[Bug fix] Bad typing in links.py introduced in bcc36dd (#88)

[Bug fix] Bad typing in links.py introduced in bcc36dd

Author: BastienTr

commpy/links.py

@@ -16,8 +16,8 @@
 from __future__ import division  # Python 2 compatibility
 
 import math
-from inspect import getfullargspec
 from fractions import Fraction
+from inspect import getfullargspec
 
 import numpy as np
 
@@ -95,7 +95,7 @@ class LinkModel:
          *Default* Es=1.
 
     decoder : function with prototype decoder(array) or decoder(y, H, constellation, noise_var, array) that return a
-                binary array.
+                binary ndarray.
               *Default* is no process.
 
     rate : float or Fraction in (0,1]
@@ -127,7 +127,7 @@ class LinkModel:
     Es : float
          Average energy per symbols.
 
-    decoder : function with prototype decoder(binary array) that return a binary array.
+    decoder : function with prototype decoder(binary array) that return a binary ndarray.
               *Default* is no process.
 
     rate : float
@@ -233,7 +233,7 @@ def link_performance_full_metrics(self, SNRs, tx_max, err_min, send_chunk=None,
                 # Deals with MIMO channel
                 if isinstance(self.channel, MIMOFlatChannel):
                     nb_symb_vector = len(channel_output)
-                    received_msg = np.empty(int(math.ceil(len(msg) / float(self.rate))), dtype=np.int8)
+                    received_msg = np.empty(int(math.ceil(len(msg) / float(self.rate))))
                     for i in range(nb_symb_vector):
                         received_msg[receive_size * i:receive_size * (i + 1)] = \
                             self.receive(channel_output[i], self.channel.channel_gains[i],
@@ -251,7 +251,7 @@ def link_performance_full_metrics(self, SNRs, tx_max, err_min, send_chunk=None,
                 # calculate number of error frames
                 for i in range(number_chunks_per_send):
                     errors = np.bitwise_xor(msg[send_chunk * i:send_chunk * (i + 1)],
-                                            decoded_bits[send_chunk * i:send_chunk * (i + 1)]).sum()
+                                            decoded_bits[send_chunk * i:send_chunk * (i + 1)].astype(int)).sum()
                     bit_err[id_tx] += errors
                     chunk_loss[id_tx] += 1 if errors > 0 else 0
 
@@ -319,7 +319,7 @@ def link_performance(self, SNRs, send_max, err_min, send_chunk=None, code_rate=1
                 # Deals with MIMO channel
                 if isinstance(self.channel, MIMOFlatChannel):
                     nb_symb_vector = len(channel_output)
-                    received_msg = np.empty(int(math.ceil(len(msg) / float(self.rate))), dtype=np.int8)
+                    received_msg = np.empty(int(math.ceil(len(msg) / float(self.rate))))
                     for i in range(nb_symb_vector):
                         received_msg[receive_size * i:receive_size * (i + 1)] = \
                             self.receive(channel_output[i], self.channel.channel_gains[i],
@@ -332,9 +332,9 @@ def link_performance(self, SNRs, send_max, err_min, send_chunk=None, code_rate=1
                     decoded_bits = self.decoder(channel_output, self.channel.channel_gains,
                                                 self.constellation, self.channel.noise_std ** 2,
                                                 received_msg, self.channel.nb_tx * self.num_bits_symbol)
-                    bit_err += np.bitwise_xor(msg, decoded_bits[:len(msg)]).sum()
+                    bit_err += np.bitwise_xor(msg, decoded_bits[:len(msg)].astype(int)).sum()
                 else:
-                    bit_err += np.bitwise_xor(msg, self.decoder(received_msg)[:len(msg)]).sum()
+                    bit_err += np.bitwise_xor(msg, self.decoder(received_msg)[:len(msg)].astype(int)).sum()
                 bit_send += send_chunk
             BERs[id_SNR] = bit_err / bit_send
             if bit_err < err_min:

commpy/tests/test_links.py

@@ -8,52 +8,94 @@
 from numpy.testing import run_module_suite, assert_allclose, dec
 from scipy.special import erfc
 
+from commpy.channelcoding.ldpc import get_ldpc_code_params, triang_ldpc_systematic_encode, ldpc_bp_decode
 from commpy.channels import MIMOFlatChannel, SISOFlatChannel
 from commpy.links import link_performance, LinkModel
-from commpy.modulation import QAMModem, kbest
+from commpy.modulation import QAMModem, kbest, best_first_detector
 
 
 @dec.slow
 def test_link_performance():
     # Set seed
-    seed(17121996)
+    seed(8071996)
+    ######################################
+    # Build models & desired solutions
+    ######################################
+    models = []
+    desired_bers = []
+    snr_range = []
+    labels = []
+    rtols = []
+    code_rates = []
 
-    # Apply link_performance to SISO QPSK and AWGN channel
+    # SISO QPSK and AWGN channel
     QPSK = QAMModem(4)
 
     def receiver(y, h, constellation, noise_var):
         return QPSK.demodulate(y, 'hard')
 
-    model = LinkModel(QPSK.modulate, SISOFlatChannel(fading_param=(1 + 0j, 0)), receiver,
-                      QPSK.num_bits_symbol, QPSK.constellation, QPSK.Es)
+    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)
 
-    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')
-    full_metrics = model.link_performance_full_metrics(range(0, 9, 2), 1000, 600)
-    assert_allclose(full_metrics[0], desired, rtol=0.25,
-                    err_msg='Wrong performance for SISO QPSK and AWGN channel')
-
-    # Apply link_performance to MIMO 16QAM and 4x4 Rayleigh channel
+    # 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')
 
-    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')
-    full_metrics = model.link_performance_full_metrics(SNRs, 1000, 600)
-    assert_allclose(full_metrics[0], desired, rtol=1.25,
-                    err_msg='Wrong performance for MIMO 16QAM and 4x4 Rayleigh channel')
+    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])
 
 
 if __name__ == "__main__":