Backhaulds?Speed?Users?

[Mithrandir]

Hi

I am kinda new to this WiMax thing I was wondering if someone could answer a couple simple questions I have.

First of, what are Backhauls? I understand that they are something of ISPs, but why not just say ISP instead of backhaul. There has to be some kind of difference.Right?

Secondly, I was wondering what capacity WiMax has? How many connections could one supply with one machin?(I understand that is depends also on the machin so lets say a average machine, like with say AN-50e Redline (http://www.redlinecommunications.com/)) and what speeds it could stand(the more practical ones, not the 54Mbps on wireless devices!hehe).

Thx in advance for all and any help.

[M/Q]

BackHaul in this technology is usually referring to the replacement of hard wire lines like copper and fiber. The third definition pretty much sums it up.

From my notes:

backhaul: 1. The practice of routing telecommunications traffic beyond its intended destination, and then back to the intended destination, usually for the purpose of taking advantage of tariffs or prices that are lower than those afforded by direct routing. 2. In security, to bring a call that has been routed along a particular path (usually via satellite) to some earlier position in the switching sequence (also using satellites). Note: The technique supports CALEA, the Communications Assistance to Law Enforcement Act and LAES, Lawfully Authorized Electronic Surveillance. <<<<3. In commercial telephone networks, referring to a trunk or line between two central offices that may not share the same facilities or geographic location, and which trunk is used to support special services, e.g., orderwires, off-premises extensions, common exchange number routing, or least-cost routing of customer centrex services. >>>>4. In mission programs requiring contingency networking, referring to a link that provides feedback to the mission control center to verify that the transmission via a primary communications has been successful. Note: In cases where the primary path fails to deliver the transmission, the communications may occur over the backhaul connection or an alternative network connection. 5. In contingency networking, an alternative connection that is routed via a diversified path, e.g., an alternative frequency, satellite facility, cable, trunk, or time slot.


As for bandwidth per user is it similar to WiFi in that you take the total and divide it amongst the QoS you are advertising and then you determine the number of users. In a 20 MHz channel, the device you mentioned can provide up to 72 Mbps over the air (coded) or approximately 48 Mbps at the Ethernet port. Another analogy is that it can support up to four T1/E1 circuits, plus high-speed data if desired, for backhaul applications including mobility.

[Mithrandir]

Thank you. That helped alot.

Another question I have is what are the differences between broadcasting at lower Mhz and at higher Mhz? I understand that using lower frequencys will interfere with other equipment. Like 2.4 Mhz will interfere alot of other equipment, but might also be a whole lot less costly to broadcast then at 20 Mhz.

PS: Wasent there somekind of airballon over some city in the US that was going to provide the city with wireless internet?If so, wouldnt WiMax be the optimal solution for that?

[M/Q]

The higher the frequency the greater the reliability, but the coverage distance is exponentially less. A for instance is if you used 802.11a (5gHz) it would not have the ability to get more than a third the distance that 802.11b/g (2.5gHz) is able to achieve. The higher the frequency the more difficult to control and every part of the entire system becomes critical. Another for instance is that at the higher frequencies antenna lead is not coaxial cable it becomes metal waveguides.

The blimp thing as far as I know is a dream concept that is rather strange IMO. I feel being an amateur radio operator that satellites will become increasingly more important. I use them all the time to communicate with friends around the world, even though it is just for seconds. WiMax is in reality just a stepping stone to the next more impressive technology.

I may get into trouble here, but I suspect that the cell phone technology may put WiMax out of business, just from the fact that they have so much infrastructure in place.

[golfnut]

I think the greater potential is broadband over power lines which could provide many more services beyond browsing the Internet.

Speakeasy.net launched WiMax here not too long ago from the Space Needle with limited range (a few miles) but the pricing was almost twice as much for a T1 from the same company. Now they've removed WiMax info from their web site which is probably a very good sign about its potential or lack of.

I'm keeping my fingers crossed for BPL. At the very least it would bring a little competition to the monoply that cable and dsl companies own.

Greg

[M/Q]

Oh no Greg, we disagree for once. I can tell you are not an amateur radio operator. We have many issues with BPL and the powers that be have not come to grips with it or even given us amateurs the courtesy of explaining their position.

Obviously there is a personal bias here as there is a huge potential for BPL to interfere with many of the amateur radio bands ranging from 7mHz to 56mHz. That is not anywhere near as disasterous as the possible elimination of one of the most powerful civil defense and emergency comms systems in this country.

I personally have the capability to stay on air for over 56 hours and provide civil defense comms for my local area, without any local infrastructure. I have been a Ham for almost 45 years now and have been proud to say that I have participated in numerous disaster situations. Just to name a few, I and countless other Hams were relaying phone calls during the NorthEast blackout last year. This year I was relaying phone comms for days on end during the hurricanes. Many of my Ham friends, were activated and went to the disaster area to initially provide the only comms to the police and rescue effort.

What does this have to do with BPL, well all those phone calls I relayed to loved ones and relatives are most likely going to be affected rather adversely by BPL as it will produce spurious harmonics (aka interference) in the frequency range of our medium to long range skip communications.

Many other countries have stopped experimentation with BPL for all the reasons I mentioned, I fear that in this country the dollar will always trumph reason until it is too late.

If you are interested here is the ARRL web page that discusses BPL and all of its ramifications.

http://www.arrl.org/tis/info/HTML/plc/

[golfnut]

okay, okay, I get the picture....

I didn't know that was an issue.

You're probably right that because this has a huge profit potential for the power companies and city government (taxes), they probably won't listen.

I have a much better understanding and respect for the value of Ham operators.

Happy Holidays!

Greg

[Mithrandir]

I dont live in the US. I live in Norway, and I dont know what Ham is.

I have an idea I would like to bounce off you guys that seem to know these things.
I live in Norway, Oslo. Here we dont have as many hotspots. Very few actually.
But I gather that people are starting to use wireless internet more and more.
And Oslo is not that big. POP:500.000 !!You get my point!
When I heard about the airballon thing it hit me that with a population of this size it would be reasonably simply to get a couple of ballons in the air and provide wireless internet to the most of the people using wireless devices. I am not saying we will providing 10 Mbit/s, but atleast enough to read their mail and read the news paper without having to find a hotspot. I thought it could be like a free public service through the goverment for the entier city(Oslo is known for going infront with new technology). And since it is the goverment that is paying for this, the cost of the equipment and maintenance wont be an issue.

What do you guys think?

[M/Q]

There are companies that are already working on this. I have mixed feelings about it, but it certainly is interesting. Here is a link to one such website.

http://www.spacedata.net/technology.htm

Also Ham is a nickname for amateur radio operators. I talk on occasion to a few fellow Hams in Norway. Here is a link to your national association similar to our ARRL.

http://www.nrrl.no/