Ramón Martínez Rodríguez-O

Dr. Ramón Martínez Rodríguez-O


Research Focus & Metrics

Academic Career Length

23Years (2004-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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23 March 2022 in Electronics
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Journal Article
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Flor OrtizFlor Ortiz
Flor Ortiz
LLLei Lei
Lei Lei
Eva LagunasEva Lagunas
Eva Lagunas
RRRamón Martínez Rodríguez-O
Ramón Martínez Rodríguez-O
Daniele TarchiDaniele Tarchi
Daniele Tarchi
SCSymeon Chatzinotas
Symeon Chatzinotas
Satellite communications (SatComs) systems are facing a massive increase in traffic demand. However, this increase is not uniform across the service area due to the uneven distribution of users and changes in traffic demand diurnal. This problem is addressed by using flexible payload architectures, which allow payload resources to be flexibly allocated to meet the traffic demand of each beam. While optimization-based radio resource management (RRM) has shown significant performance gains, its intense computational complexity limits its practical implementation in real systems. In this paper, we discuss the architecture, implementation and applications of Machine Learning (ML) for resource management in multibeam GEO satellite systems. We mainly focus on two systems, one with power, bandwidth, and/or beamwidth flexibility, and the second with time flexibility, i.e., beam hopping. We analyze and compare different ML techniques that have been proposed for these architectures, emphasizing the use of Supervised Learning (SL) and Reinforcement Learning (RL). To this end, we define whether training should be conducted online or offline based on the characteristics and requirements of each proposed ML technique and discuss the most appropriate system architecture and the advantages and disadvantages of each approach.

10 September 2020 in IEEE Systems Journal
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Journal Article
Open access
Flor OrtizFlor Ortiz
Flor Ortiz
Daniele TarchiDaniele Tarchi
Daniele Tarchi
RRRamón Martínez Rodríguez-O
Ramón Martínez Rodríguez-O
AVAlessandro Vanelli-Coralli
Alessandro Vanelli-Coralli
Miguel Salas-NateraMiguel Salas-Natera
Miguel Salas-Natera
SLSalvador Landeros-Ayala
Salvador Landeros-Ayala
Very high throughput satellite (VHTS) systems are expected to have a large increase in traffic demand in the near future. However, this increase will not be uniform throughout the service area due to the nonuniform user distribution, and the changing traffic demand during the day. This problem is addressed using flexible payload architectures, enabling the allocation of the payload resources in a flexible manner to meet traffic demand of each beam, leading to dynamic resource management (DRM) approaches. However, DRM adds significant complexity to the VHTS systems, which is why in this article, we are analyzing the use of convolutional neural networks (CNNs) to manage the resources available in flexible payload architectures for DRM. The VHTS system model is first outlined, for introducing the DRM problem statement and the CNN-based solution. A comparison between different payload architectures is performed in terms of DRM response, and the CNN algorithm performance is compared by three other algorithms, previously suggested in the literature to demonstrate the effectiveness of the suggested approach and to examine all the challenges involved.

5 July 2021 in Remote Sensing
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Flor OrtizFlor Ortiz
Flor Ortiz
Miguel Salas-NateraMiguel Salas-Natera
Miguel Salas-Natera
RRRamón Martínez Rodríguez-O
Ramón Martínez Rodríguez-O
SLSalvador Landeros-Ayala
Salvador Landeros-Ayala
Very High Throughput Satellites (VHTS) have a pivotal role in complementing terrestrial networks to increase traffic demand. VHTS systems currently assume a uniform distribution of traffic in the service area, but in a real system, traffic demands are not uniform and are dynamic. A possible solution is to use flexible payloads, but the cost of the design increases considerably. On the other hand, a fixed payload that uses irregular beam coverage depending on traffic demand allows maintaining the cost of a fixed payload while minimizing the error between offered and required capacity. This paper presents a proposal for optimizing irregular beams coverage and beam pattern, minimizing the costs per Gbps in orbit, the Normalized Coverage Error, and Offered Capacity Error per beam. We present the analysis and performance for the case study and compare it with a previous algorithm for a uniform coverage area.

3 February 2022 in Neural Processing Letters
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Journal Article
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Ivan CornejoIvan Cornejo
Ivan Cornejo
SLSalvador Landeros-Ayala
Salvador Landeros-Ayala
JMJose M. Matias
Jose M. Matias
Flor OrtizFlor Ortiz
Flor Ortiz
RRRamón Martínez Rodríguez-O
Ramón Martínez Rodríguez-O
Miguel Salas-NateraMiguel Salas-Natera
Miguel Salas-Natera

22 August 2021 in International Journal of Satellite Communications and Networking
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Journal Article
Closed access
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Flor OrtizFlor Ortiz
Flor Ortiz
Daniele TarchiDaniele Tarchi
Daniele Tarchi
RRRamón Martínez Rodríguez-O
Ramón Martínez Rodríguez-O
AVAlessandro Vanelli‐Coralli
Alessandro Vanelli‐Coralli
Miguel Salas-NateraMiguel Salas-Natera
Miguel Salas-Natera
SLSalvador Landeros‐Ayala
Salvador Landeros‐Ayala

12 March 2020 in Electronics
Verified
Journal Article
Open access
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Flor OrtizFlor Ortiz
Flor Ortiz
RRRamón Martínez Rodríguez-O
Ramón Martínez Rodríguez-O
Miguel Salas-NateraMiguel Salas-Natera
Miguel Salas-Natera
Ivan CornejoIvan Cornejo
Ivan Cornejo
SLSalvador Landeros-Ayala
Salvador Landeros-Ayala
The concept of geostationary VHTS (Very High Throughput Satellites) is based on multibeam coverage with intensive frequency and polarization reuse, in addition to the use of larger bandwidths in the feeder links, in order to provide high capacity satellite links at a reduced cost per Gbps in orbit. The dimensioning and design of satellite networks based on VHTS imposes the analysis of multiple trade-offs to achieve an optimal solution in terms of cost, capacity, and the figure of merit of the user terminal. In this paper, we propose a new method for sizing VHTS satellite networks based on an analytical expression of the forward link CINR (Carrier-to-Interference-plus-Noise Ratio) that is used to evaluate the trade-off of different combinations of system parameters. The proposed method considers both technical and commercial requirements as inputs, including the constraints to achieve the optimum solution in terms of the user G/T, the number of beams, and the system cost. The cost model includes both satellite and ground segments. Exemplary results are presented with feeder links using Q/V bands, DVB-S2X and transmission methods based on CCM and VCM (Constant and Variable Coding and Modulation, respectively) in two scenarios with different service areas.