![]() ; ; et al in International Journal of Satellite Communications and Networking (2020) This paper studies the use of optical feeder links in very high throughput satellites (VHTS) networks with emphasis on gateway diversity techniques to mitigate the inherent propagation losses in optical ... [more ▼] This paper studies the use of optical feeder links in very high throughput satellites (VHTS) networks with emphasis on gateway diversity techniques to mitigate the inherent propagation losses in optical frequencies. Focusing on a GEO scenario, the paper considers a system‐wide approach investigating various challenges of optical feeder links. These include transmission schemes amenable for transparent on‐board processing, optical channel models taking into account blockage by clouds and fading caused by atmospheric turbulence in addition to complexity of on‐board and on‐ground processing. The channel models are then used to dimension the ground segment towards ensuring a given availability percentage (e.g., 99.9%). The channel model and payload complexity further influence the choice of link layer techniques used for counteracting fading due to atmospheric turbulence in the absence of blockage. An elaborate end‐to‐end simulator incorporating the proposed channel models capturing the nuances of various processing blocks like optical‐electrical conversion is developed. The system performance results provide interesting insights and a framework for assessing the feasibility and advantages of optical feeder links in VHTS systems. [less ▲] Detailed reference viewed: 49 (3 UL)![]() Bandi, Ashok ![]() ![]() ![]() in International conference on signal processing and communications (SPCOM) (2020, July) This paper studies the joint design of user scheduling and precoding for the maximization of spectral efficiency (SE) for a multigroup multicast scenario in multiuser MISO downlink channels. Noticing that ... [more ▼] This paper studies the joint design of user scheduling and precoding for the maximization of spectral efficiency (SE) for a multigroup multicast scenario in multiuser MISO downlink channels. Noticing that the existing definition of SE fails to account for group sizes, a new metric called multicast spectral efficiency (MC-SE) is proposed. In this context, the joint design is considered for the maximization of MC-SE. Firstly, with the help of binary scheduling variables, the joint design problem is formulated as a mixed-integer non-linear programming problem such that it facilitates the joint update of scheduling and precoding variables. Further, useful reformulations are proposed to reveal the hidden difference-of-convex/concave structure of the problem. Thereafter, we propose a convex-concave procedure based iterative algorithm with convergence guarantees to a stationary point. Finally, we compare different aspects namely MC-SE, SE and number of scheduled users through Monte-Carlo simulations. [less ▲] Detailed reference viewed: 110 (7 UL)![]() Alaeekerahroodi, Mohammad ![]() ![]() in Information Theoretic Approach for Waveform Design in Coexisting MIMO Radar and MIMO Communications (2020, May 14) We investigate waveform design for coexistence between a multipleinput multiple-output (MIMO) radar and MIMO communications (MRMC), with a radar-centric criterion that leads to a minimal interference in ... [more ▼] We investigate waveform design for coexistence between a multipleinput multiple-output (MIMO) radar and MIMO communications (MRMC), with a radar-centric criterion that leads to a minimal interference in the communications system. The communications use the traditional mode of operation in Long Term Evolution (LTE)/Advanced (FDD), where we formulate the design problem based on information-theoretic criterion with the discrete phase constraint at the design stage. The optimization problem, is nonconvex, multi-objective and multi-variable, where we propose an efficient algorithm based on the coordinate descent (CD) framework to simultaneously improve radar target detection performance and the communications rate. The numerical results indicate the effectiveness of the proposed algorithm in designing discrete phase set of sequences, potentially binary. [less ▲] Detailed reference viewed: 69 (1 UL)![]() Sedighi, Saeid ![]() ![]() in IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) (2020) Parameter estimation from noisy and one-bit quantized data has become an important topic in signal processing, as it offers low cost and low complexity in the implementation. On the other hand, Direction ... [more ▼] Parameter estimation from noisy and one-bit quantized data has become an important topic in signal processing, as it offers low cost and low complexity in the implementation. On the other hand, Direction-of-Arrival (DoA) estimation using Sparse Linear Arrays (SLAs) has recently gained considerable interest in array processing due to their attractive capability of providing enhanced degrees of freedom. In this paper, the problem of DoA estimation from one-bit measurements received by an SLA is considered and a novel framework for solving this problem is proposed. The proposed approach first provides an estimate of the received signal covariance matrix through minimization of a constrained weighted least-squares criterion. Then, MUSIC is applied to the spatially smoothed version of the estimated covariance matrix to find the DoAs of interest. Several numerical results are provided to demonstrate the superiority of the proposed approach over its counterpart already propounded in the literature. [less ▲] Detailed reference viewed: 61 (1 UL)![]() Arora, Aakash ![]() ![]() ![]() in Proc. 2020 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP) (2020) In this paper, we provide a framework for the direction of arrival (DOA) estimation using a single moving sensor and evaluate performance bounds on estimation. We introduce a signal model which captures ... [more ▼] In this paper, we provide a framework for the direction of arrival (DOA) estimation using a single moving sensor and evaluate performance bounds on estimation. We introduce a signal model which captures spatio-temporal incoherency in the received signal due to sensor motion in space and finite bandwidth of the signal, hitherto not considered. We show that in such a scenario, the source signal covariance matrix becomes a function of the source DOA, which is usually not the case. Due to this unknown dependency, traditional subspace techniques cannot be applied and conditions on source covariance needs to imposed to ensure identifiability. This motivates us to investigate the performance bounds through the Cramer-Rao Lower Bounds (CRLBs) to set benchmark performance for future estimators. This paper exploits the signal model to derive an appropriate CRLB, which is shown to be better than those in relevant literature. [less ▲] Detailed reference viewed: 93 (21 UL)![]() Tedgue Beltrao, Gabriel ![]() ![]() in Proceedings of the 21st International Radar Symposium (IRS), Warsaw, Poland, 2020 (2020) Waveform design and optimization algorithms generally assume a zero-Doppler ideal case to reach an optimum or satisfactory solution in terms of the matched filter output. Therefore, its performance is ... [more ▼] Waveform design and optimization algorithms generally assume a zero-Doppler ideal case to reach an optimum or satisfactory solution in terms of the matched filter output. Therefore, its performance is usually characterized only in terms of the resultant waveforms autocorrelation function, neglecting the practical situation in which the received signal is modulated by the target’s Doppler shift. Within this context, this work investigates the Doppler mismatch effects in the Integrated Sidelobe Level (ISL) performance of previously designed/optimized noise waveforms. The analysis has shown that, despite much better results for steady targets, the increasing Doppler mismatch reduces the ISL performance of optimized waveforms, until similar levels achieved when no optimization is performed. To address that, a subpulse Doppler processing approach is also considered, and the results have shown that, besides increasing the Doppler tolerance, it has also increased the optimized waveform robustness to the Doppler mismatch, reducing the resultant ISL loss and thus extending its applicability. [less ▲] Detailed reference viewed: 72 (6 UL)![]() Tedgue Beltrao, Gabriel ![]() ![]() in Proceedings of the 2020 IEEE Radar Conference (RadarConf20), Florence, Italy, 2020 (2020) This paper presents the joint design of discrete slow-time radar waveform and receive filter, with the aim of enhancing the Signal to Interference and Noise Ratio (SINR) in phase coded radar systems for ... [more ▼] This paper presents the joint design of discrete slow-time radar waveform and receive filter, with the aim of enhancing the Signal to Interference and Noise Ratio (SINR) in phase coded radar systems for vital-sign monitoring. Towards this, we consider maximizing the SINR at the input of the vital-sign estimation block, when transmitting hardware efficient Mary Phase Shift Keying (MPSK) sequences. This multi-variable and non-convex optimization problem is efficiently solved based on a Minimum Variance Distortionless Response (MVDR) filter, with the Coordinate Descent (CD) approach for the sequence optimization, and the obtained results have shown attractive interference suppression capabilities, even for the simple binary case. [less ▲] Detailed reference viewed: 134 (9 UL) |
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