A subspace-based online calibration algorithm for an asynchronous CDMA-based antenna array

In this paper a new iterative calibration algorithm for an asynchronous CDMA-based antenna array in the presence of unknown gain and phase errors is presented. The algorithm is applicable to a nonuniform array where the number of users could be greater than the number of antennas, and does not require a prior knowledge of the DOAs of the signals of any user. The method requires the code sequence of a reference user only. The proposed algorithm provides us with the joint estimates of the DOAs and the multi-path impulse response of the used signal sources as well as the calibration of the sensor gains and phases, even under multiple access interference. The algorithm is near-far resistant and thus well suited for multi-path fading channel