RSSInterop panel: Finally finalizing 802.11n
By Jacqueline Emigh | Published September 18, 2008, 11:21 AM
You may think the 802.11n Wi-Fi networking standard is already here. The fact is, equipment manufacturers have been relying on drafts. At last, the final draft is on its way, and an Interop panel discussed its implications Wednesday.
NEW YORK, NY (BetaNews) - The now emerging IEEE 802.11n Wi-Fi standard will add some major new twists to Wi-Fi, or in many cases, finalize some of the twists manufacturers have already begun implementing while waiting for the finalized draft. Some of the most important of these changes will include three modes of operation and two frequency ranges, speakers said at the Interop conference here Wednesday.
Although the IEEE has not yet approved the final 802.11n standard, some wireless devices, such as routers, are already available that comply with the emerging specification.
The three modes of operation encompass "802.11n only, 802.11b/g only, and mixed mode," noted Paul DeBeasi, a senior analyst at the Burton Group. The standard also supports both the 2.4 GHz and 5 GHz frequency ranges.
Underneath the covers, the new standard -- with is backwards-compatible with 802.11b/g -- introduces new technologies that include multiple-input/multiple output (MIMO) and channel-bonding/40 MHz operation. MIMO is aimed at using the diversity of multipath signals -- or reflected signals that arrive at the receiver after the line of sight (LOS) signal has been received, to increase the receiver's ability to recover the message information.
"MIMO will do a lot to improve reliability and predictability for 802.11b/g transmissions," asserted Chris Kozup, senior manager, mobility solutions marketing, at Cisco, another speaker.
Channel bonding, on the other hand, is supposed to increase the amount of data that can be sent by utilizing two separate non-overlapping channels for transmission.
By and large, the panel agreed that the standard's "802.11n only" mode isn't likely to play much of a role in the near future. Some also contended that deployments done in "mixed mode" are likely to suffer from performance hits. "It'll definitely slow things down," predicted Wade Williamson, director of product management for AirMagnet.
One way to solve this problem will be to section off Wi-Fi networks into "801.11b/g only" and "802.11n" segments, suggested another speaker.
As for the two frequency ranges, when should the newly supported 5 GHz spectrum be used? The choice of spectrum depends in large measure on which frequency range is most available in a specific environment, pointed out Kevin Goulet, senior director, product marketing, Motorola Enterprise WLAN Division. Yet speakers argued that, with the 2.4 GHz band already saturated, the newly supported 5 GHz will allow for faster operations. Cisco's Kozup proposed that, in order to full what he called "the promise of 802.11n," devices will need DHS certification for using radar channels in the 5 GHz band. Otherwise, Wi-Fi devices operating in that spectrum shift channels in the presence of radar.
Cisco and Xirrus are the only vendors certified to use these radar channels so far, contended Kurt Sauter, Xirrus' director of product marketing.
-- with is backwards-compatible with 802.11b/g --
you mean:
-- WHICH is backwards-compatible with 802.11b/g --
lol
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LOL!
Why bother?
They have been selling 802.11n 'compliant' crap for almost 5 years!
The irony is that the higher frequencies are more prone to line of sight interference as well as EMI/RF interference than the lower frequencies, although they 'sound better' in print!
People would be better served to find a effective (as many are not!) MIMO implementation on existing b/g frequencies.
By the time the herd of cats called IEEE gets their political act together, the entire issue will be moot anyway.
In fact, the only real advantage to 802.11n is not what most assume. It is that most vendors were waiting for "n" to fully implement the security standard known as 802.11i-AES ( and not simply the PSK - pre-shared key- version)!! And THAT is well worth it - despite a ridiculously excessive wait since the spring of 2004 when 802.11i-AES was finalized!
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This time I'm not picking fault with you but asking you a question:
I've never looked in to this myself, but from first reaction I would have thought 2.4GHz would produce a longer range of signal than 5GHz, but that 5GHz would produce a higher quality signal when inside its operating range?
That means it would be an advantage in certain situations but not in others, would it not?
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RF signals are subject to diffraction effects - in other words, you need to think in terms of the size of the wavelength.
The higher the frequency, the shorter the wavelength.
Wavelengths smaller than an encountered incident surface/object are reflected or absorbed (depending upon their acoustic impedance - but we won't go there now! ;-)
Wavelengths larger than the surface diffract -'go around'- the surface/object, and are thus less likely to be impeded. In fact, objects with dimensions smaller than the wavelength are not even 'seen' by the signal.
{This is also the source of the common rain fade one encounters with satellite/microwave transmission when the raindrops are of certain size and intensity - as they are read as noise.}
Thus, the lower frequencies exhibiting longer/larger wavelengths are less subject to terrestrial interference ('stuff') that typically dominates office and home environments.
Additionally, 'most' (but not all!) EMI generated is in the higher frequencies as video microwave sources tend to live their.
But this is a much larger can of worms that is secondary to the other issue, and one can argue that neither band offers much advantage...)
But for the average user, the lower frequencies actually offer advantages lost as one goes up in frequency. Likewise the older 900MHz wireless devices - provided they employed security techniques such as Spread Spectrum methodologies actually offer advantages as well.
The primary reason the frequencies are increasing is that the FCC is reallocating spectrum - not because higher frequencies offer better performance.
Other than that, the frequencies themselves are just carriers that are modulated. In and of themselves they do not impart any quality factor to the signal.
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Cheers. I'll try to remember that.
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Just a hint, if you are looking for a HIGH quality wireless phone for home use, check out the Panasonic 900MHz Spread Spectrum (SST) units available on EBay for about $15. Available with and without answering machines, these digital units are sweet! Not only are they near bulletproof with EXCELLENT SECURE performance, they are a fraction of the cost of the new units.
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The general theory is correct. However, in most realistic and intended setups the increased absorption of the smaller wavelength is insignificant. MIMO is also available for N. Handling multiple clients has been improved and from a practical perspective 2.4GHz is simply a very crowded space with lots of interference. The only reason to consider G is it's more mature (if you are lucky to pick the right router) and of course cost.
Btw - I can't believe we have one of the most technical comments for a long time on one of Jaq's articles of all people!
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I was just about to recommend exactly the same technology, and I add that the 900mhz units also offer improved operating range (+-150ft indoors with walls, easy).
I am glad to see your resume foxfyre. My respects!
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MIMO is fundamental to the N standard. But it has been retrofitted to G and others. Nothing limits its use to N.
Note, the main holdup in the standard is that heretofore, ONLY Airgo's MIMO chipset has come anywhere near the touted performance gains.
If you choose to go with the a router, I would seriously suggest making sure it has the Airgo chipset. Other vendors are making big performance claims in their marketing which simply have not been reproducible in the real world.
Its not the absorption of signal that will cause the most problems, rather it is the increase in virtual sources caused by increased diffractive effects that will increase the 'multi-path' characteristics - thus placing increased demands upon the receiver to reject the slightly delayed signals... this is similar to what many have seen in their TV reception as single or multiple offset 'ghost' images.
This can indeed be significant with data transfers and significantly result in adverse throughput - precisely the reason most will consider N.
Although, in my estimation, the most significant reason for going with N is for the full implementation of 802.11i-AES, as it FINALLY allows for secure encrypted communications featuring robust AES encrypted authentication that is NOT easily hacked.
...And yes, anyone who is serious can easily hack WEP or WPA, even with the TKIP bandaid due to the inappropriate use of the RC4 cipher primitive! That is an old issue conclusively demonstrated and it has precluded wireless being installed in many critical site installations.
802.11i-AES is also referred to as WPA-2.
One more note, some routers are firmware upgradeable to 802.11i-AES.
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in other words, N will help your pr0n load faster on that laptop you keep inside the bathroom,... so no need to worry
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Most Linksys WAG models come with WPA2 already. Mine did, and one I fitted today for someone did. I don't trust anything that isn't from Cisco or Linux in networking at the moment. I've had too many bad experiences with other makes.
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