3 from gnuradio import gr
4 from gnuradio import audio
5 from gnuradio import trellis
6 from gnuradio import eng_notation
12 def make_rx(tb,fo,fi,dimensionality,tot_constellation,K,interleaver,IT,Es,N0,type):
13 scale = gr.multiply_const_ff(math.sqrt(1.0/N0))
14 gnd = gr.vector_source_f([0],True);
23 inter.append( trellis.permutation(interleaver.K(),interleaver.INTER(),fi.I(),gr.sizeof_float) )
24 siso_in.append( trellis.siso_combined_f(fi,K,0,-1,True,False,type,dimensionality,tot_constellation,trellis.TRELLIS_EUCLIDEAN) )
25 deinter.append( trellis.permutation(interleaver.K(),interleaver.DEINTER(),fi.I(),gr.sizeof_float) )
27 siso_out.append( trellis.siso_f(fo,K,0,-1,False,True,type) )
29 siso_out.append( trellis.viterbi_s(fo,K,0,-1) ) # no soft outputs needed
32 tb.connect (gnd,inter[0])
33 tb.connect (scale,(siso_in[0],1))
38 tb.connect (scale,(siso_in[it+1],1))
39 tb.connect (siso_in[it],deinter[it],(siso_out[it],1))
40 tb.connect (gnd,(siso_out[it],0))
41 tb.connect (siso_out[it],inter[it+1])
42 tb.connect (inter[it],(siso_in[it],0))
44 tb.connect (siso_in[it],deinter[it],siso_out[it])
45 tb.connect (inter[it],(siso_in[it],0))
47 return (scale,siso_out[IT-1])
50 def run_test (fo,fi,interleaver,Kb,bitspersymbol,K,channel,modulation,dimensionality,tot_constellation,Es,N0,IT,seed):
55 # this for loop is TOO slow in python!!!
58 for i in range(len(packet)):
59 packet[i] = random.randint(0, 2**bitspersymbol - 1) # random symbols
60 src = gr.vector_source_s(packet,False)
61 enc_out = trellis.encoder_ss(fo,0) # initial state = 0
62 inter = trellis.permutation(interleaver.K(),interleaver.INTER(),1,gr.sizeof_short)
63 mod = gr.chunks_to_symbols_sf(modulation[1],modulation[0])
66 isi = gr.fir_filter_fff(1,channel)
68 noise = gr.noise_source_f(gr.GR_GAUSSIAN,math.sqrt(N0/2),seed)
71 (head,tail) = make_rx(tb,fo,fi,dimensionality,tot_constellation,K,interleaver,IT,Es,N0,trellis.TRELLIS_MIN_SUM)
72 dst = gr.vector_sink_s();
74 tb.connect (src,enc_out,inter,mod)
75 tb.connect (mod,isi,(add,0))
76 tb.connect (noise,(add,1))
85 for i in range(ntotal):
86 if packet[i]==data[i]:
91 return (ntotal,ntotal-nright)
100 esn0_db=float(args[1])
103 sys.stderr.write ('usage: test_turbo_equalization.py fsm_name_out Es/No_db repetitions\n')
107 Kb=64*16 # packet size in bits (multiple of 16)
108 modulation = fsm_utils.pam4 # see fsm_utlis.py for available predefined modulations
109 channel = fsm_utils.c_channel # see fsm_utlis.py for available predefined test channels
110 fo=trellis.fsm(fname_out) # get the outer FSM specification from a file
111 fi=trellis.fsm(len(modulation[1]),len(channel)) # generate the FSM automatically
113 sys.stderr.write ('Incompatible cardinality between outer and inner FSM.\n')
115 bitspersymbol = int(round(math.log(fo.I())/math.log(2))) # bits per FSM input symbol
116 K=Kb/bitspersymbol # packet size in trellis steps
117 interleaver=trellis.interleaver(K,666) # construct a random interleaver
118 tot_channel = fsm_utils.make_isi_lookup(modulation,channel,True) # generate the lookup table (normalize energy to 1)
119 dimensionality = tot_channel[0]
120 N0=pow(10.0,-esn0_db/10.0); # noise variance
121 tot_constellation =[0]*len(tot_channel[1])
122 for i in range(len(tot_channel[1])):
123 tot_constellation[i] = tot_channel[1][i] * math.sqrt(1.0/N0)
124 if len(tot_constellation)/dimensionality != fi.O():
125 sys.stderr.write ('Incompatible FSM output cardinality and lookup table size.\n')
127 IT = 3 # number of turbo iterations
129 tot_s=0 # total number of transmitted shorts
130 terr_s=0 # total number of shorts in error
131 terr_p=0 # total number of packets in error
134 (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
137 terr_p=terr_p+(terr_s!=0)
138 if ((i+1)%10==0) : # display progress
139 print i+1,terr_p, '%.2e' % ((1.0*terr_p)/(i+1)),tot_s,terr_s, '%.2e' % ((1.0*terr_s)/tot_s)
140 # estimate of the (short or bit) error rate
141 print rep,terr_p, '%.2e' % ((1.0*terr_p)/(i+1)),tot_s,terr_s, '%.2e' % ((1.0*terr_s)/tot_s)
145 if __name__ == '__main__':