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Concerns Over Increased 802.11n Power Usage
alphadogg writes "Next-generation 802.11n systems promise to considerably improve WLAN performance. But the processing required for the boost sucks up more power than the older 802.11a/b/g networks. Still, many enterprise-class Wi-Fi vendors claim to deliver full 802.11n capabilities without enterprise customers having to touch their power infrastructures. So what gives?"
Maybe skimming TFA wasn't the best basis for comment. The article mentions no power issue at the client. It's basically saying that:
First of all, this has little to do with what is usually considered power infrastructure. This has to do with power-over-ethernet. It appears some dual band 802.11n radios require more power than one particular specification (802.3af) allows. Solution? Don't use 802.3af, or, don't use the radios which require too much power. Not really a big deal. I expect that manufacturers will bring the power requirements down to allowable levels over time.
From TFA: "some 802.11n Draft 2.0-based access points consume up to 18 watts."
From TFA: "802.3af power-over-Ethernet (PoE) switches and power injectors supply about 15 watts of power at the switch port."
No go sit in the corner and think about what you've done...
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
Multiple radios in simultaneous operation (Read: MIMO) plus the circuits to coordinate and control the radios and it has *double the bandwidth* (in the physical layer) = more power use by the 802.11n device. Duh! (Also notice there are more and larger antennas?) http://en.wikipedia.org/wiki/IEEE_802.11n
If the big deal in the article is over PoE powered 802.11n solutions, just exceed the power spec at the power injector and use 24 Gauge CAT6 UTP (or larger Gauge CAT6 for longer runs) for your PoE runs to lower electrical resistance.
I have installed PoE devices that have their own proprietary power injectors that exceed the PoE power standard. The problem is where people use long runs of super cheap CAT5 and lots of punch-downs and they expect also their large switch with PoE injection to provide PoE to whatever is connected. There is a reason that the manufacturers' of powered by PoE devices do provide their own wall-wart PoE injectors...
The summary sucked, but this is clearly about Power over Ethernet, for which that 5% can be quite significant.
I bet most of the energy is in the form of heat from the individual DC converters plugged in to long extension cords laid along the drop ceiling to the nearest electric column.
And you'd be incorrect. Most corporate infrastructures that heavily/professionally deploy wireless is going to due it via PoE - putting in a PoE switch or injector is much cheaper than wiring dozens or hundreds of new power jacks up in ceilings and such. With PoE all you need to do is run a ethernet cable over to the AP to provide both network access and power.
And PoE is only capable of transmitting so much power. 12.95 watts at the device. The new N devices are being reported at 18 watts. We have a little problem here...
While the processing requirements of N is requiring more wattage at the processor, I figure that the dual-radio feature of N is also significant - corporate ones you normally have both a 2.4GHz and a 5GHz radio. With N you're possibly doubling the number of radios to four. This increases power demand. If nothing else, you're also subletting the frequency spectrum even more, thus need to, on average, transmit at a higher power level overall to beat the noise floor.
I don't read AC A human right
Enterprise hardware does not use general-purpose CPUs, it uses special-purpose ASICs
Actually they don't - take a look in a high-end AP some time. "Enterprise" wireless systems use the same, or often older generation, of wireless technology that is in consumer access points. Competition in the consumer AP market is what drives all the incredible price/performance in wireless technology, and I assure you nobody is going to spend the tens of millions to do a custom spin of one of those chipsets for the relatively small high-end market. Those products sell on branding, special software features, and support contracts, not silicon performance. And as far as the CPU/memory etc, these are going to be much LESS specialized in a high-end system than in a consumer AP. Low-cost APs use highly integrated ARM or MIPs-based SOCs that are designed for sub $20 BOM cost. A higher-end system, however, is not bound by BOM costs and might have four times the memory and a more general purpose processor capable of running more software.
Routers and switches are a different story, and those DO use ASICs and FPGAs. The high-end models of these have to deliver a totally different hardware feature set than consumer equipment, and unlike wireless technology, the bleeding edge tends to be developed for the highest priced products before trickling down.
Actually my informations is only 5 years out of date and from a quick Google search the 1300 series AP which is their next to newest offering is also ASIC based, so I wouldn't consider it so out of date =) They considered the stuff they could build into the ASIC to be a competitive advantage and knew that they could be to market with a new product months before the major chip houses would have even engineering samples. To be more on-topic their 1250AP which is 802.11n draft 2 compliant is only supported with one radio if powered by a 802.3af switch but you can use two radios if you have a Catalyst switch with 18.5W power capability or if you use the power injector. They claim 16.9W max power draw with 2 radios or 12.95W with one radio.
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