Error Performance of Faded Narrowband DQPSK with Adjacent Channel Interference

摘要

A new and simple error rate formulae for narrow-band Differential Quaternary Phase Shift Keyed system in a Rayleigh fading channel has been obtained in closed form. The formulae consists of two terms. The first term represents the usual error rate values that decreases with increasing SNR while the other term represents, an error rate floor which is independent of the SNR.The formulae has been applied to a frequency division multiplex arrangement of subcarmers where adjacent channel interference contribute to signal distortion. Optimum values for the receiver IF filter bandwidth and interchannel frequency spacing are obtained. An IF filter bandwidth of one times the bit rate leads to a minimal error probability, while an interchannel frequency spacing has to be maintained above 1.8 times the bit rate if severe performance degradation is to be avoided.