----- Original Message ----- From: "Forrest W. Christian" <[EMAIL PROTECTED]> To: "WISPA General List" <wireless@wispa.org> Sent: Friday, October 24, 2008 8:58 AM Subject: Re: [WISPA] Raining on the whitespaces parade
> I'm going to ignore the first part of your email (since I'm sure others > will discuss), and point out a couple of things you missed: > > Marlon K. Schafer wrote: >> I have MAJOR problems with the stance on adjacent channels. We give up 3 >> for 1 every time a TV channel, or microphone etc. fires up in our area. > The proposal indicates that we give up the channel, plus the adjacent > ones for each DTV channel.... not microphone users. Microphone users are licensed users of the band. If the TV won't work do you think the mics will???? > > I'm not sure where it occured, but there was one discussion I > participated in where part of the discussion were that the microphone > users indicated they were perfectly happy in the middle of the adjacent > channels. As a microphone user myself, I know that I'm happy operating > on adjacent channels. > > So, say you have a location where channels 1 and 5 are used. We could > locate on channel 3. The microphone users would end up on channels 2 > and 4, since they would not be limited by the adjacent channel > limitation. The purpose of the microphone users being in the > database, in my mind, is so we know where they are and so we can either > work around or with them... For instance, if they were on channel 3, > we could perhaps work with them to clear out channel 3 for our own use. > > I think the idea is that you separate "high power", nominally-licensed > users by at least one channel, and then you can let the unlicensed users > use what is left. >> Next, I HATE geolocation as the only mechanism. > Ask many operators in 5.2 and 5.4 about how well they like sensing, and > you'll understand why sensing does not make sense. It's new technology. And the problems with the 5 gig sensing are (as I've been told from more than one manufacturer) mostly related to the fact that they are supposed to sense a signal that they know little about. Remember, 5 gig shares space with top secret military radar.... Sensing isn't likely to be as much of a problem if you know what you are looking for. And TV bands will be more of a constant use than radar.... > > I like the proposal, in that it basically says, "broadcasters are > important in this band, and so are the WISP's running licensed lite. > Both of you should be able to put out plenty of power, as long as you > don't interfere with each other Agreed. That's good common sense stuff. > - and since we can define where your > transmitters are, you don't have to use sensing. If you instead want > to operate unlicensed you can do that as well, but you must use lower > power and sensing". I can live with that. I just worry about what happens when the GPS system gets taken offline. If that happens it'll be terrorism and/or war. In such times the ability to communicate will be even more important. Anything that has, as it's only option, a call home system worries me from a security standpoint. > > I agree that unlicensed operation in this band is of interest, but I am > also a firm believer that permitting even 1W using just sensing is never > going to fly, just because of the interference potential - what if a > device with a deaf receiver decides it can't hear anything on a TV > station's channel and fires up running 20W? The way that sensing should be implemented is that ALL devices listen for the incombant signals. All data is then transfered to the AP which must then make a choice. Technology should allow us to build smart networks, not just smart devices. It's important to protect the incombants. > > For high power, we're probably going to have to live with geolocation. > If we have to live with geolocation, why don't we just discard the > sensing since all it will do is reduce reliability of the service? See above secutiry discussion. Also see the any discussions about how real world unreliable the average circle on a map mechanism is when it comes to actual coverage zones. Here's a 3650 example for you. I'm in an exclusion zone. Can't use it out here. Even though the earth station is on the other side of a mountain and I'm at the very edge of the exclusion zone. Oh well, circles on a map..... > >> Geolocation should be used until such time as a sensing mechanism can be >> found that will work. > Already in the proposal. Sensing can be used for unlicensed devices. >> Licensed lite is a great idea. There should be NO first in mechanism >> though. This leads to those with all of the money getting all of the >> prime >> slots and the rest of us sucking hind teet again. > From the proposal: > > "In the unlikely event that no non-interfering base station facilities > could be designed through techniques > such as location changes, power reductions, antenna polarity changes or > channel > selection, the registrant and the incumbent registrant would be > obligated to negotiate in > good faith to coordinate their facilities for a period of 30 days and > keep records of their > discussions in case the information is needed by the Commission." That's in the section dealing with WISP to WISP interference. And read that again please. If you are the incombant and the system allows a new entrant to fire up a system you have no real protection for at least 30 days. You are supposed to negociate with the other guy and, failing that, the commission will step in. I don't know about you, but I don't have very many customers that will stick around for 30 days while I try to get an interference problem worked out. As I read all of this we'd be assigned a channel for use when we fire up. We'd not be allowed to change that channel, even to deal with interference issues. > >> Just think about how >> many mics could cover the Indy 500 if they effectively had 1000 channels >> available in every 6 MHz TV channel!?!? >> > In reality, existing products are nearly this dense. The Microphone > users are just worried about having thousands of 'baby monitors' in > their space. One poorly designed 'baby monitor' could take out dozens > of microphones at an event. As long as the Microphone users can set > their gear to a frequency and have some assurance that an interferer > isn't going to come up on-channel, they will be happy. On this we agree. It's why I've had trouble with unlicsned devices in this space. At least for now. I like the idea of limiting their power, a lot. But I think we should have offered that as a secondary choice, not the first choice. First choice is wait 5 years and see if sensing and other technologies make incompant protection better. >> We also need to set max channel sizes. > I agree in principle... I would like to see an eirp per channel > related to the width. That is, the narrower the channel, the more > power. > > The problem today is that if you spread out to a 40mhz wide channel, you > can get more bandwidth just because you are limited to power. If you > were able to increase your power such that higher modulations were able > to work in a narrow channel, I suspect that people would be using > smaller channels. Most of the wide channels I use today have to do > more with total bandwidth needs for the link distances. Yeah. But then again, some protocols are very good with enough space. And someone, say in the city where distances are short anyway, may not care about higher power levels. I think there should be a channel width standard. >> Never mind the fact that most of us that need the TV band's can't use >> the 5.4 band due to it's low power levels. > And that many of the people that can use the 5.4 band find it unusable > due to DFS (sensing). Yeah. It sucks. But again, it's my understanding that the problem has more to do with the radar signature than the sensing it's self. >> Unlicensed whitespaces devices should ONLY be allowed to connect to >> a registered base station. It should be nearly impossible to use >> whitespaces for home/office WLANs. >> > Assuming that the FCC sticks to very low power (tens of mW) for > unlicensed devices in the band, and we're given 20W, I don't see this as > a problem. What's the EIRP on a Linksys router? From a mile away I have an AP that's picking up just shy of 100 of them. In a town of maybe 10,000. In a 45* sector. With a 50' coax run. No amp. With 2.4ghz free space and building losses. I'd love to see a test of how far away a 600mhz signal can be detected at 100mw eirp and a -95 rssi. I'll bet we'd all be shocked at how far it would go. Anyone know???? Great discussion! marlon > > -forrest > > > -------------------------------------------------------------------------------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > -------------------------------------------------------------------------------- > > WISPA Wireless List: wireless@wispa.org > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ -------------------------------------------------------------------------------- WISPA Wants You! 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