A Same-Frequency Cellular Repeater Using Adaptive Feedback Cancellation

A same-frequency cellular repeater is proposed that uses adaptive signal processing to cancel the feedback path, thereby allowing high gain while maintaining stability. This technique has application wherever it is desired to boost signal strength in outlying areas of cell coverage, particularly inside homes and buildings. It is intended to provide useful gain without needing special donor/transmit antennas requiring directional gain, separation beyond a meter or so, or roof installation. A simulation of a 900-MHz repeater with 10-MHz bandwidth is presented that demonstrates the feasibility and determines the effect of parameter values on convergence and cancellation performance. Preliminary results are also presented for a real-time laboratory demonstration using an FPGA development board, realizing cancellation of about 20 dB over a 10-MHz bandwidth