Towards Integrated Terrestrial-Satellite Network via Intelligent Reflecting Surface

Dong, Hao; Hua, Cunqing; Liu, Lingya; Xu, Wenchao

doi:10.1109/icc42927.2021.9500640

Cited by 20 publications

(9 citation statements)

References 13 publications

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“…c) Multiple users: The above-reviewed literature analyzes and optimizes the achievable rate of point-to-point wireless communications by deploying TRIS in the propagation environment. The rate maximization problems can be naturally extended to MU scenarios [49], [83], [99], [100], [135], [136]. Consequently, the solutions will be more involved due to the interference and resource competition among different users.…”

Section: ) Terrestrial Rismentioning

confidence: 99%

“…As a solution, Yu et al [160] showed that it can be efficiently solved by manifold optimization, as the unit modulus constraints define a Riemannian manifold. Therefore, the Riemannian conjugate gradient algorithm is adopted in [135], [136], [138], and [153], thereby enabling an efficient optimization for the RIS configuration. 4) Fractional programming: For the problems whose objective function in a fractional program is a ratio of two functions that are in general nonlinear, the fractional programming method is preferred to be invoked.…”

Section: A Alternating Optimization Algorithmmentioning

confidence: 99%

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Nonterrestrial Communications Assisted by Reconfigurable Intelligent Surfaces

Qiao

Kammoun

et al. 2022

Proc. IEEE

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| Nonterrestrial communications have emerged as a key enabler for seamless connectivity in the upcoming generation networks. This kind of network can support high data rate communications among aerial platforms (i.e., unmanned aerial vehicles (UAVs), high-altitude platforms (HAPs), and satellites) and cellular networks, achieving anywhere and anytime connections. However, there are many practical implementation limitations, especially overload power consumption, high probability of blockage, and dynamic propagation environment. Fortunately, the recent technology reconfigurable intelligent surface (RIS) is expected to be one of the most cost-efficient solutions to address such issues. RIS with low-cost elements can bypass blockages and create multiple line-of-sight (LoS) links and provide controllable communication channels. In this article, we present a comprehensive literature review on the RIS-assisted nonterrestrial networks (RANTNs). First, the framework of the RANTNs is introduced with detailed discussion about distinct properties of RIS in NTNs and the two Manuscript

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Section: ) Terrestrial Rismentioning

confidence: 99%

Section: A Alternating Optimization Algorithmmentioning

confidence: 99%

Nonterrestrial Communications Assisted by Reconfigurable Intelligent Surfaces

Qiao

Kammoun

et al. 2022

Proc. IEEE

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“…Recently, some researchers have integrated RIS with satellite communications. For example, Dong et al [31] have maximized the weighted sum rate of integrated terrestrial satellite networks by simultaneously optimising the transmit beamforming at the base station and phase shift matrix at RIS. The authors of [32] have provided a new framework to enhance the average throughput of RIS-enabled LEO networks by jointly optimizing the orientation and passive beamforming at RIS.…”

Section: A Recent Literature On Leo Satellite Networkmentioning

confidence: 99%

“…Xu et al [37] have also studied a physical layer security problem in RIS-assisted cognitive radio satellite-terrestrial integrated networks. Of late, the author of [31] have extended their work in [38] to maximize the weighted sum rate of RIS-assisted LEO satellite networks by jointly optimizing user scheduling, transmit beamforming and phase shift design.…”

Section: A Recent Literature On Leo Satellite Networkmentioning

confidence: 99%

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When RIS Meets GEO Satellite Communications: A New Sustainable Optimization Framework in 6G

Khan

Lagunas

Mahmood

et al. 2022

2022 IEEE 95th Vehicular Technology Conference: (VTC2022-Spring)

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Low Earth Orbit (LEO) satellite networks are expected to play a crucial role in providing high-speed internet access and low-latency communication worldwide. However, some challenges can affect the performance of LEO satellite networks. For example, they can face energy and spectral efficiency challenges, such as high power consumption and spectral congestion, due to the increasing number of satellites. Furthermore, mobile ground users tend to operate with low directive antennas, which pose significant challenges in closing the LEO-toground communication link, especially when operating at a highfrequency range. To overcome these challenges, energy-efficient technologies like reconfigurable intelligent surfaces (RIS) and advanced spectrum management techniques like non-orthogonal multiple access (NOMA) can be employed. RIS can improve signal quality and reduce power consumption, while NOMA can enhance spectral efficiency by sharing the same resources among multiple users. This paper proposes an energy-efficient RIS-assisted downlink NOMA communication for LEO satellite networks. The proposed framework simultaneously optimizes the transmit power of ground terminals of the LEO satellite and the passive beamforming of RIS while ensuring the quality of services. Due to the nature of the considered system and optimization variables, the energy efficiency maximization problem is non-convex. In practice, obtaining the optimal solution for such problems is very challenging. Therefore, we adopt alternating optimization methods to handle the joint optimization in two steps. In step 1, for any given phase shift vector, we calculate satellite transmit power towards each ground terminal using the Lagrangian dual method. Then, in step 2, given the transmit power, we design passive beamforming for RIS by solving the semi-definite programming. We also compare our solution with a benchmark framework having a fixed phase shift design and a conventional NOMA framework without involving RIS. Numerical results show that the proposed optimization framework achieves 21.47% and 54.9% higher energy efficiency compared to the benchmark and conventional frameworks.

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