Download Block Parameters

BPSK AWGN Channel
BPSK AWGN Channel
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.
Block Parameters
The block parameter is the decimal starting seed value.
Vivado: Designing with System Generator
UG958 (v2012.3) November 16, 2012
www.xilinx.com
329