Evolution of Wireless Systems-Wireless Networks-Lecture Slides, Slides of Wireless Networking

Download Evolution of Wireless Systems-Wireless Networks-Lecture Slides and more Slides Wireless Networking in PDF only on Docsity! 2  Review of previous lecture #7  1G wireless cellular networks ► NMT ► AMPS ► TACS  2G cellular systems ► GSM ► IS-136 ► PDC ► IS-95  Summary of today’s lecture docsity.com 3 Last Lecture Review  CSMA ► Versions of CSMA ► CSMA/CA ► Example  Spread Spectrum ► Frequency Hoping ► Direct Sequence docsity.com Evolution Tree of Wireless Systems B-PAN (1 Gbps) 2020 Broadband services MBS/WBMCS PAN (10 bps—10 Mbps) s N ° 2005 High-bit-rate multimedia services 0 FPLMTS/IMT-2000/ UMTS B Speech and data ‘ 2000 PHS/PHP pect — 1998 GSM/ DCS1800 ~ CT2/ CT2+ GPRS / EDGE International PDC “IS-54/ 136 Digital speech ™is-95 1990 TACS/ ETACS JTAC/ NTACS RTMS RADIOCOM-2000 C-450 NMT450/900 —~ Analog speech Local / international 1980 docsity.com 7 NMT  First fully-automatic cellular phone system ► Started in 1970, in service 1981  Two standards NMT-450 and NMT-900 ► Corresponds to frequency and the later has higher bands.  Cell size range from 2 km to 30 km. ► Use smaller size in urban areas for better quality and larger in less-populated areas.  Handsets 1 watt and Car phone uses 6-15 watt  Automatic switching (dialing) and handover. docsity.com 8 NMT Contd.  No spec. for voice traffic encryption ► Buy a scanner, tune to the desired channel and intercept.  NMT also supported a simple data transfer mode called DMS (Data and Messaging Service) or NMT- Text  Using DMS, also text messaging was possible between two NMT handsets before SMS service started in GSM  but this feature was never commercially available except in Russian and Polish NMT networks.  NMT Suspended ► In Finland TeliaSonera's NMT on December 31, 2002. ► Norway's last NMT network on December 31, 2004. ► Sweden's TeliaSonera NMT on December 31, 2007. docsity.com 11 Second-Generation Cellular Networks  Digital system i.e. voice is digitized  Unlike 1G that relies on FDMA/FDD, 2G use digital modulation formats and TDMA/FDD, CDMA/FDD multiple access techniques  Can be divided into two standards; TDMA and CDMA  The main 2G standards are ► GSM (TDMA-based), originally from Europe but used worldwide ► IS-136 aka D-AMPS, TDMA-based, used in the Americas ► IS-95 aka cdmaOne, CDMA-based, used in the Americas and parts of Asia ► PDC (TDMA-based), used exclusively in Japan docsity.com 12 2G Contd.  Using digital signals between the handsets and the towers increases system capacity in two key ways: ► Digital voice data can be compressed and multiplexed much more effectively than analog voice encodings through the use of various CODECs, allowing more calls to be packed into the same amount of radio bandwidth. ► The digital systems were designed to emit less radio power from the handsets. This meant that cells could be smaller, so more cells could be placed in the same amount of space. This was also made possible by cell towers and related equipment getting less expensive. docsity.com 13 2G Advantages  The lower powered radio signals require less battery power, so phones last much longer between charges, and batteries can be smaller.  The digital voice encoding allowed digital error checking which could increase sound quality by reducing dynamic and lowering the noise floor.  Going all-digital allowed for the introduction of digital data services, such as SMS and email.  Better security, harder to be scanned docsity.com 16 Other Systems Contd..  IS-95 or cdmaOne ► Supports up to 64 users that are orthogonally coded ► Channel bandwidth is 1.25 MHz ► Widely deployed in N. America, Korea, Japan, China, S. America, Australia ► Channel data rate is 1.2288 Mchips/s (Mega Chips) docsity.com Subscriber statistics end Q1 2007 World 2,831,345,390 GSM 2,278,095,380 80.5% 3GSM (WCDMA) 114,664,827 4.0% CDMA 18,138,942 0.6% CDMA 1X 289,963,166 10.2% CDMA 1X EV-DO 57,376,347 2.0% TDMA 16,235,932 0.6% PDC 27,857,370 1.0% iDEN 26,494,743 0.9% Analog 2,518,683 0.1% 17 docsity.com  Top 10 growth countries GSM net additions in Q1 2007: China 18,040,914 India 13,728,036 Pakistan 7,662,993 Indonesia 5,394,269 Iran 5,135,330 Brazil 3,877,141 Argentina 3,809,765 Nigeria 3,321,118 Thailand 3,255,817 Russian Federation 3,215,204 18 docsity.com