def test_decoding_did_not_converge(systematic, sparse):
n = 15
d_v = 4
d_c = 5
seed = 0
H, G = make_ldpc(n, d_v, d_c, seed=seed, systematic=systematic,
sparse=sparse)
assert not binaryproduct(H, G).any()
n, k = G.shape
snr = 1
v = np.arange(k) % 2
y = encode(G, v, snr, seed=seed)
with pytest.warns(UserWarning, match="stopped before convergence"):
decode(H, y, snr, maxiter=1)
def dec(self, LLR):
x = decode(self.H, LLR, maxiter=self.maxiter)
if x.ndim == 1:
d = get_message(self.G, x)
return d[:self.K]
else:
d = []
for i in range(x.shape[1]):
d.append(get_message(self.G, x[:, i]))
d = np.vstack(d)
return d[:, :self.K]
def test_decoding_random(systematic, sparse):
n = 15
d_v = 4
d_c = 5
seed = 0
H, G = make_ldpc(n, d_v, d_c, seed=seed, systematic=systematic,
sparse=sparse)
assert not binaryproduct(H, G).any()
n, k = G.shape
snr = 100
v, y = encode_random_message(G, snr, seed)
d = decode(H, y, snr)
x = get_message(G, d)
assert abs(v - x).sum() == 0
def test_decoding(systematic, log, sparse):
n = 15
d_v = 4
d_c = 5
seed = 0
H, G = make_ldpc(n,
d_v,
d_c,
seed=seed,
systematic=systematic,
sparse=sparse)
assert not binaryproduct(H, G).any()
n, k = G.shape
snr = 100
v = np.arange(k) % 2
y = encode(G, v, snr, seed)
d = decode(H, y, snr, maxiter=10, log=log)
x = get_message(G, d)
assert abs(v - x).sum() == 0
H, G = make_ldpc(n, d_v, d_c, seed=seed, systematic=True, sparse=True)
n, k = G.shape
print("Number of coded bits:", k)
##################################################################
# Now we simulate transmission for different levels of noise and
# compute the percentage of errors using the bit-error-rate score
# To parallelize coding and decoding, simply stack the messages as columns:
errors = []
snrs = np.linspace(-2, 10, 20)
v = np.arange(k) % 2 # fixed k bits message
n_trials = 50 # number of transmissions with different noise
V = np.tile(v, (n_trials, 1)).T # stack v in columns
for snr in snrs:
y = encode(G, V, snr, seed=seed)
D = decode(H, y, snr)
error = 0.
for i in range(n_trials):
x = get_message(G, D[:, i])
error += abs(v - x).sum() / (k * n_trials)
errors.append(error)
plt.figure()
plt.plot(snrs, errors, color="indianred")
plt.ylabel("Bit error rate")
plt.xlabel("SNR")
plt.show()
n_messages = np.arange(1, 20)
n_runs = 50
snr = 10
times_parallel = []
times_sequential = []
for pp in n_messages:
t_parallel = 0
t_seq = 0
V = rng.randint(2, size=(k, pp)) # simulate messages
Y = encode(G, V, snr, seed=seed)
for _ in range(n_runs):
t = time()
decode(H, Y, snr)
t_parallel += time() - t
t = time()
for y in Y.T:
decode(H, y, snr)
t_seq += time() - t
times_sequential.append(t_seq / n_runs)
times_parallel.append(t_parallel / n_runs)
plt.figure()
plt.plot(n_messages,
times_sequential,
color="indianred",
lw=2,
label="Sequential")
def dec(self, LLR):
d = get_message(self.G, decode(self.H, LLR, maxiter=200))
return d[:self.K]
