It’s a shame not knowing common knowledge of 3G networks while working in a mobile phone manufacturer. Well, Obviously, some people do not think so. Here’s the brief outline of radio network change: from first generation to 2G, 2.5G, and 3G. Although 4G is coming on its way, knowing current technologies will help catching up the new ones. Introduction to 3G network History 1G NMT (Nordic Mobile Telephone) NMT-450 NMT-900 International Roaming is possible Scandinavia, Ecntral and Southern Europe TACS (Total Access Communications System) UK standard, based on AMPS 900 MHz AMPS (Advanced Mobile Phone Service) US standard 800 MHz MCS NTT: first cellular network in Japan 2G Feature use digital radio transmission for traffic basic GSM uses 900 MHz 1800 MHz GSM (Global System for Mobile communications) Most successful and widely used 2G system TDMA D-AMPS (digital AMPS) US-TDMA, IS-136, or just TDMA CDMA IS-95 (Code-division Multiple Access) Developed by Qualcomm the only 2G CDMA standard so far IS-95 also called cdmaOne (brand name) PDC (Personal Digital Cellular) Frequency bands 800 MHz 1500 MHz Feature physical layer: similar to D-AMPS protocal stack: resembles GSM Only operated in Japan Digital Cordless systems CT2 DECT (Digital Enhanced Cordless Telecommunications) PHS (Personal Handyphone System) 2.5G new technologies HSCSD High-speed Circuit-switched Data) allocate 4 time slots for transmisstion (9.6 Kbps or 14.4 x 4) summary Good: software updates to network, and phone; good for real time apps Bad: usage of scarce radio resources GPRS (General Packet Radio Services) up to 115 Kbps packet switched suitable for non real-time apps bursty data is well handled do not guarantee an absolute maximum delay EDGE (Enhanced Data Rates for Global Evolution) 3 folds of original GSM speed 8PSK (eight-phase shift keying) GPRS –> EGPRS 384 Kbps maximum IS-136 + (GPRS || EDGE) –> 2.5G Qualcomm CDMA2000 1xRTT IS-95: 14.4 Kbps, 1xRTT: 64 Kbps IS-95 + IS-95B or upgrade CDMA2000 1xRTT –>2.5G HDR (High Data Rate) 2.4 Mbps standardized in IS-856 1xEV-DO (1x Evolved Data Optimized) Add a TDMA component beneath code component PDC-P (NTT DoCoMo) i-mode 3G standard proposals UMTS (Universal Mobile Telecommunications System) Done by ETSI SMG (Special Mobile Group) UMTS Forum was created in 1996 new technologies WCDMA the bandwidth is 5 MHz or more (144kbps, 384kbps or even 2Mbps network Synchronous CDMA2000 compatible with IS-95 manufacturer: Qualcomm, Lucent, Motorola use ANSI-41 core network 3GPP2 (less support than 3GPP) good/not good good: effecient radio interface bad: expensive H/W Asynchronous ETSI/ARIB WCDMA most popular 3G system manufacturer: Ericsson, Nokia, NTT DocoMo rename to UTRAN (FDD) based on GSM MAP network 3GPP feature fast power control vary bit rate, service params on frame by frame basis Advanced TDMA UWC-136 only Hybrid CDMA/TDMA Not supported in fact, it likes UTRAN TDD OFDM spectrum: effecient user: DAB, DVB, 802.11a, 802.11g, ADSL TDMA/CDMA possible good bandwidth effecient resistance to narrow band interference multipath interefrence IMT-2000 umbrella spec of all 3G systems (origin from ITU) IMT Direct Spread (IMT-DS) UTRA FDD 3GPP IMT Multicarrier (IMT-MC) CDMA2000 3GPP2 IMT Time Code (IMT-TC) UTRA-TDD/TD-SCDMA narrowband TDD 3GPP IMT Single Carrier (IMT-SC) UWC-136 IMT Frequency Time (IMT-FT) DECT 3GPP an org that develops spec for 3g system based on UTRA radio interface partners ETSI ARIB TTA TTC CWTS(china wireless telecommunications Standard ULTRA FDD vocabs chip: a bit in a code word spreading factor: chip rate / data bit rate spreading code: a sequence of chips used to modulate the data bits up/down use separate freq bands chip rate: 3.84 Mcps TDD NOrmal: 3.84 Mcps TD-SCDMA: 1.28 Mcps channels physical (air interface) transport between layer 1 and 2 define how data is sent over the air logical within layer 2 define the type of data to be sent 3GPP2 should be backward compatible with IS-95 and here’s the Introduction to 3G network in tree view for better reading.

Avignon.France Recently, I’ve been busy with digging out some possible memory leaks in the program. Without a good memory tracker, it means endless tests with different scenarios in order to narrow down the files where the code defects may lie on. Some mechanisms are developed for this purpose by other teams; however, it did not help me a lot. Eventually, I gave Entrek CodeSnitch another try. I used it last summer when I just came back from France. The stability of CodeSnitch at that time is horrible! You can’t even call it a product. Some patches should be installed in order to make it work on Windows Mobile 5. Even so, some minor tweaks are needed to make it run a little smoothlier. To be worse, it only works with small scale programs. Speaking of our program with a size of around 900 k, don’t even think a bout it. Sometimes, the program can’t be launched; sometimes, it terminates abnormally. After several weeks’ trial, I gave up. I’d rather keep an eye on how I code instead of being a QA for Entrek and discuss the results with their engineers. ...

Seattle.US By clicking on the link of “Liste de partage”, it will list posts that you want to share with others, and with a header listing some common used actions: send the RSS feed address to others by email embed this feed to your blog or website A direct link to this RSS feed By choosing the 3rd item, you will see the posts in a normal way. On the right side of the page, there’s a general RSS feed icon at your service. That’s where you can get a normal RSS feed address to be added to outlook. So, please copy the link first, and then launch Outlook 2007. It’s a memory eating big monster. The performance is not either. However, the new menu design is much more useful than outlook 2003. Moreover, it has built-in RSS reader. It’s convenient to share with others the articles in the RSS feeds. ...

家裡不久前終於裝了無線網路。 中華電信的機子就放在書桌下，所以桌上的筆記型電腦其實用不到無線網路， 只要用條一公尺長的網路線就行了。 裝無線網路的目的是為了讓自己n台device可以三不五時上個網。 ...

又是個看雜誌畫的人。不過不像。 兩部電影。 前一部，好像得了最佳外語獎。 後一部，亞當山德勒的新作。

Kenting.Taiwan Excel對我來說一直只是個擁有多頁Word中大表格的軟體。看到別人製作的excel file時，總覺得相當神奇。尤其是之前和日本人工作的那段時間，更是佩服他們的excel製作功力，讓人不禁懷疑他們花比較多的時間在製表還是在寫code解bug。 ...

Kenting.Taiwan 緣起 不知道是週三下午的咖啡作祟，還是因為突如起來的消息，週三夜一直無法如睡。在床上翻來覆去胡思亂想，心情愈來愈糟。衝動行事的我，這時又亂了分寸，半夜四五點時，透過VPN連回公司內部網站請了一天半的假。處在工作量一直都很大的部門，所以即使是兩天左右的短暫假期，也有可能讓別人人仰馬翻。不過…這時我也管不了那麼多了。我已經沒有半點心思可以放在工作上。 ...

l’église saint Maurice. Annecy. France