Dynamic Beam-Layout Design for MEO High Throughput Satellite Systems

Scientific Conference (2022, December 04)

We propose a traffic-oriented beam-layout optimization framework for a medium Earth orbit (MEO) high throughput satellite (HTS) system. The designed beam-layout plans have the objective of dynamic traffic ... [more ▼]

We propose a traffic-oriented beam-layout optimization framework for a medium Earth orbit (MEO) high throughput satellite (HTS) system. The designed beam-layout plans have the objective of dynamic traffic load balancing with minimal radio resource management. We model and evaluate the high directivity and the high reconfigurability capabilities of next-generation HTS systems that are equipped with a processing power on board. The resulting payload flexibility is compared numerically against the on-ground counterpart. Adequate key performance indicators, such as the Jain’s fairness index, the load distribution gap and optimization convergence time, are used to benchmark the system against state-of-the-art solutions. Results show that a dynamic HTS in MEO is capable of efficiently attaining high quality load balancing performance under realistic spatiotemporally varying traffic demands. [less ▲]

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

in IEEE Communications Surveys & Tutorials (2022)

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 ... [more ▼]

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. [less ▲]

Enablers for Matching Demand in GEO Multi-Beam Satellites: Dynamic Beamforming, Precoding, or Both?

Scientific Conference (2021, September 30)

In trending satellite communication applications, the traffic demand is not only rapidly increasing, it is also spatiotemporally evolving. This motivates the deployment of high throughput satellite ... [more ▼]

In trending satellite communication applications, the traffic demand is not only rapidly increasing, it is also spatiotemporally evolving. This motivates the deployment of high throughput satellite systems with flexible radio resource management and transmission techniques. In contrast to regular beam layout plans (RBLP) currently used in GEO payloads, future flexible payloads are capable of dynamic beamforming (DBF) in order to illuminate the coverage area using highly-directive and traffic-adaptive beampatterns. The beampatterns in an adaptive beam layout plan (ABLP) can have irregular shapes and mutual overlaps, potentially causing excessive inter-beam interferences (IBI) compared to the RBLP case. In this work, we evaluate the combination of DBF and precoding as the latter promises high throughputs in interference-limited conditions and is supported by the recent DVB-S2X norm. Under realistic non-uniform traffic patterns, we compare a typical RBLP against an ABLP in terms of their traffic matching performances with and without precoding. Through the comparisons, we show that DBF enables to significantly reduce the capacity mismatches using an ABLP that uniformly balances the demand distribution across beams. Noting that the ABLP is IBI agnostic, an unpredictable interference environment is built. In such conditions, precoding enables to reliably provide high throughputs through full frequency reuse. [less ▲]

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

in IEEE Internet of Things Journal (2021), 8(9), 7437-7449

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 ... [more ▼]

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. [less ▲]