Bit Error Performance

1. SOQPSK and GMSK Performance in Phase NoiseAfzal Syed, Erik Perrins {afzal@ittc.ku.edu, esp@eecs.ku.edu} Introduction Phase Noise Model • SOQPSK and GMSK are highly bandwidth efficient continuous phase modulation (CPM) schemes with several desirable qualities. • Both SOQPSK and GMSK have good performance in AWGN. • Noncoherent receivers are preferred because they are easy to synchronize and are more robust. • This work develops reduced complexity noncoherent detectors for SOQPSK and GMSK and compares their performance in phase noise channels. • The motivation for a noncoherent receiver is the case when the carrier phase is not known and assumed to be varying. • Phase noise is modeled as a first order Markov process with Gaussian transition probability distribution defined by where are independent and identically distributed Gaussian random variables with zero mean and variance . Bit Error Performance Bit Error Performance SOQPSK- MIL GMSK BT=0.3 GMSK BT=0.25 SOQPSK- TG • The natural choice for benchmark is optimal coherent Maximum Likelihood Sequence Detection (MLSD). • a is the forgetting factor in the recursive update for phase reference in the noncoherent detector. • Noncoherent detectors for GMSK perform at least 0.5 dB better than SOQPSK detectors in phase noise.