Method and device for estimating signal noise ratio

Abstract

This invention discloses a method for estimating S / N ratio including: selecting demodulation signal constellation points with the absolute value of the signal component greater than that of the edge constellation point of the modulation signal to compute noise power utilizing the selected demodulated signal constellation points, computing emission power and the ratio with noise power to get an estimated value of the S / N ratio. This invention also discloses a device estimating S / N ratio including: a constellation scheme mapping unit, a constellation point selection unit, a noise power computation unit, an emission signal power computation unit and S / N ratio computation unit.

Description

technical field [0001] The invention relates to digital communication technology, in particular to a method and device for estimating signal-to-noise ratio. Background technique [0002] A digital communication system includes a transmitter, a receiver, and a channel. Figure 1 is a simple structural block diagram of a digital communication system, where the transmitter includes information source, encoding, and constellation mapping, and the receiver includes constellation mapping, decoding, and sink. The transmitting end encodes the bit stream generated by the information source, maps the constellation map, and transmits it; the signal transmitted by the transmitting end is transmitted to the receiving end through a channel; the receiving end performs constellation map mapping and decoding on the received signal, and then transmits it to the sink. Wherein, encoding usually adopts error-correcting code encoding, and corresponding decoding adopts error-correcting code decodin...

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Problems solved by technology

[0013] It is easy to see from Fig. 4, Fig. 5 and Fig. 7 that the constellation points of the demodulated signal are distributed around the constellation points of the modulated signal, or even farther away from the constellation points of the modulated signal, and the constellation points of the demodulated signal are easier to communicate with each other. Stacked together, it is difficult to judge which modulated signal constellation point is sent by the demodulated signal constellation point

For example, for the demodulated signal constellation points near the two coordinate axes shown in Figure 4, for the demodulated signal near the middle of the demodulated signal constellation points and the modulated signal constellation points near the two coordinate axes shown in Figure 7 Constellation points, for the demodulated signal constellation points close to the two coordinate axes shown in Figure 5 and the demodulated signal constellation points far away from the modulated signal constellation point, it is impossible to ensure that the correct determination of the demodulated signal constellation point and the modulated signal constellation point The corresponding relationship between them will cause the calculation error of the noise power, and further cause the estimation error between the estimated value of SNR and the actual value to be large

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