DoD Dreams of Efficient Spectrum Usage

Unstrung writes "US Military research agency DARPA is sick of all those static-filled cellphone calls and dropped connections too. The shadowy eggheads are working on a way of using the bandwidth available today more efficiently."

Comments

this just in...

[red_five_standing_by]

DoD reports that they have fortified the radio spectrum with "stuff" for more "goodness." They declined further comment.

Doubt it.

[smittyoneeach]

After ten years active duty, and one in the Reserves, I can attest that the DOD has few, if any, dreams of efficiency. Keep trying.

Re:Doubt it.

[PD]

Let me shorten that down a bit for you:

The efficiency isn't about money, it's about efficiently destroying the enemy, weighed against the expense of our own soldier's lives.

DOD, DARPA and Inovation

[haz-mat]

The DOD and DARPA have a long history of bringing about technical innnovation, regardless of how slowly it comes into actual being, the very medium we are using (or abusing) right now is a result of that... unfortunately given the fact that i am at "work" right now, i can attest that they are not interested in efficency, mine is dropping like a rock... TGIF

Re:DOD, DARPA and Inovation

[craw]

The role that DARPA played in the "early" days of computing is often overlooked. DARPA funded the initial prototype development of something called the Stanford University Network workstation. IIRC, a guy by the name of Joy at UCB also received DARPA funding to enhance some of the capabilites of a "new" OS called UNIX. Eventually, the two efforts joined forces and produced a commercial product.

RISC technology was pushed forward by DARPA. One effort eventually led to MIPS. Another effort led to the development of the RISC I and RISC II. This technology was licenced to Sun Microsystems, and eventually evolved into a more scalable architecture. I believe that this had some modest commercial success.

Warp and the Connection Machine were the result of DARPA funded efforts to push forward and test the capabilites of massively parallel computers. These were technnological wonders, but did not achieve commercial success. At least, one of these was featured in a very successful motion picture. Furthermore, thanks to MIPS, probably the geekiest line in motion picture history was spoken, "This is a UNIX system. I know this."

I would also have to speculate that a there are numerous computer industry leaders that had RA's in grad school via DARPA funding.

Well.

[Krapangor]

As far as I understood the article is that some dude got a research grant and the guy at the DoD thinks that he might get results eventually.
This is nothing very expectional.
People in research always get some grants and think that they'll get some results in some time.
But often they get only one result: Is doesn't work. Or it does the same as the old stuff but more expensive.

If often wonder if anyone has tried to get a grant for "the development of a disc-shaped flying object" yet.

GSM

[Zephy]

Why not just convert everything to GSM? it works fine for the rest of the world. You never get static (digital transmission), and the call drop rate is a lot lower than analogue

Re:GSM

[funky womble]

Errm, don't you mean that US cellular industry would rather use an incompatible system to help protect it's native manufacturers from higher levels of competition from international manufacturers?

I don't see many countries converting GSM to CDMA... maybe some of the 3G protocols are CDMA, but that's adding to the GSM networks already in place, certainly not replacing them anytime soon.

And I don't think the existing US cellular infrastructure is really on a par with what's planned for 3G. A lot of changes will be needed, whatever the current tech.

There's quite a difference between GSM and MS: GSM does what it's supposed to, and works pretty damn well. You tried taking a CDMA phone to a different country lately?

Sure, there are advantages with CDMA. Better range, for example, though that's less important for more densely-populated parts of the world (and analogue probably still has the edge). But GSM has advantages too - well-established packet data, SIMs, global roaming...

If CDMA has won, how come GSM is expanding so much in the US?

Re:GSM

[Moridineas]

Ok, I'm going to totally ignore your cell phone bashing which I'm sure others can refute better than I. However I have to make a point with the test of your message.

You say that "90% of americans don't have passports". Let's check the data--I couldn't find anywhere a specific mention of how many passports in total are issued at any one time. however I could find press releases such as this one:

http://secretary.state.gov/www/briefings/stateme nt s/970919.html

Which state that:
-In 1997 a record number of 6 million passports were issued
-each year 40 million americas go abroad
-in 1996 5.7 million passports were issued
-each year since 1992 has seen more passports issued in 1992, in which 3.5 million passports were issed.

So, we can assume that 40 million passports is the absolute floor number of possible passports. Also take note that many people who travel to other countries (Canada for instance, one of our two langbased neighbors in the US. Actually I just checked, and a border crossing into Mexico doesn't require a passport either) don't always have passports--I got into canada with a driver's license. So all those "international" travellers (of which there are a large number! don't always get passports).

Also let's assume that since not everyone who has a passport goes broad every-year (and thus won't be represented in above 40M) that there are 30M who have passports sitting in a box at home. So we have a conservative number of 70M people with passports (I'm guessing the 30M is an under-representation).

Also, on the web I read that around 16M people from the US visit Mexico every year. I couldn't find a number for Canada, but I'd bet it's similar. So right there we have 40M going abroad, and 30M going to other North American countries. That number alone is practically the population of Germany!! But anyway, disregarding Canada+Mexico (and also Alaska,Hawaii, smaller US islands etc, options most European nations don't have) somewhere around 1/4 of the population (population is around 270M) has a passport by my estimation, and enough people to roughly equal the population of Germany visit another country. And you're complaining about this why??

This is just fud, fud, fud, us bashing.

Re:GSM

[mesocyclone]

Next generation GSM uses CDMA. Period.

CDMA proved itself technologically superior to TDMA. It allows more users in the same piece of space/bandwidth than TDMA does.

"Better Range" is not an advantage of CDMA. The advantage is better spectral efficiency. I think it may also be more resistant to multipath, but I am not sure. Certainly WCDMA will be.

Market forces and regulation, of course, distort how this affects what people actually have. Compatibility is in fact very important, which is why GSM provides, today, superior service in *that* particular regard. I am not sure why GSM is expanding so fast in the US, but I would bet it is to take advantage of the vast variety of GSM phones due to its superior compatibility. Also, due to the spectacular collapse of share values in telecom companies (partly caused by their grossly overbidding for bandwidth sold by greedy governments), the next generation (3 G wireless) has been delayed... perhaps for a long time.

Today, the US has in inferior system due to its lack of compatibility and resultant duplication of resources. You might say that US users are suffering from the regulatory decision that allowed mankind to realize the benefits of CDMA in the future!

The multiple standards had nothing to do with the us "protecting its native manufacturers." You may have noticed that if that was the goal, it failed! The multiple standardsd were due to a regulatory philosophy of reducing the standardization ordered by the government. The FCC decided to regulate based on spectral efficiency, rather than specific technical specifications. Both TDMA and CDMA met the initial requiremens, and the US thus has two kinds of TDMA (GSM and US) and CDMA. The choice was made completely by the providers. A provider could choose whatever standard he desired, as long as it met the FCC's spectral efficiency standards (and related things such as tolerance of out of band interference, etc). The result is this very frustrating hodge podge of systems. In the short run, it certainly provides on benefit to US telecom providers: it reduces churn - it makes it harder for a consumer to change providers. In the long run, I think it will hurt them, because various applications (such as instant messaging, etc) will not appear as quickly or be as ubiquitous as they are in GSM countries.

BTW... the US is not the only country with multiple standards. Japan also has at least two.

Frankly, I wish the French or some other country had done the experiment so we in the US could have a single standard... but that's not how it worked out. We are the guinea pigs.

CDMA, btw, was invented by the president of Qualcomm, and would never have made it as a standard without this competitive build-out. In general, the "established" carriers took the proven approach - TDMA. Others took the gamble of the unproven technology (CDMA). CDMA is so bizarre that it was not really possible to predict it's bandwidth efficiency without large scale builds.

BTW... from a technical standpoint, CDMA is a very elegant way to do things. Basically, one takes a high rate pseudo-random bit sequence and multiplies the data stream (at a slower bit rate) by it. One transmits the result, perhaps after shifting the frequency.

The receiver has a synchronized pseudo-random bit sequence, and inverts the transform by multiplying the received RF signal (mixing) by it, and out of a loss pass filter appears the original data (audio) stream.It is a form of Direct Sequence Spread Spectrum technology.

Pretty cool - nice an isomorphic - with pseudorandom. I love it! I've loved DSS for years.

Interfering signals in the same bandwidth are multiplied, of course, by the same bit stream. But since it is pseudorandom, and the interfering signals are not correlated to it, they appear as broadband noise to the receiver. With techniques like this, you can also hide a signal so it is not detectable except by a receiver with the synchronized code. This stuff was first used for military secure and LPD (Low Probability of Detection) systems. The original inventor was the 1940's actress Heddy Lamar, who invented a system which multiplied music from a phonograph by audio (and recovered it by the same process). This was used to allow Roosevelt and Churchill to communicate over short wave radio without being deciphered.

Re:GSM

[Cato]

GSM is not going to go away! Those GSM operators who have a 3G license (about 100 of them, out of hundreds of GSM operators) will deploy overlay UMTS/W-CDMA networks, but an absolutely critical feature of these networks and any 3G phones will be seamless roaming to GSM.

GSM has over 70% of the world market, and UMTS (or CDMA2000 1x etc) will not have anything like universal coverage for a long time... CDMA is more spectrum-efficient than GSM, but GSM is going to stay around particularly in rural areas where large cells are important and 3G won't have that sort of coverage. CDMA2000 1x is an easy upgrade from cdmaOne, but going to 1xEV-DO/DV (the true 3G versions) will be a similarly expensive operation.

GSM was decreed by the European standards bodies, but it has been an incredible success - you can use GSM phones in almost every country in the world, on over 400 networks. Call quality is great, coverage is good wherever I've been (including parts of India), and you have universal services such as short message service (text messaging).

Re:GSM

[alexburke]

CDMA, btw, was invented by the president of Qualcomm

At no time did Hedy Lamarr hold a position at Qualcomm...

Interference Problems

[Detritus]

Give me a couple of RDF (radio direction finding) stations and an 8" howitzer and I will eliminate all of your interference and congestion problems.

BUZZWORD ALERT! BUZZWORD ALERT!

[Dthoma]

"These demonstrations will include demonstrating a low power/wideband spectrum sensor, time/frequency agile waveforms, and dynamic spectrum access and control."

For all we know, this project description might actually MEAN something.

Must be listening to George Gilder

[John Jorsett]

George Gilder has been talking about this for years. He gets your attention by making statements like, "available bandwidth is infinite." His basic point is that if the whole spectrum was available and if communicating entities continually adjusted their power levels and frequency to just what's necessary to communicate, the reuse of the spectrum could make it seem nearly infinite. I think he's probably right; I've seen some special radios designed on this principle, and their ability to communicate great distances with teensy power levels was nothing short of phenomenal.

Re:frequency allocations

[mz001b]

this link seems to actually work: http://www.ntia.doc.gov/osmhome/allochrt.html

Not backward compatible.

[DraconPern]

This technology may be good for a spectrum where all the devices have the 'sharing' capability, but how are they going to make existing spectrum like the wireless network 'dynamic' without making everyone buy new equipment?

July 26, 1947

[totallygeek]

You know that it is the Department of Defense's birthday? It is also the first day of the CIA.

But that's the point :-)

[billstewart]

The military *does* like spending money on new toys, and Darpa's job is partly to design lots of new toys. So why was it you thought that "making everyone buy new equipment" was bad? :-)

Cynicism aside, though, a lot of their existing communications tools are really expensive, and use old technology or newer technology that's made extra-complex to retain compatibility with older technology, and new equipment made with new commercially-viable parts can be *much* less expensive, often less expensive than maintaining existing equipment. For a computer example, compare the cost of buying a 1GHz 256M RAM 20GB disk machine today (about $400) with the cost of replacing fixing your 486 (which used different memory technology, EGA video, 5.25" disk drives, backup tape drives, no CDROMs, etc.) In some cases, the military does need militarized equipment (throwing radios around in trucks and dropping them off airplanes can be a bit rough), but often it's cheaper to buy 10 commercial units and have 8 of them break.

GSM is not very spectrum efficient

[Cato]

GSM does not make very efficient use of spectrum - while it is very handy to be able to use my GSM phone almost everywhere in the world, most GSM operators are having to upgrade to the CDMA-based UMTS (aka W-CDMA) in order to use spectrum more efficiently.

GSM works well, but suggesting it as a solution for spectrum efficiency is quite bizarre, particularly when cdmaOne (used by Sprint PCS and Verizon in the US) is more spectrum-efficient.