def test_link_performance():
# Apply link_performance to SISO QPSK and AWGN channel
QPSK = QAMModem(4)
def receiver(y, h, constellation):
return QPSK.demodulate(y, 'hard')
model = LinkModel(QPSK.modulate, SISOFlatChannel(fading_param=(1 + 0j, 0)), receiver,
QPSK.num_bits_symbol, QPSK.constellation, QPSK.Es)
BERs = link_performance(model, range(0, 9, 2), 600e4, 600)
desired = erfc(sqrt(10**(arange(0, 9, 2) / 10) / 2)) / 2
assert_allclose(BERs, desired, rtol=0.25,
err_msg='Wrong performance for SISO QPSK and AWGN channel')
# Apply link_performance to MIMO 16QAM and 4x4 Rayleigh channel
QAM16 = QAMModem(16)
RayleighChannel = MIMOFlatChannel(4, 4)
RayleighChannel.uncorr_rayleigh_fading(complex)
def receiver(y, h, constellation):
return QAM16.demodulate(kbest(y, h, constellation, 16), 'hard')
model = LinkModel(QAM16.modulate, RayleighChannel, receiver,
QAM16.num_bits_symbol, QAM16.constellation, QAM16.Es)
SNRs = arange(0, 21, 5) + 10 * log10(QAM16.num_bits_symbol)
BERs = link_performance(model, SNRs, 600e4, 600)
desired = (2e-1, 1e-1, 3e-2, 2e-3, 4e-5) # From reference
assert_allclose(BERs, desired, rtol=1.25,
err_msg='Wrong performance for MIMO 16QAM and 4x4 Rayleigh channel')
def test_link_performance():
# Set seed
seed(8071996)
######################################
# Build models & desired solutions
######################################
models = []
desired_bers = []
snr_range = []
labels = []
rtols = []
code_rates = []
# SISO QPSK and AWGN channel
QPSK = QAMModem(4)
def receiver(y, h, constellation, noise_var):
return QPSK.demodulate(y, 'hard')
models.append(
LinkModel(QPSK.modulate, SISOFlatChannel(fading_param=(1 + 0j, 0)),
receiver, QPSK.num_bits_symbol, QPSK.constellation, QPSK.Es))
snr_range.append(arange(0, 9, 2))
desired_bers.append(erfc(sqrt(10**(snr_range[-1] / 10) / 2)) / 2)
labels.append('SISO QPSK and AWGN channel')
rtols.append(.25)
code_rates.append(1)
# MIMO 16QAM, 4x4 Rayleigh channel and hard-output K-Best
QAM16 = QAMModem(16)
RayleighChannel = MIMOFlatChannel(4, 4)
RayleighChannel.uncorr_rayleigh_fading(complex)
def receiver(y, h, constellation, noise_var):
return QAM16.demodulate(kbest(y, h, constellation, 16), 'hard')
models.append(
LinkModel(QAM16.modulate, RayleighChannel, receiver,
QAM16.num_bits_symbol, QAM16.constellation, QAM16.Es))
snr_range.append(arange(0, 21, 5) + 10 * log10(QAM16.num_bits_symbol))
desired_bers.append((2e-1, 1e-1, 3e-2, 2e-3, 4e-5)) # From reference
labels.append('MIMO 16QAM, 4x4 Rayleigh channel and hard-output K-Best')
rtols.append(1.25)
code_rates.append(1)
# MIMO 16QAM, 4x4 Rayleigh channel and soft-output best-first
QAM16 = QAMModem(16)
RayleighChannel = MIMOFlatChannel(4, 4)
RayleighChannel.uncorr_rayleigh_fading(complex)
ldpc_params = get_ldpc_code_params(
'commpy/channelcoding/designs/ldpc/wimax/1440.720.txt', True)
def modulate(bits):
return QAM16.modulate(
triang_ldpc_systematic_encode(bits, ldpc_params,
False).reshape(-1, order='F'))
def decoder(llrs):
return ldpc_bp_decode(llrs, ldpc_params, 'MSA',
15)[0][:720].reshape(-1, order='F')
def demode(symbs):
return QAM16.demodulate(symbs, 'hard')
def receiver(y, h, constellation, noise_var):
return best_first_detector(y, h, constellation, (1, 3, 5), noise_var,
demode, 500)
models.append(
LinkModel(modulate, RayleighChannel, receiver, QAM16.num_bits_symbol,
QAM16.constellation, QAM16.Es, decoder, 0.5))
snr_range.append(arange(17, 20, 1))
desired_bers.append((1.7e-1, 1e-1, 2.5e-3)) # From reference
labels.append(
'MIMO 16QAM, 4x4 Rayleigh channel and soft-output best-first')
rtols.append(2)
code_rates.append(.5)
######################################
# Make tests
######################################
for test in range(len(models)):
BERs = link_performance(models[test], snr_range[test], 5e5, 200, 720,
models[test].rate)
assert_allclose(BERs,
desired_bers[test],
rtol=rtols[test],
err_msg='Wrong performance for ' + labels[test])
full_metrics = models[test].link_performance_full_metrics(
snr_range[test], 2500, 200, 720, models[test].rate)
assert_allclose(full_metrics[0],
desired_bers[test],
rtol=rtols[test],
err_msg='Wrong performance for ' + labels[test])
return modem.modulate(cc.conv_encode(bits, trellis1, 'cont'))
# Demodulation function
def demode(msg):
return modem.demodulate(msg, 'hard')
# Receiver function (no process required as there are no fading)
def receiver(y, h, constellation, noise_var):
return modem.demodulate(y, 'hard')
# Decoder function
def decoder(msg):
return cc.viterbi_decode(msg, trellis1)
# Build model from parameters
code_rate = trellis1.k / trellis1.n
model = lk.LinkModel(modulate, channels, receiver, modem.num_bits_symbol,
modem.constellation, modem.Es, decoder, code_rate)
# Test
BERs = lk.link_performance(model, SNRs, 10000, 600, 5000, code_rate)
plt.semilogy(SNRs, BERs, 'o-')
plt.grid()
plt.xlabel('Signal to Noise Ration (dB)')
plt.ylabel('Bit Error Rate')
plt.show()