def test_bit_lvl_repr():
# Set seed
seed(17121996)
# Test the BLR by comparing the performance of a receiver with and without it.
qam = QAMModem(4)
nb_rx = 2
nb_tx = 2
RayleighChannel = MIMOFlatChannel(nb_tx, nb_rx)
RayleighChannel.fading_param = (zeros(
(nb_rx, nb_tx), complex), identity(nb_tx), identity(nb_rx))
SNR = arange(10, 16, 5)
def receiver_with_blr(y, H, cons, noise_var):
# Create w
beta = int(log2(len(cons)))
reel = [pow(2, i) for i in range(beta // 2 - 1, -1, -1)]
im = [1j * pow(2, i) for i in range(beta // 2 - 1, -1, -1)]
w = concatenate((reel, im), axis=None)
# Compute bit level representation
A = bit_lvl_repr(H, w)
mes = array(mimo_ml(y, A, [-1, 1]))
mes[mes == -1] = 0
return mes
def receiver_without_blr(y, H, cons, noise_var):
return qam.demodulate(mimo_ml(y, H, cons), 'hard')
my_model_without_blr = \
LinkModel(qam.modulate, RayleighChannel, receiver_without_blr, qam.num_bits_symbol, qam.constellation, qam.Es)
my_model_with_blr = \
LinkModel(qam.modulate, RayleighChannel, receiver_with_blr, qam.num_bits_symbol, qam.constellation, qam.Es)
ber_without_blr = link_performance(my_model_without_blr, SNR, 300e4, 300)
ber_with_blr = link_performance(my_model_with_blr, SNR, 300e4, 300)
assert_allclose(ber_without_blr,
ber_with_blr,
rtol=0.5,
err_msg='bit_lvl_repr changes the performance')
# Test error raising
with assert_raises(ValueError):
bit_lvl_repr(RayleighChannel.channel_gains[0], array((2, 4, 6)))
def receiver_with_blr(y, H, cons):
beta = int(log2(len(cons)))
# creation de w
reel = [pow(2, i) for i in range(beta // 2 - 1, -1, -1)]
im = [1j * pow(2, i) for i in range(beta // 2 - 1, -1, -1)]
w = concatenate((reel, im), axis=None)
A = bit_lvl_repr(H, w)
mes = array(mimo_ml(y, A, [-1, 1]))
mes[mes == -1] = 0
return mes
def receiver_with_blr(y, H, cons, noise_var):
# Create w
beta = int(log2(len(cons)))
reel = [pow(2, i) for i in range(beta // 2 - 1, -1, -1)]
im = [1j * pow(2, i) for i in range(beta // 2 - 1, -1, -1)]
w = concatenate((reel, im), axis=None)
# Compute bit level representation
A = bit_lvl_repr(H, w)
mes = array(mimo_ml(y, A, [-1, 1]))
mes[mes == -1] = 0
return mes