1 #!/usr/bin/env python 2 3 from gnuradio import gr 4 from gnuradio import audio 5 from gnuradio import trellis 6 from gnuradio import eng_notation 7 import math 8 import sys 9 import random 10 import fsm_utils 11 12 def run_test (f,Kb,bitspersymbol,K,channel,modulation,dimensionality,tot_constellation,N0,seed): 13 tb = gr.top_block () 14 L = len(channel) 15 16 # TX 17 # this for loop is TOO slow in python!!! 18 packet = [0]*(K+2*L) 19 random.seed(seed) 20 for i in range(len(packet)): 21 packet[i] = random.randint(0, 2**bitspersymbol - 1) # random symbols 22 for i in range(L): # first/last L symbols set to 0 23 packet[i] = 0 24 packet[len(packet)-i-1] = 0 25 src = gr.vector_source_s(packet,False) 26 mod = gr.chunks_to_symbols_sf(modulation[1],modulation[0]) 27 28 # CHANNEL 29 isi = gr.fir_filter_fff(1,channel) 30 add = gr.add_ff() 31 noise = gr.noise_source_f(gr.GR_GAUSSIAN,math.sqrt(N0/2),seed) 32 33 # RX 34 skip = gr.skiphead(gr.sizeof_float, L) # skip the first L samples since you know they are coming from the L zero symbols 35 #metrics = trellis.metrics_f(f.O(),dimensionality,tot_constellation,trellis.TRELLIS_EUCLIDEAN) # data preprocessing to generate metrics for Viterbi 36 #va = trellis.viterbi_s(f,K+L,0,0) # Put -1 if the Initial/Final states are not set. 37 va = trellis.viterbi_combined_s(f,K+L,0,0,dimensionality,tot_constellation,trellis.TRELLIS_EUCLIDEAN) # using viterbi_combined_s instead of metrics_f/viterbi_s allows larger packet lengths because metrics_f is complaining for not being able to allocate large buffers. This is due to the large f.O() in this application... 38 dst = gr.vector_sink_s() 39 40 tb.connect (src,mod) 41 tb.connect (mod,isi,(add,0)) 42 tb.connect (noise,(add,1)) 43 #tb.connect (add,metrics) 44 #tb.connect (metrics,va,dst) 45 tb.connect (add,skip,va,dst) 46 47 tb.run() 48 49 data = dst.data() 50 ntotal = len(data) - L 51 nright=0 52 for i in range(ntotal): 53 if packet[i+L]==data[i]: 54 nright=nright+1 55 #else: 56 #print "Error in ", i 57 58 return (ntotal,ntotal-nright) 59 60 61 def main(args): 62 nargs = len (args) 63 if nargs == 2: 64 esn0_db=float(args[0]) 65 rep=int(args[1]) 66 else: 67 sys.stderr.write ('usage: test_viterbi_equalization1.py Es/No_db repetitions\n') 68 sys.exit (1) 69 70 # system parameters 71 Kb=2048 # packet size in bits 72 modulation = fsm_utils.pam4 # see fsm_utlis.py for available predefined modulations 73 channel = fsm_utils.c_channel # see fsm_utlis.py for available predefined test channels 74 f=trellis.fsm(len(modulation[1]),len(channel)) # generate the FSM automatically 75 bitspersymbol = int(round(math.log(f.I())/math.log(2))) # bits per FSM input symbol 76 K=Kb/bitspersymbol # packet size in trellis steps 77 78 tot_channel = fsm_utils.make_isi_lookup(modulation,channel,True) # generate the lookup table (normalize energy to 1) 79 dimensionality = tot_channel[0] 80 tot_constellation = tot_channel[1] 81 N0=pow(10.0,-esn0_db/10.0); # noise variance 82 if len(tot_constellation)/dimensionality != f.O(): 83 sys.stderr.write ('Incompatible FSM output cardinality and lookup table size.\n') 84 sys.exit (1) 85 86 tot_s=0 # total number of transmitted shorts 87 terr_s=0 # total number of shorts in error 88 terr_p=0 # total number of packets in error 89 90 for i in range(rep): 91 (s,e)=run_test(f,Kb,bitspersymbol,K,channel,modulation,dimensionality,tot_constellation,N0,-long(666+i)) # run experiment with different seed to get different data and noise realizations 92 tot_s=tot_s+s 93 terr_s=terr_s+e 94 terr_p=terr_p+(terr_s!=0) 95 if ((i+1)%100==0) : # display progress 96 print i+1,terr_p, '%.2e' % ((1.0*terr_p)/(i+1)),tot_s,terr_s, '%.2e' % ((1.0*terr_s)/tot_s) 97 # estimate of the (short or symbol) error rate 98 print rep,terr_p, '%.2e' % ((1.0*terr_p)/(i+1)),tot_s,terr_s, '%.2e' % ((1.0*terr_s)/tot_s) 99 100 101 if __name__ == '__main__': 102 main (sys.argv[1:])