Mobile Network Generation
0G refers to pre-cell-phone mobile telephony technology, such as radio telephones that some had in cars before the advent of cell-phones.
One such technology is the Auto radio puhelin (ARP) launched in 1971 in Finland as the country's first public commercial mobile phone network.
1G
1G (or 1-G) is short for first-generation wireless telephone technology, cell-phones. These are the analog cell-phone standards that were introduced in the 80's and continued until being replaced by 2G digital cell-phones.
One such standard is NMT (Nordic Mobile Telephone), used in Nordic countries, Eastern Europe and Russia. Another is AMPS (Advanced Mobile Phone System) used in the United States.
Anticedant to 1G technology is the mobile radio telephone, or 0G.
2G
2G (or 2-G) is short for second-generation wireless telephone technology. It cannot normally transfer data, such as email or software, other than the digital voice call itself, and other basic ancillary data such as time and date. Nevertheless, SMS messaging is also available as a form of data transmission for some standards.
2G services are frequently referred as Personal Communications Service or PCS in the US.
2G technologies can be divided into TDMA-based and CDMA-based standards depending on the type of multiplexing used. The main 2G standards are:
GSM (TDMA-based), originally from Europe but used worldwide
IDEN (TDMA-based), proprietary network used by Nextel in the United States and Telus Mobility in Canada
IS-136 aka D-AMPS, (TDMA-based, commonly referred as simply TDMA in the US), used in the Americas
IS-95 aka cdmaOne, (CDMA-based, commonly referred as simply CDMA in the US), used in the Americas and parts of Asia
PDC (TDMA-based), used exclusively in Japan
2.5G services are already available in many countries and 3G will be widely available in many countries during 2004. Work on 4G has already started although its scope is not clear yet.
2.5G
2.5G is a stepping stone between 2G and 3G cellular wireless technologies. The term "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. It does not necessarily provide faster services because bundling of timeslots is used for circuit switched data services (HSCSD) as well.
While the terms "2G" and "3G" are officially defined, "2.5G" is not. It was invented for marketing purposes only.
2.5G provides some of the benefits of 3G (e.g. it is packet-switched) and can use some of the existing 2G infrastructure in GSM and CDMA networks. The commonly known 2.5G technique is GPRS. Some protocols, such as EDGE for GSM and CDMA2000 1x-RTT for CDMA, officially qualify as "3G" services (because they have a data rate of above 144kbps), but are considered by most to be 2.5G services (or 2.75G which sounds even more sophisticated) because they are several times slower than "true" 3G services.
2G is the current generation of full digital mobile phone systems. It transmits primarily voice but is used for circuit-switched data service and SMS as well.
3G is now the third generation of mobile phone systems. They provide both a packet-switched and a circuit-switched domain from the beginning. It requires a new access network, different from that already available in 2G systems. Due to cost and complexity, rollout of 3G has been somewhat slower than anticipated.
2.75G
A 2G mobile phone is a circuit switched digital mobile phone. A 3G mobile is a digital phone with rapid data according to one of the standards being a member of the IMT-2000 family of standards. After those terms were defined, slow packet switched data was added to 2G standards and called 2.5G. 2.75G is the term which has been decided on for systems which don't meet the 3G requirements but are marketed as if they do (e.g. CDMA-2000 without multi-carrier) or which do, just, meet the requirements but aren't strongly marketed as such. (e.g. EDGE systems).
The term 2.75G has not been officially defined anywhere, but as of 2004 is beginning to be used quite often in media reports.
3G
3G (or 3-G) is short for third-generation mobile telephone technology. The services associated with 3G provide the ability to transfer both voice data (a telephone call) and non-voice data (such as downloading information, exchanging email, and instant messaging).
3G Standards
3G technologies are an answer to the International Telecommunications Union's IMT-2000 specification. Originally, 3G was supposed to be a single, unified, worldwide standard, but in practice, the 3G world has been split into three camps.
UMTS (W-CDMA)
UMTS (Universal Mobile Telephone System), based on W-CDMA technology, is the solution generally preferred by countries that used GSM, centered in Europe. UMTS is managed by the 3GPP organization also responsible for GSM, GPRS and EDGE.
FOMA, launched by Japan's NTT DoCoMo in 2001, is generally regarded as the world's first commercial 3G service. However, while based on W-CDMA, it is not generally compatible with UMTS (although there are steps currently under way to remedy the situation).
CDMA2000
The other significant 3G standard is CDMA2000, which is an outgrowth of the earlier 2G CDMA standard IS-95. CDMA2000's primary proponents are outside the GSM zone in the Americas, Japan and Korea. CDMA2000 is managed by 3GPP2, which is separate and independent from UMTS's 3GPP.
TD-SCDMA
A less well known standard is TD-SCDMA which is being developed in the People's Republic of China by the companies Datang and Siemens. They are predicting an operational system for 2005.
3.5G
High-Speed Downlink Packet Access or HSDPA is a mobile telephony protocol. Also called 3.5G (or "3½G"). High Speed Downlink Packet Access (HSDPA) is a packet-based data service in W-CDMA downlink with data transmission up to 8-10 Mbit/s (and 20 Mbit/s for MIMO systems) over a 5MHz bandwidth in WCDMA downlink. HSDPA implementations includes Adaptive Modulation and Coding (AMC), Multiple-Input Multiple-Output (MIMO), Hybrid Automatic Request (HARQ), fast cell search, and advanced receiver design.
HSDPA is beginning to reach deployment status in North America. Cingular has announced that they will begin to deploy UMTS with expansion to HSDPA in 2005.
In 3rd generation partnership project (3GPP) standards, Release 4 specifications provide efficient IP support enabling provision of services through an all-IP core network and Release 5 specifications focus on HSDPA to provide data rates up to approximately 10 Mbit/s to support packet-based multimedia services. MIMO systems are the work item in Release 6 specifications, which will support even higher data transmission rates up to 20 Mbit/s. HSDPA is evolved from and backward compatible with Release 99 WCDMA systems.
4G
4G (or 4-G) is short for fourth-generation the successor of 3G and is a wireless access technology. It describes two different but overlapping ideas.
High-speed mobile wireless access with a very high data transmission speed, of the same order of magnitude as a local area network connection (10 Mbits/s and up). It has been used to describe wireless LAN technologies like Wi-Fi, as well as other potential successors of the current 3G mobile telephone standards.
Pervasive networks. An amorphous and presently entirely hypothetical concept where the user can be simultaneously connected to several wireless access technologies and can seamlessly move between them (See handover). These access technologies can be Wi-Fi, UMTS, EDGE or any other future access technology. Included in this concept is also smart-radio technology to efficiently manage spectrum use and transmission power as well as the use of mesh routing protocols to create a pervasive network.
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