Low earth orbit (LEO) satellite communication based on 3GPP standard is seen as a promising solution to rolling out services in areas without terrestrial base stations. However, due the fast movement of satellites and large beam footprint size, existing 5G timing advance (TA) estimation mechanism cannot be directly applied when global navigation system unavailable. In this article, an enhanced TA approach proposed for LEO networks. Specifically, user-side time-frequency pre-compensation...

Biaxial strain and electric field engineering induced the Schottky to Ohmic contact transition of a germanene/GaAs metal–semiconductor junction with electron injection efficiency exceeding 27%.

Low earth orbit (LEO) satellite communication networks have been considered as promising solutions to providing high data rate and seamless coverage, where beam management plays a key role. However, due the limitation of resource, dynamic network topology, spectrum reuse, time-varying traffic arrival service continuity requirement, it is challenging effectively allocate time-frequency resource beams multiple cells. In this paper, aiming at reducing time-averaged revisit time mitigate...

The authors study the effects of sensor pattern and position perturbations on angle estimation performance bound for multiple narrow-band sources. Cramer-Rao lower (CRLB) is used with a probabilistic modeling perturbations. CRLBs linear uniform array under are evaluated in detail case two narrowband sources.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A definition of least cyclostationary order (LCO) is proposed based on the inner cyclic period single carrier and orthogonal frequency division multiplexing (OFDM) signals. The LCOs OFDM signals are derived. Since LCO has a relationship with offset (CFO), blind CFO estimation scheme for can be proposed. novel entirely without any priori information proved to same as cumulants when known. However, new superior cumulant unknown. mean‐square error M ‐phase shift keying approaches Cramér–Rao...

In this paper a new high-resolution method is presented for direction finding in the presence of multipath. The method, called coherent wide-band modified forward-backward linear prediction (CWB-MFBLP), based on idea frequency-domain smoothing [1] to remove singularity correlation matrix completely correlated signals. Simulation results are provided demonstrate effectiveness and discussion comparison approach spatial also included.

The passive synthetic aperture antenna array (PSAAA) technology is inspired by the idea of sonar and radar, which a new method used to radar source localization using only one small aircraft. Virtual time difference arrival (VTDOA) estimation critical for PSAAA technology, it defined as pulse transmission from position different virtual receivers, where receivers are flight track aircraft at time. In this paper, we present three algorithms curve fitting approximate main-beam pattern antenna,...

An approach is suggested to wideband adaptive beamforming for correlated signal and interference. Unlike other approaches, such as spatial smoothing, the new solves cancellation problem by employing idea of frequency-domain smoothing. Advantages smoothing over are identified. Preliminary performance studies a simple method show that proper filtering can be achieved whether desired interference or not.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML"...

A novel three-dimensional printed dual-wideband complementary antenna with a dual-layer bow-tie dipole structure is proposed for WLAN/WiMAX applications. By using dual-η-shaped feeding to feed the U-shaped dipole, and characteristics can be obtained. In addition, its MIMO system defected ground which obviously improve diversity performance also designed. The element offer an impedance bandwidth of 8.1% (2.38 GHz-2.58 GHz) stable gain 4.3±0.5 dBi, 60.3% (3.20 GHz- 5.96 7.5±1.7 dBi lower upper...

This paper considers the problem of how to accurately and passively localise hostile radar position based on only one small size aircraft. Inspired by Synthetic Aperture Sonar (SAS), Radar (SAR) multi-static passive radar, a similar concept Passive Antenna Array (PSAAA) is introduced into this paper. The same single receiver carried aircraft virtually taken as PSAAA element at different flight track positions multiple moments. Taking full advantages space movement antenna circular rotation,...

A approach for tone resolution and estimation problems in applications such as pulse Doppler processing direction finding is presented. The approach, based on frequency-diversity signaling coherent wideband high-resolution processing, shown to significantly outperform those using the conventional narrowband under equal-transmitted-energy constraint with either completely correlated or independent targets. Both analytical analysis simulations are provided, well some insights issues related...

To achieve ubiquitous wireless connectivity, low earth orbit (LEO) satellite networks have drawn much attention. However, effective beam management is challenging due to time-varying cell load, high dynamic network topology, and complex interference situations. In this paper, under inter-satellite handover frequency satellite-terrestrial/inter-beam constraints, we formulate a practical problem, aiming maximize the long-term service satisfaction of cells. Particularly, Lyapunov framework...

Distribution center links the relief suppliers and affected people, making it an indispensable part in transportation network of earthquake supplies. Therefore, location distribution for supplies has significant influence on cost, operation efficiency logistics performance, which are important reducing loss lives property.

For high-resolution active direction finding of completely correlated targets, one can use two approaches, i.e. frequency-domain smoothing and non-frequency-domain smoothing, such as spatial or a multidimensional search signal-subspace. A performance comparison the approaches is presented for fluctuating target cases under an equal transmitted-energy constraint. both theoretical analysis simulations are used to study detection (determination number targets) angle estimation. It found that...

A novel approach is presented to wideband adaptive beamforming for correlated desired signal and interferences. Unlike spatial smoothing, it solves the cancellation problem by using idea of frequency-domain smoothing. Advantages over smoothing are identified, a particular method developed moderately system applications. preliminary performance study shows that proper filtering can be achieved whether interferences or not.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML"...

The authors study the effects of sensor-pattern and sensor-position perturbations on angle-estimation performance bound for multiple narrowband sources. Cramer-Rao lower is used with a probabilistic modeling perturbations. For uniformly spaced sensor array position are found to be more serious problem than pattern perturbation, in sense that raising SNR offers very limited help compensating degradation caused by perturbation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML"...

For high-resolution active direction-finding of completely-correlated targets, one can use two approaches: the frequency-domain smoothing and nonfrequency-domain such as spatial or multidimensional search signal-subspace. The authors present a performance comparison approaches for fluctuating target cases under equal transmitted-energy constraints. Both theoretical analysis simulations are used to study performances detection (determination number targets) angle estimation. It is found that...