The Fourth-Generation Communications System, also known as the 4G wireless network, follows 3G and 2G as the next stage of the worldwide system of wireless communications. There are actually two separate types of 4G wireless network being developed and deployed around the world. One, Long Term Evolution, abbreviated LTE, first became publicly available in December 2009 in the cities of Oslo, Norway and Stockholm, Sweden. LTE is slated to complete deployment in 2012–2015. The other type, Worldwide Interoperability for Microwave Access (WiMAX), has already been rolling out for some time and in April 2010, over 148 countries already had 568 fixed and mobile WiMAX networks, and the numbers continue to grow, sometimes daily.
Although LTE is called “4G,” debates go on about whether the term is appropriate for it. The technology as it existed on first operation is defined by the 3G Partnership Project (3GPP) Release 8 specification and complies with International Mobile Telecommunications-2000 (IMT-2000) standards for 3G, rather than IMT-Advanced standards for 4th generation systems. LTE Advanced was submitted to the International Telecommunications Union (ITU) for approval under the IMT-Advanced standard in 2009. Both Verizon Wireless and AT&T plan to migrate to LTE.
WiMAX is a 4G wireless network based on two standards. It draws both on the IEEE (Institute of Electrical and Electronics Engineers) 802.16 Working Group standard, as well as the ETSI (European Telecommunications Standards Institute) HiperMAN group. WiMAX is using two profiles: 802.16d and 802.16e, and as of April 2010 had the largest number of networks in service in Europe, with a proportionally large number in Central America and fewer in the United States. The majority of networks in service are using 3.5 GHz frequency, with others at 2.3 GHz, 2.5 GHz, 3.5GHz, and more than 5 GHz.
As of April 2010, WiMAX is being made available worldwide by a number of suppliers with varying numbers of networks. Alvarion has the most with 55 active networks. ZTE has 28 networks in service, while Motorola, Cisco, and Redline Communications all have 4G wireless networks numbering in the upper teens. A number of companies have a single active network, thus far. There are currently 23 active WiMAX networks in the United States, but Sprint Nextel, which has no active networks yet, has announced plans to use WiMAX for its 4G wireless network.
