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UAV assisted wireless sensor networks play a key role in the detection of toxic gases and aerosols. UAVs can be used to remotely deploy sensor nodes and then collect gas concentration readings and GPS positioning from them to delimit an affected area. For such purpose, a dual-band communication system is required, supporting GPS reception, and sens...
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As a new technology for reconstructing communication environments, intelligent reflecting surfaces (IRSs) can be applied to UAV communication systems. However, some challenges exist in IRS-assisted UAV communication system design, such as physical layer security issues, IRS design, and power consumption issues owing to the limitation of the hardwar...
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... Global navigation satellite system (GNSS) is one important positioning and navigation system widely used in aerial vehicles and ground transportations [1,2]. Integrity, including the ability to provide timely warnings to users when GNSS should not be used for navigation, is one of the most important indicators to evaluate and keep the performance of GNSS. ...
Global navigation satellite system (GNSS) plays a crucial role in many fields, such as aerospace and transportation. Integrity is the measure of trust used in GNSS positioning especially in safety-critical applications. Advanced receiver autonomous integrity monitoring (ARAIM), taking full advantage of multi-constellation GNSS, shows huge potential to provide vertical navigation in civil aviation en route navigation and terminal approaches. However, the multi-constellation ARAIM also greatly exposes computational complexity and potential performance hazards in fault modes determination and fault-tolerant positioning. From the perspective of integrity risk control, rather than the pursuit of better positioning accuracy blindly for safety-critical applications, the concept of constellation dynamic selection is proposed and implemented in ARAIM and the performance analysis is discussed in this paper. Only the best two constellations which have the best vertical geometry performance are involved in ARAIM calculation anytime anywhere. The proposed method shows superiority in both integrity availability and computational complexity in both simulations and actual GNSS signal experiments. While the computational complexity is less than 10% of that using four constellations, 100% availability under LPV-200 criteria can be achieved in worldwide coverage experiment. The proposed method also overcomes the shortcomings of ARAIM with two fixed constellations and shows good robustness under depleted scenarios. Furthermore, the statistics results from observation stations proved the applicability and generality of the proposed method under current developing GNSS constellations.
... The major drawbacks of microstrip antennas include the difficult trade-off between the achieved bands (IBW and ARBW) and their size, low efficiency and poor polarisation purity antennas [72,73]. Nevertheless, several methods can be used to improve antenna performance and expand the IBW. ...
With the rapid changes in wireless communication systems, indoor wireless communication (IWC) technology has undergone tremendous development. Antennas are crucial components of IWC systems that transmit and receive signals within indoor environments. Thus, the development of indoor technology is highly dependent on the development of indoor antennas. However, indoor environments with limited space require the fewest indoor antenna units and the smallest indoor antenna sizes possible. Hence, indoor antennas with compact size and broad applications have become widely preferred. In an IWC system, circularly polarised (CP) antennas are generally important, especially in dense indoor environments, because compared with linearly polarised (LP) antennas, CP antennas reduce polarisation mismatch and multipath losses. This paper combs through the existing studies related to three-dimensional (3D) geometry (nonplanar) or waveguide indoor antennas and the two common approaches to two-dimensional (2D) geometry (planar) indoor antennas, namely, broadband CP printed monopole antennas (BCPPMAs) and broadband CP printed slot antennas (BCPPSAs). The advantages, disadvantages and limitations of previous works are highlighted as well. These research works are summarised, compared and analysed to understand the recent specifications of BCPPMAs and BCPPSAs to generate the most appropriate design structure suitable for current IWC systems.
Tis research article designs and develops a planar small-size antenna design for smart Internet of Tings (IoT) communication
with long-range technology (LoRa). Te proposed system is best suited for transceiver systems in this automation and sensing era.
In the proposed antenna, the ground, the radiating element, and the stub feed are designed on the same side of the substrate,
keeping in mind that it can print the LoRa module. Te design consists of a meandered monopole, a dipole structure as a ground,
and a stub feed. A diferent design approach is employed to get an optimized result. Te antenna is made up of a rectangular feed
stub to which a connecting wire is attached. Te overall dimension of the antenna is 55 m × 55 m × 1.6 mm. To verify the proposed
design, an antenna was fabricated and measured, which covers the LoRa frequency band at 868 MHz, providing a sufcient
bandwidth of 10 MHz and a gain of more than 0.5 dB in the operating band. A designed antenna is implemented for sensor data
communication with the LoRa module device and device interface Arduino platform. Te antenna is connected as a transmitter
and receiver one by one to verify its performance with machine-to-machine communication using the LoRa module. Te size,
bandwidth, and radiation efciency of this antenna are better than the antennas in the literature. Te designed antenna is
successfully implemented with LoRa connectivity and communicates the data up to 8 km in line-of-sight communication, more
than 1 km in urban environments, and approximately 250 m of connectivity in building areas.
This research article designs and develops a planar small-size antenna design for smart Internet of Things (IoT) communication with long-range technology (LoRa). The proposed system is best suited for transceiver systems in this automation and sensing era. In the proposed antenna, the ground, the radiating element, and the stub feed are designed on the same side of the substrate, keeping in mind that it can print the LoRa module. The design consists of a meandered monopole, a dipole structure as a ground, and a stub feed. A different design approach is employed to get an optimized result. The antenna is made up of a rectangular feed stub to which a connecting wire is attached. The overall dimension of the antenna is 55 m × 55 m × 1.6 mm. To verify the proposed design, an antenna was fabricated and measured, which covers the LoRa frequency band at 868 MHz, providing a sufficient bandwidth of 10 MHz and a gain of more than 0.5 dB in the operating band. A designed antenna is implemented for sensor data communication with the LoRa module device and device interface Arduino platform. The antenna is connected as a transmitter and receiver one by one to verify its performance with machine-to-machine communication using the LoRa module. The size, bandwidth, and radiation efficiency of this antenna are better than the antennas in the literature. The designed antenna is successfully implemented with LoRa connectivity and communicates the data up to 8 km in line-of-sight communication, more than 1 km in urban environments, and approximately 250 m of connectivity in building areas.
