Layer 3 Protocol Engineer

Job Title: RAN L3 Protocol Engineer (LTE/5G)

Job Summary

• We are seeking a skilled RAN L3 Protocol Engineer to design, develop, and validate Layer 3 (L3) functionality for LTE/5G Radio Access Network systems. The ideal candidate will have strong expertise in RRC, NAS, and related L3 protocol layers, along with hands-on experience defining and managing L3 profiles, and a solid understanding of overall RAN architecture.

Key Responsibilities

• Design and implement RRC/ S1AP/X2AP/ NGAP/F1AP/E1AP/XnAP and higher-layer control-plane features for LTE and NR
• 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
• Understand and work with core RAN network elements (eNB/gNB) and their key interfaces toward the core network and neighboring cells
• Support protocol conformance testing and validation against 3GPP specifications (i.e. 3GPP 36.42x and 38.42x)
• Analyze protocol logs and traces (QXDM, AT commands, or equivalent tools) to debug L3-layer issues
• Contribute to architecture and design documentation for L3 modules and profile schemas
• Participate in requirement analysis, scope definition, and delivery planning for RAN-related features
• Work closely with QA teams to define test cases and acceptance criteria tied to L3 profile behavior
• Support mobility/handover procedures, carrier aggregation, and inter-RAT scenarios as relevant to L3 design

Required Skills & Experience

• Strong understanding of LTE/5G RAN architecture, particularly Layer 3 protocols (RRC, NAS)
• General working knowledge of RAN network elements and interfaces (e.g., eNB/gNB, S1/NG, X2/Xn, Uu)
• Experience defining or working with L3 layer profiles (UE capability, feature/parameter sets, configuration profiles)
• 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

Preferred Qualifications

• Bachelor's/Master's degree in Electronics, Telecommunications, or Computer Science
• Prior experience with eNB/gNB stack development or RAN integration projects
• Experience with mobility/handover, carrier aggregation, or inter-RAT (LTE-5G) scenarios
• Experience working in multi-vendor or multi-team RAN integration environments