SUMMARYThis paper presents a feasibility study for a fixed broadband access High Throughput Satellite terabit/second system by considering appropriate state‐of‐the‐art communication technologies. For the investigated system model, DVB‐S2 and DVB‐RCS2 are assumed as the air interfaces for the forward and return link, respectively. The performance of DVB‐S2 and DVB‐RCS2 Adaptive Coding and Modulation is examined along with potential extensions of these standards. For example, the performance of very low rate DVB‐RCS turbo codes are investigated and their performance is evaluated. In addition, a performance comparison for M‐ary (M=16, 32, 64) constellations in the presence of a linear and a high power amplifier non‐linear channel is carried out. Various frequency reuse schemes and different antenna models are also considered, and their performance is analyzed and evaluated. It is demonstrated that, by using the Q/V (40/50 GHz) bands for the gateways and the Ka (20–30 GHz) band for the user terminals, around 20 gateways and 200 beams are required to provide with the proposed satellite system terabit/second capacity. The obtained performance evaluation results have shown that the forward link is limited by noise rather than interference, whereas the return link is interference limited. Additionally, some further aspects of the system design in relation with the total number of gateways and the payload are discussed. Copyright © 2014 John Wiley & Sons, Ltd.
Motivated by a recently published robust geometric programming approximation, a generalized approach for approximating efficiently the max * operator is presented. Using this approach, the max * operator is approximated by means of a generic and yet very simple max operator, instead of using additional correction term as previous approximation methods require. Following that, several turbo decoding algorithms are obtained with optimal and near-optimal bit error rate (BER) performance depending on a single parameter, namely the number of piecewise linear (PWL) approximation terms. It turns out that the known Max-Log-MAP algorithm can be viewed as special case of this new generalized approach. Furthermore, the decoding complexity of the most popular previously published methods is estimated, for the first time, in a unified way by hardware synthesis results, showing the practical implementation advantages of the proposed approximations against these methods.Terms-Turbo codes, iterative decoding. I. INTRODUCTIONO VER the past decade or so several algorithmic approaches aiming to simplify the well-known max * operator [1] for decoding turbo codes [2] have been proposed and analyzed. These algorithms include: Improved Max-Log-MAP [3], Constant Log-MAP [4], Linear Log-MAP [5], Average Log-MAP [6], and recently the algorithms in [7], [8]. The penalty paid for such approximations is a small bit error rate (BER) performance degradation as compared with the performance achieved by the optimal Log-MAP algorithm [9]. However, although these sub-optimal algorithms are computationally simpler as compared with the optimal solution, an additional correction term is required to be added to the max operation in order to minimize performance degradation.Geometric programing is an optimization problem used in various fields, such as information theory, analog/RF circuit design, power control of wireless communication networks and statistics [10]. However, its application to turbo decoding has not been investigated so far. Recently, the authors in [11] have dealt with the convex log-sum-exp (lse) function and considered a robust geometric programming problem as robust S. Papaharalabos and P. T. Mathiopoulos are with the Institute for Space Applications and Remote Sensing (ISARS),
Abstract-A panoramic view on the study and design of digital designed by the DVB-T2 group. Again, the DVB-T2 specifisatellite communication links is the focus of this paper. Starting cations will be OFDM-based and will include state-of-the-art from the characterization of satellite propagation channel in solutions such as MIMO, low density parity check (LDPC) different application environments (from broadcast to fixed terminals, to broadband mobile satellite access), we address scodin scm,prolayrorte rocreinFC physical layer aspects related to satellite communications in the smart and fast synchronization techniques. attempt of providing the Reader with an overview of the new Satellite communications are not immune from this wave trends and open issues in this field.of innovation. In the DVB forum, after the publication of the DVB-S2 standard and the approval of the DVB-SH specifica-
In this paper, we present a novel Deep Neural Network-based indoor localization method that estimates the position of a Bluetooth Low Energy (BLE) transmitter (tag) by using the received signals’ characteristics at multiple Anchor Points (APs). We use the received signal strength indicator (RSSI) value and the in-phase and quadrature-phase (IQ) components of the received BLE signals at a single time instance to simultaneously estimate the angle of arrival (AoA) at all APs. Through supervised learning on simulated data, various machine learning (ML) architectures are trained to perform AoA estimation using varying subsets of anchor points. In the final stage of the system, the estimated AoA values are fed to a positioning engine which uses the least squares (LS) algorithm to estimate the position of the tag. The proposed architectures are trained and rigorously tested on several simulated room scenarios and are shown to achieve a localization accuracy of 70 cm. Moreover, the proposed systems possess generalization capabilities by being robust to modifications in the room’s content or anchors’ configuration. Additionally, some of the proposed architectures have the ability to distribute the computational load over the APs.
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