Author Archive

LTE abbreviations - Take Your Pick!!

Miscellaneous 2 Comments »

Light up Turn on Engage
Laptop and Terminal Euphoria
Linking The Earth
Linking Telephony Everywhere
Luscious Telephony Experience
Limitless Technology for Everyone
Limited Time Enigma
Laugh Track Escapade
Lightning-fast Transfer of Everything
Let’s Turnaround East
Late Troublesome Expensive
Look, Talk, and Enjoy
Live Telecommunication Environment
Leading Telecommunication Excellence
Loads of Traffic for Everyone
Live connection To Everyone
Live communication To Everyone
Lifeline To Everyone
Let’s Take it Easy
Life Time Eternal
Love Thy Enemy
Link Technology Enhancement
Legacy Terminal Equipment

- from LTE / LTE-A TSG RAN mailing list

Some people also say “Long Term Employment” or “Life Time Employment.” :)
But my pick is “Love Thy Enemy.” How about you?

Write a good paper or file a good patent? Or both?

Miscellaneous 2 Comments »

As a grad student and possibly a system engineer in the near future, I have been thinking about the importance between the two: writing a good paper or filing a good patent? If you are capable of doing both, what is your choice?

Writing a patent is quite different from writing a paper. A good paper should have a clear derivation of a good algorithm that has never been proven before. It should be academically challenging, mathematically tractable & reversible and conceptually innovative. A good example is Teletar’s MIMO capacity paper, Zheng & Tse’s D-MG tradeoff paper and the GLP paper by Dr. Love and Dr. Heath.

A good patent, however, is quite different. A good patent should have broad (as broad as possible) claims which are important in implementing and making real systems / devices. It focuses on new concepts, new methods and new apparatus that have never been claimed before. A good example of it is a series of handover patents by Qualcomm. Qualcomm’s MAHO (mobile assisted handover) patent and so called “501” (soft handover) patents has the following first claims:
[MAHO] 1. A method of mobile assisted handoff in a cellular communication system comprising a plurality of mobile stations and a land system and a plurality of cells, comprising the steps of:
assigning a mobile station a list of cells to measure, wherein said list is divided into two sections, a steady section and an alternating section;
measuring quality level of each assigned cell;
reporting said quality levels to said land system;
transferring a cell from the alternating section of the list to the steady section of the list when said cell has a quality level higher than one of the cells in the steady section, wherein the cell with the lowest quality level in the steady section is transferred to said alternating section; and
changing said cells listed in said alternating section every predetermined period of time.

[501] 1. In a cellular telephone system in which a mobile system user and another system user communicate user information signals therebetween via at least one of a plurality of geographically separated cell-sites each defining a respective geographic service area, a system for directing communications between said mobile system user and said another system user via said at least one of said plurality of cell-sites as said mobile system user changes cell-site service areas, comprising:
means for, while said mobile system user is in a service area of one cell-site and communicating user information signals with said another system user via said one cell-site, determining a transition of said mobile system user from said one cell-site service area to a service area of another cell-site, and for providing a handoff request identifying said another cell-site;
means responsive to said handoff request for coupling a communication of said user information signals between said mobile system user and said another system user via said another cell-site while said mobile system user and said another system user continue in communication of said user information signals via said one cell-site such that said mobile system user and said another system user concurrently communicate said user information signals through said one cell-site and said another cell-site; and
means responsive to said coupling of communication of said user information signals between said mobile system user and said another system user via said another cell-site for terminating said communication of said user information signals between said mobile system user and said another system user via said one cell-site with said communication of said user information signals continuing between said mobile system user and said another system user via said another cell-site.

As you see, MAHO and ‘501’ patents contain almost every possible method for the soft handover (SO) and mobile assisted handover (MAHO). It means that if you build a system with handover algorithms at cell edge, you have to design a system without SO and MAHO, to avoid those patents. You can’t either receive two pilot sequences from two base stations simultaneously, or compare the signal strength at the mobile side between the two. Then, what can you do? Will you pay millions of dollars to the legal owner of it, or try not to use both SO and MAHO?

This is the main reason why the WiMAX system uses only hard handover (HO) and why the cell edge performance of that system doesn’t quite good. Another bad new is that even SO and MAHO was flied in 1992 and 1994 respectively (the patent right is valid for 15 years) there are tons of patents which covers another aspect of SO and MAHO. It will be the same in CDMA, LDPC, and probably MIMO.

As explained above, a well-written patent influence on the whole system design. In addition, it presents a huge amount of money to the legal owner (usually a company) and to the inventor (as some form of incentives). For example, Samsung pays about several hundred million dollars to Qualcomm as the CDMA patent right PER YEAR. And when they make a cell phone, they must use Qualcomm’s MSM chip and pay 5.25% - 5.75% of whole retail price as a royalty. Samsung makes at least 100 million cellphones per year.. imagine the amount of money that the CDMA patent makes. Yes, it is quite huge, and a little part of it (which is given to the inventor) is also huge.

The reason that I am writing this article is not to debase the importance of writing a good paper. I think it is one of the most important things to do as a grad student. (Especially the best paper award is a life-long honor. Isn’t it, Kaibin, Ramya, Chan-Byoung?) But it could be better, if you think about filing a patent for your brilliant idea BEFORE you submit it as a paper. (Usually if a thing is already presented and published before, it can’t be the claim of a patent.) You could be a millionaire, or if not so, there is nothing to lose.

I think a good patent may not guarantees a good paper. But a good paper may guarantees a good patent, because the patent can scale down the novel idea in the paper into a practical method and apparatus. One good example is the Alamouti Code. S. Alamouti and V. Tarokh have filed a patent (US 6185258) in Sep. 16, 1997, just before they submit the famous Alamoti code paper.
[Alamoti] 1. An arrangement comprising:
a coder responsive to incoming symbols, forming a set of channel symbols that incorporate redundancy, where the coder employs replications and, at least for some of the channel symbols, forms a negative of an incoming symbol, forms a complex conjugate of an incoming symbol, or forms a negative complex conjugate of an incoming symbol; and
an output stage that applies said channel symbols to at least one transmitter antenna to form at least two distinct channels over a transmission medium.


As you see in the first claim above, technically any diversity based STBC may infringe their right. It is really terrifying. And it is more terrifying if I can find a patent that has a claim like this: “a device that uses multiple transmit antennas and multiple receive antennas for communication.” It will be all MIMO companies’ nightmare.

The Mobile WiMAX takes on 3G (as 6th standard)

WSIL News & Views 5 Comments »

I just heard that the mobile WiMAX standard (IEEE 802.16e) was approved as the sixth international standard for the IMT-2000 third-generation (3G) telecommunication platform, by the International Telecommunication Union (ITU) today. The decision may accelerate the transition from the 2.XG to the 3.XG, but it depends on the operators. Also, the competitor for the mobile WiMAX will be, in my point of view, the legacy WiFi or the IEEE 802.11n standard.

When I came to Austin permanently in July and took a metro bus, I was so surprised about the wireless internet accessibility in a moving bus. At first I thought it was the mobile WiMAX, but it was not. Still I am not sure it is the EDGE (2.5G) or the WiFi (APs along the path), but it is fast enough (for a grad-student) to check my email, and moreover, it is FREE. For me, there’s no demand to use the mobile WiMAX, especially if I pay for it. I can use free WiFi on the campus, in a bus and even in my home (thanks to my reckless neighbor).

I am curious how the operator (such as Sprint, who is implementing the Mobile WiMAX around DC area) take advantage of the official approval today. They may combine it with legacy system to reduce the deployment cost, but the money for the FCC to license the band (5 - 20MHz) will be huge. if they convince some potential users (including me) to pay some money for the service, the money doesn’t matter. But if they don’t, I think they may not win in the 3G game - a step stone to the promising 4G, regardless of the new technological features in itself.

What is your opinion?