Where to start, Frank?
"Any thoughts on this, and how best to leverage wireless assets that are suited for the telecommuter or the power user at home, both now and into the future?"
- The stuff below will be an unholy mix, in part, of the present and possibly, the future.
"Are you referring to fixed wireless a la xmds, or to x.gen mobile, or both?"
- Both. More, to x.gen. Wireless LANs will be readily extended from wired LANs, and will benefit from frequency re-use, especially in in-building usage (à la Starbucks). Scalable systems will help. Both will benefit from increased cellular density: I'm not sure that, once you start talking about OFDM-based systems, the infrastructure (cellular) costs shouldn't be resolved in favor of a hybrid wireless system. There are cost and aesthetic reasons to at least consider this possibilty: if you consider the likelihood of software radio being well advanced by this stage, some interesting possibilities emerge.
However, WRT x.gen, as Slacker pointed out, the capacity increase is notable. With an eye to the longstanding complaints of one Frank Coluccio about peak demand in the Big Apple, it's not too hard to envision a point where the cost of creating new capacity is satisfied by changing the form of modulation, as opposed to say, increasing cellular density.
In a more general sense, we've kicked around the ideas and concepts you're discussing, more or less for years. I recall posting you a question about making the termination of fiber, wireless, thus eliminating the battery/ground requirement. You had, of course, posted a number of times on the subject.
Looking at the results from Atheros' 802.11a implementation, Wi-LAN's years-old demo of simultaneous transmission of two MPEG-2 video streams using W-OFDM, and the more recent Cisco VOFDM video demo - it seems clear that the termination of almost any LAN could be wireless - unless you're talking about the huge demands of something like uncompressed digital video streams.
"The latter design would also support a degree of mobility, as well, albeit not in the traditional sense of wireless pcs or cellular, although with future voice over IP adaptations, perhaps connections to the PSTN, too."
- There is no reason why an xMDS LAN cannot terminate to an 802.11x LAN I'm a little rusty on my IEEE stuff, but the use of VOIP in an in-building wireless LAN could certainly give you mobility within the structure: digital voice is far from demanding. Though Wi-LAN has demo'd mobility using W-OFDM (MPEG-2 video at 70 mph, a proof-of-concept demo as opposed to a real trial, I believe) OFDM systems presently lean to nomadic usage as opposed to mobile usage. For the next while, I don't see anyone displacing x.gen wireless as the mobile champion. But again, when one tries to imagine a cellular xOFDM network around 2010, 4G, and prevalent 802.11x - the question will likely be where does one end, and the other begin?
The only justification for duplication and triplication of resources will be commercial: certainly not aesthetic or pragmatic.
"Will shorter distances from micro-cells allow greater frequency re-use in future architectures, thus mitigating some of the downsides that are associated with sharing bandwidth?" Yes, and no: frequency re-use will be endemic, I think, especially in metro areas.
Where this all started was with Peter's response, on the use of newer forms of modulation to more efficiently use existing spectrum.
Slacker then brought up the much negelected fact that these newer forms of modulation offer increased capacity to carriers. Rob brought up the excellent point that migration to newer forms of modulation would not necessarily provide a good return on investment. It was my feeling that at some point, as populations densities and traffic increase, that carriers would have to migrate to newer modulations to accomodate them.
In the strictly x.gen sense, the provision of additional capacity would be quickly erased by increased usage, by our traditional models.
However, the implications of 802.11a , OFDM, and software radio are that the network may be 5 GHz. here, 2.5 GHz there, and fiber-optic there. If that is the case, then the number of users enabled by the infrastructure will be much greater.
If not, then demographics will inevitably saturate the network with traffic. That may not be bad, for the carrier: they will then be able to start shutting people out, as they charge higher prtices for those who remain. Probably a dream scenario for someone...
Hope this speculation makes some kind of sense.
Best regards,
Jim |
