Intel To Include Draft 802.11n In Centrino

filenavigator writes "Intel announced at the Globalcom 2006 Expo that they will be including Draft 802.11n hardware in their Centrino chips. It will be interesting since they said that they will start doing this sometime in the middle of 2007, and the 802.11n standard is not to be finalized until 2008. Additionally Draft 802.11n has been dogged by interoperability problems." From the article: "Although the news caused barely a ripple of reaction in the audience of software and hardware engineers, there are industry analysts who have already warned large buyers of wireless technology to resist the temptation to deploy high-speed IEEE 802.11n devices until the standard is ratified."

Comments

Can someone explain this?

[troll -1]

The technology will someday scale to 600Mbps, according to Bill McFarland, a member of the IEEE committee, with a range 50 percent greater than available with Wi-Fi now.

In physics there's measurement called "skin depth" which is the distance a wave travels before its power level drops by 1/e or about 1/3. The formula is something like (wavelength/2*pi). The FCC regulates the power of 802.11n to something like 1mW per channel. So unless these new chips will have more power than is currently allowed, how can they have a greater range?

Re:Can someone explain this?

[b0s0z0ku]

So unless these new chips will have more power than is currently allowed, how can they have a greater range?

Better error correction or use of a transmission method that's more robust when faced with a low signal/noise ratio, possibly. With a directional mic and possibly some filtering software, you may be able to hear shouting five miles away, for example.

-b.

Re:Can someone explain this?

[Andy Dodd]

Ugh, that's the most horrible "let's throw some random terms into my post and make myself look smart" post I've seen in a while.

Skin depth has ABSOLUTELY NOTHING to do with this. Skin depth determines how far an RF signal will penetrate into a conductive or semi-conductive material (usually metal, often used to discuss RF penetration into water). Skin depth is a function of wavelength - The shorter the wavelength, the shallower the skin depth. Remember, this is a term of RF penetration *into a conductive or semi-conductive material* and is usually measured in fractions of a millimeter for most metals. It can be a matter of meters for water though, which is why submarines usually are contacted via VLF or ELF (very low frequency/extremely low frequency) - skin depth of VLF/ELF into water is pretty large due to the long wavelength. Still, in general, as far as Wi-Fi goes, skin depth is irrelevant and meaningless.

Freespace RF propagation follows the inverse square law, just like any other electromagnetic radiation.

That said, indoor wireless is typically NOT free space. The nature of indoor wireless means that a signal can take multiple paths between transmitter and receiver. Unfortunately, these paths can sometimes result in the signals at the receiver interfering destructively with each other, causing a significant reduction in signal strength. The best example you might be familiar with is FM radio - have you ever been sitting at an intersection in your car and the reception of the station you were listening to completely dropped out, only to come back to full strength when you moved your car a few feet? That's classic multipath fading.

One solution to multipath is to use two or more antennas to provide what is called diversity. Usually, if one antenna is in a "dead spot", an antenna a half wavelength or so away (or closer but with a different polarization) won't be. This is why almost all normal 802.11a/b/g routers have dual antennas and most PC cards and built-in WLAN cards have dual antennas. The card (usually) selects the one antenna that gives the best reception and uses it. (This is called selection combining. There are other diversity techniques that are better than selection combining but a bit more complex.) Some newer cards may use other diversity reception methods to improve 802.11a/b/g performance.

Now, 802.11n takes diversity to whole new levels. It uses what is commonly called "multiple input multiple output" or MIMO. Fundamentally, MIMO takes multipath and turns it from a disadvantage to an advantage by transmitting different data on each path. Thus, a MIMO system can achieve higher data rates by effectively using multipath to create multiple independent channels.

I have a paper saved somewhere that describes how MIMO works in detail, but the basics are that if you form a matrix with the complex path gains (i.e. both amplitude and phase) between individual transmit and receive antennas (e.g. t1, t2, t3, r1, r2, r3 for a 3x3 MIMO system) of the form
[[gT1R1 gT1R2 gT1R3]
[gT2R1 gT2R2 gT2R3]
[gT3R1 gT3R2 gT3R3]]

(BTW, Malda, LaTeX or MathML please? Octave/Matlab format isn't quite the hottest for representing a matrix in human readable form...)

you can perform operations (I believe a singular value decomposition but my memory could be wrong and it may be another decomposition) on that matrix to form two transformation matrices and a diagonal matrix. The diagonal matrix contains the path gains of three independent pseudochannels (which I believe are either the square root of the matrix eigenvalues, the eigenvalues themselves, or the square of their eigenvalues), and the transformation matrices can be used to take transmissions intended for the three pseudochannels and convert them to actual transmissions/reception on each antenna.

I'm sorry I did such a crap job explaining this, I really need to find that paper as it does a much better job. :)

Beware! Many companies have begun calling anything

Re:Why so long to finalize the standard?

[ArchAbaddon]

"Pre-N" was just a fancy marketing ploy be Belkin; their "Pre-N" products was made well before even Draft 1 was released. It is proprietary, and when the 802.11n draft is standardized, will probably not be upgradeable to the standard, and will only be backwards compatible to 802.11g with other wireless devices.

Taco: Please Start Using Intel's New Logo, Huh?

[Glasswire]

...It's only been 12 months since they changed it to the new one