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Wireless Growth & Wireless Interference
windowpain writes "An article in Monday's Washington Post says "The explosive growth of the mobile phone industry has crowded and tangled the nation's airwaves to such an extent that wireless company signals are increasingly interfering with emergency radio frequencies used by police and firefighters, public safety agencies said." Wifi is not a problem, evidently. Understandable, given its short range."
"Wifi is not a problem, evidently. Understandable, given its short range." Yah, that and the fact that the public safety networks operate in the 700 and 800 Mhz bands, whereas 802.11a and b currently operate primarily at 2.4 Ghz.
- If spectrum is reshuffled, could this be an opportunity for the wifi-friendly (but still evil) Powell to allocate more unlicensed spectrum?
- Alternately, does the emergence of the interference bogeyman in such a prominent publication imply a tough PR road for more free spectrum?
- Could this be an opportunity for the cell carriers operating in the 800MHz band to switch to different technologies, or roll out newer services?
- Could these sorts of problems be used to get some federal money thrown toward development of software radio? would multi-format devices help avoid this problem?
As the submitter mentions, these emergency bands don't appear to be abutting or affecting the 2.4GHz range, but I imagine these issues will be relevant as wifi expands and interference problems begin cropping up.Most of the WiFi I know of uses 2.4 Ghz band (I know there are others out there though) And there doesn't seem to be a whole hell of a lot of it out there yet. Maybe it will one day be a bigger problem as it's deployment picks up. I'm looking forward to the seeded frequency hopping options rolling out in the long term, which won't cause very many people problems (at least for more than a fraction of a second) The frequency hopping method also adds the 'security by obscurity' slant to the signal as well -- if you don't have the seed and the algorithm by which the frequency is determined, you may have trouble sniffing out the data on the signal. All really neat stuff. I don't see the wireless stuff, at least the internet variety, as being all that useful, (pardon me all of you blackberry junkies) I think wifi has the solution to it all, conceivably (someday) even cellular could just use some of that bandwidth. It's just a matter of changing the infrastructure -- something that seems to take forever with folks like Verizon involved.
Speak for yourself.
I thought one of the reasons the FCC exists is to allocate frequency blocks precisely to avoid problems like this? Aren't wireless devices supposed to be certified by the FCC?
I would've thought emergency services always had some backup mechanisms in place to get back to the station in case of emergency.
Heck, I even thought the dash-cam that police cars are all supposed to have also relayed video back to a surveillance team back at HQ. Apparently it is not so. With risky, unpredictable work like emergency services at hand, I for one, am surprised they thought of fallback procedures only now.
I know transmitting live video from the surveillance cams is difficult, and multiple backup contact mechanisms would be expensive (cellphones, satellite phones et al), but then, I thought these guys would be the ones who deserve it most of all.
An Indian-American Hindu committed to non-violent thought/speech/action alarmed by the global explosion of radical Islam
Is it possible that the FCC benefits from the artificial scarcity that its own policies impose on frequencies? There exist technologies to make much more efficient use of frequencies and to eliminate all interference, but mysteriously we still get all our services squashed into a small and crowded space where the right to broadcast commands high fees and prestige for the authorizing body (=FCC).
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Wifi is not a problem, evidently. Understandable, given its short range.
The reason it's not a problem has nothing to do with range at all. It's more because of the low usage when compared to other RF. If there were as many wifi users as mobile phone users, it would be just as big of a problem.
Bureacracy will inevitably develop when such systems reach a certain size, and bureacracies will inevitably suffer inefficiencies. But I don't think adding profit motive to the equation necessarily makes the systems run any better -- it just shifts the mandate of the organization to revenue generation by system maintenance, rather than purely system maintenance -- and consequently opens the door to Worldcom/Enron-type problems.
I would rather not have market forces detemining whether I get 911 service on my cell, thanks
I wouldnt be surprised for one bit if the GOVT blocked consumer celluar signals near crucial buildings.
It sounds like most of the problem is local agencies not monitoring the QOS of their radio systems. Most organization get a contractor to install the equipment, towers and contract for basic maintainence and then expect the system to run for years with little oversight..
Cell providers (and most commercial radio operators) know that the precise interrelationships are always changing. New buildings, new transmitters, malicious/accidental interference. Most wireless carriers send drivers with GPS/inertial locators and signal strength meters wandering about their coverage areas to locate areas of poor coverage. "..hear me now, Good!"
A friend once showed a map drawn by a wireless system installer showing that with X number of towers the entire coverage area would have maximum signal strength. Most government entities would stop here, believing the installer. But this wireless company did a standard mapping of signal strengths and found inadequate coverage all over, the number of towers had to be almost doubled from the original estimate and dead spots still exist.
Good radio operation is more than just getting a license and standing up a tower. Whining that the FCC should step in just becuase you're too lazy to fix you own stuff is irresponsible.
To preface my comments, I am a holder of a First Class Radiotelephone FCC license, and an active Amateur Radio Operator. I have been involved in communications of all types, from TV and FM transmitters to engineering two-way radio installations. Now with that said --
What a load of crap! It's not the problem of the wireless providers, it's a problem of coverage due to poor system engineering.
Most, if not all, 800 mhz emergency service systems operate on what is call a "Trunking System". What this is, essentially, a system of linked towers that communicate with the vehicle or officer on the street, then relay from tower to tower ultimately connecting to either the dispatcher or another officer. These systems are designed to be interoperable with each service, such as police, fire, ambulance, etc, so a single dispatch facility can communicate with everyone, and all services can communicate with each other.
To work effectively, you must have sufficient towers properly placed to assure that there is no dead zones. Given the expense involved in site purchase, permits, tower erection, equipment installation, and backup generators, the bare minimum is pretty much the rule. Plus, you cannot physically survey the entire area of coverage, you use topo charts to try to make sure your engineering is sound.
To blame the wireless providers is silly and stupid. Modern 800 mhz equipment is very selective, most newer systems operate via spread spectrum digital, and the chances of interference are minimum.
Additionally, emergency services have priority so if there is a provable case of direct intererence, the wireless provider must take steps to either stop the interfering signal, or cease operations entirely.
There is still a need for cheap, simple, mid-range, solutions that are not dependent on repeaters; do you think that everyone lives, works or plays in line-of-sight of a tower?
In most cases, it is Nextel's somewhat unusual way of getting spectrum. They bought out a whole bunch of SMR operators and cobbled together spectrum, and made a cellular phone company out of it. It is Nextel in most cases that causes the problems.
What they are proposing is moving public safety to different bands, and giving themselves some more prime spectrum for free. They offered $850 million to move public safety into different bands, which is of course, not anywhere near what the spectrum that Nextel gets is worth.
Nextel has set up a site, which is of course, pro their plan. But don't be fooled, it's wholesale theft.
There is an interesting whitepaper by people from MIT and harvard here http://cyber.law.harvard.edu/ltac98/whitepaper.doc
This brings out the need for changing spectrum regulations from auctions to open spectrum access for three specific reasons:
Technical: The system of allocating a particular frequency band to a single user is based on outdated technology. Early receivers and transmission schemes were such that we needed to be concerned about the possibility of interference. The development and implementation of spread spectrum and digital radio technology allow us to use receivers and transmission schemes such that interference is not a significant concern.
Economic: An auction acts as barrier to entry to small firms and unproven technologies, which are often the sites of innovation.
Constitutional/Legal: By allocating spectrum licenses, the government is essentially picking who can talk and who cannot.
It would be interesting to see if the technical reasons stand the test of these problems of interference. On another note: With so much electromagnetic transmissions, I wonder if the health hazards are being evaluated and addressed systematically and strategically.