Signal to Interference and Noise Ratio in Communication Systems as a Quality Measure

The overall quality of the communication link...is completely related to the ratio of the signal power at the receiver to the noise (or interference and noise as the case may be) power, called the signal-to-noise ratio, SNR (or signal-to-interference-noise ratio, SINR). In analog communication systems, the ratio indicates the level of distortion to the signal e.g., in voice telephony, this ratio may indicate the extent of "hiss" or "clicks" that the listener experiences. In digital communication systems, the signal-to-noise ratio directly affects the bit-error rate (BER) (also typically quantified as the error rate for a block of bits called Block Error Rate or BLER). A review of various digital modulation techniques (see, for example, [2]) will show that BER or BLER is related to the SNR via a non-linear function, usually the complementary error function, in cases when the noise is characterized as white Gaussian.