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Need comment, help and suggestion with my Wireless Setup. - Page 3

post #21 of 24
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Quote:
Originally Posted by Nick2253 View Post

So, you'd want to mount this by the window near the access point. I'm not sure exactly what cabling you'd need to hook it up to the access point: http://www.amazon.com/TP-LINK-TL-ANT2412D-Omni-directional-connector-resistant/dp/B003CFATO2

For the remote site (your friend's place) you'd want something like this, and also mount it at the window. You'll need to align this antenna with your window mounted unit: http://www.amazon.com/TP-LINK-TL-ANT2409B-Outdoor-Directional-connector/dp/B001OQQ01W

The best way to mount and align the directional antenna may be to fab up a bracket that attaches to the friend's window with suction cups, and then the router mounts in bracket with something adjustable.

OMG, This is gonna be perfect for my setup! Thank you so much!

So, that's all right? ermm, i was wondering that if the router that act as a bridge are able to give out wireless internet connection?
post #22 of 24
One thing I have always liked about this forum, is there are people willing to help others. With that said, there are a few things in this thread that need to be corrected.

"And with a directional antenna, you'd basically have to have that signal pointed directly at the antenna for it to make a difference." "Even with a high-gain omni-directional antenna, you won't have to worry about much interference across only 80 meters."

Both of those statement are incorrect. Without doing a survey to see what other modulated or unmodulated signals are in the area, you could have issues. It has also been proposed you use TL-ANT2409B antenna which as a horizontal beamwidth of 60°. The TP-LINK TL-ANT2412D has a horizontal beamwidth of 360°. You are going to be throwing signal all over the place. As soon as you run into any co-channel interference from other wireless networks, they are all going to be contending for time to talk within the same channel.
http://www.tp-link.co.il/products/details/?categoryid=&model=TL-ANT2409B#spec (Specifications tab.)

As for the friends that live below you the TL-ANT2412D ony has a vertical beamwidth of 12°. The worst place for clients to be around an omni direction antenna is above or below the antenna itself. The signal dispersion of an omni directional antenna that has around 2 dBi of gain looks like a doughnut. As you increase the gain on the omni, the signal dispersion will start to look more like a pancake.
http://www.tp-link.co.il/products/details/?model=TL-ANT2412D#spec (Specifications tab.)

Omni Antenna Pros and Cons
http://www.cisco.com/en/US/tech/tk722/tk809/technologies_tech_note09186a00807f34d3.shtml#topic3

"The advantage of having two antenna is to reduce dead spots near the access point." Diversity does not work to fix dead spots near the access point. Diversity is used to solve multipath issues, and signals being out of phase. http://www.cisco.com/en/US/tech/tk722/tk809/technologies_tech_note09186a008019f646.shtml


One thing I did not see in this thread is how the rest of your network is setup. For the connection from window to window across the 80m, this needs to be on a different channel and SSID from the access point you are using for your personal use inside your house. I can only assume you already have an access point for your personal wireless devices. If there are any other users in either building using the same channel you are using for the link between the buildings, you are going to have issues. You are going to end up with a Near-Far problem and a Hidden Node problem. This is going to cause collisions, and a ton of retries. If you are on the same channel for your personal wireless, they will carry over and cause your laptop to have issues.




Near-Far: https://www.youtube.com/watch?v=mxXQ43BtZgo
Hidden Node: https://www.youtube.com/watch?v=WjZ8wi5Qggc

You said you live in a building, and I bet there are a bunch of wireless routers there.

The only way i see this working with 2.4 GHz is using two Parabolic Dish desktop antennas (if they make them), or possibly two Yagi antennas. You can see the beamwidth and signal maps on this page. http://www.cisco.com/en/US/prod/collateral/wireless/ps7183/ps469/product_data_sheet09186a008008883b.html
Look for AIR-ANT3338 and AIR-ANT1949. I am not saying buy these as they will be expensive. I only deal with enterprise grade wireless, so these are only examples to show you.


If it were me, the only way I would attempt this project would be to use 5 GHz. There are a bunch more channels you can use to get away from other modulated signals. There are also only a few unmodulated signals that would cause you interference such as doppler radar. With using 5 GHz, I wouldn't have an issue using the TL-ANT2409B antennas on both sides. I would not try to connect the people downstairs though.




You just have to be careful when using these high gain antennas. You can cause yourself and others around you all types of problems. You can also end up with this.




I know this is alot, but there are many different ways to mess up when you are trying to do something like this with other network around. I would start by downloading inSSider to see what exactly what other wireless networks are out there. http://www.metageek.net/support/downloads/
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post #23 of 24
Now, in turn, I get to poke at issues in your correction (and nice pictures, by the way).

Many of your complaints I think stem from issues you have with my choice of language. For example, I could have explained multipath and diversity issues, but, quite frankly, the phrase "dead spot" gets the idea across in a much more friendly manner.

I frankly don't think that he's going to run into near-far problems with this setup, and the hidden node problem is very effectively dealt with using the handshaking scheme standard in 802.11. It won't be perfect, and sure you could construct a setup that completely deals with that issues, but given this guy's use cases, I really don't think it'll affect him in a significant way.

I really question your recommendation for two parabolic antennas. You can send signals for miles with those things; I just can't come up with a reason for why that kind of a setup would be even remotely necessary for an 80m bridge, unless you needed 100% of the bandwidth at almost no latency (and still I'd find it to be overkill), which is never really needed in a consumer solution..

Good call on the vertical transmission angle; it slipped my mind that he was trying to use it with downstairs neighbors.

Just to be clear, the issues that raise are real ones; it's just that they won't be nearly as significant in a consumer-grade wireless situation compared to an enterprise wireless situation.
post #24 of 24
"Many of your complaints I think stem from issues you have with my choice of language. For example, I could have explained multipath and diversity issues, but, quite frankly, the phrase "dead spot" gets the idea across in a much more friendly manner."

Fair enough...

"I frankly don't think that he's going to run into near-far problems with this setup, and the hidden node problem is very effectively dealt with using the handshaking scheme standard in 802.11. It won't be perfect, and sure you could construct a setup that completely deals with that issues, but given this guy's use cases, I really don't think it'll affect him in a significant way."

Near-far and hidden node don't have anything to do with the 802.11 handshaking scheme. The only way this could be somewhat avoided is if he was able to enable RTS/CTS. That in itself has it's own issues. Think about this for a minute. You are connecting what appear to be two apartment complexes with 2.4 GHz devices per the links he has supplied above. Just from what you have said, I know you have above average intelligence when it comes to wireless. That also tells me you have more than likely seen apartment scans. Everyone one and their brother has a wireless network, and the majority of them are either 2.4 or running dual band. You now go and throw a bridge between the two buildings. You know there is going to be hidden node issues. There are hidden node issues in apartment complexes even without filling the space between two buildings with a bridge.

"I really question your recommendation for two parabolic antennas. You can send signals for miles with those things; I just can't come up with a reason for why that kind of a setup would be even remotely necessary for an 80m bridge, unless you needed 100% of the bandwidth at almost no latency (and still I'd find it to be overkill), which is never really needed in a consumer solution."

Check what I wrote again. I said " Parabolic Dish desktop antennas". I seem to remember seeing some really small ones that would sit on a desk. biggrin.gif This is why I also brought up Yagi antennas. The whole point was to show the OP about beam width.


"Just to be clear, the issues that raise are real ones; it's just that they won't be nearly as significant in a consumer-grade wireless situation compared to an enterprise wireless situation."

It is actually the opposite. The OP is not installing a Ruckus controller with Beamflex.
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