3G Handset and Network Design

CHAPTER 4

3G Handset Hardware Form Factor and Functionality

In Chapter 2 we described the physical hardware needed to realize a multislot, multiband, multimode handset. In Chapter 3 we described the physical hardware needed to deliver multiple per-user channel streams. In this chapter we describe the application hardware components needed to realize a multimedia mobile handset and the impact of various hardware items in the handset on the offered traffic mix.

Impact of Application Hardware on Uplink Offered Traffic

First, we review the impact of the microphone and audio vocoder, the CMOS imager (or CCD imager), and the keyboard on uplink offered traffic. We then move on to a brief overview of rich media, followed by a section on the smart card SIM. These components are shown in Figure 4.1.

Voice Encoding/Decoding (The Vocoder)

Let's first look at the microphone and its impact on uplink offered traffic. In Chapter 1 we described briefly the process of talking into a microphone to produce an analog waveform (a varying voltage), which is then digitized in an analog-to-digital converter (ADC). In GSM, this produces a digital bit stream of 104 kbps, which then has to be compressed, typically to 13 kbps or lower, using a transfer from the time to the frequency domain—the basis for all speech synthesis codecs.

Figure 4.1 Application hardware components in a 3G handset.

Initially, cellular ...