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I'm trying to evaluate received signals from a transceiver. I want to make a threshold of received signals so that we can say some signals are meaningless.

I have learnt something about Signal-to-Noise-Ratio (SNR) and Received-Signal-Strength (RSS). But I found that symbols can still be decoded even in low SNR ($\le 0$ dB).

Here are my questions:

  1. If I choose SNR as my metrics, will my threshold be relevant to modulation or coding schemes?

  2. Will RSS be suitable for theoretic analysis as metrics?

Marcus Müller
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Mr.Budapest
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1 Answers1

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Indeed, in practical systems there is usually a cut-off SNR above which communication is possible with a given amount of reliability. This is usually determined according to a design goal, expressed in terms of a bit error rate (BER) or a packet error rate (PER). Typically, the BER should not exceed $10^{-4}$ or $10^{-5}$. According to your signal parameters (modulation and coding), sometimes it is possible to derive the BER as a function of the SNR. This depends on the complexity of your transmitter-receiver architecture and the channel model you use. So:

  1. Yes.

Now, regarding the RSS, I would say that it is not a standard metric. Some equipments give RSS metrics, according to an unknown criteria. Sometimes, it is just a table where a given range of received power is indexed. Hence:

  1. It depends. In general, we don't use the RSS to directly determine design parameters of a demodulator (in this case, a threshold). But if you know exactly what it means, you may derive a relation SNR-RSS. But since RSS measures the total received signal power--including noise--I suppose you will have to estimate the noise power also.
vaz
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