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Diffstat (limited to 'gr-trellis/src/examples/python/test_turbo_equalization.py')
| -rwxr-xr-x | gr-trellis/src/examples/python/test_turbo_equalization.py | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/gr-trellis/src/examples/python/test_turbo_equalization.py b/gr-trellis/src/examples/python/test_turbo_equalization.py new file mode 100755 index 000000000..6fa6749f0 --- /dev/null +++ b/gr-trellis/src/examples/python/test_turbo_equalization.py @@ -0,0 +1,142 @@ +#!/usr/bin/env python + +from gnuradio import gr +from gnuradio import trellis, digital +from gnuradio import eng_notation +import math +import sys +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 (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,tot_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 iouter 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 + # essentially here we implement the combination of modulation and channel as a memoryless modulation (the memory induced by the channel is hidden in the innner FSM) + mod = gr.chunks_to_symbols_sf(tot_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,tot_constellation,K,interleaver,IT,Es,N0,trellis.TRELLIS_MIN_SUM) + 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() + + ntotal = dst.ntotal () + nright = dst.nright () + runlength = dst.runlength () + #print ntotal,nright,runlength + + 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 + print 'size = ',K + 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,dimensionality,tot_constellation,1,N0,IT,-long(666+i)) # run experiment with different seed to get different noise realizations + print s + 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:]) + |