An unmanned aerial vehicle for at least one of direction finding and spectrum monitoring includes a main body including at least one electronic circuit and at least one motor. The unmanned aerial vehicle also has at least one rotor associated with the motor. The unmanned aerial vehicle includes an outer housing surrounding the rotor partially, the outer housing including at least one antenna module configured to receive a radio signal.

A two-dimensional direction-of-arrival estimation method for a coprime planar array based on structured coarray tensor processing, the method includes: deploying a coprime planar array; modeling a tensor of the received signals; deriving the second-order equivalent signals of an augmented virtual array based on cross-correlation tensor transformation; deploying a three-dimensional coarray tensor of the virtual array; deploying a five-dimensional coarray tensor based on a coarray tensor dimension extension strategy; forming a structured coarray tensor including three-dimensional spatial information; and achieving two-dimensional direction-of-arrival estimation through CANDECOMP/PARACFAC decomposition. The present disclosure constructs a processing framework of a structured coarray tensor based on statistical analysis of coprime planar array tensor signals, to achieve multi-source two-dimensional direction-of-arrival estimation in the underdetermined case on the basis of ensuring the performance such as resolution and estimation accuracy, and can be used for multi-target positioning.

A two-dimensional direction-of-arrival estimation method for a coprime planar array based on structured coarray tensor processing, the method includes: deploying a coprime planar array; modeling a tensor of the received signals; deriving the second-order equivalent signals of an augmented virtual array based on cross-correlation tensor transformation; deploying a three-dimensional coarray tensor of the virtual array; deploying a five-dimensional coarray tensor based on a coarray tensor dimension extension strategy; forming a structured coarray tensor including three-dimensional spatial information; and achieving two-dimensional direction-of-arrival estimation through CANDECOMP/PARACFAC decomposition. The present disclosure constructs a processing framework of a structured coarray tensor based on statistical analysis of coprime planar array tensor signals, to achieve multi-source two-dimensional direction-of-arrival estimation in the underdetermined case on the basis of ensuring the performance such as resolution and estimation accuracy, and can be used for multi-target positioning.

A method performed by a first communication device operating in a wireless communications network. The first communication device obtains a set of correspondences associating: i) each set (ω.sub.i) of a plurality of sets of antenna weights (ω.sub.1 . . . ω.sub.i) having been sent by a third communication device in response to having received a respective set (RSs.sub.i) of a plurality of sets of radio signals (RSs.sub.1 . . . RSs.sub.i) from a set of antenna ports in a second communication device, with ii) a respective direction of transmission (d.sub.i) between the second communication device and the third communication device. The respective direction is relative to an orientation (α.sub.i) of the second communication device. The respective direction of transmission (d.sub.i) is a selected direction of transmission (d.sub.i,αi). The first communication device then initiates transmission of a new radio signal, based on the obtained set of correspondences.

A radio receiver is made much more immune to jamming signals. A vector EM sensor, in a 2-dimensional (3-axis sensor) or 3-dimensional (6-axis sensor) sensor configuration, is combined with a unique digital rotation to a preferred direction to create a new reference channel and, using an advanced frequency domain noise mitigation algorithm or other noise cancellation algorithm, can effectively reject jamming and other interference signals and improve the signal-to-noise ratio (20-40 dB) and the receiving performance of the receiver. The method can cancel both near-field and far-field interference and improve accuracy for various applications concerned with establishing the direction, or bearing, to a source. A communication receiver with the vector sensor and the cancellation algorithm has unique anti-jamming capabilities even for multiple jamming sources.

Provided is a technology for increasing accuracy of position estimation by estimating a position of a signal source based on an error due to altitudes of a sensor and a signal source and an error due to a pitch of an aircraft as well as an error due to curvature of the earth. At this time, a position estimation method may include receiving measurement data from a plurality of sensors, estimating first position data of the signal source based on the measurement data, identifying an altitude error of the first position data, and estimating second position data that is data obtained by correcting the first position data based on the altitude error.

Disclosed is a high-resolution accurate two-dimensional direction-of-arrival estimation method based on coarray tensor spatial spectrum searching with coprime planar array, which solves the problem of multi-dimensional signal loss and limited spatial spectrum resolution and accuracy in existing methods. The implementation steps are: constructing a coprime planar array; tensor signal modeling for the coprime planar array; deriving coarray statistics based on coprime planar array cross-correlation tensor; constructing the equivalent signals of a virtual uniform array; deriving a spatially smoothed fourth-order auto-correlation coarray tensor; realizing signal and noise subspace classification through coarray tensor feature extraction; performing high-resolution accurate two-dimensional direction-of-arrival estimation based on coarray tensor spatial spectrum searching. In the present method, multi-dimensional feature extraction based on coarray tensor statistics for coprime planar array is used to implement high-resolution, accurate two-dimensional direction-of-arrival estimation based on tensor spatial spectrum searching, and the method can be used for passive detection and target positioning.

Methods, systems, and devices for wireless communications are described. A base station may request a user equipment (UE) to report location information for the UE using a specific format. The UE may report the location information to the base station based on the request. The base station may use the location information reported by the UE to determine the location of the UE.

The present invention is directed to energy-efficient hibernation in indoor wireless localization systems. A tag passively associates with a detection point (DP) and establishes a reveille time. The tag will awaken at the reveille time and send or receive a beacon to or from its associated DP. If the tag is receiving a beacon, it will awaken, receive, phase-lock its clock based on when the beacon was expected and when it was actually received, and return to hibernation. The DP transmits a scattershot of beacons, one for every tag in the system. If the tag is sending a beacon, it will awaken, send its beacon, and return to hibernation. The DP will receive the beacon and adjust its own clock based on the delay between when the beacon was expected and when it was actually received. The tag will broadcast its location to the DP on a set interval.

The present invention is directed to energy-efficient hibernation in indoor wireless localization systems. A tag passively associates with a detection point (DP) and establishes a reveille time. The tag will awaken at the reveille time and send or receive a beacon to or from its associated DP. If the tag is receiving a beacon, it will awaken, receive, phase-lock its clock based on when the beacon was expected and when it was actually received, and return to hibernation. The DP transmits a scattershot of beacons, one for every tag in the system. If the tag is sending a beacon, it will awaken, send its beacon, and return to hibernation. The DP will receive the beacon and adjust its own clock based on the delay between when the beacon was expected and when it was actually received. The tag will broadcast its location to the DP on a set interval.