3G Handset Software Form Factor and Functionality
In Chapter 3 we described the various hardware inputs that we have on a 3G handset—the wideband audio microphone (to capture high-quality audio streaming), the wideband megapixel CMOS imager, the keyboard (application capture), and USIM (access and policy rights control). We now need to consider how handset software is evolving to manage and multiplex these multiple inputs. We will also define how handset software determines session persistency and session quality.
An Overview of Application Layer Software
The raison d'être of the application layer is to take a simple exchange—for example, a voice or messaging exchange—and transform it into a rich media exchange, as follows:
- I talk to a friend.
- The application layer software prompts me to exchange an image file.
- The application software prompts me to send some simultaneous data (information on the image file).
- The application layer prompts me to load a simultaneous video exchange.
- The application software then prompts me to increase the color depth, resolution, or frame rate.
- I end up spending lots of money.
The software has influenced session persistency. What started off as a short, bursty exchange has become a persistent duplex flow of complex content, separately managed on multiple physical layer channel streams.
In our very first chapter, we pointed out how code bandwidth has expanded with each successive cellular generation (see Table 6.1). This has a largely unrecognized ...