Lucent Work

Last Update: Dec 2007

I have been working in the global adaptive feature (GAF) group of CDMA core network since I graduate in July 2004. Our group develops and tests adaptive features from customers in U.S, China, Russia, Vietnam, India, Poland and other countries. The customers include Verizon Wireless, Sprint PCS, Metro PCS, India Reliance, China Unicom, Telecom New Zealand. The team is customer-driven. The Application Engineers convert the customer requests to a RDAF document; System Engineers then write requirements based on this RDAF. Developers and testers in the GAF group will implement the feature according the the feature requirements. Most of the features are delivered in a couple of months (development + testing), which is really very fast compared with Lucent's half year regular product Development cycle. We are the 'little engine that could'.

I'm a full-time feature tester since I join Lucent. Below is part of the features/projects I've taken since 2004. A feature is basically a functionality required by the customer (for example, the color ring back tone) and is indeed a project in other companies.

MMC for China Unicom (Test Only), Nov 2007 -- Dec 2007

MMC (Mobility Manager Compact) is a new platform of Lucent mobile switching center. It has smaller footprint than old flexent mobility manager (FMM) platform. China UniCom required this product and need some regression test. This project is under way. We are doing test on specific configurations of the Unicom, e.g. SS7 ITU-24 signaling, two-way global title translation, color ring back tone, international roaming, wireless intelligent network, multiple digital cellular switch. This feature is being tested in Lucent Shanghai lab.

IT Trigger Based CRBT Service at O-MSC, Sep 2007 -- Apr 2008

Sprint PCS now is using CRBT (color ring back tone) and need IS-771 WIN service support. Sprint wants to migrate IS-771 to IS-826 WIN service, and requires Lucent develop a CRBT feature that is compatible with IS-826. 50% of the test has been p run in Lucent system lab at Lisle, Chicago.

Per Cell Based Max CPAGE SMS Bearer Data Size, May 2007 -- Sep 2007

Lucent base station supports sending and receiving short messages via traffic channel and paging channel. Whether going via traffic or paging channel is decided on the mobile switching center (MSC) by the length of the message. Verizon wireless requests Lucent base station make the decision instead of MSC. This feature has development work on both MSC and base station. Interface tests are conducted in Beijing lab. Around 100 tests are done including deliverable test, feature test, interaction test, regression test, and cell platform test. The testing team includes Olina, the base station tester and me, the MSC tester.

Support Packet Pipe Information in PCMD, Feb 2007 -- May 2007

Metro PCS requested to place packet pipe information in the per-call measurement data (PCMD) for the initial and final cell. The information need to be transferred from the CDN for the initial and final cell. This feature has only been tested in the domestic market (North America).

SDCA Display Suppression for Packet Data Call, Nov 2006 -- Feb 2007: honors!

'Without Data there is no Voice'

The 1st packet data feature I took. India Reliance has 'Limited Mobility Services' feature active, which sent SDCA info to mobile station for displaying, thus blocked the calling party number when mobile in voice/data call. Then this feature is created to suppress the SDCA info in a data call.

I did all the tests physically in U.S. system lab, which is very similar to Reliance field site.

Initial Cell Based Billing feature enhancement for ISPAGE2, Jun 2006 -- Oct 2006

Initially the problem was found on Russia site that the AMA sub-system (for subscriber billing information on Lucent MSC) get incorrect data when user have slipped (via ISPAGE2 feature) to another MSC. The reason is the original serving MSC does not know the cell information on the bordering MSC. To get such information, border MSC need to send the cell information in the ISPAGE2 Return Result, and serving MSC store them in the AMA record for later use.

My work in this feature includes ISPAGE2 scenario, Inter-MSC Soft Handoff, etc.

There has been a U.S. patent for this feature but with a little difference: Reliable related billing ID information method for call delivery. They said when you are careful and patient enough, and keep the patent application in your mind, then you can succeed to have one patent one day...but I doubt we can wait till that day to come.

Deliverable/Feature Test for "Support of Hard Handoff for Voice Transparency", Nov 2005 -- Apr 2006

This feature is for China Unicom, which plans to deploy a new service called voice transparency (VT) Service to serve government and army for security purpose. Subscriber will use a new type of mobile station (produced by ZTE) with special button. After normal traffic channel set up between A party and B party, the subscriber will push the special button to set up new application upon the traffic channel. The new voice coding and decoding work will be done by mobile station, not voice coder in MSC. The call processing is transparent to MSC and the base station.

Over 80 percent testing work (the deliverable and the feature test) are done in U.S. system lab. Basically all the air interface test that need to be executed at real system lab, while the code change on the MSC/switch is allowed to be tested in a simulated environment.

My work includes:

Make end-to-end voice call scenario in U.S. system labs located at Lisle, IL. End-to-end call uses the real handset and real base station. All the Lucent system labs use a Radio Frequency (RF) matrix to control the signal that goes to the handset. This is a good way to minimize the RF leakage. To make it, users have to be a skilled user of QualComm CAIT suite.
Reload, Reboot, bring up and troubleshoot the base station. Base stations are among the most profitable CDMA products in north America region and Asia-Pacific. They also are such sophisticated equipments that even Lucent engineers have to make great effort to get their knowledge. In this feature’s testing phase, I added a new software package (i.e. a new operating system, usually Vxworks) to the cell, brought it up online and attenuate it to get the right RF signal I want.
Configure RF Signal in multi-carrier environment (AMPS, TDMA, CDMA cellular, CDMA PCS). The cells in the laboratory include CDMA, TDMA and even AMPS (the 1st generation telecommunication system in North America). I successfully excluded the interference of unwanted RF signal and made the expected signal 'the active set' on mobile phone.
Deliverable, feature and regression test on Lucent proprietary soft handoff, semi-soft handoff, inter-vender hard handoff, including both sunny day and rainy day scenario. The 'Voice Transparency' feature takes most advantage of exiting inter-vender hard handoff strategy. The result is the minimized development work but large amount of feature interaction test and regression test. The difference between soft handoff, semi-soft and hard Handoff is that they release and allocate resource at a different level. Soft handoff barely releases any resource and therefore has a most stable call, while hard handoff releases and the then seizes almost all the resource again, so the risk of dropping a call increases.

Mobile Equipment Identifier (MEID), Jul 2005 -- Oct 2005

This is a mandatory feature required by IS2000 for Verizon U.S. MEID is the upgraded mobile electronic serial number (ESN). In this feature no significant architecture is changed but since ESN is widely used in the whole Call Processing (mobile origination, mobile termination, paging and authentication, etc), the development and unit testing work is huge.

My part of unit test covered voice call, circuit/packet data call, 911 emergency call, call termination, short message service (SMS), inter-MSC soft handoff, malicious call, over the air service provisioning. Also about 12 technical Input (TI) test cases are executed in this phase. TI is widely used in Lucent product for people at service provider and Lucent field engineers to monitor system and make configuration change.

Most of the unit test cases are executed in COOL, which is a simulated MSC (different platform but real code for application layer). Lucent development and verification requirements state that unit test cases can be executed in simulated environment, while deliverable/feature test and regression test must be verified in real laboratory. In the system lab, we have a powerful tool, the automated verification system that reloads the whole MSC (switch, base station) in a couple of hours. In Motorola it takes a couple of days to complete the same task.

ISPAGE Support for CRBT feature, May 2005 -- Jul 2005

This is a very interesting feature, and also a hot feature at the time it was requested. ISPAGE means inter-system paging. This is a paging strategy introduced by ANSI-41D. Lucent has its own proprietary ISPAGE prior to IS41D. ISPAGE feature pages the abutting MSC when a subscriber slips (enter but has not registered) into another MSC, and increases the paging response rate dramatically.

CRBT means 'color ring back tone'. The color ring is widely used on users' mobile handset. Indeed color ring comes from South Korea with its original name as 'X-Ring'. Lucent developed the 'Color Ring' by temporarily connecting the incoming trunk/channel to a CRBT server. When the called party answers the call, MSC disconnects the incoming trunk with the CRBT server and connects it with the called party trunk.

This feature deals with the feature interaction between the ISPAGE and CRBT. I finished most of the testing work before being transferred to aother project with higher priority.

Return Cause Code 4 (not 65) to SMDPP for TDMA mobile, Sep 2005 -- Nov -- -- 2005

This feature allows the Lucent MSC with co-existence of TDMA and CDMA base stations to respond with the cause code of 4 (Invalid Teleservice ID) to the message center (MC) when receiving the TIA/EIA-41 SMDPP (SMSDeliveryPointToPoint Invoke) message with a CDMA Teleservice ID for a TDMA mobile phone.

In the test I verified the SMS functionality on an idle/busy mobile station in both TDMA and CDMA system. Lucent have same MSC for TDMA and CDMA system, except that they have different base stations.