XVi PREFACE
for reducing near-far interference. Although PacTel supported TDMA, but
due to the relative high-risk of developing TDMA and for the sake of safety,
PacTel helped Qualcomm develop an alternative digital cellular CDMA sys-
tem. CDMA has been theoretically proven to have twenty times more capacity
over the current analog cellular system. PacTel was unselfish, following MFJ
restrictions, in contributing its technical and financial resources to help
Qualcomm, a small but technically strong U.S. company, develop world-
leading cellular CDMA technology for capacity. A trial CDMA system
was built in six months starting from scratch, and a cellular CDMA dem-
onstration was held in San Diego on Two PacTel sites. Cellular CDMA is
introduced in the new Chapter 9.
I also felt the need to develop a microcell technology to further increase
capacity in analog and digital systems for future PCS (Personal Communi-
cation Service). The difference between conventional microcells and the PacTel
patented microcell is that the former are dumb cells and the latter are intel-
ligent cells. The new microcell system is introduced in the new Chapter 10.
Since publication of the first edition in 1986, there has been a tremendous
increase in the use of mobile communications. In the United States there
were 650 thousand cellular units in operation in 1986 and revenues of $46.2
million, and now in 1992 there are 8 million units and revenues close to $4
billion. In the year 2000 the predicted number of cellular units in operation
will be 20 million. In the European community, there were 815 thousand
cellular units in 1987 and there are 5 million units now. This rapid growth in
wireless communication shows the need for technology that will increase
capacity and improve system performance. Also, narrowband and wideband
radio access technologies are needed. Furthermore in June 1990, the FCC
encouraged the wireless communication industry to look into "Personal Com-
munication Service (PCS)" systems. PCS is a generic name for a future per-
sonal wireless communication system. In Europe, current systems such as
cellular communications (analog and digital), cordless telephone-2 (CT-2)
system, and the personal communication networking (PCN) system are all
mobile radio communications. In Japan, digital cellular and PCS are already
in the development stage. Therefore, this book, with its new added material,
such as CDMA and microcell technologies can aid in understanding and
developing all mobile radio systems including the future PCS.
Besides adding two new chapters, 9 and 10, I have also expanded the
discussion in Chapter 2 on the microcell prediction model, in Chapter 5 on
spectrum efficiency and cellular systems, in Chapter 6 on basestation design,
and in Chapter 7 on field component diversity antennas. To make the book
suitable for graduate course work, I have added problems to the end of each
chapter.
I have written three books covering the why, what, and how of mobile
radio system design. My other two volumes in this series of books deal with
the why and what. This volume presents the theoretical framework for radio