Darren Tat

Integrated and validated Ericsson and Nokia LTE/5G RAN in Faraday labs and Production, focusing on IMS, VoLTE/VoNR, data, and SIP-based services. Performed RAN node bring-up and configuration using RF emulators and lab setups across 4G, 5G SA/NSA access technologies. Tested a wide range of End-to-End (E2E) user scenarios, validating user/control plane call flows from UE to core to ensure seamless network attach, mobility, and session management.

Network Engineer - AT&T

(2022-05 - 2026-07)

• Integrated and validated Ericsson and Nokia LTE/5G RAN in Faraday labs and Production, focusing on IMS, VoLTE/VoNR, data, and SIP-based services.
• Performed RAN node bring-up and configuration using RF emulators and lab setups across 4G, 5G SA/NSA access technologies.
• Tested a wide range of End-to-End (E2E) user scenarios, validating user/control plane call flows from UE to core to ensure seamless network attach, mobility, and session management.
• Collected and analyzed control/user plane logs (QXDM, Wireshark, PCAP, NGxP, Iris, Radcom, ADB) to troubleshoot issues, isolate faults, and drive defect resolution.
• Developed and executed system-level regression and acceptance test object lists (TOLs) for data, call flows, IMS registration, and SIP signaling.
• Collaborated with Ericsson/Nokia RAN and EPC/5G core engineers on failure analysis, bug tracking (Jira), and customer acceptance support.
• Supported end-to-end negative, regression, sanity, and functionality testing and rollback validation to ensure network resilience and reliability.
• Applied Python scripting for log parsing, KPI extraction, and basic automation of repeatable test cases.

Field Test Engineer - SAMSUNG ELECTRONICS AMERICA

(2022-01 - 2022-05)

• Conducted field and lab validation of 4G/5G NR features (VoNR, EN-DC, EPSFB, GPS, NSA, SA, FR1/FR2) for AT&T and T-Mobile networks.
• Executed first-office-application (FOA) / NPI acceptance testing in collaboration with carrier engineering teams.
• Diagnosed protocol failures and optimized device performance through detailed AP/CP log analysis (QXDM, RDX).
• Delivered daily customer-facing reports and acceptance documentation covering test case results, KPIs, and defect summaries.
• Ensured device and RAN compliance with North American carrier standards and multi-band deployment requirements.

Electrical Engineer Intern - STI OPTRONICS INC.

(2020-12 - 2021-06)

• Led a 4-person team to design and prototype a custom RF controller generating three low-distortion RF signals at 3MHz, 66MHz, and 99MHz.
• Designed, debugged, and tested PCB schematics using oscilloscopes, spectrum analyzers, and power meters.

B.S. - Electrical Engineering - UNIVERSITY OF WASHINGTON (2019-09 - 2021-06)