What is 4G

4G (or 4-G) is short for fourth-generation, the successor wireless access technology to 3G. It describes two different, but overlapping ideas. The IEEE (Institute of Electrical and Electronics Engineers) official name for 4G is "3G and beyond".

1. 4G technology stands to be the future standard of wireless devices. The Japanese company NTT DoCoMo is testing 4G communication at 100 Mbit/s while moving, and 1 Gbit/s while stationary. NTT DoCoMo plans on releasing the first commercial network in 2010. Despite the fact that current wireless devices seldom utilize full 3G capabilities, there is a basic attitude that if you provide the pipeline then services for it will follow.
2. 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. These access technologies can be Wi-Fi, UMTS, EDGE or any other future access technology. Included in this concept is also smart-radio aka cognitive radio technology to efficiently manage spectrum use and transmission power as well as the use of mesh routing protocols to create a pervasive network.

In general, a generation is defined by the result of technology changes over a 10-15 year time frame. Thus, 4G would refer to whatever is deployed in the 2010-2015 period, assuming 3G deployment spans the 2000-2009 period. Typically, this means a new air-interface with higher data rates in the least, and some see change in the way data transport is handled end-to-end.

Ideally, 4G would provide users with on-demand high quality video and audio. The killer application of 4G is not clear, but video is one of the big differences between 4G and 3G. 4G may use OFDM (Orthogonal Frequency Division Multiplexing), and also OFDMA (Orthogonal Frequency Division Multiple Access) to better allocate network resources to multiple users. 4G devices may use SDR (Software-defined radio) receivers which allows for better use of available bandwidth as well as making use of multiple channels simultaneously.

Unlike the 3G networks which are a jumble of circuit switched and packet switched networks, 4G will be based on packet switching only. This will allow low-latency data transmission.

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