3G Handset and Network Design

CHAPTER 1

Spectral Allocations—Impact on Handset Hardware Design

In this first chapter we explain the characteristics of the radio spectrum, how over the past 100 years enabling component technologies have provided us with access to progressively higher frequencies, and how this in turn has increased the amount of RF (radio frequency) bandwidth available. We show how enabling component technologies initially provided us with the ability to deliver increasingly narrow RF channel spacing in parallel with the introduction of digital encoding and digital modulation techniques. We explain the shift, from the 1980s onward, toward wider RF channel spacing through the use of TDMA (Time Division Multiple Access) and CDMA (Code Division Multiple Access) multiplexing techniques and identify benefits in terms of component cost reduction and performance gain, in particular the impact of translating tasks such as selectivity, sensitivity, and stability from RF to baseband.

Setting the Stage

By baseband, we mean the original information rate. For analog voice, baseband would be used to refer to the 3 kHz of audio bandwidth. This would then be preprocessed. Preemphasis/de-emphasis would be used to tailor the high-frequency response and reduce high-frequency noise. Companding (compression/expansion) would be used to compress the dynamic range of the signal. The signal would then be modulated onto an RF carrier using amplitude or frequency modulation. Usually, an intermediate step between baseband ...