Mobile Telephone System

Mobile Telephone System * First generation (1G) analog cellular network * Second generation (2G) digital cellular networks * Third generation (3G) broadband data services to the current state of the art * Fourth generation (4G) native-IP networks.
1G (or 1-G) refers to the first-generation of wireless telephone technology, mobile telecommunications. These are the analog telecommunications standards that were introduced in the 1980s. The main difference between two succeeding mobile telephone systems, 1G and 2G, is that the radio signals that 1G networks use are analog, while 2G networks are digital.
1G standards * NMT (Nordic Mobile Telephone) - Switzerland - Netherlands - Eastern Europe - Russia * AMPS (Advanced Mobile Phone System) - Northern Amera - Australia * TACS (Total Access Communications System) - United Kingdom -Western Germany - Portugal - South Africa

NMT (Nordic Mobile Telephone) * is the first fully automatic cellular phone system. NMT is based on analog technology (first generation or 1G) and two variants exist: NMT-450 and NMT-900. The numbers indicate the frequency bands uses. NMT-900 was introduced in 1986 because it carries more channels than the previous NMT-450 network. * The cell sizes in an NMT network range from 2 km to 30 km. NMT used full duplex transmission, allowing for simultaneous receiving and transmission of voice. * A disadvantage of the original NMT specification is that voice traffic was not encrypted, therefore it was possible to listen to calls using e.g. a scanner.
Advanced Mobile Telephone Systems (AMPS) * is an analog mobile phone system standard developed by Bell Labs, and officially introduced in the Americas in 1978, Israel in 1986, and Australia in 1987. It was the primary analog mobile phone system in North America (and other locales) through the 1980s and into the 2000s. As of February 18, 2008, carriers in the United States were no longer required to support AMPS and companies such as AT&T and Verizon have discontinued this service permanently. AMPS was discontinued in Australia in September 2000. * Dr. Martin Cooper, developed portable cellular telephony, and Mitchell was among the Motorola employees granted a patent for this work in 1973 * AMPS is a first-generation cellular technology that uses separate frequencies, or "channels", for each conversation. It therefore required considerable bandwidth for a large number of users. In general terms, AMPS was very similar to the older "0G" Improved Mobile Telephone Service, but used considerably more computing power in order to select frequencies, hand off conversations to PSTN lines, and handle billing and call setup. * What really separated AMPS from older systems is the "back end" call setup functionality. In AMPS, the cell centers could flexibly assign channels to handsets based on signal strength, allowing the same frequency to be re-used in various locations without interference. This allowed a larger number of phones to be supported over a geographical area. AMPS pioneers coined the term "cellular" because of its use of small hexagonal "cells" within a system. * AMPS was originally standardized by ANSI as EIA/TIA/IS-3. EIA/TIA/IS-3 was superseded by EIA/TIA-553 and TIA interim standard IS-91 (Narrowband Advanced Mobile Phone System)
Total Access Communication System (TACS) * Total Access Communication System (TACS) and ETACS are mostly-obsolete variants of AMPS which were used in some European countries (including the UK & Ireland in 1983). TACS was also used in Japan under the name Japanese Total Access Communication (JTAC). It was also used in Hong Kong. ETACS was an extended version of TACS with more channels.
Second Generation (Digital Cellular Networks) * Or 2G, it is short for second-generation wireless telephone technology. Second generation 2G cellular telecom networks were commercially launched on the GSM standard in Finland by Radiolinja in 1896.
Three primary benefits of 2G networks over their predecessors * phone conversations were digitally encrypted; * 2G systems were significantly more difficult on the spectrum allowing for far greater mobile phone penetration levels; * and 2G introduced data services for mobile, starting with SMS text messages.

2G technologies can be divided into Time Division Multiple Access (TDMA)-based and Code Division Multiple Access (CDMA)-based standards depending on the type of multiplexing used. The main 2G standards are: * GSM (TDMA-based) * IS-95 aka cdmaOne * iDEN (TDMA-based) * IS-136 a.k.a. D-AMPS (TDMA-based, commonly referred as simply 'TDMA' in the US)
2G services are frequently referred as Personal Communications Service, or PCS, in the United States.
2G Capacity
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 system base through the use of various codecs, allowing more calls to be transmitted in same amount of radio bandwidth. * The digital systems were designed to emit less radio power from the handsets. This meant that cells had to be smaller, so more cells had to be placed in the same amount of space. This was possible because cell towers and related equipment had become less expensive.
2G Advantages * While digital calls tend to be free of static and background noise, the lossy compression they use reduces their quality, meaning that the range of sound that they convey is reduced. Talking on a digital cell phone, a caller hears less of the tonality of someone's voice.
2G Evolutions * 2G networks were built mainly for voice services and slow data transmission, but are considered by the general public to be 2.5G or 2.75G services because they are several times slower than present-day 3G service.
2G GPRS * 2.5G ("second and a half generation") is used to describe 2G-systems that have implemented a packet-switched domain in addition to the circuit-switched domain.
Third Generation (Tri-Band 3G)
3G telecommunication networks support services that provide an information transfer rate of at least 200 kbit/s. However, many services advertised as 3G provide higher speed than the minimum technical requirements for a 3G service. Recent 3G releases, often denoted 3.5G and 3.75G, also provide mobile broadband access of several Mbit/s to smartphones and mobile modems in laptop computers.
3G finds application in wireless voice telephony, mobile Internet access, fixed wireless Internet access, video calls and mobile TV.
3G Standardization
This is a set of standards used for mobile devices and mobile telecommunication services and networks that comply with the International Mobile Telecommunications-2000 (IMT-2000) specifications by the International Telecommunication Union. 3G finds application in wireless voice telephony, mobile Internet access, fixed wireless Internet access, video calls and mobile TV. Several telecommunications companies market wireless mobile Internet services as 3G, indicating that the advertised service is provided over a 3G wireless network. Services advertised as 3G are required to meet IMT-2000 technical standards, including standards for reliability and speed (data transfer rates). To meet the IMT-2000 standards, a system is required to provide peak data rates of at least 200 kbit/s (about 0.2 Mbit/s). However, many services advertised as 3G provide higher speed than the minimum technical requirements for a 3G service. Recent 3G releases, often denoted 3.5G and 3.75G, also provide mobile broadband access of several Mbit/s to smartphones and mobile modems in laptop computers.

3G Standards * The UMTS system, first offered in 2001, standardized by 3GPP, used primarily in Europe, Japan, China and other regions predominated by GSM 2G system infrastructure. The cell phones are typically UMTS and GSM hybrids. Several radio interfaces are offered, sharing the same infrastructure: * The original and most widespread radio interface is called W-CDMA. * The TD-SCDMA radio interface was commercialized in 2009 and is only offered in China. * The latest UMTS release, HSPA+, can provide peak data rates up to 56 Mbit/s in the downlink in theory (28 Mbit/s in existing services) and 22 Mbit/s in the uplink.
The CDMA2000 system * It was first offered in 2002, standardized by 3GPP2, used especially in North America and South Korea, sharing infrastructure with the IS-95 2G standard. The cell phones are typically CDMA2000 and IS-95 hybrids. The latest release EVDO Rev B offers peak rates of 14.7 Mbit/s downstream.
Applications of 3G
The bandwidth and location information available to 3G devices gives rise to applications not previously available to mobile phone users. Some of the applications are: * Mobile TV * Video on demand * Video Conferencing * Telemedicine * Location-based services * Global Positioning System (GPS)