Demodulation of bluetooth GFSK signals under carrier frequency error conditions

Bluetooth, the short range wireless communications standard, operates in the unlicensed ISM frequency band at 2.4 GHz using Gaussian Frequency Shift Keying (GFSK) modulation. Previous work has shown that the BER rate performance of a Bluetooth link can degrade by more than 19 dB when the transmitted carrier frequency differs from the ideal, yet is still within the limits imposed by the Bluetooth specification. Therefore a combination of demodulator and decision algorithm with adaptive thresholding which mitigates for carrier frequency errors is analysed. The efficacy of this method is demonstrated through the presentation of simulation results. An performance improvement of 13 dB for an initial carrier frequency offset of 70 kHz is reported.