802.11ac 0 Will it have limited range (since only 5GHz frequencies used)?

[njweb]

While reading up on 802.11ac a bit, I noticed that one concern, relative to 802.11n 2.4 Ghz, is that 802.11ac may have limited range since it reportedly only operates in the 5.x Ghz frequencies (x being the digits covered by the range)?

If this is the case, I will personally stick with dual band (2.4 and 5 Ghz) routers given the short range of 5 Ghz which does not cover my home adequately (which is an understatement).

Any thoughts?

 

[stevech]

If products for this new standard have higher transmit power the range can be the same as in 2.4GHz. At the same time, with higher data rates in a new standard, a better signal to noise ratio is needed. These can negate each other. The hardware cost increases with the need for higher power plus higher data rates. We'll have to see if vendors can crack the catch-22 in price vs. Volume.

 

[thiggins]

I would not expect any range increase over current 5 GHz band products for 802.11ac products.

 

[njweb]

Thanks Steve.
Agreed. Right, while they could theoretically use some techniques, including amplification upgrades and perhaps beamforming, to overcome the 5 GHz band's typical limitations, the cost to do so could prove impractical.
As you said, it will be interesting to see what develops.

In the meantime the RT-N66U may meet my needs. In fact I may not feel any special need for 802.11ac (aside from the techie in me wanting to always the latest technology), if its 2.4 GHz wifi performance is close enough to my current Amped Wireless R10000's incredible signal strength and throughput real world performance in controlled tests.
I know in other areas primarily including, but not limited to, concurrent data sessions capacity , gigabit LAN and WAN ports, 450 Mbps on both bands (vs single band 300 Mbps on the R10000), processing power (and IPv6 which I do not think the Amped supports unfortunately), the RT-N66U exceeds the Amped, which all combine to account for the reason I am going to try the Asus...
All that being said, if the Asus wifi performance does not match the lofty numbers observed with the Amped (I compared it to the E4200 v1 I still had back in December), I will have a tough decision to make.

 

[stevech]

Yes, doubling the transmitter power in an OFDM signal quadruples the price of the HPA (power amp section). The HPA is a major or the largest cost in consumer WiFi products, I've been told when I worked on a large OFDM pioneering project with Cisco Aironet people.

The other issue is that as the bit rate increases (modulation order increases), the transmitted bits per Hz of bandwith per second increases. Cramming more info in the same sized channel bandwidth pipe. Common sense and RF engineering says that as you increase the information rate in a fixed-size channel, other things have to improve greatly to support. These include the transmitted signal's distortions (rho) and the received signal to noise - both have to improve to support the higher rates. Higher transmitter power is very expensive in OFDM because of the peak to average ratio in power for OFDM.

In the lower modulation rates of 802.11, and some are non-OFDM, the transmitter power can increase by 5-6 dB (fourfold) because the peak/average ratio is less demanding. This is why 802.11b yields the best range - far lower information rate in the same 20MHz channel.

The state of the art in affordable broadband is about 2-3 bits per Hz (of channel bandwidth) per second. 802.11g at best is a burst rate of 54Mbps in 20MHz; that's between 2-3 bps/Hz/sec. The IP layer yield is of course about 60% of the this burst rate due to WiFi being half duplex, error correcting codes (FEC) and so on. The problematic 40MHz mode of 802.11 (uses 2/3 of the entire band) doesn't much improve this 2-3 bps/Hz/sec factor.

The consumers' user interface or DD-WRT might ask for 100mW but the radio hardware/firmware ignores attempts to use power settings that the HPA cannot do while supporting the rho (distortion) that WiFi certification requires. Too much distortion = higher bit error rate at the receiver = lower throughput. Just common sense.

 

[sfx2000]

I think it will give higher bit rates, but not much better range... coding gain only takes one so much further, RF prop loss is basic physics... witness 802.11n in 5GHz vs. 802.11a in the same space.

It will be an improvement, but not as much as the marketeers would like you to believe...

 

[njweb]

Thanks a lot for all the valuable insights gentlemen!

I think I will more than happily stick with my current setup then. It more than meets my current needs anyway.

 

[dunkin]

beamforming

802.11ac will use beamforming to improve the range.

Here is an interesting article

http://www.5gwifi.org/advantages-of-80211ac.php

according to the article, 802.11ac has better range than 2.4G 802.11n