NOMA-Based Calibration for Large-Scale Spaceborne Antenna Arrays

Abstract

Abstract-In the parallel calibration for transmitting phased arrays, the calibration receiver must separate the signals belonging to different antenna elements to avoid mutual interference. Existing algorithms encode different antenna elements' radiation with orthogonal signature codes, but these algorithms are far from desired for large-scale spaceborne antenna arrays. Considering the strictly limited resources on satellites, to improve hardware efficiency of large-scale spaceborne antenna arrays, in this work inspired by the idea of non-orthogonal multiple access (NOMA) we design a series of non-orthogonal signature codes for different antenna elements by Cyclically Shifting an m-Sequence (CSmS) with different offsets named as CSmS-NOMA signaling. This design can strike an elegant balance between the performance and complexity and is very suitable for large-scale spaceborne antenna arrays. It is shown that no matter how many antenna elements there are to be calibrated simultaneously, CSmS-NOMA signaling needs only one calibrating waveform generator and one matched filter. Hence it is much more efficient than the existing fully orthogonal schemes. In order to evaluate the achievable calibration accuracy, a unified theoretical framework is developed based on which the relationship between calibration accuracy and signal to noise ratio (SNR) has been clearly revealed. Furthermore, a hardware experiment platform is also built to assess the theoretical work. For all the considered scenarios, it can be concluded that the theoretical, simulated and experimental results coincide with each other perfectly.

Security Enhancement for NOMA-UAV Networks

“…On the other hand, non-orthogonal multiple access (NO-MA) is becoming an important technique for future wireless networks, due to its low latency, high reliability, massive connectivity and high throughput [21]- [23]. In the powerdomain NOMA scheme, the base station (BS) performs power allocation (PA) according to the quality of channels [24].…”

Low-Complexity Online Calibration for Large-Scale Multi-Beam Antennas

“…where β = 1 − uM −1 u T . A code-division calibration method proposed in [21] can take advantage of the binary autocorrelation property of m-sequence. The elements on the diagonal of the matrix M are all 1 and other elements are −1/L.…”

Impact Analysis and Calibration Methods of Excitation Errors for Phased Array Antennas

“…However, this requires some hardware burden. A more popular alternative technique allows simultaneously measuring excitations of multiple elements relying on code modulation [102][103][104][105][106]. A method that controls the element phases based on time multiplexed orthogonal codes was proposed in [102], thus the individual element excitation can be derived from the combined array signal.…”