A stepping stone between 2G and 3G mobile networks, 2.5G is second-generation (ie digital) cellular network technology enhanced with packet data (GPRS) capability. Supporting enhanced services such as internet access and multimedia messaging (MMS), GPRS enables the transmission of data at speeds averaging 40 to 50kbps, depending on the class of mobile device being used.
Used to describe GPRS networks that have been upgraded with enhanced data rates for GSM volution (Edge) technology to support data speeds in excess of 144kbps, but which remain slower than “true” 3G networks.
Third-generation cellular communication system: a generic term referring to the next generation of cellular technologies defined within the ITU’s IMT-2000 family and supporting average downlink rates of around 300 kbps, for the delivery of a range of multimedia services and more efficient over-the-air transmission of existing services – such as voice, text and data.
Third Generation Project Partnership
Fourth-generation cellular communication system: since there are many technologies being touted as “4G”, it is difficult to define what the next generation of cellular systems after 3G will comprise. However, there are those that believe the radio access network will evolve from a centralised architecture to a distributed one that takes in 3G, Wifi and Wimax, to provide users with an always-on, high-speed mobile connection to multimedia services based on a fixed monthly fee. Key 4G technologies could also include orthogonal frequency division multiplexing (OFDM), software defined radio (an enabler for the aggregation of multi-standardpico cells) and multiple-input multiple-output (Mimo) antennas, which provide greater spectral efficiency.