5Ghz Upper Channels Power

[cantholdanymore]

I found a couple of old references stating that the upper channels in the 5Ghz band can use more power than in the lower band:

http://tidbits.com/article/10849

http://www.macworld.com/article/1140685/wifi_spectrumbands.html?page=2

Is this still the case?. I tried this at home at it didn't work. My router is a RT-N56U and my network adapter a PCE-N53 both by asus.

Using inSSIDer to look at the signals, my router always picks the lower band channels in auto mode (I have no other 5Ghz signal in my area). But when I manually pick the upper band channels inSSIDer reports a lower power. In both cases the power setting in my router is set to 100%.
Any Ideas?

 

[Fardringle]

Higher frequencies (shorter wavelengths) do not pass through obstacles as well. It's not that they can use higher power transmissions, but that they must use higher power transmissions in order to achieve the same signal strength at the receiving end. So if there are walls and other things between your computer and the router, you generally want to use lower frequencies unless they are already being used by something else.

 

[cantholdanymore]

I understand what you're saying but I don't think the difference will be huge between the lower channels @5.1GHz-5.2GHz vs the upper channels @5.7GHz-5.8GHz from the propagation point of view. Now the transmitter and/or receiver may perform different between the upper and lower channels due to design or antennas used.

 

[Ghiedo27]

The 5.1 channel already needs more power than 2.4 channels so moving to a 13% shorter wavelength is just going to make it that much worse. It's not like we're talking about a drastic change in frequency adding a new propagation characteristic. It's just that little bit less power efficient than lower bands.

 

[JackMDS]

All of this is ridiculous, these differences are correct theoretically, but they produce No difference in functionally in the real environment.

It is like saying: "I prefer to commute to a place that is 1 mile away rather than another place that is a mile and 10 feet".

Rearranging the furniture (or getting rid of substance that absorb high frequencies) in the environment will probably produce much more significant effect.

There is No end to this "Holy Grail" nonsense. If One needs more Wireless power, a second AP to be placed in secondary location will be the answer.

 

[alkemyst]

I believe both G and N suffer from slow downs at higher power levels.

 

[donfm]

All of this is ridiculous, these differences are correct theoretically, but they produce No difference in functionally in the real environment.

It is like saying: "I prefer to commute to a place that is 1 mile away rather than another place that is a mile and 10 feet".

Rearranging the furniture (or getting rid of substance that absorb high frequencies) in the environment will probably produce much more significant effect.

There is No end to this "Holy Grail" nonsense. If One needs more Wireless power, a second AP to be placed in secondary location will be the answer.

I so enjoy your no nonsense analysis of these technological witch hunts. People get too wrapped up in specs in these forums and lose common sense at times....just my opinion.

 

[spidey07]

The upper channels of 5Ghz (UNI-III band) can interfere with radar and all APs are required to lower their power if they detect it any radar. It's somewhat frequent for the AP to lower it's power in the upper band, nothing you can do about it, a FCC/regulatory thing.

 

[cantholdanymore]

The upper channels of 5Ghz (UNI-III band) can interfere with radar and all APs are required to lower their power if they detect it any radar. It's somewhat frequent for the AP to lower it's power in the upper band, nothing you can do about it, a FCC/regulatory thing.

Thanks, finally a relevant reply.
Just did some research on the FCC regulations and found this to be the case. No wonder, I live in the approaching path to IAD.
1Watt devices are also required to have power control mechanism that can reduce their power by 6dB (I think this is the source of the confusion on the OP links); so manually increasing the power, if possible, won't produce any gain.

 

[freakneck]

The upper channels of 5Ghz (UNI-III band) can interfere with radar and all APs are required to lower their power if they detect it any radar. It's somewhat frequent for the AP to lower it's power in the upper band, nothing you can do about it, a FCC/regulatory thing.

This is incorrect, according to the FCC.

UNII Indoor Only - 5150-5250 Mhz/50mW TX Pwr limit/200mw ERP limit/Integrate antenna only/DFS

UNII Low Power - 5250-5350 Mhz/250mW TX Pwr Limit/1W ERP/DFS

UNII ISM - 5725-5825/800mw TX Pwr/200W ERP/NO DFS

Cisco Whitepaper on DFS: http://www.cisco.com/en/US/prod/col...aecd801c4a88_ps5279_Products_White_Paper.html

 

[imagoon]

U-NI-3 allows for 1 watt total power which is above 250mw for U-NI-2 and 1.

DFS dynamically instructs a transmitter to switch to another channel whenever a particular condition (such as the presence of a radar signal) is met. Prior to transmitting, a device's DFS mechanism monitors its available operating spectrum, listening for a radar signal. If a signal is detected, the channel associated with the radar signal will be vacated or flagged as unavailable for use by the transmitter.

U-NII Upper (U-NII-3): 5.725 to 5.825 GHz. Sometimes referred to as U-NII / ISM due to overlap with the ISM band. Regulations allow for a user-installable antenna. Power limited to 1W

 

[Cabletek]

In addition to information supplied here look into this.

http://www.ko4bb.com/Manuals/05%29_GPS_Timing/E10589_Propagation_Losses_2_and_5GHz.pdf