def hard_decode(cls, uber, dfree):
"""Calculate bit-error probability for hard decision decoded RCPC.
:param uber: Probability of bit-error for uncoded system.
:param dfree: Free distance of convolutional code.
:return: BER for hard decision decoded RCPC coded system.
"""
pd, p = 0, uber
dmin = int(ceil((dfree+1.0)/2) )
q = 1 - p
for k in range(dmin, dfree+1):
pd += nchoosek(dfree,k)*(p**k)*(q**(dfree-k) )
if (int(dfree)%2<1):
pd += 0.5*nchoosek(dfree,int(dfree/2))*(p**(dfree/2))*(q**(dfree/2))
return pd
def per(self, p, ber):
"""Calculate packet-error rate (PER).
:param p: Packet (packet length in bytes) to compute PER for.
:param ber: BER of uncoded system.
:return: Packet-error rate (PER) in [0,1].
:note: If `ber` is a `numpy` array, this method will return an array of
values corresponding to the specified parameters.
"""
n, k = self.blocklength, self.messagelength
m, t = self.bitspersymbol, self.ncorrectable
plen = p
if isinstance(p, Packet): plen = len(p)
# calculate uncorrectable error rate for symbols
ser = 1 - (1 - ber)**m
# calculate uncorrectable error rate
s = 0
for b in range(t+1):
s +=nchoosek(n,b)*(ser**b)*((1-ser)**(n-b))
uer = 1 - s
# calculate PER
nblocks = int(ceil(plen/k) )
per = 1 - (1-uer)**nblocks
return per
