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
|
#!/usr/bin/env python
from gnuradio import gr
from gnuradio import trellis
from gnuradio import eng_notation
import math
import sys
import random
import fsm_utils
def make_rx(tb,fo,fi,dimensionality,constellation,K,interleaver,IT,Es,N0,type):
metrics_in = trellis.metrics_f(fi.O(),dimensionality,constellation,trellis.TRELLIS_EUCLIDEAN) # data preprocessing to generate metrics for innner Viterbi
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 (metrics_in,(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,dimensionality,constellation,Es,N0,IT,seed):
tb = gr.top_block ()
# TX
src = gr.lfsr_32k_source_s()
src_head = gr.head (gr.sizeof_short,Kb/16) # packet size in shorts
s2fsmi = gr.packed_to_unpacked_ss(bitspersymbol,gr.GR_MSB_FIRST) # unpack shorts to symbols compatible with the outer FSM input cardinality
enc_out = trellis.encoder_ss(fo,0) # initial state = 0
inter = trellis.permutation(interleaver.K(),interleaver.INTER(),1,gr.sizeof_short)
enc_in = trellis.encoder_ss(fi,0) # initial state = 0
mod = gr.chunks_to_symbols_sf(constellation,dimensionality)
# 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,constellation,K,interleaver,IT,Es,N0,trellis.TRELLIS_MIN_SUM)
#(head,tail) = make_rx(tb,fo,fi,dimensionality,constellation,K,interleaver,IT,Es,N0,trellis.TRELLIS_SUM_PRODUCT)
fsmi2s = gr.unpacked_to_packed_ss(bitspersymbol,gr.GR_MSB_FIRST) # pack FSM input symbols to shorts
dst = gr.check_lfsr_32k_s()
tb.connect (src,src_head,s2fsmi,enc_out,inter,enc_in,mod)
tb.connect (mod,(add,0))
tb.connect (noise,(add,1))
tb.connect (add,head)
tb.connect (tail,fsmi2s,dst)
tb.run()
#print enc_out.ST(), enc_in.ST()
ntotal = dst.ntotal ()
nright = dst.nright ()
runlength = dst.runlength ()
return (ntotal,ntotal-nright)
def main(args):
nargs = len (args)
if nargs == 5:
fname_out=args[0]
fname_in=args[1]
esn0_db=float(args[2]) # Es/No in dB
IT=int(args[3])
rep=int(args[4]) # number of times the experiment is run to collect enough errors
else:
sys.stderr.write ('usage: test_sccc_turbo.py fsm_name_out fsm_fname_in Es/No_db iterations repetitions\n')
sys.exit (1)
# system parameters
Kb=1024*16 # packet size in bits (make it multiple of 16 so it can be packed in a short)
fo=trellis.fsm(fname_out) # get the outer FSM specification from a file
fi=trellis.fsm(fname_in) # get the innner FSM specification from a file
bitspersymbol = int(round(math.log(fo.I())/math.log(2))) # bits per FSM input symbol
if fo.O() != fi.I():
sys.stderr.write ('Incompatible cardinality between outer and inner FSM.\n')
sys.exit (1)
K=Kb/bitspersymbol # packet size in trellis steps
interleaver=trellis.interleaver(K,666) # construct a random interleaver
modulation = fsm_utils.psk8 # see fsm_utlis.py for available predefined modulations
dimensionality = modulation[0]
constellation = modulation[1]
if len(constellation)/dimensionality != fi.O():
sys.stderr.write ('Incompatible FSM output cardinality and modulation size.\n')
sys.exit (1)
# calculate average symbol energy
Es = 0
for i in range(len(constellation)):
Es = Es + constellation[i]**2
Es = Es / (len(constellation)/dimensionality)
N0=Es/pow(10.0,esn0_db/10.0); # calculate noise variance
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,dimensionality,constellation,Es,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:])
|
