Simulations of Convolutional Coding/Viterbi Decoding with Noncoherent CPFSK

Simulation results are presented for the bit error rate performance of binary and quaternary noncoherent CPFSK when used in conjunction with
K=7
,
R=1/2
convolutional encoding and Viterbi decoding. Although coding does not appear to offer any significant advantage in the binary case, the results indicate that the quaternary CPFSK modulation with three-symbol demodulation is a good match to the coding, with performance to within a decibel of coherent QPSK at an error rate of 10
^-5
. Also, simplified optimum demodulator structures are presented, in the case of multisymbol processing, which require only
N
correlator branches in the case of
N
-ary CPFSK regardless of the number of symbols being used by the demodulator. This is in contrast to conventional receivers which require N
ⁿ
correlator branches with
n
-symbol processing.