#### In-depth

# 2.1 Factors affecting system design

## Technological limitations

### Hardware and software availability #### It is often the case in engineering that we know of an optimum design of a system, but do not yet have the technology invented or sufficient processing power to implement it. A recent example in data communications is the new digital cellular system GSM, where the modulation format GMSK (Gaussian Minimum Shift Keying) was chosen, rather than the technically superior QPSK format, owing to the problems with realizing a cost, and power efficient linear power amplifier required by QPSK in the handsets. (Subsequently, suitable amplifiers have been invented and the latest cellular system proposals use QPSK.) Digital signal processors (very fast special-purpose microprocessors) are now being used in many applications to implement functions traditionally realized using hardware components. In fact most high-speed telephone modems are implemented in digital signal processing. The processing power of these devices is increasing approximately 2-3 fold every year. |