40 research outputs found
The Role of Physical Layer Security in Satellite-Based Networks
In the coming years, 6G will revolutionize the world with a large amount of
bandwidth, high data rates, and extensive coverage in remote and rural areas.
These goals can only be achieved by integrating terrestrial networks with
non-terrestrial networks. On the other hand, these advancements are raising
more concerns than other wireless links about malicious attacks on
satellite-terrestrial links due to their openness. Over the years, physical
layer security (PLS) has emerged as a good candidate to deal with security
threats by exploring the randomness of wireless channels. In this direction,
this paper reviews how PLS methods are implemented in satellite communications.
Firstly, we discuss the ongoing research on satellite-based networks by
highlighting the key points in the literature. Then, we revisit the research
activities on PLS in satellite-based networks by categorizing the different
system architectures. Finally, we highlight research directions and
opportunities to leverage the PLS in future satellite-based networks
Rate-splitting multiple access for non-terrestrial communication and sensing networks
Rate-splitting multiple access (RSMA) has emerged as a powerful and flexible
non-orthogonal transmission, multiple access (MA) and interference management
scheme for future wireless networks. This thesis is concerned with the application of
RSMA to non-terrestrial communication and sensing networks. Various scenarios
and algorithms are presented and evaluated.
First, we investigate a novel multigroup/multibeam multicast beamforming strategy
based on RSMA in both terrestrial multigroup multicast and multibeam satellite
systems with imperfect channel state information at the transmitter (CSIT). The
max-min fairness (MMF)-degree of freedom (DoF) of RSMA is derived and shown
to provide gains compared with the conventional strategy. The MMF beamforming
optimization problem is formulated and solved using the weighted minimum mean
square error (WMMSE) algorithm. Physical layer design and link-level simulations
are also investigated. RSMA is demonstrated to be very promising for multigroup
multicast and multibeam satellite systems taking into account CSIT uncertainty
and practical challenges in multibeam satellite systems.
Next, we extend the scope of research from multibeam satellite systems to satellite-
terrestrial integrated networks (STINs). Two RSMA-based STIN schemes are
investigated, namely the coordinated scheme relying on CSI sharing and the co-
operative scheme relying on CSI and data sharing. Joint beamforming algorithms
are proposed based on the successive convex approximation (SCA) approach to
optimize the beamforming to achieve MMF amongst all users. The effectiveness and
robustness of the proposed RSMA schemes for STINs are demonstrated.
Finally, we consider RSMA for a multi-antenna integrated sensing and communications (ISAC) system, which simultaneously serves multiple communication users
and estimates the parameters of a moving target. Simulation results demonstrate
that RSMA is beneficial to both terrestrial and multibeam satellite ISAC systems by
evaluating the trade-off between communication MMF rate and sensing Cramer-Rao
bound (CRB).Open Acces
SLNR-based Secure Energy Efficient Beamforming in Multibeam Satellite Systems
Motivated by the fact that both security and energy
efficiency are the fundamental requirements and design targets
of future satellite communications, this letter investigates secure
energy efficient beamforming in multibeam satellite systems, where
the satellite user in each beam is surrounded by an eavesdropper
attempting to intercept the confidential information. To simul-
taneously improve the transmission security and reduce power
consumption, our design objective is to maximize the system secrecy
energy efficiency (SEE) under the constraint of total transmit
power budget. Different from the existing schemes with high
complexity, we propose an alternating optimization scheme to
address the SEE problem by decomposing the original nonconvex
problem into subproblems. Specifically, we first utilize the signal-
to-leakage-plus-noise ratio (SLNR) metric to obtain closed-form
normalized beamforming weight vectors, while the successive convex
approximation (SCA) method is used to efficiently solve the power
allocation subproblem. Then, an iterative algorithm is proposed
to obtain the suboptimal solutions. Finally, simulation results are
provided to verify the superiority of the proposed scheme compared
to the benchmark scheme
Joint beamforming design for secure RIS-assisted IoT networks
This paper studies secure communication in an internet-of-things (IoT) network, where the confidential signal is sent by an active refracting reconfigurable intelligent surface (RIS)-based transmitter, and a passive reflective RIS is utilized to improve the secrecy performance of users in the presence of multiple eavesdroppers. Specifically, we aim to maximize the weighted sum secrecy rate by jointly designing the power allocation, transmit beamforming (BF) of the refracting RIS, and the phase shifts of the reflective RIS. To solve the non-convex optimization problem, we propose a linearization method to approximate the objective function into a linear form. Then, an alternating optimization (AO) scheme is proposed to jointly optimize the power allocation factors, BF vector and phase shifts, where the first one is found using the Lagrange dual method, while the latter two are obtained by utilizing the penalty dual decomposition method. Moreover, considering the demands of green and secure communications, by applying the Dinkelbach’s method, we extend our proposed scheme to solving a secrecy energy maximization problem. Finally, simulation results demonstrate the effectiveness of the proposed design
Recommended from our members
Total and Minimum Energy Efficiency Tradeoff in Robust Multigroup Multicast Satellite Communications
Data Availability: All data needed to evaluate the conclusions of the study are presented in the paper.Copyright © 2023 Bin Jiang et al. Satellite communication is an indispensable part of future wireless communications given its global coverage and long-distance propagation. In satellite communication systems, channel acquisition and energy consumption are two critical issues. To this end, we investigate the tradeoff between the total energy efficiency (TEE) and minimum EE (MEE) for robust multigroup multicast satellite communication systems in this paper. Specifically, under the total power constraint, we investigate the robust beamforming aimed at balancing the TEE-MEE, so as to achieve the balance between the fairness and total performance on the system EE. For this optimization problem, we first model the balancing problem as a nonconvex problem while deriving its approximate closed-form average user rate. Then, the nonconvex problem is handled by solving convex programs sequentially with the help of the semidefinite relaxation and the concave-convex procedure. In addition, depending on the solution rank value, Gaussian randomization and eigenvalue decomposition method are applied to generate the feasible solutions. Finally, simulation results illustrate that the proposed approach can effectively achieve the balance between the TEE and MEE, thus realizing a tradeoff between fairness and system EE performance. It is also indicated that the proposed robust approach outperforms the conventional baselines in terms of EE performance.This work was supported by the National Natural Science Foundation of China under Grant 62341110, the Key Technologies R&D Program of Jiangsu (Prospective and Key Technologies for Industry) under Grants BE2022067 and BE2022067-5, the Jiangsu Province Basic Research Project under Grant BK20192002, the Fundamental Research Funds for the Central Universities under Grants 2242021R41148 and 2242022k60007, and the Young Elite Scientist Sponsorship Program by China Institute of Communications. The work of J.Z. was supported by the National Natural Science Foundation of China under Grant U2233216
Symbol-level and Multicast Precoding for Multiuser Multiantenna Downlink: A State-of-the-art, Classification and Challenges
Precoding has been conventionally considered as an effective means of mitigating or exploiting the interference in the multiantenna downlink channel, where multiple users are simultaneously served with independent information over the same channel resources. The early works in this area were focused on transmitting an individual information stream to each user by constructing weighted linear combinations of symbol blocks (codewords). However, more recent works have moved beyond this traditional view by: i) transmitting distinct data streams to groups of users and ii) applying precoding on a symbol-per-symbol basis. In this context, the current survey presents a unified view and classification of precoding techniques with respect to two main axes: i) the switching rate of the precoding weights, leading to the classes of block-level and symbol-level precoding, ii) the number of users that each stream is addressed to, hence unicast, multicast, and broadcast precoding. Furthermore, the classified techniques are compared through representative numerical results to demonstrate their relative performance and uncover fundamental insights. Finally, a list of open theoretical problems and practical challenges are presented to inspire further research in this area