BPSK AWGN Channel - 2020.2 English

Vivado Design Suite Reference Guide: Model-Based DSP Design Using System Generator (UG958)

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2020.2 English

The Xilinx BPSK AWGN Channel reference block adds scaled white Gaussian noise to an input signal. The noise is created by the White Gaussian Noise Generator reference block.

The noise is scaled based on the SNR to achieve the desired noise variance, as shown below. The SNR is defined as (Eb/No) in dB for uncoded BPSK with unit symbol energy (Es = 1). The SNR input is UFix8_4 and the valid range is from 0.0 to 15.9375 in steps of 0.0625dB.

To use the AWGN in a system with coding and/or to use the core with different modulation formats, it is necessary to adjust the SNR value to accommodate the difference in spectral efficiency. If we have BPSK modulation with rate 1/2 coding and keep Es = 1 and No constant, then Eb = 2 and Eb/No = SNR + 3 dB. If we have uncoded QPSK modulation with I = +/-1 and Q = +/-1 and add independent noise sequences, then each channel looks like an independent BPSK channel and the Eb/No = SNR. If we then add rate 1/2 coding to the QPSK case, we have Eb/No = SNR + 3 dB.

The overall latency of the AWGN Channel is 15 clock cycles. Channel output is a 17 bit signed number with 11 bits after the binary point. The input port snr can be any type. The reset port must be Boolean and the input port din must be of unsigned 1-bit type with binary point position at zero.

Figure 1. BPSK AWGN Channel Diagram

Block Parameters

The block parameter is the decimal starting seed value.


[1] A. Ghazel, E. Boutillon, J. L. Danger, G. Gulak and H. Laamari, Design and Performance Analysis of a High Speed AWGN Communication Channel Emulator, IEEE PACRIM Conference, Victoria, B. C., Aug. 2001.

[2] Xilinx Data Sheet: Additive White Gaussian Noise (AWGN) Core v1.0, Xilinx, Inc. October 2002