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#!/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
from gnuradio.eng_option import eng_option
from optparse import OptionParser
def run_test (f,Kb,bitspersymbol,K,dimensionality,constellation,N0,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 FSM input cardinality
enc = trellis.encoder_ss(f,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
va = trellis.viterbi_combined_fs(f,K,0,-1,dimensionality,constellation,digital.TRELLIS_EUCLIDEAN) # Put -1 if the Initial/Final states are not set.
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,mod)
tb.connect (mod,(add,0))
tb.connect (noise,(add,1))
tb.connect (add,va,fsmi2s,dst)
tb.run()
# A bit of cheating: run the program once and print the
# final encoder state..
# Then put it as the last argument in the viterbi block
#print "final state = " , enc.ST()
ntotal = dst.ntotal ()
nright = dst.nright ()
runlength = dst.runlength ()
return (ntotal,ntotal-nright)
def main():
parser = OptionParser(option_class=eng_option)
parser.add_option("-f", "--fsm_file", type="string", default="fsm_files/awgn1o2_4.fsm", help="Filename containing the fsm specification, e.g. -f fsm_files/awgn1o2_4.fsm (default=fsm_files/awgn1o2_4.fsm)")
parser.add_option("-e", "--esn0", type="eng_float", default=10.0, help="Symbol energy to noise PSD level ratio in dB, e.g., -e 10.0 (default=10.0)")
parser.add_option("-r", "--repetitions", type="int", default=100, help="Number of packets to be generated for the simulation, e.g., -r 100 (default=100)")
(options, args) = parser.parse_args ()
if len(args) != 0:
parser.print_help()
raise SystemExit, 1
fname=options.fsm_file
esn0_db=float(options.esn0)
rep=int(options.repetitions)
# system parameters
f=trellis.fsm(fname) # get the FSM specification from a file (will hopefully be automated in the future...)
Kb=1024*16 # packet size in bits (make it multiple of 16)
bitspersymbol = int(round(math.log(f.I())/math.log(2))) # bits per FSM input symbol
K=Kb/bitspersymbol # packet size in trellis steps
modulation = fsm_utils.psk4 # see fsm_utils.py for available predefined modulations
dimensionality = modulation[0]
constellation = modulation[1]
if len(constellation)/dimensionality != f.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); # 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(f,Kb,bitspersymbol,K,dimensionality,constellation,N0,-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)%100==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()
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