Antenna array calibration methods based on simultaneous perturbation

Abstract

Antenna arrays have gained significant interest in millimetre‐wave communication systems as an enabling technology to achieve higher capacity and mitigate the high propagation loss. Such arrays with a large bandwidth need to be efficiently calibrated to maximise their performance. An antenna array calibration method based on a stochastic approximation algorithm and simultaneous perturbation has been developed and the procedures to implement it in both frequency and time domains have been presented. The approaches to define objective functions and establish gradient approximations to fulfill a successful convergence for acquiring calibration coefficients in both domains have been explored. In the time domain implementation, only a fraction of the measurement time was required to calibrate an antenna array of ultrawide bandwidth compared with other methods using a perturbation technique. The effectiveness of the proposed method has been validated via numerical experiments in both domains.

A Mutual Coupling-Based Full Self-Online Calibration Method for Antenna Arrays in Uplink

“…Large-scale phased array antennas are considered to play fundamental role in the fifth-generation (5G) [1], [2] and future sixth-generation (6G) wireless communication systems [3], [4]. The new generation 5G and 6G wireless systems are expected to be used in many civil, commercial, and military areas such as massive multiple-input multiple-output (mMIMO) [5], [6], autonomous driving [7], satellite systems [3], internet of things (IoT) [4], anti-jamming, and antispoofing [8]. With the latest developments in phased array antenna technology, beamforming is intended to be one of the key techniques for the next generation wireless systems [1], [2], [9].…”

“…The near-field or far-field probing methods usually employ rotating-element electric-field vector (REV) method [27], [28], [29]. The REV method is inefficient for large-scale antenna array calibration since the calibration time increased drastically as the number of antennas increases and in particular, near-field probing methods are only suitable for off-line calibration [5], [7]. Moreover, it is difficult to verify the correct combination of signals in the far-field due to the limited feedback path [16].…”

“…The mutual coupling methods are capable of performing parallel calibration without adding extra antennas or increasing the system size [7], [16]. However, these methods need complex calibration algorithms [33] because of the stringent requirements for isolation between array elements and the non-uniform regulation of the sensitivity of the antenna elements, resulting in calibration errors in large-scale antenna arrays [5], [7]. In [14], a self-calibration method based on mutual coupling for initial calibration is proposed which is not suitable for on-line calibration.…”

“…In [2], a built-in on-line self-calibration is proposed, however, the mutual couplings are not taken into account, thus, for largescale antenna arrays there might be calibration errors. In [5], calibration method based on simultaneous perturbation is proposed, similar to [2], mutual couplings are ignored. There are extensive studies in the literature on the improvement of the mentioned calibration methods and their use in large-scale antenna arrays.…”