Last Post: March 28, 2011:
802.11n has many enhancements to increase the throughput enormously - like using 4x4 MIMO.
However, 1x1 MIMO configurations are also being built into small, mostly handheld, client devices.
Other than being able to claim being an "n" device, what is this really going to improve in a 2.4 GHz device?
It's hard to believe that its power save modes will be that much better, or that the small increase in maximum rate will be worth the effort for most products.
About the only thing I can see as a true benefit is that it will be able to run in a true Greenfield setup.
Does anyone have any thoughts and/or experiences with this situation ?
You mentioned the two primary motivators (better rates and no protection mechanisms), but you also get LDPC code, which adds reliability. Short guard intervals add efficiency, and frame aggregation and block acknowledgments add efficiency.
These features each provide their respective gains, but the question I would ask in reply is "why not update to 802.11n?" The cost difference between 802.11n and 802.11g chips are very minimal, but the gains both to an individual device and to the surrounding networks can be helpful.
Higher data rates=shorter transmit times=more open air time=greater WLAN capacity?
That's what my nod to Greenfield was about. Good for busy networks.
As I understand it, LDPC ("n" ?) requires a [u]better [/u] S/N ratio, so for locations with little interference it sounds like it would help with throughput.
The problem I have, is that not all client devices are rate limited - they may be mechanically or power limited, and at just about any rate from 2 Mbps up, they run (scan/print/etc) at the same speed. So increasing one devices communications rate won't help much - by itself.
From a technical perspective, overall range and battery life are my main concerns.
From a cost perspective, I have not followed chip prices in the last year, but when we're talking about tens of thousands of units, every dollar counts.
That's fair, and I'm not sure I have technical answers on those points. I suspect that marketing has as much to say about it as engineering. :) 802.11n is newer, better, newer, and better, so who would want to buy anything that is 802.11a/g, even if it is just a phone.
Running Voice on 1x1 n standard requires larger packets than running in 802.11g speeds.
The little higher transmit speed does not compensate for the larger overhead in n ( mixed mode) for the small VoiP packets so the air time for the g speeds packets will be less then for n speeds. Yuo may compare the 54 mps g speed with 65 n speed. Using SGI for handhelds wil not always be an option due to the more intricae problem with multipath for a moveable device.
Very few site may have the possibility to run Voice in greefield mode, due to teh precesne of legacy devices.
n-packets requires more processing time to build and thus will consume more power cycles.
My 2 cents worth
Transmit beamforming is an integral part of the ?big picture? of 802.11n. Unfortunately, as of this time, only a few manufacturers have implemented this in their products. This will change over time ( chipset manufacturers and WLAN equipment manufacturers ).
Even if we have only a 1 x 1 scenario, we can get some pretty impressive advantages utilizing transmit beamforming.
What needs to be remembered is the Antenna Reciprocity Theorem, which roughly states ?all other things being equal, an antenna will have the same receive gain as transmit gain, at the same frequency used for reception as for transmission?. Very rough, but that?s the gist of it.
If we have an AP, say utilizing Tx beamforming, we have ?squeezed? the antenna pattern into a narrower beam, but with the same Tx power as before. This has obvious advantages in terms of range, throughput etc for even a 1 X 1 STA that is being communicated to.
It?s the opposite direction that?s interesting. Not only has the Tx beamwidth been ?made narrower?, with the inherent increase in gain, but so also has the Rx beamwidth. This means that the 1 X 1 STA is now ?talking into a bigger ear?,