Senior Engineer - 5G Cloud (RMI Core Network Operations Dep)

Job Description:

About Organization

Core Network Operations Department is responsible for the operation of Rakuten Mobile’s fully virtualized network. We manage critical infrastructure, including IMS (IP Multimedia Subsystem), RCS (Rich Communication Services), EPC (Evolved Packet Core), International Roaming, IoT, and Emergency Services. Our mission is to ensure the continuity, reliability, and availability of these services through advanced automation and AI-driven operational frameworks. The team consists of 50+ highly skilled Technical SMEs, Operations Engineers, Project Managers, and Problem Managers working within a VNF/CNF-based fully virtualized core network environment.

• 5G SA Expansion:With the launch of 5G SA services, we are initiating 5GC operations and require specialized talent to lead this transition.

• Strengthening Capabilities:As core technology becomes increasingly complex and we migrate toward cloud-native architectures, we need to reinforce our team to ensure uninterrupted and reliable service delivery using AI and automation.

• Workload Management:Due to our expanding customer base and the adoption of cutting-edge technologies, we are seeking additional resources to manage the increasing operational demands.

Job Duties

• Provide L2/L3 level troubleshooting support for 5GC E2E operations.

• Resolve technical issues related to core and cloud infrastructure, including vendor-specific product support.

• Manage and resolve complex customer issues escalated from the monitoring support team.

• Perform in-depth audits and implement improvement plans.

• Conduct regular technical analysis to ensure service optimization and quality.

• Collaborate with internal teams, partners, and vendors to resolve technical issues and implement corrective actions.

• Conduct configuration testing and verification to ensure compliance with regulatory and service requirements.

• Analyze service/operational KPIs, generate reports, and contribute to process and procedure improvements.

• Document and maintain detailed records of support activities, including resolutions and troubleshooting steps.

• Execute configuration changes and manage communication across different domains.

• Build and maintain a knowledge database to enhance daily operational efficiency.

• Identify and fix incidents within the agreed Service Level Agreement (SLA).

• Participate in an on-call shift rotation, including occasional night and weekend support for urgent issues or scheduled maintenance.

• Work Location: Tokyo Office-based.

Minimum Qualifications

• 10+ years of experience in mobile core network operations or planning.

• Hands-on experience with 5GC products.

• Hands-on experience with multi-vendor Packet Core products.

• Hands-on experience with container-based infrastructure (Kubernetes).

• Strong knowledge of automation and AI frameworks.

Preferred Qualifications

• Deep understanding of mobile network protocols (Diameter, GTP, SIP, RTP, IP-based protocols).

• Strong technical knowledge of E2E Virtual Core network architecture (IMS, EPC, RCS, CNF) and CNF-based mobile networks.

• Experience with monitoring tools, performance analysis, and 5G Core/Cloud deployment.

• Proficiency in industry-standard tools for analyzing KPIs and metrics.

• Working experience with OpenStack or Kubernetes.

• Expertise in Method of Procedure (MOP) preparation and validation.

• Experience leading Incident Bridges and preparing reports for senior management.

• Strong analytical, problem-solving, and interpersonal communication skills.

• Relevant technical certifications.

Languages:

English (Overall - 3 - Advanced)