Software Components

Software Components
Software footprint and software functionality is a product of memory bandwidth (code
and application storage space), processor bandwidth (the speed at which instructions
can be processed), and code bandwidth (number of lines of code). Over the past three
generations of cellular phone, memory bandwidth has increased from a few kilobytes
to a few Megabytes to a few Gigabytes. Processor bandwidth has increased from 10
MIPS (millions of instructions per second) to 100 MIPS to 1000 MIPS, and code bandwidth
has increased from 10,000 to 100,000 to 1,000,000 lines of code (using the Star-
Core SC140 as a recent example).
The composition of the code in a 3G handset determines how a 3G network is
used. Software form factor and functionality determine application form factor and
functionality.
Software components can be divided into those that address physical layer functionality
and those that address application layer functionality, as follows:

Physical layer software. Manages the Medium Access Control (MAC) layer�"the
allocation and access to radio and network bandwidth.
Application layer software. Manages the multiple inputs coming from the handset
application hardware (microphone, vocoder, encoder) and the media multiplex
being delivered on the downlink (network to handset).