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2.4ghz vs. 5.7ghz Wireless Broadband?
As a bit of a follow-up to our previous discussion on wireless broadband options, Linxx asks: "I work for a company in Yuma, Arizona that offers Wireless Internet access. We cover a large area that extends into Southern California as well as Mexico. We currently use 2.4ghz equipment to do this. We are looking into using 5.7ghz equipment to feed our access points and the rebroadcast at at 2.4ghz. We hope to releive some interferance issues. What I want to know is if anyone has actually compared the two, and if so what kind of results were produced."
Although I don't know much about it, it sounds a bit dangerous compared to the lower frequency technology.
Please use "GHz" for "GigaHertz". I do not know what "ghz" might mean... Well, at least we have lost the ambiguity that existed between megahertz and millihertz ...
McCartney fans pay bus tickets. [...] Lennon fans too, with discretion.
The 5.7GHz frequency shouldn't be a problem provided it is a short distance and line of sight. 5.7GHz will be worse than 2.4GHz if you have any line of sight problems.
That being said, the bandwidth you can achive out of 5.7GHz will be greater than the 2.4GHz.
i'm not entirely familiar with the specifics, but i know you can't get the 25-mile range out of the 5.7 GHz band like you can out of the 2.4 GHz band. the speed difference is phenomenal though - 54-75mbps as opposed to 11mbps. some hardware i saw released recently (it was posted on /., but i don't have the URL off-hand) allows for a little over 100mbps in "turbo mode".
i work at a small ISP in Idaho, where we're currently rolling out a wireless network with Lucent Orinoco and Avaya hardware, and we have a huge problem with the old trees in some of these neighborhoods. i expect this problem would be worse with the higher wireless bands. we're waiting for Wi-LAN to release their 3.5 GHz wireless hardware in the US, as we'd love to roll that out.
personally, i would suggest using 802.11b hardware and wait for the 3.5GHz hardware. but that's the opinion of a sysadmin's useless assistant. ^_^
grey wolf
LET FORTRAN DIE!
I've been doing wireless ISP stuff for quite a while so I know what you're talking about.
Here's the key points:
5.xGHz is EXPENSIVE. I can't in good faith recommend it for ISP to customer links, except for those customers who need to have solid, VERY high speed links. Use 5.x GHz for your backbone between pops.
5.xGHz tends to be ROCK SOLID. There are actually two chunks of bandwidth up there which are useful this. I personally have used the UNII band stuff which is below 5.8 (three bands - the highest at 5.7GHz), and I can't say I've been really interfered with. This is in a community where 2.4GHz in parts of town is completely saturated.
So if you want expensive but rock solid use the 5.8 GHz stuff.
What we tend to do is use the 5.8GHz for Backhaul from our repeater "cell" sites and use the 2.4GHz for our "last mile". Keeping the cell cites small and using polarization, channels, and sectoral antennas to your advantage is the key.
I worked with a company called Com-Pair Services that offers wireless Internet. Check it out at www.com-pair.net . We used 5.7 GHz for the backbone links and 2.4 GHz for the links from our repeater to our clients. There is no danger of course with any of this as your output is of course below FCC standards (a few mill watts). The 5.7 offered a greater bandwidth but at a higher cost. The greatest challenges we faced were the control of clients 'talking'. As the number of customers grew, we found they would try to talk at the same time with the main access point and essentially collide. We solved the problem by using highly modified Mac Airports on the clients end. Anyway the company above does provided turnkey 5.7 GHz links.