DC Estimation and Tracking for M-DPSK Channels
Original Publication Date: 2002-May-16
Included in the Prior Art Database: 2002-May-16
While direct conversion receivers or 0-IF receivers offer a low power/cost advantage to portable wireless devices, they incur a unique problem: a DC component in the received I&Q baseband signal. This DC component increases the dynamic range of the received signal, thus increasing the power consumption of the receiver. The conventional solution to the DC problem is to use a highpass analog filter to attenuate the DC in order to reduce the received signal dynamic rage. However, this highpass filter has a long acquisition time or a long response time. For burst communication, the received baseband signal thus has residual DC. This residual DC component in baseband also reduces the performance for message recovery. In addition, the highpass filter also causes a false attenuation problem since the highpass filter also attenuates the desired signal DC component. To solve the false attenuation problem, most communication systems are designed to allow data scrambling on retransmission. However, this retransmission coupled with data scrambling reduces the system throughput. Thus there is a need to estimate and compensate for the residual DC in the received baseband signal.