At some point or another, and perhaps within the next few weeks if the High Court finally forces T-Mobile and O2 to desist from their delaying tactics, Ofcom will be able to begin the auction of the 2.6GHz spectrum band.

For the benefit of the less technically literate amongst us this will be, to quote Ed Richards, the chief executive of the regulator Ofcom,  “the invisible fuel that powers mobile broadband”.

That’s because the 2.6GHz band is where 4G networks are to be located. And 4G offers download speeds that are at least twenty times faster than 3G, giving rise to a positive plethora of possibilities.

Already Nokia Siemens Networks have completed the world’s first multi-user 4G field trial in an urban environment. Using Long Term Evolution (LTE) technology they were able to deliver mobile data rates of up to 173 Megabits per second. By comparison existing 3G users are lucky to get 7.2 Mbps although, realistically, 3.5 Mbps is as much as they can usually anticipate.

Clearly such a radical increase in download speeds will make an activity like watching a live football match on your mobile a practical proposition.

In truth, you can do this already. Provided you have a 3G handset, Vodafone, T-Mobile or Orange will allow you, for an extra £5 per month, to view Sky Mobile TV. In other words, for your fiver you can have Sky Sports 1, 2 & 3, together with Sky Sports News. By comparison the monthly cost of getting those channels on your TV will be £35.50.

Good value, unquestionably, and there are currently around 200,000 subscribers to the service. Unfortunately, the viewing experience is hardly comparable to HD television. But, with 4G and other technological advances, that is going to change.

To begin with Texas Instruments recently unveiled the OMAP4430 and 4440 chipsets for mobile phones, offering up to seven times the computing performance to be found in today’s top smartphones. Both chipsets include an ARM dual-core Cortex-A9 main processor running at 1 GHz or higher, a DSP, and a dedicated graphics chip. More pertinently both support WUXGA screens, or 1920*1200 resolution, the ideal for watching 1080p video.

Also screen size soon should cease to be an impediment.

Take for example the new the Samsung i7410 projector phone . Measuring a reasonably compact 112 x 56 x 18mm the handset is able to project images in excess of 50 inches. Once more Texas Instruments are the company behind the projector’s DLP (Digital Light Processing) technology. For now the projector can only really be when the images are projected onto light surfaces in dark rooms. However, as The Motley Fool reports, TI expect to release a phone with its next-generation Pico technology by 2010.

Elsewhere another company, Microvision, has developed similar technology and is hoping for its first commercial customers no earlier than the second half of next year. Microvision claims its projector chip is smaller and more efficient, however TI has first-mover advantage.

Consequently, by the time 4G is a reality, it is probable that projector technology will have advanced to the point where performance is comparable with many existing home cinema projectors. Watching programmes in HD on a big screen will be a real possibility.

This of course assumes that you will want to use your mobile to watch television.

It’s therefore interesting to note that Richard Titus, the BBC’s controller of mobile and future media, already believes “that we are at a critical moment where the audience is finally ready to have video and radio content on the mobile.”

Similarly the Mobile Entertainment Forum, a trade body that numbers the BBC, MTV, Microsoft, Motorola, Nokia, Orange, T-Mobile and Vodafone amongst its members, predicts that “2009 will be the year that mobile video really takes off”.

However both predictions may prove more than a little optimistic.

With video consuming considerably more bandwidth than browsing the web or reading e-mails, 3G networks cannot simultaneously support a very large number of mobile viewers without overloading. As a result, and notwithstanding any consideration of picture quality, the widespread watching live broadcasts is still some years away.

But even once the technical restrictions have been overcome there remains an elephant in the room. And it is a factor that we have touched on before on this blog, namely cost.

According to Hank Kafka, vice president of network architecture for AT&T, an LTE (4G) network running at full capacity on a 5 x 5 MHz channel could deliver 1 megabyte of capacity to a user at the cost of 0.10 euros. This compares to the latest HSPA 3G networks, where the comparable cost per MBtye is 0.30 Euros. This means that 4G can deliver considerably greater bandwidth capacity than 3G, and it can do so at a third of the cost.

So far so good, because on its current 3G network the Vodafone broadband data usage calculator estimates that one minute of video equates to 1MB of data, or a movie download to 1GByte. Given that a football match is likely to be of equivalent length to a movie, and that Vodafone currently charges monthly mobile broadband contract customers £5 per GByte, should a 4G network deliver data at a third of the cost of 3G, the cost per GByte could drop to less than £2.

However, if Kafka’s calculations are correct, it is going to cost a 4G network operator no less than 100 Euros, or around £90 at current exchange rates, to deliver that GByte of data. And that’s before they can even begin to think about making a profit. It also means that, for the user, getting that same Gbyte over 3G for £5 represents a massive and, in the long term, what must be an unsustainable bargain.

Suddenly the idea that anybody who wants will be able to get Sky Sports on a 4G mobile – to view at high resolution for only a fiver on top of the cost of their current mobile contract, ceases to appear even halfway feasible.

The reality is, no matter how much better handset hardware might get, bandwidth is going to remain too expensive for decent quality video to ever be anything more than an occasional luxury on your mobile.