Fairness-Aware Inter-Slice Scheduler for IoT Services over Satellite

peer reviewedThis paper addresses the problem of scheduling the uplink bandwidth of Low Earth Orbit (LEO) satellites among multiple Internet of Things (IoT) slices with diverse Quality of Service (QoS) requirements. The scheduling process involves twofold decisions the amount of bandwidth allocated and the allocation duration. Resource scheduling for satellite IoT services is challenging because of limited bandwidth availability during a satellite pass, especially for LEO satellites. Another challenge is to compute a fair allocation schedule for IoT services with different latency demands, packet transmission frequency, required data volume, and the number of IoT devices. To address these challenges, we propose a fairness-aware inter-slice scheduler for satellite IoT services in this work. The proposed scheduler computes service priority based on respective traffic demands. We propose two algorithms for the scheduler based on weighted greedy and Simulated Annealing (SA), respectively. The weighted greedy algorithm schedules the services greedily based on the priority order. The SA algorithm enhances the greedy solution by ensuring the allocated bandwidth is proportional to the respective priority values. The simulation results show that the proposed SA algorithm achieves up to 21.11% more proportional fairness than the Simulated Annealing and Monte Carlo (SA-MC) benchmark scheme

Efficient Preamble Detection and Time-of-Arrival Estimation for Single-Tone Frequency Hopping Random Access in NB-IoT

The narrowband internet of things (NB-IoT) standard is a new cellular wireless technology, which has been introduced by the 3rd Generation Partnership Project (3GPP) with the goal to connect massive low-cost, low-complexity and long-life IoT devices with extended coverage. In order to improve power efficiency, 3GPP proposed a new Random Access (RA) waveform for NB-IoT based on a single-tone frequencyhopping scheme. RA handles the first connection between user equipments (UEs) and the base station (BS). Through this, UEs can be identified and synchronized with the BS. In this context, receiver methods for the detection of the new waveform should satisfy the requirements on the successful user detection as well as the timing synchronization accuracy. This is not a trivial task, especially in the presence of radio impairments like carrier frequency offset (CFO) which constitutes one of the main radio impairments besides the noise. In order to tackle this problem, we propose a new receiver method for NB-IoT Physical Random Access Channel (NPRACH). The method is designed to eliminate perfectly the CFO without any additional computational complexity and supports all NPRACH preamble formats. The associated performance has been evaluated under 3GPP conditions. We observe a very high performance compared both to 3GPP requirements and to the existing state-of-the-art methods in terms of detection accuracy and complexity

Matching Traffic Demand in GEO Multibeam Satellites: The Joint Use of Dynamic Beamforming and Precoding Under Practical Constraints

To adjust for the non-uniform spatiotemporal nature of traffic patterns, next-generation high throughput satellite (HTS) systems can benefit from recent technological advancements in the space-segment in order to dynamically design traffic-adaptive beam layout plans (ABLPs). In this work, we propose a framework for dynamic beamforming (DBF) optimization and adaptation in dynamic environments. Given realistic traffic patterns and a limited power budget, we propose a feasible DBF operation for a geostationary multibeam HTS network. The goal is to minimize the mismatch between the traffic demand and the offered capacity under practical constraints. These constraints are dictated by the traffic-aware design requirements, the on-board antenna system limitations, and the signaling considerations in the K-band. Noting that the ABLP is agnostic about the inherent inter-beam interference (IBI), we construct an interference simulation environment using irregularly shaped beams for a large-scale multibeam HTS system. To cope with IBI, the combination of on-board DBF and on-ground precoding is considered. For precoded and non-precoded HTS configurations, the proposed design shows better traffic-matching capabilities in comparison to a regular beam layout plan. Lastly, we provide trade-off analyses between system-level key performance indicators for different realistic non-uniform traffic patterns

A Survey on Non-Geostationary Satellite Systems: The Communication Perspective

The next phase of satellite technology is being characterized by a new evolution in non-geostationary orbit (NGSO) satellites, which conveys exciting new communication capabilities to provide non-terrestrial connectivity solutions and to support a wide range of digital technologies from various industries. NGSO communication systems are known for a number of key features such as lower propagation delay, smaller size, and lower signal losses in comparison to the conventional geostationary orbit (GSO) satellites, which can potentially enable latency-critical applications to be provided through satellites. NGSO promises a substantial boost in communication speed and energy efficiency, and thus, tackling the main inhibiting factors of commercializing GSO satellites for broader utilization. The promised improvements of NGSO systems have motivated this paper to provide a comprehensive survey of the state-of-the-art NGSO research focusing on the communication prospects, including physical layer and radio access technologies along with the networking aspects and the overall system features and architectures. Beyond this, there are still many NGSO deployment challenges to be addressed to ensure seamless integration not only with GSO systems but also with terrestrial networks. These unprecedented challenges are also discussed in this paper, including coexistence with GSO systems in terms of spectrum access and regulatory issues, satellite constellation and architecture designs, resource management problems, and user equipment requirements. Finally, we outline a set of innovative research directions and new opportunities for future NGSO research

From fibers to satellites: Lessons to learn and pitfalls to avoid when optical communications move to long distance free space

peer reviewedThe paper summarizes the recent investigation on feasibility of adapting state-of-the-art coherent fiber-optics (FO) systems for Free Space Optical (FSO) scenarios. This investigation is critically dependent on the intertwined aspects of architecture, as well as device and propagation impairments (including the channel) appearing in the aforementioned systems. Towards this, the work identified the key system differences between the two systems. Particularly, the FSO channel model was investigated, impact of atmospheric turbulence on FSO was discussed and a channel series was generated. Subsequently, relevant FO techniques including coherent detection, wavelength division multiplexing and Time-Frequency packing (TFP) were reviewed. Another departure from FSO works was the emphasis on coherent reception; receiver architectures and diversity schemes were first investigated. The former strived to make fair comparison amongst the receivers considering the diverse nature of perturbation added, while the latter indicated gain in performance through increase of diversity order (2-4 dB gain). An immediate conclusion is a suggestion on adaptation of wavelength diversity when coherent receivers. The investigation also evaluated the capacity and outage of fast and slow fading channels with parameters motivated by the channel modelling work. The shaping gain was evaluated and an LDPC code design example was provided for FSO downlinks. Finally, TFP enabled a remarkable performance gain when applied to coherent detection schemes, but only marginal with direct detection. The paper concludes by pointing to the next steps that build on this investigation and the need to corroborate with measurements

Design and implementation of digital reception algorithms for IR-UWB radio link in body area networks

The impulse radio ultra-wideband (IR-UWB) technology has been recently adopted in the new IEEE 802.15.6 standard for Body Area Networks (BAN), in particular for communications between devices on or near the body surface. A priori, this technology is very attractive for mobile devices with limited energy resources, due to its flexibility in terms of throughput, complexity, and capacity for energy savings. However, the number of existing real implementations of UWB systems for BAN is very limited. In this context, the current Ph.D. thesis proposes a novel contribution in this area. The study focuses on digital baseband processing design for low-complexity non-coherent IR-UWB receivers. It concerns both the design of IR-UWB reception algorithms for BAN applications and their efficient hardware implementation. First, a complete non-coherent baseband reception chain has been proposed, tested, and validated through system simulations. Afterward, low-complexity hardware architectures have been designed to implement the proposed algorithms targeting an FPGA prototype. Finally, the feasibility of the complete communication system has been confirmed through practical experiments of real-time wireless transmissions with a complete hardware demonstrator. The obtained results demonstrate the technical viability of the proposed approach to implement efficiently IR-UWB technology for body area networks.La radio impulsionnelle ultra large bande (IR-UWB) a été retenue récemment pour la nouvelle norme IEEE 802.15.6 dédiée aux réseaux Body Area Network (BAN), en particulier pour les communications entre objets à la surface ou à proximité du corps. Cette technologie est apriori très attractive pour des objets nomades aux ressources énergétiques limitées, de par sa flexibilité en termes de débit, de complexité et de capacité à être économe en énergie. On peut cependant constater qu'il n'existe que peu d'implémentations réelles de systèmes UWB pour les BAN. Ce travail de thèse apporte une contribution dans ce domaine. L'étude est centrée sur le traitement numérique en bande de base pour les récepteurs non-cohérents de faible complexité et porte d'abord sur la conception d'algorithmes de réception UWB pour les BAN puis sur leur implémentation matérielle efficace sur cible FPGA. Dans un premier temps, une chaine de réception non-cohérente en bande de base complète a été proposée, testée, puis validée par simulation. Par la suite, une architecture matérielle de faible complexité a été conçue pour implémenter cette chaine puis portée sur une cible FPGA. Enfin, la faisabilité du système de communication complet a été confirmée par la réalisation d'expérimentations de transmissions réelles sans fil avec un démonstrateur matériel complet, confirmant ainsi la viabilité technique de l'approche retenue pour la mise en oeuvre de la technologie IR-UWB pour les réseaux BAN

NB-IoT Random Access for Non-Terrestrial Networks: Preamble Detection and Uplink Synchronization

The satellite component is recognized as a promising solution to complement and extend the coverage of future Internet of things (IoT) terrestrial networks (TNs). In this context, a study item to integrate satellites into narrowband-IoT (NBIoT) systems has been approved within the 3rd Generation Partnership Project (3GPP) standardization body. However, as NBIoT systems were initially conceived for TNs, their basic design principles and operation might require some key modifications when incorporating the satellite component. These changes in NB-IoT systems, therefore, need to be carefully implemented in order to guarantee a seamless integration of both TN and non-terrestrial network (NTN) for a global coverage. This paper addresses this adaptation for the random access (RA) step in NBIoT systems, which is in fact the most challenging aspect in the NTN context, for it deals with multi-user time-frequency synchronization and timing advance for data scheduling. In particular, we propose an RA technique which is robust to typical satellite channel impairments, including long delays, significant Doppler effects, and wide beams, without requiring any modification to the current NB-IoT RA waveform. Performance evaluations demonstrate the proposal’s capability of addressing different NTN configurations recently defined by 3GPP for the 5G new radio system

Efficient synchronization technique for non-coherent IR-UWB receiver targeting IEEE 802.15.6 wireless BAN

International audienceThe introduction in 2012 of the IEEE 802.15.6 standard for wireless body area networks (BAN) stimulates the research of practical and efficient receiver implementations. One of the main challenges in this context deals with the signal synchronization for the impulse radio ultra wideband (IR-UWB) physical layer. Targeting non-coherent detectors, which are known to offer significant energy-per-bit savings over their coherent counterparts, this paper presents a novel standard-compliant synchronization technique. The proposed technique is based on inter-pulse time interval detection and comparison. The associated performance has been evaluated using relevant channel models specified in the IEEE 802.15.6 standard. Promising results are demonstrated in terms of number of synchronization success rate and time

Hardware implementation of a non-coherent IR-UWB receiver synchronization algorithm targeting IEEE 802.15.6 wireless BAN

International audienceSynchronization acquisition is one of the main challenges for practical and efficient implementations of impulse radio ultra wideband (IR-UWB) receivers. This is particularly true in the context of the recently adopted IEEE 802.15.6 standard for wireless body area networks (BAN). Targeting energy-efficient non-coherent detectors, this paper presents a low-complexity hardware implementation of an efficient standard-compliant synchronization algorithm. The proposed architecture is described, together with performance and FPGA implementation results. A sub-optimal estimator of path selection and recombining is also proposed in the presented solution to improve the sensitivity of the receiver. Obtained results constitute a reference in this domain where the available literature is rather scarce