5.11: Summary

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Radio frequency and microwave design continues to rapidly evolve, responding to new communication, radar, and sensor architectures. The long-term evolution also exploits opportunities made available with larger-scale monolithic integration and by advances in high-performance, low-power digital signal processing.

If filters and other hardware in a communication receiver are ideal, the final \(E_{b}/N_{o}\) and BER achieved are directly related to the RF SIR as described in this chapter. With practical filters and analog hardware there is a performance degradation and an SIR higher than the theoretical SIR is required to achieve a particular BER, or \(E_{b}/N_{o}\). The difference is

Modulation	Implementation Margin
BPSK	\(0.5\text{ dB}\)
QPSK	\(0.8\text{ dB}\)
8-PSK	\(1-1.6\text{ dB}\)
16-QAM	\(1.5-2.1\text{ dB}\)
CDMAOne	\(0.5-1\text{ dB}\)
WCDMA	\(2\text{ dB}\)

Table \(\PageIndex{1}\): Implementation margins for modern communication receivers [41, p. 328], [25, 42]. These implementation margins are what can be achieved by good system designs.

captured by the implementation margin, \(k\), usually specified in decibels. To achieve a specific BER, SIR must greater than the theoretical SIR by \(k\). The implementation margin is therefore a measure of the performance of RF hardware and is an important metric in design and in planning design. The implementation margin captures many imperfections. A design group and a company learns what it can achieve, e.g. see Table \(\PageIndex{1}\), and uses this in budgeting design costs and planning design effort. The design cost of RF systems are considerable and the ability to manage the design process and be able to estimate design effort is critical to timely success. Higher implementation margins result from the choice of lower-performing technologies, perhaps resulting from a compromise of performance, cost, and design effort.