https://plateaukao.github.io/blog/tags/mobile/Recent content in Mobile on Daniel @ Nowherehttps://plateaukao.github.io/blog/images/banner/og.jpghttps://plateaukao.github.io/blog/images/banner/og.jpgHugoen-usMon, 23 Nov 2009 22:42:00 +0000https://plateaukao.github.io/blog/posts/enfin-iphone/Mon, 23 Nov 2009 22:42:00 +0000https://plateaukao.github.io/blog/posts/enfin-iphone/<p><a href="http://www.flickr.com/photos/plateau/4120966172/" title="R8077562 by plateaukao, on Flickr"><img alt="R8077562" loading="lazy" src="https://plateaukao.github.io/blog/images/blogger/4820866235427505746/4120966172_59cfe5c643.jpg"></a><br> des feuilles.Central Park.New York.US</p> <p>Enfin, j&rsquo;ai acheté un iPhone à Taiwan. Quand j&rsquo;étais aux etats-unis, j&rsquo;utilisais souvent les portables qui sont fabriquées par ma compagnie. Bien que l&rsquo;on ait bien travaillé sur eux, ils sont encore loins d&rsquo;être parfaits.</p> <p>Donc, j&rsquo;ai décidé d&rsquo;acheter un iPhone pour moi-même. Pour fabriquer de bons produits, on doit bien savoir les uns des competitors.Bah&hellip;. je sais c&rsquo;est seulement un excuse pour mon achat. :p</p>https://plateaukao.github.io/blog/posts/introduction-to-3g-network/Sun, 05 Apr 2009 05:57:00 +0000https://plateaukao.github.io/blog/posts/introduction-to-3g-network/<p><a href="http://www.flickr.com/photos/plateau/3413966068/" title="Introduction to 3G network.png by plateaukao, on Flickr"><img alt="Introduction to 3G network.png" loading="lazy" src="https://plateaukao.github.io/blog/images/blogger/771316999248406169/3413966068_b518685f39.jpg"></a></p> <p>It&rsquo;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&rsquo;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.</p> <ul> <li>Introduction to 3G network <ul> <li>History <ul> <li>1G <ul> <li>NMT (Nordic Mobile Telephone) <ul> <li>NMT-450</li> <li>NMT-900 <ul> <li>International Roaming is possible</li> </ul> </li> <li>Scandinavia, Ecntral and Southern Europe</li> </ul> </li> <li>TACS (Total Access Communications System) <ul> <li>UK standard, based on AMPS</li> <li>900 MHz</li> </ul> </li> <li>AMPS (Advanced Mobile Phone Service) <ul> <li>US standard</li> <li>800 MHz</li> </ul> </li> <li>MCS <ul> <li>NTT: first cellular network in Japan</li> </ul> </li> </ul> </li> <li>2G <ul> <li>Feature <ul> <li>use digital radio transmission for traffic</li> <li>basic GSM uses 900 MHz</li> <li>1800 MHz</li> </ul> </li> <li>GSM (Global System for Mobile communications) <ul> <li>Most successful and widely used 2G system</li> <li>TDMA</li> </ul> </li> <li>D-AMPS (digital AMPS) <ul> <li>US-TDMA, IS-136, or just TDMA</li> </ul> </li> <li>CDMA IS-95 (Code-division Multiple Access) <ul> <li>Developed by Qualcomm</li> <li>the only 2G CDMA standard so far</li> <li>IS-95 also called cdmaOne (brand name)</li> </ul> </li> <li>PDC (Personal Digital Cellular) <ul> <li>Frequency bands <ul> <li>800 MHz</li> <li>1500 MHz</li> </ul> </li> <li>Feature <ul> <li>physical layer: similar to D-AMPS</li> <li>protocal stack: resembles GSM</li> </ul> </li> <li>Only operated in Japan</li> </ul> </li> <li>Digital Cordless systems <ul> <li>CT2</li> <li>DECT (Digital Enhanced Cordless Telecommunications)</li> <li>PHS (Personal Handyphone System)</li> </ul> </li> </ul> </li> <li>2.5G <ul> <li>new technologies <ul> <li>HSCSD High-speed Circuit-switched Data) <ul> <li>allocate 4 time slots for transmisstion (9.6 Kbps or 14.4 x 4)</li> <li>summary <ul> <li>Good: software updates to network, and phone; good for real time apps</li> <li>Bad: usage of scarce radio resources</li> </ul> </li> </ul> </li> <li>GPRS (General Packet Radio Services) <ul> <li>up to 115 Kbps</li> <li>packet switched</li> <li>suitable for non real-time apps</li> <li>bursty data is well handled</li> <li>do not guarantee an absolute maximum delay</li> </ul> </li> <li>EDGE (Enhanced Data Rates for Global Evolution) <ul> <li>3 folds of original GSM speed</li> <li>8PSK (eight-phase shift keying)</li> <li> <ul> <li>GPRS &ndash;&gt; EGPRS</li> </ul> <ul> <li>384 Kbps maximum</li> </ul> </li> </ul> </li> </ul> </li> <li>IS-136 + (GPRS || EDGE) &ndash;&gt; 2.5G</li> <li>Qualcomm <ul> <li>CDMA2000 1xRTT <ul> <li>IS-95: 14.4 Kbps, 1xRTT: 64 Kbps</li> <li>IS-95 + IS-95B or upgrade CDMA2000 1xRTT &ndash;&gt;2.5G</li> </ul> </li> <li>HDR (High Data Rate) <ul> <li>2.4 Mbps</li> <li>standardized in IS-856</li> <li>1xEV-DO (1x Evolved Data Optimized) <ul> <li>Add a TDMA component beneath code component</li> </ul> </li> </ul> </li> </ul> </li> <li>PDC-P (NTT DoCoMo) <ul> <li>i-mode</li> </ul> </li> </ul> </li> </ul> </li> <li>3G standard proposals <ul> <li>UMTS (Universal Mobile Telecommunications System) <ul> <li>Done by ETSI SMG (Special Mobile Group)</li> <li>UMTS Forum was created in 1996</li> </ul> </li> <li>new technologies <ul> <li>WCDMA <ul> <li>the bandwidth is 5 MHz or more (144kbps, 384kbps or even 2Mbps</li> <li>network <ul> <li>Synchronous <ul> <li>CDMA2000 <ul> <li>compatible with IS-95</li> <li>manufacturer: Qualcomm, Lucent, Motorola</li> <li>use ANSI-41 core network</li> <li>3GPP2 (less support than 3GPP)</li> </ul> </li> <li>good/not good <ul> <li>good: effecient radio interface</li> <li>bad: expensive H/W</li> </ul> </li> </ul> </li> <li>Asynchronous <ul> <li>ETSI/ARIB WCDMA <ul> <li>most popular 3G system</li> <li>manufacturer: Ericsson, Nokia, NTT DocoMo</li> <li>rename to UTRAN (FDD)</li> <li>based on GSM MAP network</li> <li>3GPP</li> </ul> </li> </ul> </li> </ul> </li> <li>feature <ul> <li>fast power control</li> <li>vary bit rate, service params on frame by frame basis</li> </ul> </li> </ul> </li> <li>Advanced TDMA <ul> <li>UWC-136 only</li> </ul> </li> <li>Hybrid CDMA/TDMA <ul> <li>Not supported</li> <li>in fact, it likes UTRAN TDD</li> </ul> </li> <li>OFDM <ul> <li>spectrum: effecient</li> <li>user: DAB, DVB, 802.11a, 802.11g, ADSL</li> <li>TDMA/CDMA possible</li> <li>good <ul> <li>bandwidth effecient</li> <li>resistance to <ul> <li>narrow band interference</li> <li>multipath interefrence</li> </ul> </li> </ul> </li> </ul> </li> </ul> </li> <li>IMT-2000 <ul> <li>umbrella spec of all 3G systems (origin from ITU)</li> <li>IMT Direct Spread (IMT-DS) <ul> <li>UTRA FDD</li> <li>3GPP</li> </ul> </li> <li>IMT Multicarrier (IMT-MC) <ul> <li>CDMA2000</li> <li>3GPP2</li> </ul> </li> <li>IMT Time Code (IMT-TC) <ul> <li>UTRA-TDD/TD-SCDMA narrowband TDD</li> <li>3GPP</li> </ul> </li> <li>IMT Single Carrier (IMT-SC) <ul> <li>UWC-136</li> </ul> </li> <li>IMT Frequency Time (IMT-FT) <ul> <li>DECT</li> </ul> </li> </ul> </li> </ul> </li> <li>3GPP <ul> <li>an org that develops spec for 3g system based on UTRA radio interface</li> <li>partners <ul> <li>ETSI</li> <li>ARIB</li> <li>TTA</li> <li>TTC</li> <li>CWTS(china wireless telecommunications Standard</li> </ul> </li> <li>ULTRA <ul> <li>FDD <ul> <li>vocabs <ul> <li>chip: a bit in a code word</li> <li>spreading factor: chip rate / data bit rate</li> <li>spreading code: a sequence of chips used to modulate the data bits</li> </ul> </li> <li>up/down use separate freq bands</li> <li>chip rate: 3.84 Mcps</li> </ul> </li> <li>TDD <ul> <li>NOrmal: 3.84 Mcps</li> <li>TD-SCDMA: 1.28 Mcps</li> </ul> </li> <li>channels <ul> <li>physical (air interface)</li> <li>transport <ul> <li>between layer 1 and 2</li> <li>define how data is sent over the air</li> </ul> </li> <li>logical <ul> <li>within layer 2</li> <li>define the type of data to be sent</li> </ul> </li> </ul> </li> </ul> </li> </ul> </li> <li>3GPP2 <ul> <li>should be backward compatible with IS-95</li> </ul> </li> </ul> </li> </ul> <p>and here&rsquo;s the <a href="http://daniel.kao.googlepages.com/Introductionto3Gnetwork.mm.html">Introduction to 3G network in tree view</a> for better reading.</p>