Extreme Hatches Switch Surprise

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dbeberman 12/5/2012 | 12:15:07 AM

re: Extreme Hatches Switch Surprise If I understand UWB correctly, it spreads over a very wide range say 2 Ghz. Right now, if you took the 160 Mhz roughly that 802.11a occupies, the raw data rate total is 8 * 54 = 432 Mbps.
If the data rate increases to 108 Mbps. per channel, thats 864. Since this is only 160 Mhz, as the technology is adopted, if say another 160Mhz is added, then the bandwidth is 1.7 Gbps.

I fully believe that UWB will probably reach the speeds you are talking about eventually. My question is, is it an efficient use of the spectrum for data communications?

Also, if it isn't, and it interferes with other technologies like 802.11, will this be a workable situation?

If it turns out that UWB can offer another .5 Gbps., without interfering with other efficient modulation techniques (OFDM, DSSS, etc.), then it should be a successful technology. As I understand it, this is UWB is supposed to be virtually undectable to other technologies. If this proves true, then this is not an either-or case, but a case of both technologies winning.

David Beberman

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jacksullivan66 12/5/2012 | 12:13:51 AM

re: Extreme Hatches Switch Surprise Although I optimistically anticipate UWB to replace nearly every current Bluetooth application within the 3-5 year timeframe, I agree with you that some form of 802.11 (either g, or combo a/b) will continue to be successful for intermediate range, in-building applications (which is where I'm drawing the comparison)...

Technically speaking, UWB actually operates in 7.5Ghz of spectrum, and the proposed "multi-band" approach being considered within the IEEE 802.15.3a TG will likely carve up that spectrum into 500Mhz bands (roughly 15 of them)... So whereas 802.11a has 8 channels, UWB potentially has up to 15 at it's disposal. With this technique, any potential interference can also be avoided by simply notching out one of the 500 Mhz bands where interference would likely occur (say in the lower 5Ghz band where 802.11a currently operates).

This type of technical architecture would support your conclusion of "both technologies winning" in the shortterm. As a result, we'll likely see multi-mode devices being shipped with 802.11/UWB just as they are currently being shipped with 802.11/Bluetooth.

From an efficiency perspective, I'm not an engineer, but I can't imagine a "more" spectrally efficient technology than UWB. Everything that has been operating in the 3.1Ghz-10.6Ghz range can still operate just as before. But now you have the benefit of an high-performance, unlicensed technology operating in the same frequencies, with individual UWB bands intelligently notched out to ensure there is no interference with existing services operating in the same geographic area. That sounds spectrally efficient to me... ;)

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dbeberman 12/5/2012 | 12:13:37 AM

re: Extreme Hatches Switch Surprise If UWB is able to operate in 15 channels, that will be very helpful. I am unaware of that capability at this time. 500 Mhz wide channels using UWB sound promising. My understanding was that bandlimiting UWB was extremely difficult to do. I haven't looked at it in depth in the last 18 - 24 months. Advances may (will) have occured.

The concept of simultaneous operation of UWB with spread spectrum, OFDM, or others, in the low power range of wireless LAN is something that I remain
skeptical about. Power is still power. If you increase the background noise floor intentionally with UWB, it will impact the performance of every other modulation scheme in my opinion. I'm only a guy that thinks in terms of looking at signals on
a spectrum analyzer, not an expert in all the different modulation techniques.
I certainly agree that with narrowband systems
like analog voice transmission, UWB will have near zero effect. On other technologies, I would like
to see the math that matches the claims.

If UWB can successfully notch out the current bands for 802.11, that doesn't make UWB any more efficient, it just means that 802.11 will continue to operate where it its. It seems wasteful to me to allow UWB to have everything else. I do understand the concept of dynamic frequency allocation, and perhaps the idea is that all the devices using different modulation schemes cooperatively figure out what bands each should use for optimal frequency use. It is beyond my imagination how such a thing might be managed, or enforced by the FCC and similar regulatory bodies.

Does UWB have a future as one of the modulation techniques, I would think the answer is definitely yes. Every technology has found its place historically. I'm not sure where UWB will find
its fit. I still hold to the idea that it
won't deliver the same density of bits per second per frequency that other technology does. Whether that is a critical factor in the long run remains to be seen.

It may turn out that UWB has superior battery life performance, or better coverage, or a host of other parameters that make it a winner.

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wap545 12/5/2012 | 12:09:25 AM

re: Extreme Hatches Switch Surprise Some of the dream or Wireless utopia will be possible with the right type antenna (ie Phase Array or beam steering) and some of the new products that will come out of the 802.16a committee. Forgetting the Spectrum (selection of 802.11b was a good universal first step) issue for a moment:The impact the Vivato system design or approach will have on this Broadband Wireless Space will be totally disruptive if for no other reason the Business Model they present allows a Service provider to eliminate the single biggest hit in costing out a competitive service and that is the Customer/Subscriber access device is provided by user and does not require any install/support. Plus it opens up the Fixed market to include a Portable capability which is where the real money will be made in this broadband Wireless Market. Mobile Narrowband services (universal coverage) will be handle well enough by the existing carriers planned 3G networks that will fill in the gaps the Wireless LANs decide to ignore. We already have hand off capabilities between GPRS and WiFi systems being introduced.

Jim

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