Andrew Cho

ac3rj9@r.postjobfree.com

Career Objective

As wireless CDMA, EvDo, WCDMA, LTE, VoLTE Engineer, I have experience about Wireless Network, Planning, Design, Deployment, Installations and Systems Engineering and able to troubleshoot end to end wireless networks. To also develop and mature in a challenging work environment that will create further career opportunities and responsibility.

Skill Set

Wireless Technologies: CDMA 1xRTT, EVDO Rel.0/Rev.A, WCDMA,eHRPD, LTE, VoLTE.

Good understanding EPC elements (MME,S-GW,P-GW) and interface (S1AP,S1-U,S11,S5/S8,S6a)

Good understanding 3GPP and 3GPP2

Knowledge of Cisco Switch and Router (create configuration for installing in field and Lab setup)

Knowledge of IP-related protocols : VoIP, SIP, VPN, TCP/IP, UDP, IPSEC, VLAN, DNS, DHCP, PPP, AAA, MIP

Wireless IP data : PDSN, AN-AAA, AAA, HSGW,PDN GW, ASR5000

Network analyzer tool : Wireshark.

I have experience to design and implement for CDMA and LTE system

System test by using mobiles of Samsung, LG, Motorola, HTC, Apple, Kyosera, Sony etc.

Unix Operating System Experience

Wireless development tool : QXDM, QPST, QCAT

Experience with IMS (Ericsson SDS), IPsec GW for Linux (StrongSwan), TCS (Tatara Convergence Server) and Femtocell Service Manager(FSM) for CDMA Enterprise Femto network.

Experience in the calibration and operation of RF equipments : signal generators, spectrum analyzers, code domain (VSA), power meter.

Wireless system integration and troubleshooting.

Work Experience

CVE Technology – Allen, Tx

QA Manager, October 2016 till present

Mobiles test for ATT and T-Mobile

Functional test and verify various Mobiles using Pervacio and zero mode

Connectivity and RF test : Max power and throughput

Lab setup and create test cases

Troubleshooting and make a report to send customer.

Discussion with customer to resolve issues

Ericsson – Richardson, Tx

IOT engineer, September 2015 till March 2016

CDMA/EvDo and LTE cabled Interoperability Testing (IOT) with various Mobile Stations and Tablets

Test and verify various new Mobiles and Tablet for VZW, Sprint, ATT and T-Mobile

-EvDo,eHRPD, eCSFB, CCF57, VoLTE

To validate software, hardware and performance with Ericsson CDMA/EvDo and LTE network in IOT lab.

-Using EvDo/CDMA RAN, EMS, DOMs,PDSN,HSGW,AAA,AN-AAA for CDMA/EvDo/eHRPD

-Using eNB,MME,SGW,PGW and Moshell for LTE

Lab setup, test cases development, analysis and debugging with Ericsson network

-Router and Switch configuration to test

-Analyze SIP message

-Analyze root cause the issues with QXDM and Wireshark logs.

-Change and verify RF and Bandwidth for testing.

-Throughput test

Create IOT test reports and problem reports

Support customer testing activity (field and commercial issues)

Using QXDM, Wireshark, ADB, Iperf during IOT testing

Samsung – Herndon, VA

LTE/CDMA/EvDo system engineer, September 2014 till June 2015

Samsung LTE/CDMA/EvDo system Verification at Sprint Project

New software Package/Feature/Patch verification in the lab.

BSM/ LSM configuration, testing and monitoring system.

Design test cases and procedure for new features

Analyze drive test data (QXDM log) from field to find root cause

Reproduce field issues in the lab and inform each software block log and QXDM log to developer.

Support emergency field issues.

eCSFB test through S102 between MME and IWS

System performance test (heavy call load for voice and throughput test )

Auto call load and throughput test using ADB and Iperf

Verify RF spectrum and performance between CDMA and LTE at the same RRH

System management in the lab

Technical document verification to publish to customer

NexelOne – Carrollton, TX

System Sr. staff engineer, August 2013 till August 2014

Developed WCDMA Femto system, development verification and field trial / support

Linux based Software Package verification to develop WCDMA Femto

Verify SON(Self Optimized Networks) function

Verify frequency hopping function

RMS server, client development verification

Make test items for verifying system development

Support field trial with QXDM and mobiles

-To check and solve RF coverage and interference issue

-To check end to end wireless network to resolve issues

System performance test.

STIC Lab at Sprint – Overland Park, KS

LTE and CDMA System Engineer March 2013 till July 2013

Samsung CDMA and LTE (Macro and Pico) system Verification at Sprint Project

Software Package verification to apply to the field.

eCSFB (Circuit Switched Fallback) test through S102 between MME and IWS

Voice quality test (SO3 and SO73)

WPS (Wireless Priority Service) test

Performed interoperability debugging and troubleshooting for inter vendor Handoff in Sprint lab: inter-networking with equipment from other vendors like CISCO, Alcatel-Lucent, Ericsson.

TAI (Tracking Area Identity) and TAC (Tracking Area Code) configuration for paging optimization

BSM, LSM test

Field support to resolve issues at field

Analysis log with Sprint Engineer to verify software feature.

UbeeAirwalk Communications. – Richardson, TX

System Sr. Manager, December 2003 till January 2013

System (BTS and BSC) development at system team

System (BTS and BSC) SW verification.

-Product test plans for verification of new features for SW releases in role. Owner of the test strategy, test plan and test procedure for each New SW Release, Upgrade and Installation

Conducted acceptance testing with Customer.

Field support and SW upgrade remotely

Acting as Project Management technical advisor: providing technical advice and driving projects to completion on teams of designers, architects and support organizations helping PMs communicate with executive teams.

Performed interoperability debugging and troubleshooting on live networks working on installation teams for cutting edge technology trials: inter-networking with equipment from other vendors like CISCO, Alcatel-Lucent, Ericsson-Nortel etc.

Setup and maintenance Lab network for internal testing with IPsec GW (StrongSwan), IMS (Ericsson SDS), TCS (Tatara Convergence Server), AN-AAA, PDSN and FSM for internal testing.

Testing the voice call by SIP signaling

Self-trained to gain knowledge on CDMA lab tools for monitoring and traffic simulation

LTE

-Network Architecture (eNB, MME, S-GW, P-GW, HSS, PCRF)

-Basic call process : Attach, Detach, S1 release, Service request

-Handover procedure : S1 and X2 Handover

-NAS Security, AS Security and Mutual Authentication

-C-Plane : RRC, S1AP, S11 GTP-C, S5 GTP-C

-U-Plane : DRB, S1 Bearer, S5 Bearer

Enterprise Femto : This is combo unit with 1xRTT,EvDo and Pilot Beacon.

- Enterprise Femto network is comprised of secret GW, IP Multimedia Subsystem(IMS), Convergence Server(CS), Femtocell Service Manager(FSM), AAA, MG and PDSN.

- Executed acceptance testing with Sprint.

EvDo Rev.0/Rev.A (IPRAN) :

- EvDo network is comprised of AN-AAA, AAA and PDSN.

1x RTT (IPRAN)

- 1x RTT network is comprised of IP Concentrator, Call Agent(CA), Media Gateway(MG) and Packet Data Serving node(PDSN).

Activity

o Basic call processing and application test with mobiles and air cards by setting PRL with QPST.

Mobiles : Samsung, LG, Motorola, HTC, Apple, Kyosera, Sony etc.

Air Cards : Sierra, Verizon etc.

oThroughput test by accessing FTP or media server.

o Authentication and authorization test by AN-AAA and PDSN (A10,A11,A12,PPP)

o Handoff test

Collect air message through mobile with QXDM during driving.

Verify the handoff performance with collected air message.

o Check the system parameters with air message through mobile or air card

o Application download test through WAP gateway

o Hand in test by hopping pilot beacon (macro to femto cell)

o Capacity and performance test with mobiles, air cards and Dyaptive system

o Capture packet at network and analyze it

o Capture air message using QXDM and analyze it

o System monitoring and statistical analysis through BSM and problem investigating, solving through SSH or telnet.

o Cell site Optimization

Check Ec/Io and RSSI for checking cell coverage

Check RF signal at cell boundary for Handover

Optimizing the network by analyzing drive test log files

Update parameters related RF (Pilot strength, HO parameters, neighbor list etc.)

Frequency and PN offset planning

Cisco Systems. – Seoul, Korea

Digital Hardware & Software Engineer, February 2001 till November 2003

Develop and Field support for PDSN

PDSN (Packet Data Serving Node) : developing and testing / debugging.

- PDSN is equipment for data service(IP Network) in CDMA network.

- Responsible for installing, testing and debugging in service provider’s site.

- Creating new feature with customer and verification.

- PDSN test that installed at field using Mobile and aircard

o Basic call processing and authentication test through PDSN (A10,A11,A12,PPP)

o Throughput test through mobile or air card.

o Session test.

o MIP and SIP test

o Capture packet at network and analyze for problem investigating and solving.

SamSung Electronics Co. – Seoul, Korea

Digital Hardware Engineer, August 1991 till December 2000.

Develop CDMA BTS HW

HDR channel card

- Hardware high level and circuit design.

- Testing and system integration.

PicoBTS development for 800MHz(Cellular) and 1.8/1.9GHz(PCS)

- Developed IF Card that to be interface between Channel card and Tranceiver.

Design and development Base Station Test Unit for 1.8GHz PCS System

Design and development E1/T1 card for Analog Cellular System (AMPS)

System intergration and optimization.

System debugging and analyzing.

Education

Kwangwoon University, Seoul, Korea

Bachelor in Electronic Communication Engineering, Feb.1991

Major Training History

* Oct. 2002, PDSN(Packet Data Serving Node) training in the Cisco systems, San Jose

* Dec. 2001, ICND training, Seoul

* July 2000, CDMA HDR training in the Qualcomm, San Diego

* March 1996, CDMA system training in the Qualcomm, San Diego

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