L3 Developer Telecom Wireless 5G 4G LTE

Role & responsibilities

Position/Title- L3 Developer

Overall exp- 2-8 Years

Any domain specification- TELECOM / WIRELESS /5G/4G/LTE

Qualification Criteria- BE/ B tech

Mandatory Skills- RAN, L3 Layer (PDCP, RRC), C++, 3GPP Specifications

Preferred Skills: Google Test Framework (GTF)

Work location- Bengaluru (Manyata)

Details JD-

Skill-set & Expertise Level

• Protocol knowledge: RRC, S1AP, X2AP
• 4G/5G Layer 3 Procedures Knowledge: attach, handover, re-establishment, carrier aggregation (CA), EN-DC/NR-DC
• Expertise in mobility control, measurement control & configuration, bearer/session signaling, reconfiguration, security activation flows, release, dual connectivity, idle/connected transitions, RLF handling, cell reselection, and paging/idle mode procedures and core-triggered session/bearer coordination and inter-node procedures for both LTE/E-UTRAN and NG-RAN/NR
• Knowledge of control-plane interfaces and procedures including S1AP/X2AP for LTE and NGAP/F1AP/E1AP/XnAP for 5G architectures, along with understanding of how RRC procedures interact with AMF/MME, SMF/SGW-C/PGW-C
• Programming: C/C++/ Python Programming Language, memory pooling, Programming & Debugging state machine design, error handling, traceability, and robust interoperability engineering across different UE/chipset/core/network-vendor combinations, ASN.1/protocol decode workflows
• L3 data path expertise - GTPU, DPDK & VPP expertise
• Understanding of Linux Environment, Inter-Process Communication (IPC), Processes, Threads, and Multithreading
• Knowledge of containerization (Kubernetes, Pods, and Docker)
• Experience in field issue analysis using RRC/NGAP/S1AP/F1AP/E1AP traces, Wireshark decodes, KPI dashboards, and log-correlation from RAN and core, and in translating issues into reproducible lab scenarios
• Knowledge of call-flow, ASN.1 handling, timer/state management, error recovery, and backward/forward compatibility across releases
• Log Analysis: Proficiency in analyzing system logs to diagnose issues.
• Specialized Tools: Expertise in using tools like QCAT (UE logs) Viavi (network testing and measurement equipment) plus IxLoad Wireless, IxNetwork, Spirent Landslide, Wireshark for testing/debugging
• Expertise on FPGA/SoC-based acceleration, SmartNIC/DPU-assisted data paths, DPDK/hugepages/SR-IOV, Linux performance tuning for virtualized DU/CU implementations, x86/ARM servers deployment, diagnosis of KPI loss using traces, PCAPs, timing logs, etc
• L3 software development experience
• Additional years of driving delivery of 4G/5G L3 programs

Roles & Responsibilities

• Design and implement RRC/ S1AP/X2AP/ NGAP/F1AP/E1AP/XnAP and higher-layer control-plane features for LTE and NR
• Review and Mentor high performance L3 teams towards delivery excellence in the following:
• Investigate and close defects such as attach/registration failures, handover drops, security-mode failures, RRC resume issues, paging misses, Xn/F1/E1 mis-synchronization, and UE/vendor-specific interoperability issues.
• Work closely with verification, OAM, and core-network teams to create call-flow validation, stress scenarios, interoperability campaigns, and negative/failure-recovery tests
• Ability to drive large scale 4G/5G L3 product development, sustenance and customer support programs involving multiple variants of eNodeBs/gNodeBs in various forms including vRAN/ORAN/custom
• Ability to communicate with senior levels of internal and external stakeholders