4 research outputs found
Multiple Satellites Collaboration for Joint Code-aided CFOs and CPOs Estimation
Low Earth Orbit (LEO) satellites are being extensively researched in the
development of secure Internet of Remote Things (IoRT). In scenarios with
miniaturized terminals, the limited transmission power and long transmission
distance often lead to low Signal-to-Noise Ratio (SNR) at the satellite
receiver, which degrades communication performance. A solution to address this
issue is the utilization of cooperative satellites, which can combine signals
received from multiple satellites, thereby significantly improve SNR. However,
in order to maximize the combination gain, the signal coherent combining is
necessary, which requires the carrier frequency and phase of each receiving
signal to be aligned.
Under low SNR circumstances, carrier parameter estimation can be a
significant challenge, especially for short burst transmission with no training
sequence. In order to tackle it, we propose an iterative code-aided estimation
algorithm for joint Carrier Frequency Offset (CFO) and Carrier Phase Offset
(CPO). The Cram\'er-Rao Lower Bound (CRLB) is suggested as the limit on the
parameter estimation performance. Simulation results demonstrate that the
proposed algorithm can approach Bit Error Rate (BER) performance bound within
0.4 dB with regards to four-satellite collaboration
On the Security of LEO Satellite Communication Systems: Vulnerabilities, Countermeasures, and Future Trends
Low Earth Orbit (LEO) satellite systems undergo a period of rapid development
driven by the ever-increasing user demands, reduced costs, and technological
progress. Since there is a paucity of literature on the security issues of LEO
Satellite Communication Systems (SCSs), we aim for filling this knowledge gap.
Specifically, we critically appraise the inherent characteristics of LEO SCSs
and summarize their unique security vulnerabilities. In light of this, we
further discuss their security vulnerabilities, including the issues of passive
and active eavesdropping attacks, interference scenarios, single event upsets,
and space debris. Subsequently, we discuss the corresponding active and passive
security countermeasures, followed by unveiling a range of trade-offs, security
vulnerabilities and their countermeasures. Furthermore, we shed light on
several promising future research directions for enhancing the security of LEO
SCSs, such as secure quantum communications, three-dimensional virtual arrays,
artificial intelligence-based security measures, space-based blockchain, and
intelligent reflecting surface enabled secure transmission. Finally, the
take-away messages of this paper are crystallized in our concluding design
guidelines
Low Earth Orbit satellite security and reliability: issues, solutions, and the road ahead
Low Earth Orbit (LEO) satellites undergo a period of rapid development driven by ever-increasing user demands, reduced costs, and technological progress. Since there is a lack of literature on the security and reliability issues of LEO Satellite Communication Systems (SCSs), we aim to fill this knowledge gap. Specifically, we critically appraise the inherent characteristics of LEO SCSs and elaborate on their security and reliability requirements. In light of this, we further discuss their vulnerabilities, including potential security attacks launched against them and reliability risks, followed by outlining the associated lessons learned. Subsequently, we discuss the corresponding security and reliability enhancement solutions, unveil a range of trade-offs, and summarize the lessons gleaned. Furthermore, we shed light on several promising future research directions for enhancing the security and reliability of LEO SCSs, such as integrated sensing and communication, computer vision aided communications, as well as challenges brought about by megaconstellation and commercialization. Finally, we summarize the lessons inferred and crystallize the take-away messages in our design guidelines