The main driver for '4G' is data. Recently carriers have become agressive and started offering some decently priced 'Wireless Broadband' data plans. Rather than confuse people with HSDPA, etc., they have decided to use the term 'Wireless Broadband' or 'Mobile Broadband'. Personally both the terms have managed to confuse some people who associate Mobile Broadband with Internet access on Mobile and Wireless Broadband as broadband on WiFi.
- AT&T: USA's largest network in terms of subscribers, AT&T plans to use LTE to upgrade to 4G, but not for a long, long time. For now it’s content with its current 3G network. It will upgrade to HSPA+ in 2009 and 2010. Eventually it will go to LTE, but won’t begin testing until 2010 or 2011 with full deployment coming after that.
- Verizon Wireless: Verizon is already testing LTE equipment from several vendors, with plans to roll out the network in 2010 and have most of the country covered by 2012; Verizon’s would likely be the first full U.S. deployment of the LTE technology.
- Sprint-Nextel: The outlier in the whole transition to 4G, Sprint is going with WiMAX rather than LTE. After a number of delays, the company is set to launch its network in September. By the end of the year it will join with Clearwire to operate a nationwide WiMAX network under the Clearwire brand.
- T-Mobile: T-Mobile is still launching its 3G coverage, so its 4G networks may take a while to come to fruition. The carrier’s German parent appears to favor LTE.
- Metro PCS: This budget carrier plans to use LTE but it doesn’t yet have a time frame for deployment, pointing out that its customers aren’t heavy data users yet.
- U.S. Cellular: The company is unsure of its deployment plans but it would likely choose to follow the rest of the industry with LTE. As for deployment, the time frame isn’t set.
- Leap Wireless: Recently said it had not made a decision or public comment about its 4G plans.
The picture is a bit different here in UK because all the operators are going to LTE. There may be some ISP's that may be tempted to move to WiMAX as they would get economy of scale. There is also the news of BT (the largest landline phone provider) planning to roll out nationwide WiMAX network in the 2.6GHz spectrum. If BT is able to fulfil its ambition that it could be a big win for the people.