US Patent 8027642 Transmission canceller for wireless local area network

A frequency translating repeater (200) for use in a wireless local area network includes a cancellation unit. Canceller (402) is controlled by control (401) to provide an injection signal for canceling leakage in a receive signal path. Reference coupler (403) provides a reference signal from the transmit signal, injection coupler (404) injects a correction signal, and sample coupler (405) provides a sample for feedback. A processor (510) receives the sample signal through a detector (415). Although the present invention is intended for a frequency translating repeater, it has broad applications in radio transceivers in general. One specific application is with frequency division duplex (FDD) handsets or base stations utilizing CDMA technologies such as W-CDMA and IS-2000 or 1XEV-DV/DO.