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Noise Performance Evaluation Example: 16-QAM What is the C/N ratio when the noise is at the threshold of causing errors?. Assuming all 16 symbols are equally likely, the average carrier power is proportional to:. For threshold noise performance, the noise power is proportional to:.
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Noise Performance Evaluation Example: 16-QAM What is the C/N ratio when the noise is at the threshold of causing errors? Assuming all 16 symbols are equally likely, the average carrier power is proportional to: For threshold noise performance, the noise power is proportional to: To exceed threshold noise performance,
7 dB Compare to QPSK (4-QAM): 16 QAM needs ~7 dB better C/N for equal error performance, but bit rate is doubled.
Modulation Bandwidth For data with symbol (baud) rate fB, we have estalished that we need a single sided bandwidth of fB/2. If this signal is modulated onto a carrier, we need a double sided bandwidth of 2(fB/2) = fB. Thus for M-ary signalling (M possible carrier states),