Energy-Efficient Service-Aware Multi-Connectivity Scheduler for Uplink Multi-Layer Non-Terrestrial Networks

in IEEE Transactions on Green Communications and Networking (2023)

This paper introduces the concept of energy efficiency (EE) in the uplink with the capability of multi-connectivity (MC) in a multi-orbit non-terrestrial network (NTN), where user terminals (UTs) can be ... [more ▼]

This paper introduces the concept of energy efficiency (EE) in the uplink with the capability of multi-connectivity (MC) in a multi-orbit non-terrestrial network (NTN), where user terminals (UTs) can be simultaneously served by more than one satellite to achieve higher peak throughput at reduced energy consumption. This concept also considers the service classification of the users, so that network dimensioning is performed in order to satisfy the quality of service (QoS) requirement of users. MC can increase throughput, but this entails increased power consumption at user terminal for uplink transmissions. To this end, an energy-efficient service-aware multi-connectivity (EE-SAMC) scheduling algorithm is developed in this paper to improve the EE of uplink communications. EE-SAMC uses available radio resources and propagation information to intelligently define a dynamic resource allocation pattern, that optimally routes traffic so as to reduce the energy consumption at the UT while ensuring QoS is maximized. EE-SAMC is designed based on the formulation of a non-convex combinatorial problem, it is solved in two ways involving firstly an optimization solution and secondly a heuristic approach. The effectiveness of EE-SAMC is compared with random allocation, round robin and heuristic schedulers in terms of EE, throughput and delay; EE-SAMC outperforms all schedulers. [less ▲]

Characterizing and Utilizing the Interplay between Quantum Technologies and Non-Terrestrial Networks

in IEEE Transactions on Quantum Engineering (2023)

Quantum technologies have been widely recognized as one of the milestones towards the ongoing digital transformation, which will also trigger new disruptive innovations. Quantum technologies encompassing ... [more ▼]

Quantum technologies have been widely recognized as one of the milestones towards the ongoing digital transformation, which will also trigger new disruptive innovations. Quantum technologies encompassing quantum computing, communications, and sensing offer an interesting set of advantages such as unconditional security and ultra-fast computing capabilities. However, deploying quantum services at a global scale requires circumventing the limitations due to the geographical boundaries and terrestrial obstacles, which can be adequately addressed by considering non-terrestrial networks (NTNs). In the recent few years, establishing multi-layer NTNs has been extensively studied to integrate space-airborne-terrestrial communications systems, particularly by the international standardization organizations such as the third-generation partnership project (3GPP) and the international telecommunication union (ITU), in order to support future wireless ecosystems. Indeed, amalgamating quantum technologies and NTNs will scale up the quantum communications ranges and provide unprecedented levels of security and processing solutions that are safer and faster than the traditional offerings. This paper provides some insights into the interplay between the evolving NTN architectures and quantum technologies with a particular focus on the integration challenges and their potential solutions for enhancing the quantum-NTN interoperability among various space-air-ground communications nodes. The emphasis is on how the quantum technologies can benefit from satellites and aerial platforms as an integrated network and vice versa. Moreover, a set of future research directions and new opportunities are identified. [less ▲]

An Overview of Channel Models for NGSO Satellites

Scientific Conference (2022, September)

Performance Evaluation of Forward Link Packet Scheduling in Satellite Communication Systems with Carrier Aggregation

Scientific Conference (2022)

The rapidly growing demand for increased data rates and spectrum scarcity in satellite communication systems require new paradigms to effectively utilize radio resources. Of many candidate techniques ... [more ▼]

The rapidly growing demand for increased data rates and spectrum scarcity in satellite communication systems require new paradigms to effectively utilize radio resources. Of many candidate techniques, carrier aggregation (CA) is a promising solution that combines multiple carriers across the available spectrum to achieve a substantial increase in peak data rate and improve user experience. The concept of CA was introduced in 3GPP standards for the terrestrial communication systems and has been successfully deployed and commercialized worldwide. Recently, satellite communication community has investigated the requirements for adopting CA technique to satellite infrastructures. In this setting, aggregating multiple heterogeneous satellite links to boost a single-user peak throughput requires an efficient data packet scheduler at the gateway in order to avoid the out-of-order packet issues and the subsequent queuing delays at the receiver side. Thereby, several research efforts have been devoted to circumvent this challenge through developing packet schedulers that are aiming at delivering data packets without perturbing their original transmission order. In this paper, the performance of the developed schedulers is evaluated using end-to-end system simulations to investigate the impact of different network metrics. The obtained results demonstrate the design tradeoffs and summarize the pros and cons of the schedulers. [less ▲]

Combining Time-Flexible Satellite Payload with Precoding: The Cluster Hopping Approach

in IEEE Transactions on Vehicular Technology (2022)

High throughput geostationary (GEO) satellite systems are characterized by a multi-beam wide coverage. However, developing efficient resource management mechanisms to meet the heterogeneous user traffic ... [more ▼]

High throughput geostationary (GEO) satellite systems are characterized by a multi-beam wide coverage. However, developing efficient resource management mechanisms to meet the heterogeneous user traffic demands remains an open challenge for satellite operators. Furthermore, the spectrum shortage and the ever increasing demands claim for more aggressive frequency reuse. In this paper, we combine the time-flexible payload capabilities known as beam hopping (BH) with precoding techniques in order to satisfy user traffic requests in areas of high demand (i.e. hot-spot areas). The proposed framework considers a flexible beam-cluster hopping where adjacent beams can be activated if needed, forming clusters with various shapes and sizes. In this context, we present three strategies to design the beam illumination patterns. First, a max-min user demand fairness satisfaction problem; second, a penalty-based optimization is considered to penalize the occurrence of adjacent beams in an attempt to avoid precoding whenever possible. Third, seeking a low-complexity design, we propose a queuing-based approach to solve the problem in a time-slot by time-slot basis trying to provide service to users based on the requested demands. The three methods are discussed in detailed and evaluated via numerical simulations, confirming their effectiveness versus benchmark schemes and identifying the pros and cons of each proposed design. [less ▲]

Channel Estimation for UAV Communication Systems Using Deep Neural Networks

in Drones (2022)

Channel modeling of unmanned aerial vehicles (UAVs) from wireless communications has gained great interest for rapid deployment in wireless communication. The UAV channel has its own distinctive ... [more ▼]

Channel modeling of unmanned aerial vehicles (UAVs) from wireless communications has gained great interest for rapid deployment in wireless communication. The UAV channel has its own distinctive characteristics compared to satellite and cellular networks. Many proposed techniques consider and formulate the channel modeling of UAVs as a classification problem, where the key is to extract the discriminative features of the UAV wireless signal. For this issue, we propose a framework of multiple Gaussian–Bernoulli restricted Boltzmann machines (GBRBM) for dimension reduction and pre-training utilization incorporated with an autoencoder-based deep neural network. The developed system used UAV measurements of a town’s already existing commercial cellular network for training and validation. To evaluate the proposed approach, we run ray-tracing simulations in the program Remcom Wireless InSite at a distinct frequency of 28 GHz and used them for training and validation. The results demonstrate that the proposed method is accurate in channel acquisition for various UAV flying scenarios and outperforms the conventional DNNs. [less ▲]

Traffic-Aware Satellite Switch-off Technique for LEO Constellations

Scientific Conference (2022)

Broadband Non-Geostationary Satellite Communication Systems: Research Challenges and Key Opportunities

Scientific Conference (2021, June)

Besides conventional geostationary (GSO) satellite broadband communication services, non-geostationary (NGSO) satellites are envisioned to support various new communication use cases from countless ... [more ▼]

Besides conventional geostationary (GSO) satellite broadband communication services, non-geostationary (NGSO) satellites are envisioned to support various new communication use cases from countless industries. These new scenarios bring many unprecedented challenges that will be discussed in this paper alongside with several potential future research opportunities. NGSO systems are known for various advantages, including their important features of low cost, lower propagation delay, smaller size, and lower losses in comparison to GSO satellites. However, there are still many deployment challenges to be tackled to ensure seamless integration not only with GSO systems but also with terrestrial networks. In this paper, we discuss several key challenges including satellite constellation and architecture designs, coexistence with GSO systems in terms of spectrum access and regulatory issues, resource management algorithms, and NGSO networking requirements. Additionally, the latest progress in provisioning secure communication via NGSO systems is discussed. Finally, this paper identifies multiple important open issues and research directions to inspire further studies towards the next generation of satellite networks. [less ▲]

Scheduling Design and Performance Analysis of Carrier Aggregation in Satellite Communication Systems

in IEEE Transactions on Vehicular Technology (2021)

Carrier Aggregation is one of the vital approaches to achieve several orders of magnitude increase in peak data rates. While carrier aggregation benefits have been extensively studied in cellular networks ... [more ▼]

Carrier Aggregation is one of the vital approaches to achieve several orders of magnitude increase in peak data rates. While carrier aggregation benefits have been extensively studied in cellular networks, its application to satellite systems has not been thoroughly explored yet. Carrier aggregation can offer an enhanced and more consistent quality of service for users throughout the satellite coverage via combining multiple carriers, utilizing the unused capacity at other carriers, and enabling effective interference management. Furthermore, carrier aggregation can be a prominent solution to address the issue of the spatially heterogeneous satellite traffic demand. This paper investigates introducing carrier aggregation to satellite systems from a link layer perspective. Deployment of carrier aggregation in satellite systems with the combination of multiple carriers that have different characteristics requires effective scheduling schemes for reliable communications. To this end, a novel load balancing scheduling algorithm has been proposed to distribute data packets across the aggregated carriers based on channel capacities and to utilize spectrum efficiently. Moreover, in order to ensure that the received data packets are delivered without perturbing the original transmission order, a perceptive scheduling algorithm has been developed that takes into consideration channel properties along with the instantaneous available resources at the aggregated carriers. The proposed modifications have been carefully designed to make carrier aggregation transparent above the medium access control (MAC) layer. Additionally, the complexity analysis of the proposed algorithms has been conducted in terms of the computational loads. Simulation results are provided to validate our analysis, demonstrate the design tradeoffs, and to highlight the potentials of carrier aggregation applied to satellite communication systems. [less ▲]

Traffic Simulator for Multibeam Satellite Communication Systems

Scientific Conference (2020, October 20)

Assume that a multibeam satellite communication system is designed from scratch to serve a particular area with maximal resource utilization and to satisfactorily accommodate the expected traffic demand ... [more ▼]

Assume that a multibeam satellite communication system is designed from scratch to serve a particular area with maximal resource utilization and to satisfactorily accommodate the expected traffic demand. The main design challenge here is setting optimal system parameters such as number of serving beams, beam directions and sizes, and transmit power. This paper aims at developing a tool, multibeam satellite traffic simulator, that helps addressing these fundamental challenges, and more importantly, provides an understanding to the spatial-temporal traffic pattern of satellite networks in large-scale environments. Specifically, traffic demand distribution is investigated by processing credible datasets included three major input categories of information: (i) population distribution for broadband Fixed Satellite Services (FSS), (ii) aeronautical satellite communications, and (iii) vessel distribution for maritime services. This traffic simulator combines this three-dimensional information in addition to time, locations of terminals, and traffic demand. Moreover, realistic satellite beam patterns have been considered in this work, and thus, an algorithm has been proposed to delimit the coverage boundaries of each satellite beam, and then compute the heterogeneous traffic demand at the footprint of each beam. Furthermore, another algorithm has been developed to capture the inherent attributes of satellite channels and the effects of multibeam interference. Data-driven modeling for satellite traffic is crucial nowadays to design innovative communication systems, e.g. precoding and beam hopping, and to devise efficient resource management algorithms. [less ▲]