1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
#!/usr/bin/env python
from gnuradio import gr
from gnuradio import trellis, digital
from gnuradio import eng_notation
import math
import sys
import random
import fsm_utils
def make_rx(tb,fo,fi,dimensionality,tot_constellation,K,interleaver,IT,Es,N0,type):
metrics_in = trellis.metrics_f(fi.O(),dimensionality,tot_constellation,digital.TRELLIS_EUCLIDEAN) # data preprocessing to generate metrics for innner SISO
scale = gr.multiply_const_ff(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_f(fi,K,0,-1,True,False,type) )
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
tb.connect (gnd,inter[0])
tb.connect (metrics_in,scale)
tb.connect (scale,(siso_in[0],1))
# connect the rest
for it in range(IT):
if it < IT-1:
tb.connect (scale,(siso_in[it+1],1))
tb.connect (siso_in[it],deinter[it],(siso_out[it],1))
tb.connect (gnd,(siso_out[it],0))
tb.connect (siso_out[it],inter[it+1])
tb.connect (inter[it],(siso_in[it],0))
else:
tb.connect (siso_in[it],deinter[it],siso_out[it])
tb.connect (inter[it],(siso_in[it],0))
return (metrics_in,siso_out[IT-1])
def run_test (fo,fi,interleaver,Kb,bitspersymbol,K,channel,modulation,dimensionality,tot_constellation,Es,N0,IT,seed):
tb = gr.top_block ()
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(tb,fo,fi,dimensionality,tot_constellation,K,interleaver,IT,Es,N0,trellis.TRELLIS_MIN_SUM)
dst = gr.vector_sink_s();
tb.connect (src,enc_out,inter,mod)
tb.connect (mod,isi,(add,0))
tb.connect (noise,(add,1))
tb.connect (add,head)
tb.connect (tail,dst)
tb.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]
tot_constellation = tot_channel[1]
if len(tot_constellation)/dimensionality != fi.O():
sys.stderr.write ('Incompatible FSM output cardinality and lookup table size.\n')
sys.exit (1)
N0=pow(10.0,-esn0_db/10.0); # noise variance
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:])
|
