Downlink Coverage and Rate Analysis of Low Earth Orbit Satellite Constellations Using Stochastic Geometry

As low Earth orbit (LEO) satellite communication systems are gaining increasing popularity, new theoretical methodologies are required to investigate such networks' performance at large. This is because deterministic and location-based models that have previously been applied to analyze satellite systems are typically restricted to support simulations only. In this paper, we derive analytical expressions for the downlink coverage probability and average data rate of generic LEO networks, regardless of the actual satellites' locality and their service area geometry. Our solution stems from stochastic geometry, which abstracts the generic networks into uniform binomial point processes. Applying the proposed model, we then study the performance of the networks as a function of key constellation design parameters. Finally, to fit the theoretical modeling more precisely to real deterministic constellations, we introduce the effective number of satellites as a parameter to compensate for the practical uneven distribution of satellites on different latitudes. In addition to deriving exact network performance metrics, the study reveals several guidelines for selecting the design parameters for future massive LEO constellations, e.g., the number of frequency channels and altitude.Comment: Accepted for publication in the IEEE Transactions on Communications in April 202

Performance of quantized random beamforming in delay-tolerant machine-type communication

Machine-to-machine (M2M) communication represents a new paradigm for mobile cellular networks, where a massive number of low-cost devices request the transfer of small amounts of data without human intervention. One option to tackle this problem is obtained by combining random beamforming (RBF) with opportunistic scheduling. RBF can be used to induce larger channel fluctuations, and opportunistic scheduling can be used to select M2M devices when their overall channel quality is good. Traditional RBF does not fulfill M2M requirements, because overall channel quality needs to be tracked continuously. In order to tackle this limitation, a novel codebook-based RBF architecture that identifies in advance the time instants in which overall channel quality should be reported, within a coherence time window, is proposed. This opportunistic feedback mechanism reduces signaling overhead and enables energy saving at M2M devices. A simplified methodology is presented to evaluate the system mean data rate, using for this purpose closed form formulas derived from SNR distribution approximations. Results reveal that the performance loss that is experienced for introducing the proposed modifications to traditional RBF scheme is negligible. The concepts analyzed in this paper provide useful insights, and show that codebook-based RBF with simplified opportunistic scheduling algorithms is an excellent combination to provide wide-area M2M services with low-cost devices and limited signaling overhead.Fil: Dowhuszko, Alexis Alfredo. Centre Tecnològic de Les Telecomunicacions de Catalunya; España. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Corral Briones, Graciela. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; ArgentinaFil: Hamalainen, Jyri. Aalto University; FinlandiaFil: Wichman, Risto Ilari. Aalto University; Finlandi

On routing protocols in inter-satellite communications

Low earth orbit (LEO) satellite networks offer broadcasting to remote places or places at the time of natural or human-caused calamities. LEO satellites are preferable in a real-time communication compared to e.g. geostationary satellites due to smaller propagation delay and packet loss. Inter-satellite communication may further reduce the end-to-end delay between two terrestrial nodes. Routing of the networks will play a crucial role in optimizing the potential capacity of the network. We present and analyze a simple ALOHA type routing protocol for inter-satellite links in a satellite network.publishedVersio

Performance Evaluation of Low Earth Orbit Communication Satellites

Recently, there is a growing trend toward deploying low Earth orbit communication satellites due to lower latency and easier launching compared with geostationary satellites. In this paper, we study the effect of altitude and inclination angle on the coverage probability and data rate of a user located in Tampere. The simulations show that the minimum inclination angle that results in sufficient coverage and data rate decreases as altitude increases. On the other hand, for inclination angles which are larger than the minimum required inclination, the better performance is obtained for lower altitudes. This study provides a guideline for LEO constellation design based on coverage and data rate needs.publishedVersio

Bit Loading Using Imperfect CSIT for Prediction-Based Resource Allocation in Mobile OFDMA

We present a prediction-based resource allocation algorithm (RA) for orthogonal frequency-division multiple-access (OFDMA) downlink, where inaccuracies in the wireless channel predictions are accounted for in the problem formulation. As the prediction quality significantly degrades with the prediction horizon, we propose a solution based on the histogram of the prediction error. This characterization also enables different mobile stations (MSs) to use different channel predictors as it does not rely on a specific prediction scheme. Using this characterization of the prediction error and based on classical resource allocation strategies, we derive an algorithm that incorporates imperfect channel prediction information of future time slots. We evaluate the proposed algorithm using a practical low-complexity channel predictor suitable for implementation at the MSs. Simulation results show that the proposed algorithm outperforms previous prediction-based RA strategies without the characterization of the prediction error, and the system throughput is comparable with the case with perfect channel state information in the transmitter (CSIT).Fil: Schmidt, Jorge Friedrich. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Cousseau, Juan Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Wichman, Risto Ilari. Aalto University; FinlandiaFil: Werner, Stefan. Aalto University; Finlandi

Low-Complexity Channel Prediction Using Approximated Recursive DCT

We present a novel channel estimator/predictor for OFDM systems over time-varying channels using a recursive formulation of a basis expansion model (BEM) based on an approximated discrete cosine transform (DCT). We derive a recursive implementation of the approximated DCT-BEM for tracking time-varying channels based on a filter bank. The recursive approximated DCT-BEM structure is then used for long range channel prediction by proper scaling and time extrapolation of the filter bank. As the implicit BEM is time invariant we further simplify the implementation by employing a steady-state Kalman filter whose overall complexity is comparable to an LMS algorithm. The derived predictor outperforms, in terms of predictor range, previously proposed long range predictors that are based on autoregressive (AR) modeling of the time-varying channel. For a similar performance, in terms of MSE, the computational complexity of the proposed predictor is significantly lower than conventional sum-of-sinusoids (SOS) channel predictors as no channel delays nor Doppler frequencies need to be estimated.Fil: Schmidt, Jorge Friedrich. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Cousseau, Juan Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Wichman, Risto Ilari. Aalto University; FinlandiaFil: Werner, Stefan. Aalto University; Finlandi

BEP Analysis of OSTBC-OFDM systems with broadband pa and imperfect memory compensation

We analyze the performance of an OFDM system with diversity, in particular Orthogonal Space Time Block Coding (OSTBC) systems, including a broadband nonlinear power amplifier (PA) with memory. Closed-form expressions for the BER are obtained for cases when PA memory is compensated at the transmitter or the receiver. The results confirm that not only clipping noise, but also imperfect PA memory compensation has a significant impact on the system performance.Fil: Gregorio, Fernando Hugo. University of Helsinski; Finlandia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Werner, Stefan. University of Helsinski; FinlandiaFil: Hamalainen, Jyri. Nokia Siemens Networks; FinlandiaFil: Wichman, Risto Ilari. University of Helsinski; FinlandiaFil: Cousseau, Juan Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras; Argentin

Receiver-side nonlinearities mitigation using an extended iterative decision-based technique

This work presents an iterative receiver cancellation technique for mitigating the inband distortion introduced by a nonlinear wideband transmitter power amplifier (PA). The proposed decision-based technique employs a Wiener–Hammerstein model that accounts for the nonlinear transfer function and memory of the PA as well as for the wireless propagation channel. As such, the mitigation technique can be seen as a generalization of existing iterative decision-based techniques assuming memoryless PA nonlinearities. For successful distortion mitigation, the iterative technique requires an estimate of the nonlinear model that characterizes the PA. We propose to perform this model identification at the receiver, embedded in an iterative decision-based scheme, avoiding the nonideal analog-to-digital feedback loop associated with transmitter-based model identification. A stochastic algorithm is proposed for the model identification providing the necessary PA model parameters required for symbol detection. In addition, we analyze the convergence properties of the proposed technique. Simulation results confirm that the proposed mitigation technique provides distortion cancellation at almost the same level to the case of perfect knowledge of the PA model. These results enable us to employ power amplifiers with more relaxed linearity requirement, moving the operation point to a region with improved power efficiency while reducing the system overall degradation.Fil: Gregorio, Fernando Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Werner, Stefan. Aalto University; FinlandiaFil: Cousseau, Juan Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Figueroa, Jose Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Wichman, Risto Ilari. Aalto University; Finlandi

Theoretical and simulation-based analysis of terrestrial interference to LEO satellite uplinks

The integration of satellite-terrestrial networks is beneficial in terms of the increase of the network capacity and coverage. In such a heterogeneous network, highly efficient spectrum utilization is extremely important. This could be achieved by the single frequency reuse which allows increasing the capacity at the cost of increased interference. Interference is one of the main parameters that limits the link-level performance in such a network. In this paper, we examine the frequency reuse scenario by analyzing the impact of terrestrial interference to the uplink of a low Earth orbiting (LEO) satellite constellation in the high International Mobile Telecommunications (IMT) frequency bands. To this end, we propose a novel stochastic geometry based analytical framework that is able to accommodate various aspects of realistic satellite networks. The accuracy of the analysis is verified by using advanced simulation tools.acceptedVersionPeer reviewe