Repeater Deployment Research Articles

Building optimization testing framework (BOPTEST) for simulation-based benchmarking of control strategies in buildings

Development of new building HVAC control algorithms has grown due to needs for energy efficiency and operational flexibility. However, case studies demonstrating new algorithms are largely individualized, making algorithm performance difficult to compare directly. In addition, the effort and expertise required to implement case studies in real or simulated buildings limits rapid prototyping potential. Therefore, this paper presents the Building Optimization Testing Framework (BOPTEST) and associated software for simulation-based benchmarking of building HVAC control algorithms. A containerized run-time environment (RTE) enables rapid, repeatable deployment of common building emulators representing different system types. Emulators use Modelica to represent realistic physical dynamics, embed baseline control, and enable overwriting supervisory and local-loop control signals. Finally, a common set of key performance indicators are calculated within the RTE and reported to the user. This paper details the design and implementation of software and demonstrates its usage to benchmark a Model Predictive Control strategy.

Design and Dynamic Analysis of Rigid Foldable Aeroshells for Atmospheric Entry

A novel rigid deployable aeroshell architecture has been developed, where rigid panels with a thermal protection system layer are connected between retractable ribs. Following origami principles, an optimal fold pattern is selected and imposed on the panels to ensure efficient flat stowage during launch and repeatable deployment. The design process includes minimizing the number of folds to reduce stacking height and maximizing the angles between each fold line to avoid an unfavorable aerothermodynamic response. The dynamic behavior of the optimal design is analyzed with the aid of a dynamic multibody analysis model. Results from the dynamic model show that the process of deployment is highly sensitive to panel geometry (especially panel thickness and hinge design). Robust, repeatable, and controllable deployment is most readily achieved with a small (but nonzero) panel thickness and selection of interpanel hinges, which allow a degree of over-rotation, avoiding a premature hard stop, which would otherwise prevent full deployment. Modeled results have been verified through experimental testing of a 0.4-m-diam scale model.

Towards Quantum Satellite Internetworking: A Software-Defined Networking Perspective

Recently, quantum computing and communications rapidly developed to interconnect heterogeneous quantum devices. In particular, some researchers have been performed about terrestrial quantum communications over typical optical fiber links. However, this technology is affected by extremely high losses that can be faced only through the deployment of several repeaters, which in turn involve impractical costs for end-to-end (E2E) route management. Quantum Satellite Networks (QSNs) can overcome the limitations of terrestrial optical networks, such as a remarkable signal attenuation over long distances and difficulty of intercontinental communications. The recent studies on quantum satellite communications motivated our research towards a Low Earth Orbit (LEO) quantum satellite backbone for interconnecting quantum on Earth Servers in order to achieve an unprecedented computational capacity. Specifically, our paper proposes a near optimum E2E path evaluation procedure allowing an efficient switching in order to maximize the entanglement generation rate. Indeed, this is one of the main issues that involve the Data Link Layer and the Network Layer of the Quantum Internet (QI) protocol stack, which is in its early standardization phase. In particular, the design of our approach is based on the Software-Defined Networking (SDN) paradigm with the aim of minimizing the number of hops for E2E connection and maximizing network capacity. Therefore, we compare distributed and centralized approaches in order to achieve a trade-off between performance and cost.

High-speed quantum networking by ship.

Networked entanglement is an essential component for a plethora of quantum computation and communication protocols. Direct transmission of quantum signals over long distances is prevented by fibre attenuation and the no-cloning theorem, motivating the development of quantum repeaters, designed to purify entanglement, extending its range. Quantum repeaters have been demonstrated over short distances, but error-corrected, global repeater networks with high bandwidth require new technology. Here we show that error corrected quantum memories installed in cargo containers and carried by ship can provide a exible connection between local networks, enabling low-latency, high-fidelity quantum communication across global distances at higher bandwidths than previously proposed. With demonstrations of technology with sufficient fidelity to enable topological error-correction, implementation of the quantum memories is within reach, and bandwidth increases with improvements in fabrication. Our approach to quantum networking avoids technological restrictions of repeater deployment, providing an alternate path to a worldwide Quantum Internet.

LTE radio analytics made easy and accessible

Despite the rapid growth of next-generation cellular networks, researchers and end-users today have limited visibility into the performance and problems of these networks. As LTE deployments move towards femto and pico cells, even operators struggle to fully understand the propagation and interference patterns affecting their service, particularly indoors. This paper introduces LTEye, the first open platform to monitor and analyze LTE radio performance at a fine temporal and spatial granularity. LTEye accesses the LTE PHY layer without requiring private user information or provider support. It provides deep insights into the PHY-layer protocols deployed in these networks. LTEye's analytics enable researchers and policy makers to uncover serious deficiencies in these networks due to inefficient spectrum utilization and inter-cell interference. In addition, LTEye extends synthetic aperture radar (SAR), widely used for radar and backscatter signals, to operate over cellular signals. This enables businesses and end-users to localize mobile users and capture the distribution of LTE performance across spatial locations in their facility. As a result, they can diagnose problems and better plan deployment of repeaters or femto cells. We implement LTEye on USRP software radios, and present empirical insights and analytics from multiple AT&T and Verizon base stations in our locality.

Dynamic Gain Management for On-Channel Repeaters

Stability and output signal quality are always two major concerns with the deployment of on-channel repeaters. This paper proposes a gain management scheme and evaluates the performance of the proposed gain management technique for on-channel repeaters. The gain manager uses a loop gain metric as an indication of stability and output signal quality (SNR) of the repeater to continuously and accurately monitor the repeater status, and adjust the repeater gain accordingly. The repeater output SNR and stability can thus be tightly controlled. It is demonstrated that the proposed gain management ensures the safe and robust operation of the repeater against the dynamics of the environment.

A mobile multimedia satellite system reusing existing satellites

AbstractSince 2001, the European Space Agency has investigated a file‐based system for providing satellite radio to the automotive market. This system is significantly different from existing commercial counterparts, such as the American systems XM‐radio and Sirius. In terms of service it not only provides traditional radio services but is also capable of offering multimedia content and data transfer. In terms of infrastructure, it does not require launch of new satellites or deployment of terrestrial repeaters. As such it offers a highly efficient, low‐investment and low‐risk approach to offering satellite radio services to a consumer automotive market. Moreover, it departs from the traditional schedule‐based streaming radio concept to a concept in line with the concurrent developments within the media landscape, providing the user the full control of what entertainment to play and when to play it. This paper presents the system in more detail, outlines its performance and makes comparisons with other existing satellite radio systems. Copyright © 2008 John Wiley & Sons, Ltd.

Performance of an Echo Canceller and Channel Estimator for On-Channel Repeaters in DVB-T/H Networks

This paper investigates the design and performance of an FIR echo canceller for on-channel repeaters in DVB-T/H network within the framework of the PLUTO project. The possible approaches for echo cancellation are briefly reviewed and the main guidelines for the design of such systems are presented. The main system parameters are discussed. The performance of an FIR echo canceller based on an open loop feedforward approach for channel estimation is tested for different radio channel conditions and for different number of taps of the FIR filter. It is shown that a minimum number of taps is recommended to achieve a certain mean rejection ratio or isolation depending on the type of channel. The expected degradation in performance due to the use of fixed point rather than floating point arithmetic in hardware implementation is presented for different number of bits. Channel estimation based on training sequences is investigated. The performance of maximum length sequences and constant amplitude zero autocorrelation (CAZAC) sequences is compared for different channels. Recommendations are given for training sequence type, length and level for DVB-T/H on-channel repeater deployment.

Effect of repeaters on the performance in WCDMA networks

The target of this paper is to show the impact of repeaters on Wideband Code Division Multiple Access (WCDMA) system performance. Repeaters have been traditionally used in cellular mobile communication networks for temporary coverage extensions. However, deployment of repeaters in capacity-limited scenarios requires more careful radio network planning compared to the traditional approach for operation in coverage-limited environment. For the analysis, several system level simulations have been conducted together with actual field measurements. The measurements have been performed in order to complement and verify the simulations. The results of the simulations and field measurements reveal that a proper configuration of a repeater can provide a significant downlink gain in the cell capacity, which indicates the suitability of the repeaters also in capacity-limited environments. In addition, obtained outcomes show that repeaters can effectively improve cell dominance in pilot polluted areas, which has direct impacts on soft handover probabilities in the network. Finally, utilisation of repeaters might also improve the performance of the whole network by improving also the uplink direction.