Originally Posted by
White9900 The short answer is that none of the current commercially available technologies (in the UK, US or elsewhere), officially meet the definition of 4G however 2 different technologies (LTE and WiMAX) that are both forerunners to the technologies that will eventually provide true 4G and an Advanced version of 3G called HSDPA+ are being marketed as 4G mobile broadband.
True 4G is defined (in Wikipedia) as having �peak speed requirements for 4G service at 100 Mbps for high mobility communication (such as from trains and cars) and 1 Gbps for low mobility communication (such as pedestrians and stationary users)�. Technically this only applies to two technologies called LTE Advanced and WiMAXMAN-Advanced and excludes the current LTE, WiMAX and HSDPA+ technologies. However the International Telecommunications Union (ITU), sent out a statement in December 2010 saying that they recognised that the term could be applied to the forerunners to 4G (LTE & WiMAX) and evolved 3G (HSPA+) thus rubber stamping the carriers right to market their networks as 4G.
Interestingly whilst T-Mobile are marketing HSPA+ as 4G in the US of the UK networks only 3 has been actively rolling out HSPA+ but is not yet marketing this as 4G.
Long Term Evolution (LTE)
Of the two forerunners to true 4G LTE is behind most of the 4G networks that are both currently available in the US and planned for the UK. Even US carriers such as Sprint who currently use a WiMAX network are thought to be planning to move to the rival technology, LTE. LTE has a theoretical top download speed of 300Mbps and an Upload Speed of 75Mbps however real world download speeds (based on the US where LTE networks are in use) are 6-12Mbps.
WiMAX
None of the major UK mobile operators are planning on building a WiMAX network however US provider Sprint claims its WiMAX network achieves real world download speed of 3-6Mbps. Having used their WiMAX network myself on a few occasions I was never capable of getting close to these speeds so am a little sceptical. Theoretically WiMAX has a peak download speed of 128Mbps and upload speed of 56Mbps.
HSPA+
Whilst HSPA+ might not be capable of delivering the same potential top speeds as LTE it has an important role to play as it is much easier, quicker and cheaper to upgrade the existing 3G network to HSPA+ meaning it is a very viable short to medium term solution. In the US where T-Mobile has been using this technology for some time real world speeds are reported at between 1Mbps and 7 Mbps. In the UK 3�s HSPA+ network can theoretically reach 21Mbps though 3 say that you can realistically expect speeds of double your standard 3G connection so somewhere in the 2Mbps � 4Mbps range is realistic. It�s with noting that you will need the more pricey Huawei E367 HSPA+ compatible dongle from 3 to take advantage of these speeds.
HSPA+ has the potential to further increase download speeds to 42Mbps through something called dual-carrier which is something to watch out for in 2012.