document: I've downloaded an episode of David Attenborough's Frozen Planet in about a minute and viewed YouTube videos in the middle of London without a hint of buffering.
  I've even tested a live broadcast using nothing but a laptop connected to a mobile phone network. All of this has been thanks to 4G - a technology which is already being rolled out in many parts of the world but won't be widely available in the UK until 2013 at the earliest.
  Two big 4G trials are underway at the moment. In London, O2 has launched a test network covering various parts of the centre of town, and soon out to Canary Wharf and the Docklands.
  In Cornwall, BT and Everything Everywhere - formerly known as Orange and T-Mobile - have begun testing 4G under very different conditions. The aim there is to work out whether part of the spectrum which is being auctioned late next year will provide a mobile broadband alternative for people who struggle to get a decent service down a fixed line.
  Now I can already hear the purists shouting that neither of these trials are "real 4G". Â They will point to the standards set out by the International Telecoms Union for the next generation of mobile networks and claim they do not match up. But I think most people will be more concerned to know what the new services promise - and how soon they will arrive.
  In London the O2 trial involves dongles plugged into a computer - there are no 4G handsets available yet. I've tested the network in Soho, where I got speeds of around 35Mbps, and at the O2 in East London, where, surprise surprise, I got something much faster - up to 90Mbps.
  So far, these speeds look impressive, although you have to bear in mind that once the new networks are clogged up with thousands of users, they are bound to slow down.
  But compared with 3G coverage, which is still annoyingly patchy - as I waited for a train in West London this morning I noticed that my phone was only getting a slow EDGE connection - the 4G revolution promises to make a big difference.
  When it finally arrives, that is. Amid infighting amongst the various mobile operators, the 4G spectrum auction has been delayed until the end of next year. The networks say that's not a problem because the analogue TV spectrum which will be a key part of the sale won't be free until 2013 in any case.
  But as other countries from Sweden, to Germany to the United States, move ahead more rapidly with rolling out the new technology, there's mounting concern that the UK could be left behind.
  One company making that case forcefully is eBay. The auction site says the UK is ahead of the pack in terms of mobile use, but falling behind in terms of infrastructure.
  Sitting in Soho Square - with a good 4G signal and very patchy 3G coverage - Angus McCarey from eBay told me: "The UK leads Europe in people adopting smartphones but is behind other European countries in rolling out the next generation. 3G arrived in 2003 - it will be 10 years old before 4G arrives. That may not sound long but in the history of technology it is a very long time."
  The 4G trials are giving us some idea of what kind of contribution 4G may make to our connected future. But from business and consumers, the message to the mobile networks is clear - just get on with it.
summary: Over the last week, I've had a taste of our mobile future.