2.5G

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Mobile communication standards

GSM / UMTS (3GPP) Family

GSM (2G) GPRS EDGE (EGPRS) EDGE Evolution CSD HSCSD
UMTS (3G) HSPA HSDPA HSUPA HSPA+ UMTS-TDD TD-CDMA TD-SCDMA FOMA
UMTS Rev. 8 (Pre-4G) LTE HSOPA (Super 3G)


CDMA (3GPP2) Family

cdmaOne (2G)
CDMA2000 (3G) EV-DO
UMB (Pre-4G)


AMPS Family
AMPS (1G) TACS / ETACS
D-AMPS (2G)


Other Technologies
0G PTT MTS IMTS AMTS OLT MTD Autotel / PALM ARP
1G NMT Hicap CDPD Mobitex DataTAC
2G iDEN PDC CSD PHS WiDEN
Pre-4G iBurst HIPERMAN WiMAX WiBro GAN (UMA)


Channel Access Methods FDMA OFDMA TDMA SSMA CDMA


Frequency bands Cellular GSM UMTS PCS SMR

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. GPRS is a 2.5G technology used by GSM operators. Some protocols, such as EDGE for GSM and CDMA2000 1x-RTT for CDMA, can qualify as "3G" services (because they have a data rate of above 144 kbit/s), 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.

[edit] See also

[edit] References

Fundamentals of Cellular Network Planning and Optimisation: 2G/2.5G/3G ... Evolution to 4G, by Ajay R. Mishra, John Wiley and Sons, 2004, ISBN 047086267X