orthogonal frequency division multiplexing (OFDM), which splits the signal into different frequencies; mobile WiMAX, also know as 802.16e; ultra mobile broadband (UMB), also known as CDMA 2000 EV-DO; multiple-input multiple-output (MIMO) wireless LAN technology; and long term evolution (LTE), which is designed for GSM/UMTS-based technology and is said to support 45Mbps to 145Mbps in current test networks.
Each technology has its own pros and cons, but it is likely that LTE will be the preferred option in the UK, as it requires less investment to work with existing infrastructure.
However, one of the main disadvantages of any packet switched wireless network , such as LTE, is that voice calls and SMS messaging, the main revenue generators of mobile network operators, are no longer available, as they are based on a circuit switched radio and core network infrastructure. Consequently, it is likely that there will be some fallback mechanism to support these functions. This could include the use of voice over LTE via generic access (VoLGA), which effectively connects the existing mobile switching centres to the LTE network via a gateway. VoLGA is based on an existing generic access network standard (GAN) that allows mobile access over generic IP access networks, such as WiFi. Orange already deploys this technology, so its future adoption should be relatively straightforward if the other networks decide to follow.
Telefonica has chosen O2 UK to test the 4G concept and claims that in ‘ideal conditions’ download speed of ‘up to’ 340Mbps could be achieved; however, the reality is somewhat different with actual download speed ‘in excess of’ 140Mbps being achieved in a recent trial. Services could be available towards the end of 2010, but the cost and commercial model associated with the new technology are not available, so it is difficult to know how compelling any switch might be.