Secure Satellite Communication Systems Design with Individual Secrecy Rate Constraints

In this paper, we study multibeam satellite secure communication through physical (PHY) layer security techniques, i.e., joint power control and beamforming. By first assuming that the Channel State Information (CSI) is available and the beamforming weights are fixed, a novel secure satellite system design is investigated to minimize the transmit power with individual secrecy rate constraints. An iterative algorithm is proposed to obtain an optimized power allocation strategy. Moreover, sub-optimal beamforming weights are obtained by completely eliminating the co-channel interference and nulling the eavesdroppers' signal simultaneously. In order to obtain jointly optimized power allocation and beamforming strategy in some practical cases, e.g., with certain estimation errors of the CSI, we further evaluate the impact of the eavesdropper's CSI on the secure multibeam satellite system design. The convergence of the iterative algorithm is proven under justifiable assumptions. The performance is evaluated by taking into account the impact of the number of antenna elements, number of beams, individual secrecy rate requirement, and CSI. The proposed novel secure multibeam satellite system design can achieve optimized power allocation to ensure the minimum individual secrecy rate requirement. The results show that the joint beamforming scheme is more favorable than fixed beamforming scheme, especially in the cases of a larger number of satellite antenna elements and higher secrecy rate requirement. Finally, we compare the results under the current satellite air-interface in DVB-S2 and the results under Gaussian inputs.Comment: 34 pages, 10 figures, 1 table, submitted to "Transactions on Information Forensics and Security

Optimization of Joint Power and Bandwidth Allocation in Multi-Spot-Beam Satellite Communication Systems

Multi-spot-beam technique has been widely applied in modern satellite communication systems. However, the satellite power and bandwidth resources in a multi-spot-beam satellite communication system are scarce and expensive; it is urgent to utilize the resources efficiently. To this end, dynamically allocating the power and bandwidth is an available way. This paper initially formulates the problem of resource joint allocation as a convex optimization problem, taking into account a compromise between the maximum total system capacity and the fairness among the spot beams. A joint bandwidth and power allocation iterative algorithm based on duality theory is then proposed to obtain the optimal solution of this optimization problem. Compared with the existing separate bandwidth or power optimal allocation algorithms, it is shown that the joint allocation algorithm improves both the total system capacity and the fairness among spot beams. Moreover, it is easy to be implemented in practice, as the computational complexity of the proposed algorithm is linear with the number of spot beams

Generic Optimization of Linear Precoding in Multibeam Satellite Systems

Multibeam satellite systems have been employed to provide interactive broadband services to geographical areas under-served by terrestrial infrastructure. In this context, this paper studies joint multiuser linear precoding design in the forward link of fixed multibeam satellite systems. We provide a generic optimization framework for linear precoding design to handle any objective functions of data rate with general linear and nonlinear power constraints. To achieve this, an iterative algorithm which optimizes the precoding vectors and power allocation alternatingly is proposed and most importantly, the proposed algorithm is proved to always converge. The proposed optimization algorithm is also applicable to nonlinear dirty paper coding. In addition, the aforementioned problems and algorithms are extended to the case that each terminal has multiple co-polarization or dual-polarization antennas. Simulation results demonstrate substantial performance improvement of the proposed schemes over conventional multibeam satellite systems, zero-forcing and regularized zero-forcing precoding schemes in terms of meeting the traffic demand. The performance of the proposed linear precoding scheme is also shown to be very close to the dirty paper coding

Joint optimization of Beam Placement and Shaping for Multi-Beam High Throughput Satellite systems using Gradient Descent

El mercat de les comunicacions per satèl·lit està canviant i la nova generació de satèl·lits tindrà nivells de flexibilitat i escalabilitat sense precedents: s'espera que els futurs Satèl·lits d'Alt Rendiment de múltiples feixos (HTS, per les sigles en anglès) puguin operar milers de feixos simultàniament, cadascun amb un conjunt de paràmetres completament dinàmics per sintonitzar. Això planteja nous reptes quan es tracta d'administrar eficientment la creixent quantitat de recursos. Dos d'aquests reptes estan vinculats a: la ubicació del feix (és a dir, definint la direcció de cada feix) i la forma del feix (és a dir, optimitzant la distribució de guany entre els usuaris coberts). Comprendre com explotar aquestes dues flexibilitats podria millorar l'eficiència, reduïr la potència requerida i permetre l'allotjament de nous usuaris al sistema. Per tant, aquesta tesi es centra en l'optimització conjunta de la posició i forma dels feixos.El mercado de las comunicaciones por satélite está cambiando y la nueva generación de satélites tendrá niveles de flexibilidad y escalabilidad sin precedentes: se espera que los futuros Satélites de Alto Rendimiento de múltiples haces (HTS, por las siglas en inglés) puedan operar miles de haces simultáneamente, cada uno con un conjunto de parámtetros completamente dinámicos para sintonizar. Esto plantea nuevos desafíos cuando se trata de administrar eficientemente la creciente cantidad de recursos. Dos de estos desafíos están vinculados a: la ubicación del haz (es decir, definiendo la dirección para cada haz) y a la forma del haz (es decir, optimizando la distribución de ganancia entre los usuarios cubiertos). Comprender cómo explotar estas dos flexibilidades podría mejorar la eficiencia, reducir la potencia requerida y permitir el alojamiento de nuevos usuarios en el sistema. Por lo tanto, esta tesis se centra en la optimización conjunta de la posición y forma de los haces.The satellite communications market is changing and new generation of satellites will have unprecedented levels of flexibility and scalability: future multi-beam High Throughput Satellites (HTS) are expected to be able to operate thousands of beams simultaneously, each with a set of fully-dynamic parameters to tune. This poses new challenges when it comes to efficiently managing the increasing amount of resources. Two of these challenges are linked to the beam placement (i.e., defining the pointing direction for each beam) and beam shape (i.e., optimizing the gain distribution among covered users) problems. Understanding how to exploit these two flexibilities could improve the efficiency, reducing the required RF power and enabling the accommodation of new users into the system. Thus, this Thesis focuses on the joint beam placement and shaping optimization.Outgoin