Performance Analysis of Echo Cancellation for CDMA Repeater

Since mobile communication has been well developed, high quantity services is also expected by mobile users, so repeaters, which amplify the coverage of both analog and digital communication base stations, have been popularly used by mobile communication providers. A repeater is a device that receives a digital or analog signal on an electromagnetic or optical transmission medium and regenerates the signal along the next leg of the medium. A series of repeaters make possible the extension of signals over weak signal areas, uncovered areas and far distance. However, in reality, repeaters more or less disturb the capabilities of themselves and other equipments, due to people do not combine the theory with practice properly and systematically. Base on reading concerned literature and actual working experience, the author has provided new solutions on common disturbed conditions of repeaters after professional analysis. Echo cancellation, a technique used to reduce the effect, is often based on the auto-correlation of the repeater signal and is effective when the width of the auto-correlation of the input signal is less than the loop delay of the echo path.