Wednesday, 2 May 2007

Wireless wonderings:

Tonight's IET lecture was at Vodafone HQ, Newbury. Given by Prof. Mike Walker (big chief of R&D) on the current market, competing technologies and near-future developements in wireless telephone/data/video.
It mostly affirmed what i knew: communication and computer systems are converging: mobile phones are becoming PCs in the pocket, PCs are becoming mobile and pocket sized. Wireless services are becoming general data services (the backbone of the mob phone network is already IP packet based) hosting talk/text/browsing/video/etc.

The main limitations are radio frequency bandwidth, which ironically is most inaccesable in more developed countries where governments have tight controls on spectrum use, and are glacially slow to allocate/reallocate and expect high premiums for the privalage. This means that developing countries (like china and india) will take up future advances far more quickly, in line with their rapid economic growth. They have little legacy hardware knocking about and will be all in favour of giving out frequency bands to whoever (or even better, state controlling a single company) to ensure maximal economic benifits.

An even more fundamental limit is EM frequency: a single frequency band can only transmit roughly the number of digital data bits per second as it's carrier frequency. Current technologies are around 2-20Mhz (ish) for GPRS/3G and data rates have been prett much optimised to make use of the channels they've paid so much for (so about 5mbps currently). Using multiple adjacent frequency slots can double, triple, etc the capacity but adds much complexity (Anyone remember dual line ISDN? Thought not!). So u need higher frequencies; Do Co Mo (japan mobile company) have propose 3-4Ghz use, but this massively reduces the range of cell masts to mere 100s of meters. This means many closely spaced base stations are needed and no real coverage can be provided outside of cities and big towns...

This is a fundamental physical limitation, and just as computer perfomance increases follow the Moore's Law trend, so communications rates (mobile comms included) must follow. So they *will* be using these high frequenciesin not very long, and this *will* exclude raural residents (because there's the same infrastructure problem with physical connections over sparsely populated areas). Poor Stevie already knows this, having only *just* had ADSL become available in little ole Pailton, and even then it's not full speed of course.

The whole telecomuting thang looked (to me) set to signal the end of city life and ruaral to urban migration (mmm, GCSE geography), but i think this relatively new and increasingly powerful 'force' will consolidate cities, and perhaps aid their further growth.

Presuming an average doubling in data capaciy every year and a half (though it will undoubtably be fast, to catch up with users broadband expectations) then mobile providers will *have* to be using ~1Ghz by 2020 (though WiMax technology, etc are there *already* and is kind of in competition). From there/here it's only another 10 doublings (~15 years, though likely less) until terahertz is needed. These frequencies are closer to IR light than to microwaves, they just about pass through soft matter (like thin plastic/clothes/skin), so things like buildings would be even more of a pain in the arse than now! Then above terahertz is visible light! (maybe u could use room/street lighting to carry the data signals)

The applications for 1000'000'000'000bps wireless transmission may be elusive for now, but by 2030 they *will* exsist...any entity feeling the need to converse more thoroughly will just have to 'jack in'!

PS. The Professor made a swift exit just before i could quiz him on whether i'm likely to be able to VOIP on 3G any time soon for a semi-reasonable price! (so i can skype everywhere, and most the time for free at home) Damn, will just have to wait and see how things pan out!

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