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#!/usr/bin/env python
from gnuradio import gr
from gnuradio import audio
from gnuradio import trellis, digital, filter, blocks
from gnuradio import eng_notation
import math
import sys
import random
import fsm_utils
try:
from gnuradio import analog
except ImportError:
sys.stderr.write("Error: Program requires gr-analog.\n")
sys.exit(1)
def run_test(f, Kb, bitspersymbol, K, channel, modulation, dimensionality, tot_constellation, N0, seed):
tb = gr.top_block()
L = len(channel)
# TX
# this for loop is TOO slow in python!!!
packet = [0] * (K + 2 * L)
random.seed(seed)
for i in range(len(packet)):
packet[i] = random.randint(0, 2**bitspersymbol - 1) # random symbols
for i in range(L): # first/last L symbols set to 0
packet[i] = 0
packet[len(packet) - i - 1] = 0
src = blocks.vector_source_s(packet, False)
mod = digital.chunks_to_symbols_sf(modulation[1], modulation[0])
# CHANNEL
isi = filter.fir_filter_fff(1, channel)
add = blocks.add_ff()
noise = analog.noise_source_f(analog.GR_GAUSSIAN, math.sqrt(N0 / 2), seed)
# RX
# skip the first L samples since you know they are coming from the L zero symbols
skip = blocks.skiphead(gr.sizeof_float, L)
# metrics = trellis.metrics_f(f.O(),dimensionality,tot_constellation,digital.TRELLIS_EUCLIDEAN) # data preprocessing to generate metrics for Viterbi
# va = trellis.viterbi_s(f,K+L,0,0) # Put -1 if the Initial/Final states are not set.
# using viterbi_combined_s instead of metrics_f/viterbi_s allows larger packet lengths because metrics_f is complaining for not being able to allocate large buffers. This is due to the large f.O() in this application...
va = trellis.viterbi_combined_s(
f, K + L, 0, 0, dimensionality, tot_constellation, digital.TRELLIS_EUCLIDEAN)
dst = blocks.vector_sink_s()
tb.connect(src, mod)
tb.connect(mod, isi, (add, 0))
tb.connect(noise, (add, 1))
#tb.connect (add,metrics)
#tb.connect (metrics,va,dst)
tb.connect(add, skip, va, dst)
tb.run()
data = dst.data()
ntotal = len(data) - L
nright = 0
for i in range(ntotal):
if packet[i + L] == data[i]:
nright = nright + 1
# else:
# print "Error in ", i
return (ntotal, ntotal - nright)
def main(args):
nargs = len(args)
if nargs == 2:
esn0_db = float(args[0])
rep = int(args[1])
else:
sys.stderr.write(
'usage: test_viterbi_equalization1.py Es/No_db repetitions\n')
sys.exit(1)
# system parameters
Kb = 2048 # packet size in bits
modulation = fsm_utils.pam4 # see fsm_utlis.py for available predefined modulations
# see fsm_utlis.py for available predefined test channels
channel = fsm_utils.c_channel
# generate the FSM automatically
f = trellis.fsm(len(modulation[1]), len(channel))
# bits per FSM input symbol
bitspersymbol = int(round(math.log(f.I()) / math.log(2)))
K = Kb / bitspersymbol # packet size in trellis steps
# generate the lookup table (normalize energy to 1)
tot_channel = fsm_utils.make_isi_lookup(modulation, channel, True)
dimensionality = tot_channel[0]
tot_constellation = tot_channel[1]
N0 = pow(10.0, -esn0_db / 10.0) # noise variance
if len(tot_constellation) / dimensionality != f.O():
sys.stderr.write(
'Incompatible FSM output cardinality and lookup table size.\n')
sys.exit(1)
tot_s = 0 # total number of transmitted shorts
terr_s = 0 # total number of shorts in error
terr_p = 0 # total number of packets in error
for i in range(rep):
(s, e) = run_test(f, Kb, bitspersymbol, K, channel, modulation, dimensionality, tot_constellation,
N0, -int(666 + i)) # run experiment with different seed to get different data and noise realizations
tot_s = tot_s + s
terr_s = terr_s + e
terr_p = terr_p + (terr_s != 0)
if ((i + 1) % 100 == 0): # display progress
print(i + 1, terr_p, '%.2e' % ((1.0 * terr_p) / (i + 1)),
tot_s, terr_s, '%.2e' % ((1.0 * terr_s) / tot_s))
# estimate of the (short or symbol) error rate
print(rep, terr_p, '%.2e' % ((1.0 * terr_p) / (i + 1)),
tot_s, terr_s, '%.2e' % ((1.0 * terr_s) / tot_s))
if __name__ == '__main__':
main(sys.argv[1:])
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