis, it describes how to allocate voice and control channel resources to meet these demands. It also discusses various fixed and dynamic channel allocation schemes. Chapter 4 describes technical parameters common to many analog systems such as companding, modulation, handoff processes, and synchronization. Continuing from Chapter 2, it covers more details specific to the AMPS air interface and then embarks on a comprehensive survey of first-generation analog cellular systems from Canada, Japan, Scandinavia, Germany, and the U.K., highlighting similarities and differences in the technology and regulatory/market drivers that led to the technology choices. The chapter finishes with a snapshot of the world cellular market. Chapter 5 is a digression on design considerations for radio repeaters used for filling in coverage gaps at fringe, hole, indoor, and tunnel locations. Chapter 6 covers spectral efficiency of cellular designs, important when comparing different cellular standards. The chapter develops methods for computing spectral efficiency and analyzes several proposals for improving it such as half-bandwidth systems and partitioning of cells into inner higher reuse and outer conventional reuse zones. Chapter 7 describes the t rend towards digital cellular systems, the motivations behind these trends, and migration strategies from analog to digital. The majority of the chapter is a detailed discussion of the two secondgeneration cellular standards, the European Global System for Mobile Communication (GSM) and the American Digital Cellular standard for TDMA, IS-54. I t also introduces CDMA and extended TDMA. Chapter 8 discusses how different cellular operators work together via intersystem networking. It outlines IS-41 with respect to roaming, handoffs, and authentication. I t also discusses the X.25 and SS7 packetswitched network protocols. Chapter 9 contains methods for connecting the many base stations to the mobile switching office via digital multiplexing onto fiber optic or microwave links. These strengths a re somewhat obscured by poor editing. There are many typos throughout the text, figures are mislabeled, and the index has many incorrect references. Also, terms and acronyms are often used before defined. At a higher level, in trying to strike a balance between detail and general understanding, the coverage is uneven. Some concepts get unwarranted coverage (e.g., the simulations in Sections 3.6 and 3.7), whereas some important subtle concepts are brushed over without comment (e.g., the effect of sectorization on signal-to-interference on page 35). The result is that sections such as 6.4.2 (CDMA capacity) are cryptic at best. In some places (e.g., Section 8.3) it is difficult to discern what is a general concept and what is particular to the standard discussed in connection with it. In bringing together the multitude of information in a standard format, some mistakes have been made. For instance, some of the analysis on page 6.3.3.2 has errors (the inner hexagon should get 43% of the channels assigned to the cell, not 43% of the total number of channels in the system). In a book centered largely on standards and existing technology there is a danger of soon being out of date. In today’s rapidly evolving cellular environment this is especially acute. The discussion on CDMA uses parameters that have since changed with the issue of IS-95. The data on the cellular systems in different cities in Table A.l is six years out of date, made at a time when they were rapidly changing. There is no discussion of third-generation PCN/PCS. These criticisms aside, the book has a unique heads-up perspective to offer. It introduces many important concepts in cellular, from the basic cellular idea to system internetworking, without getting lost focusing down on mathematical and engineering detail. I have successfully used the book to teach an introduction to wireless course for a mix of engineering and nonengineering graduate students. For engineers I would recommend it as a companion to the many books which focus on mobile cellular principles without providing a comprehensive view of the existing implementations and the influence of the broader market and standards climate.