US Patent 8134990 Defining adaptive detection thresholds

A wireless device (24) receives a reference signal over a radio channel (21). The reference signal may be Positioning Reference Signals (PRS) and/or Common Referencing Signals (CRS), and may be transmitted from a transmitter (22). The wireless device (24) comprises a correlator (100); a reference signal detector (102); a threshold selector (106); and a reference signal analyzer (108). The correlator (100) use a signal received from the radio channel (21) and a replica of the reference signal to provide a correlator output value. The reference signal detector (102) compares the correlator output value with a threshold value to detect presence of a reference signal, and to estimate an arrival time of the reference signal. The threshold selector (106) adapts the threshold value to at least an estimate of a relative amount of noise and interference power in the received signal.