The Performance of Chirp Signal Used in LEO Satellite Internet of Things

Low earth orbit (LEO) constellations for enhancing global navigation satellite systems (GNSS) have been investigated and studied due to their higher floor power and rapid geometric changes. Compared with GNSS based on medium orbit (MEO) and geostationary (GEO) satellites, the higher Doppler frequency is one of the problems faced by the LEO enhanced GNSS. For the traditional BPSK signal, the complexity has been greatly improved in acquisition, especially in the cold start state, which means more requests on the signal design. The periodic chirp signal modulated by the pseudo-noise code (chirp-PC) is proposed as the ranging signal of LEO enhanced GNSS. The coupling characteristic of Doppler and delay in chirp-PC can make the search frequency grid less than the traditional BPSK signal with the same acquisition performance, which can greatly reduce the complexity. However, the delay estimation obtained by the acquisition is biased. A tracking loop based on the chirp phase locked loop (CPLL) was proposed for removing the coupling of Doppler and time delay. The simulations show that the tracking loop can track chirp-PC signals stably and unbiasedly, and the tracking accuracy is similar to that of the corresponding BPSK signal. Therefore, the chirp-PC signal is a new choice for LEO enhanced GNSS with low acquisition complexity and equivalent tracking accuracy to BPSK.

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“…Taking γ = f i /f c into the expression (17) above, the correlation results can be obtained as follows:…”

Section: Parallel Code Acquisition Based On the Fftmentioning

confidence: 99%

Chirp pseudo‐noise signal and its receiving scheme for LEO enhanced GNSS

Zhao

Huang

Tang

et al. 2021

IET Radar Sonar & Navi

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“…Asymmetric chirp signal (ACS) is therefore more applicable to LEO satellite IoT. Similarly, Qian et al 53 proposed ACS. Compared with symmetric chirp Figure 6.…”

Section: Large Dynamic Channelmentioning

confidence: 99%

“…Asymmetric chirp signal (ACS) is therefore more applicable to LEO satellite IoT. Similarly, Qian et al 53 proposed ACS. Compared with symmetric chirp signal (SCS), ACS has better auto-correlation and better cross-relation in time domain and frequency domain.…”

Section: Physical Layer Technologies Of Satellite Iotmentioning

confidence: 99%

A review on non-terrestrial wireless technologies for Smart City Internet of Things

Wang

Miao

et al. 2020

International Journal of Distributed Sensor Networks

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Smart City Internet of Things will become a fundamental infrastructure to support massive machine-type communications between the widely deployed sensors serving big cities. Since there exists many location constraints for the existing terrestrial Internet of Things, the non-terrestrial Internet of Things sheds light on breaking these limits. Therefore, this article conducts a comprehensive survey on non-terrestrial Internet of Things technologies for Smart City, which is an important complement to terrestrial Internet of Things. We first present the application scenarios of Internet of Things and point out where the existing terrestrial Internet of Things cannot work perfectly. Two non-terrestrial Internet of Things technical proposals are then introduced, namely satellite Internet of Things and unmanned aerial vehicle Internet of Things. However, the focuses of these non-terrestrial Internet of Things are distinct, that is, the major problems of satellite and unmanned aerial vehicle Internet of Things are the high dynamic nature of channel and high maneuverability of unmanned aerial vehicles, respectively. The key technologies for satellite and unmanned aerial vehicle Internet of Things are then reviewed separately. Both physical and non-physical layer technologies are surveyed for satellite Internet of Things, and the route planning is mainly investigated for the unmanned aerial vehicle Internet of Things. Finally, we draw a conclusion and give some potential research directions of non-terrestrial Internet of Things.

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“…On the contrary, the rapid variation in the Doppler frequency shift, e.g, when a lower altitude satellite flies directly above the ground station, leads to severe degradation in the performance, which reduces the duration of the radio communication session. From another perspective, the frequency shift spread spectrum in LoRa after some modification can be used to provide a multiple access technique as an alternative to direct sequence spread spectrum traditionally used in satellites [125]. It was shown that the BER performance of the proposed frequency and phase symmetry chirp spread spectrum are similar to the direct sequence multiple access.…”

Section: F Lora For Cubesatsmentioning

confidence: 99%

CubeSat Communications: Recent Advances and Future Challenges

Saeed¹,

Elzanaty²,

Dahrouj³

et al. 2020

Preprint

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The research in the emerging space industry is becoming more and more attractive, given the increasing number of space-related applications. One primary entity of current space research is the design of miniaturized satellites, known as CubeSats, due to their numerous applications and low design and deployment cost. The new paradigm of connected space through CubeSats enables a wide range of applications such as Earth remote sensing, space exploration, and rural connectivity. CubeSats further provide a complimentary connectivity solution to the pervasive Internet of things (IoT) networks, leading to a globally connected cyber-physical system. This paper presents a holistic overview of different aspects of CubeSat missions, and provides a thorough review on the topic, both from academic and industrial perspectives. We further present the recent advances in the area of CubeSats communications with an emphasis on constellation and coverage issues, channel modeling, modulation and coding, and networking. The paper finally identifies several future research directions on CubeSats communications, namely Internet of space things, low power long range networks, machine learning for resource allocation in CubeSats, etc.

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The Performance of Chirp Signal Used in LEO Satellite Internet of Things

Cited by 41 publications

References 12 publications

Chirp pseudo‐noise signal and its receiving scheme for LEO enhanced GNSS

Chirp pseudo‐noise signal and its receiving scheme for LEO enhanced GNSS

A review on non-terrestrial wireless technologies for Smart City Internet of Things

CubeSat Communications: Recent Advances and Future Challenges

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