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#!/usr/bin/env python
from gnuradio import gr
from gnuradio import audio
from gnuradio import trellis
from gnuradio import eng_notation
import math
import sys
import random
import fsm_utils
def make_rx(fg,fo,fi,dimensionality,tot_constellation,K,interleaver,IT,Es,N0,type):
scale = gr.multiply_const_ff(math.sqrt(1.0/N0))
gnd = gr.vector_source_f([0],True);
inter=[]
deinter=[]
siso_in=[]
siso_out=[]
# generate all blocks
for it in range(IT):
inter.append( trellis.permutation(interleaver.K(),interleaver.INTER(),fi.I(),gr.sizeof_float) )
siso_in.append( trellis.siso_combined_f(fi,K,0,-1,True,False,type,dimensionality,tot_constellation,trellis.TRELLIS_EUCLIDEAN) )
deinter.append( trellis.permutation(interleaver.K(),interleaver.DEINTER(),fi.I(),gr.sizeof_float) )
if it < IT-1:
siso_out.append( trellis.siso_f(fo,K,0,-1,False,True,type) )
else:
siso_out.append( trellis.viterbi_s(fo,K,0,-1) ) # no soft outputs needed
# connect first stage
fg.connect (gnd,inter[0])
fg.connect (scale,(siso_in[0],1))
# connect the rest
for it in range(IT):
if it < IT-1:
fg.connect (scale,(siso_in[it+1],1))
fg.connect (siso_in[it],deinter[it],(siso_out[it],1))
fg.connect (gnd,(siso_out[it],0))
fg.connect (siso_out[it],inter[it+1])
fg.connect (inter[it],(siso_in[it],0))
else:
fg.connect (siso_in[it],deinter[it],siso_out[it])
fg.connect (inter[it],(siso_in[it],0))
return (scale,siso_out[IT-1])
def run_test (fo,fi,interleaver,Kb,bitspersymbol,K,channel,modulation,dimensionality,tot_constellation,Es,N0,IT,seed):
fg = gr.flow_graph ()
L = len(channel)
# TX
# this for loop is TOO slow in python!!!
packet = [0]*(K)
random.seed(seed)
for i in range(len(packet)):
packet[i] = random.randint(0, 2**bitspersymbol - 1) # random symbols
src = gr.vector_source_s(packet,False)
enc_out = trellis.encoder_ss(fo,0) # initial state = 0
inter = trellis.permutation(interleaver.K(),interleaver.INTER(),1,gr.sizeof_short)
mod = gr.chunks_to_symbols_sf(modulation[1],modulation[0])
# CHANNEL
isi = gr.fir_filter_fff(1,channel)
add = gr.add_ff()
noise = gr.noise_source_f(gr.GR_GAUSSIAN,math.sqrt(N0/2),seed)
# RX
(head,tail) = make_rx(fg,fo,fi,dimensionality,tot_constellation,K,interleaver,IT,Es,N0,trellis.TRELLIS_MIN_SUM)
dst = gr.vector_sink_s();
fg.connect (src,enc_out,inter,mod)
fg.connect (mod,isi,(add,0))
fg.connect (noise,(add,1))
fg.connect (add,head)
fg.connect (tail,dst)
fg.run()
data = dst.data()
ntotal = len(data)
nright=0
for i in range(ntotal):
if packet[i]==data[i]:
nright=nright+1
#else:
#print "Error in ", i
return (ntotal,ntotal-nright)
def main(args):
nargs = len (args)
if nargs == 3:
fname_out=args[0]
esn0_db=float(args[1])
rep=int(args[2])
else:
sys.stderr.write ('usage: test_turbo_equalization.py fsm_name_out Es/No_db repetitions\n')
sys.exit (1)
# system parameters
Kb=64*16 # packet size in bits (multiple of 16)
modulation = fsm_utils.pam4 # see fsm_utlis.py for available predefined modulations
channel = fsm_utils.c_channel # see fsm_utlis.py for available predefined test channels
fo=trellis.fsm(fname_out) # get the outer FSM specification from a file
fi=trellis.fsm(len(modulation[1]),len(channel)) # generate the FSM automatically
if fo.O() != fi.I():
sys.stderr.write ('Incompatible cardinality between outer and inner FSM.\n')
sys.exit (1)
bitspersymbol = int(round(math.log(fo.I())/math.log(2))) # bits per FSM input symbol
K=Kb/bitspersymbol # packet size in trellis steps
interleaver=trellis.interleaver(K,666) # construct a random interleaver
tot_channel = fsm_utils.make_isi_lookup(modulation,channel,True) # generate the lookup table (normalize energy to 1)
dimensionality = tot_channel[0]
N0=pow(10.0,-esn0_db/10.0); # noise variance
tot_constellation =[0]*len(tot_channel[1])
for i in range(len(tot_channel[1])):
tot_constellation[i] = tot_channel[1][i] * math.sqrt(1.0/N0)
if len(tot_constellation)/dimensionality != fi.O():
sys.stderr.write ('Incompatible FSM output cardinality and lookup table size.\n')
sys.exit (1)
IT = 3 # number of turbo iterations
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(fo,fi,interleaver,Kb,bitspersymbol,K,channel,modulation,dimensionality,tot_constellation,1,N0,IT,-long(666+i)) # run experiment with different seed to get different noise realizations
tot_s=tot_s+s
terr_s=terr_s+e
terr_p=terr_p+(terr_s!=0)
if ((i+1)%10==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 bit) 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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