2.4ghz or 5ghz

[kwohlwend]

which do you prefer?

[DL33T]

2.4 by a long shot. Price and range are superior, and for most applications (read: broadband access) the ~11Mbps speed is more than enough.

[JimGeier]

This is a great question, and I'll put my engineer's hat on to answer it:

It depends on the application.

For example, 2.4 GHz (802.11b or 802.11g) makes sense in a home, when you're trying to get by with a single access point to avoid cabling multiple access points together. I've done quite a bit of testing through my home (average size) and haven't been able to figure out how to get by with a single 5 GHz (802.11a) access point. Also, 802.11b/g will likely be a good solution for most enterprise solutions due to relatively long range (fewer access points) and performance scalability.

802.11a, however, would be the best solution for high end applications, such as streaming different video (DVD quality) to individual users. MPEG-4 does a great job of compressing the video, but you still need a lot of capacity for multiple users that only 802.11a provides. If RF interference is going to be a problem (e.g., significant use of cordless phones), then 802.11a would be a better solution.

I highly recommend defining requirements of the system before choosing 802.11b/g or 802.11a.

[wirelessgeek]

It does depend on the application, but I prefer the 5 GHz. The 2.4 GHz range has too many devices that can interfere (i.e. microwaves, cordless phones, ect.) As of right now the 5 GHz spectrum only has WLAN devices that operate in it. You do however give up a little range. Orinoco just came out with a dual band A/B card that retails for 179.00 if you want one that will work with both.

[kwohlwend]

I can find 802.11b equipment for good deals, but anything in the 802.11a seems to cost like double! where can I find good 802.11a equip on the cheap?

[wirelessgeek]

Of course the 802.11a equipment is higher in cost, but any cutting edge technology is always more expensive. The reason that the 802.11b is so much cheaper now is because it is not new technology anymore. Give it some time and the prices will come down. The D-Link DWL-5000AP retails for $229.00 (thats not too bad).

[kwohlwend]

im trying to build a complete point to point link for only $500 dollars, and 802.11a would kill that kind of budget

-any ideaS?

[Sumaryo]

_
/
ofset fed /
parabolic (
dish (
(
|
| __________
wlan ant |_|PC w/ \
at dish's focal point |_802.11a__|

Kwohlwend,

Assuming you got already the PC and the dish (2 or 3 ft dish should be OK) and know how to make it waterproof and able to find mechanically strong platform above your houses that has LOS each other, with a pair of the above setup, you should be able to build a point to point link up to 3-4 miles or even longer. Equipment you should invest is a pair of 802.11a PCI card such as Dlink dwl-a520 (retail for $136 each) and a lot of mechanical work :-). Still below your $500 budget heh ???

[kwohlwend]

mechanical work as in tweaking hardware? as in doing stuff that would make it sorta illegal by the fcc, basically?
how often do they catch people? lol:cool:

[Sumaryo]

If those concern you, you should better off getting a pair of Motorolla Canopy backhaul kit or alike (user installable, no RF connection be required, FCC approved).

The previous suggestion is still within FCC allowed EIRP limitation, but yes, any slight alteration from what its come from manyfacturer design require individual site license. In that case, any attachment other than original rubber duck antenna from manufacturer will void FCC license to those equipment, requiring (again) individual site license.

I don't know how you bridge two site point to point using 802.11b bridging devices, but I'm very sure you use some kind of antenna attachment other than original one that from manufacturer. Legally, this will need site license too (imho).

[JimGeier]

It looks like 5 GHz is winning so far.

Does anyone have any unique applications for 802.11a? Do you think that enterprises will eventually go with 802.11a?

[wirelessgeek]

Enterprises will definately migrate to 5 GHz. I am already getting requests for it. The enterprises like the faster throughput with better reliability due to a less conjested frequency.

[tnsc_wrls]

my opinion i would go for 5GHz 802.11a

2.4 GHz/ 802.11b is in a crowded band of spectrum of greatly varying products, as mentioned elsewhere, with little sign of getting less crowded and noisy. cordless DSSS phones, bluetooth, microwaves, etc..
The advantages I see are: -already established standard in the WLAN world anyway, lower cost, greater range, able to more easily pentrate objects such as wall, ceilings, floors but interference is a problem who's best solution is to turn off the offending device or reconfigure it. however that is rarely the easiest solution since you usually are not in control of said device,
and such interference problems are often intermittent.

5 GHz/802.11a is in better shape respective to 11a's shortcomings. however it has a decreased range and is more sensitive to obstacles in the signal path. It may require more devices (AP's) to provide full service to a desired area, but I would forsee fewer problems with this technology providing troublefree seamless service.

and the maxim regarding bandwith/thruput for data applies here.
bigger pipe; gonna need it, gotta have it, the apps are hungry and growing.

Have I implemented or deployed a WLAN with either of these technologies yet? NO. but with my current level of knowledge I'd choose 802.11a in an ideal enviroment.

Again, FWIW, this is my opinion.

cheers,
tnsc_wrls
Can you hear me now?
DOH!!!

[Ajay Gupta]

Hello,

Here's two cents from a new comer to this forum....take it for what its worth.

I am assisting one of our country's many countys decide what sort of system to go to for communication between police, fire and EMS in case of emergency.

Naturally, the 802.11 license-free spectrum is under heavy consideration. What will finally win out is the option that presents with the a) lowest cost and b) greatest range of applications. The county is certainly interested in ensuring all devices and the overall system purchased is able to transmit photos, video and fingerprint information to improve law enforcement officers ability to fight crime. I believe this requires NCIC 2000 certification?

So far, our research leans towards the 2.4GHz/802.11b. Does anyone know of 5GHz/802.11a devices and systems that can support such apps as well. Theoretically, the application should be able to operate in either case.

Also, to deal with interference issues in 2.4GHz, the working plan is to build additional access points, or towers, however, that would also solve the problem of the lesser range of the 5GHz, so we are actually considering that a bit of a tie.

Thanks, hope this has been helpful & I will certainly appreciate any advice on these issues,
- Ajay Gupta

[JimGeier]

802.11b may fall short in satisfying your needs of transmiting video, especially if you have multiple active users operating from the same access point. You might strongly consider 802.11g (2.4GHz, 54 Mbps) or 802.11a.

[Ajay Gupta]

Hello,

Can anyone tell me how the 802.11 series compares with the 800 MHz Public Safety Band.

I know that the 800MHz band is narrow band and may not be able to support any applications beyond straightforward communications, and that this band requires a license.

However, if a license has already been granted, this need not be a strong consideration. And, as it is licensed, there should be much less inteferrence.

Does anyone know roughly how the equipment costs compare between these options?

Any other thoughts will be helpful?

Thank you,
- Ajay Gupta

[JimGeier]

802.11 operates at higher, unlicensed frequencies (2.4 and 5 GHz) using spread spectrum or OFDM and is more suited for transmitting data. Of course the license free operation means that interference between nearby, uncoordinated systems (other wireless LANs, cordless phones, etc.) may cause a problem.

The prices for 802.11 products are roughly $50-120 USD for radio cards and $100-1,500 for access points (depending on features). I'm not sure of the costs for 800MHz equipment, so I'm unable to make a comparison. My gut feeling, though, is that the 800MHz systems are more expensive.

[omanecleoh]

Since 11a’s short comings are decreased range and is more sensitive to obstacles in the signal path. Has there been any sort of study testing different combinations of Access Points with different type of antennas such as Centurion or SkyCross?

[ERNtech]

I have worked with both of these and I would much rather use 2.4ghz. Not only do i get better distance i rarely loose conection. In my experiances with 5ghz i have found it to be okay but it still has alot of bugs. I mean i was hooking up a DLINK DI754 router conecting it to a DWLA650 and i had a hard time getting it conected :mad: I finally whent with the DI614+ and a DWL650+ work right out of the box. So If any would ask me I would recomend 2.4ghz

[kb9skw.net]

For all of you who think the 5GHz band is not crowded, I advise you to take a trip over to RadioShack.com (http://www.radioshack.com/category.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F001%5F001%5F002%5F009&Page=1) and look at their 5.8GHz cordless phones. It was only a matter of time before it was going to happen. Over time more and more will occupy the 5GHz band.

[RandyW]

Originally posted by kb9skw.net
For all of you who think the 5GHz band is not crowded, I advise you to take a trip over to RadioShack.com (http://www.radioshack.com/category.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F001%5F001%5F002%5F009&Page=1) and look at their 5.8GHz cordless phones. It was only a matter of time before it was going to happen. Over time more and more will occupy the 5GHz band.

Cordless phones are allowed within the ISM allocated bands, 902-928 MHz, 2400-2483.5 MHz, and 5725-5850 MHz. The FCC regulates the UNII bands, 5150-5350 MHz and 5725-5825 MHz, for high data rate digital communications, not for low data rate applications like cordless telephones. Therefore, the lower and middle 802.11a bands (5150-5350 MHz) making up 8 of the 12 possible channels will always be free from telephone interference.

[kb9skw.net]

Originally posted by RandyW
Cordless phones are allowed within the ISM allocated bands, 902-928 MHz, 2400-2483.5 MHz, and 5725-5850 MHz. The FCC regulates the UNII bands, 5150-5350 MHz and 5725-5825 MHz, for high data rate digital communications, not for low data rate applications like cordless telephones. Therefore, the lower and middle 802.11a bands (5150-5350 MHz) making up 8 of the 12 possible channels will always be free from telephone interference.

Upes, my bad. :D

I did'nt know that there was two different bands for commercial use like 802.11a and cordless phones.