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63 lines
1.9 KiB
Python
63 lines
1.9 KiB
Python
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# Authors: Veeresh Taranalli <veeresht@gmail.com>
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# License: BSD 3-Clause
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from numpy import array, sqrt, zeros
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from numpy.random import randn
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from numpy.testing import assert_allclose
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from commpy.channelcoding.ldpc import get_ldpc_code_params, ldpc_bp_decode
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from commpy.utilities import hamming_dist
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import os
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from nose.plugins.attrib import attr
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@attr('slow')
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class TestLDPCCode(object):
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@classmethod
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def setup_class(cls):
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dir = os.path.dirname(__file__)
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ldpc_design_file_1 = os.path.join(dir, '../designs/ldpc/gallager/96.33.964.txt')
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#ldpc_design_file_1 = "../designs/ldpc/gallager/96.33.964.txt"
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cls.ldpc_code_params = get_ldpc_code_params(ldpc_design_file_1)
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@classmethod
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def teardown_class(cls):
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pass
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def test_ldpc_bp_decode(self):
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N = 96
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k = 48
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rate = 0.5
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Es = 1.0
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snr_list = array([2.0, 2.5])
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niters = 10000000
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tx_codeword = zeros(N, int)
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ldpcbp_iters = 100
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fer_array_ref = array([200.0/1000, 200.0/2000])
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fer_array_test = zeros(len(snr_list))
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for idx, ebno in enumerate(snr_list):
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noise_std = 1/sqrt((10**(ebno/10.0))*rate*2/Es)
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fer_cnt_bp = 0
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for iter_cnt in range(niters):
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awgn_array = noise_std * randn(N)
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rx_word = 1-(2*tx_codeword) + awgn_array
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rx_llrs = 2.0*rx_word/(noise_std**2)
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[dec_word, out_llrs] = ldpc_bp_decode(rx_llrs, self.ldpc_code_params, 'SPA',
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ldpcbp_iters)
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num_bit_errors = hamming_dist(tx_codeword, dec_word)
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if num_bit_errors > 0:
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fer_cnt_bp += 1
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if fer_cnt_bp >= 200:
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fer_array_test[idx] = float(fer_cnt_bp)/(iter_cnt+1)
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break
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assert_allclose(fer_array_test, fer_array_ref, rtol=2e-1, atol=0)
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