Blind equalisation and carrier offset compensation for Bluetooth signals

Bluetooth systems operating in medium to large sized rooms can suffer multipath distortion, which may be compounded by presence of frequency offsets permitted by the Bluetooth standard. Frequency errors can undermine common training based equalisation techniques. This paper establishes the effect of severe multipath indoor propagation and frequency errors on Bluetooth reception, and demonstrates the effectiveness of the constant modulus algorithm in performing channel equalisation when a frequency offset exists. A novel stochastic gradient based algorithm for frequency correction is also introduced and assessed.