Junior Researcher - Doctoral Candidate

Junior Researcher – Doctoral Candidate
Security- and Sovereignty-Aware Spectrum Operations in Multi-Operator 5G Networks

We are seeking a junior researcher to work on security- and sovereignty-aware spectrum operations in multi-operator 5G networks as part of an international Doctoral Training Network.

SpecX ( is a prestigious Marie Skłodowska-Curie Actions Doctoral Network (MSCA-DN), funded under Horizon Europe, that provides a high-level research programme and doctoral training to 15 Doctoral Candidates across leading European universities and research institutions. The network focuses on large-scale spectrum measurements, AI-empowered analytics, and applications in future telecommunications infrastructure, including 5G and emerging 6G systems.

This doctoral position aims to analyse how roaming security vulnerabilities and cloud sovereignty constraints affect the reliability, trustworthiness, and performance of spectrum-dependent 5G services in multi-operator environments. The Doctoral Candidate will develop analytical frameworks, anomaly detection and prediction mechanisms, and operator-friendly security solutions that improve the robustness of roaming and cloud-based deployments. The research will support mobile network operators in ensuring secure, sovereign, and policy-aligned operation of advanced 5G and emerging 6G networks, with direct application to systems within Telefónica.

Key Responsibilities

• Conduct original doctoral research on security, sovereignty, and spectrum performance in multi-operator 5G/6G environments, under the supervision of Telefónica Senior Researchers and UC3M faculty.
• Develop and implement analytical frameworks and anomaly detection models targeting roaming and cloud-based network deployments.
• Engage with operational requirements and insights provided by Telefónica as part of the SpecX industrial partnership.
• Publish research findings in leading peer-reviewed venues and contribute to SpecX deliverables and reports.
• Participate in SpecX network-wide training events, workshops, and consortium meetings across Europe.
• Complete a planned secondment (typically 3–6 months) at an industrial or academic partner within the SpecX consortium.
• Contribute to the dissemination and outreach activities of the SpecX project, including public engagement and policy-facing outputs.
• Enrol in and fulfil the requirements of the UC3M PhD Programme in Telematics Engineering, including coursework and annual progress reviews.

Candidate Profile

Essential Requirements

• Master's degree (or equivalent, obtained or expected before the start date) in Telecommunications Engineering, Computer Science, Electrical Engineering, or a closely related field.
• Strong background in mobile networks (5G/LTE), network security, or cloud computing architectures.
• Solid analytical and programming skills (e.g., Python or similar).
• Excellent written and oral communication skills in English.
• Eligibility under MSCA mobility rules: the candidate must not have resided or carried out their main activity in Spain for more than 12 months in the 36 months immediately prior to the recruitment date.
• Must be in the first four years of their research career and not yet have been awarded a doctoral degree at the time of recruitment.

Desirable Qualifications

• Familiarity with 3GPP standards related to roaming (e.g., SEPP, N32 interface) or cloud-native network architectures (e.g., O-RAN, MEC).
• Experience with anomaly detection, machine learning, or AI-based approaches in networked systems.
• Prior research experience demonstrated through thesis work, publications, or internships in relevant areas.
• Experience working with network measurement or operator environments.
• Knowledge of regulatory and policy frameworks governing telecommunications spectrum and data sovereignty.

What We Offer

• A fully funded doctoral position under the prestigious Marie Skłodowska-Curie Actions framework, with a competitive monthly living and mobility allowance in accordance with MSCA-DN rules.
• Enrolment in the UC3M PhD Programme in Telematics Engineering, one of Spain's leading research universities.
• Access to a pan-European research network of 15 doctoral candidates, 10+ beneficiary institutions, and leading industrial partners.
• A structured training programme including technical courses, transferable skills training, and international secondments.
• Direct contract with Telefónica, one of the world's largest telecommunications operators, through the SpecX industrial partnership.
• An international, inclusive, and interdisciplinary research environment based in Madrid.
• Career development support targeting academic, industrial, and public-sector pathways in telecommunications and beyond.

Cuando te unes a Telefónica

Te unes a casi 100 años de historia, un equipo de 106 nacionalidades presentes en más de 35 países. Te unes a un equipo que trabaja por conectar a las personas allá dónde estén, sin fronteras. Un equipo que está liderando la revolución digital con la ilusión del primer día en todos nuestros negocios, creando el mejor ecosistema digital para nuestros clientes: Red, IoT, Cloud, Ciberseguridad, Innovación etc. En Telefónica tienes todo lo que necesitas para crear la mejor versión de ti mismo. Necesitamos gente como tú que se sume a este gran reto, que quiera crear la Telefónica del mañana.

En Telefónica apostamos por las nuevas formas de trabajo y somos líderes en la implementación de la Desconexión Digital bajo el principio “Desconecta para Reconectar”.

Te unes a una compañía cuya actividad se rige por su código ético, Nuestros Principios de Negocio Responsable. Buscamos personas que se identifiquen con los mismos, que nos ayuden a tomar decisiones basadas en la integridad, el compromiso y la transparencia y que se comprometan con una gestión ética, promoviendo un desarrollo social y ambiental más justo y sostenible.

#SomosDiversos

Estamos convencidos de que los equipos diversos e inclusivos son más innovadores, transformadores y consiguen mejores resultados. Por ello promovemos y garantizamos la inclusión de todas las personas sin importar género, edad, orientación e identidad sexual, cultura, discapacidad o cualquier otra condición personal.