Karhunen-Loeve based adaptive analog/digital subspace beamforming

The authors propose a new hybrid approach in which A/D conversion at the front end of the sensor array is bypassed. They stay in the analog domain and adapt using the coefficients obtained in the truncated Karhunen-Loeve expansion of the received signal. It is demonstrated via computer simulations that for the same subspace dimension, the new approach outperforms the all-digital fully adaptive and the all-digital subspace approach for large time-bandwidth products