4G is the fourth generation of cellular wireless standards. It is a successor to the 3G and 2G families of standards. In 2009, the ITU-R organization specified the IMT-Advanced International Mobile Telecommunications Advanced requirements for 4G standards, setting peak speed requirements for 4G service at 100 Mbit/s for high mobility communication such as from trains and cars and 1 Gbit/s for low mobility communication such as pedestrians and stationary users. 

A 4G system is expected to provide a comprehensive and secure all-IP based mobile broadband solution to laptop computer wireless modems, smart phones and other mobile devices.  Pre-4G technologies such as mobile WiMAX and first-release Long term evolution or LTE have been on the market since 2009, and though often branded as 4G in marketing materials, the current versions of these technologies provide downstream peak bitrates of 144 Mbit/s and 100 Mbit/s, and do consequently not fulfill the original requirements of data rates approximately up to 1 Gbit/s for 4G systems.

To be truly a 4G compliant cellular data system, several requirements must be met. The cellular system must be based on an all-IP packet switched network. Peak data rates of up to approximately 100 Mbit/s for high mobility such as mobile access and up to approximately 1 Gbit/s for low mobility such as nomadic/local wireless access, according to the ITU requirements. Dynamically share and use the network resources to support more simultaneous users per cell. Scalable channel bandwidth 5–20 MHz, optionally up to 40 MHz with a 1 Gbit/s in the downlink possible over less than 67 MHz of bandwidth. System efficiency of up to 3 bits/Hz cell in the downlink and 2.25 bits/Hz cell for indoor usage. Smooth handovers across heterogeneous networks. Ability to offer high quality of service for next generation multimedia support.

In September 2009, the technology proposals were submitted to the International Telecommunication Union (ITU) as 4G candidates.[10] Basically all proposals are based on two technologies: LTE Advanced standardized by the 3GPP and 802.16m standardized by the IEEE, which is also known as WiMax.