First a declaration of interest - I am currently employed by Unwired who is in the process of developing a WiMAX network for Australia.
Today's iTWire contains a story trumpetting that LTE will be here sooner than we think. It had a really helpful link to an interview with Telstra's Hugh Bradlow.
He nicely summarised the real difference between LTE and WiMAX, which is about "a whole ecosystem of infrastructure" in which he includes "base stations, your switching systems, your HLRS etc., your authentication systems, your roaming systems, your OSS support, all those things, they are all carried forward from generation to generation and frankly those are the things that make network deployment difficult."
Those who watched the process of resolving 3G standards between the CDMA and GSM world would note that the 3G networks with HSPA represent the same outcome, the adoption of the superior CDMA air interface with the GSM "back end".
The deep question is whether it makes sense to continue on that backend into the wireless data world. That back end is inherently a voice centric model, with even the burgeoning SMS product just a part of the signalling network. As Bradlow notes 4G will handle voice entirely as Voice over IP, so how much of that back end is really necessary? It will be a great pity if the desire for backward capability results in the perpetuation of outmoded concepts. Bradlow is not proposing to retain ANY of that switching core for the all IP fixed network.
But more importantly, in the Australian context, the item goes on to say that 100MHz is really needed to make LTE or WiMAX fly, and there just isn't anything available till 2012 in Australia other than the spectrum owned by Austar and Unwired.