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Is there anything wrong with a TX power of 26 dBm?

post #1 of 10
Thread Starter 
running ddwrt on my wndr3700.

its there anything wrong with setting a higher tx power? I am getting a weak signal in my basement.
post #2 of 10
Quote:
Originally Posted by Argorn5757;12632571 
running ddwrt on my wndr3700.

its there anything wrong with setting a higher tx power? I am getting a weak signal in my basement.

It will not hurt to run at a higher tx. My default is 71 i believe, and running at 79 and always have 5 solid bars two rooms away.
Raise it in small increments as and check.
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post #3 of 10
In general, higher TX power will reduce your maximum throughput. It may or may not increase your range, depending on the wireless adapter you're using.
post #4 of 10
Quote:
Originally Posted by thefreeaccount;12637732 
In general, higher TX power will reduce your maximum throughput. It may or may not increase your range, depending on the wireless adapter you're using.

proof.gif
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post #5 of 10
http://www.lmgtfy.com/?q=transmit+power+throughput
Quote:
For each data rate, throughput increases with
increased transmit power and beyond a certain
transmit power it starts to fall.

There is only one path for signal, but many paths for noise. It seems obvious that if you are already getting "good" s/n, then increasing your transmit power is going to decrease your s/n ratio. Your WAP should be picking the right transmit power to give maximum throughput at whatever the developers considered "optimal" range.
Edited by thefreeaccount - 3/6/11 at 8:23pm
post #6 of 10
Quote:
Originally Posted by thefreeaccount;12638555 
http://www.lmgtfy.com/?q=transmit+power+throughput

There is only one path for signal, but many paths for noise. It seems obvious that if you are already getting "good" s/n, then increasing your transmit power is going to decrease your s/n ratio. Your WAP should be picking the right transmit power to give maximum throughput at whatever the developers considered "optimal" range.

I know how to use Google, thank you very much. And your quote disproved your statement. smile.gif

The reality is, the default may or may not be the "optimal" transmit power. If you can't get a signal ten meters from the router, it probably isn't.
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post #7 of 10
Quote:
Originally Posted by error10;12639164 
The reality is, the default may or may not be the "optimal" transmit power.
Yeesh...please spend 10 seconds reading the google links.

There is no "optimal" transmit power. There is also no single "default" for it; your WAP will up the tx until the point at which your throughput at "optimal" range would start to be degraded. If you increase the transmit power so that you get "good" s/n in the farthest corner of your house, your throughput closer to the router is going to drop. Stronger signal = stronger noise = slower connection.

What is "optimal" range? Well, it's sort of whatever The Man says it is, but basically, if your router advertises 400Mbps, then it has to give 400Mbps at some "reasonable" range even if it's put in a less-than-perfect environment or someone is going to give it a bad review.

That's assuming your wireless adapter can transmit enough signal to talk back to the router. If it can't, all you will be doing is decreasing your throughput and your range will not increase one bit.
Edited by thefreeaccount - 3/6/11 at 9:56pm
post #8 of 10
Haha.

Back in the day I was using a 802.11b PC card, with no external antenna, completely unmodified, to talk to a wireless access point over a mile away, and it worked fine (albeit very slowly). But using my laptop in the window wasn't really an option for more than very short periods.....
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post #9 of 10
As stated before, please be more specific. I read through the first three links and here is what I found.

First link: Got tired of looking for the correct Computer Communications Volume.
Second link: Old technology using CCK Encoding and DQPSK at best. Not only that I did not see anything about radiators and antennas.
Third Link: I don't see any actual testing here, and on top of it he is pushing the radiator outside it's limits.

I don't know of any AP that will automatically up it's TX power to get maximum throughput. The closest thing to this is controller based WLANs, and that is not based on clients but neighboring APs. I am going to run some test on my Cisco 1242 real quick.

OP: To answer your question. You need to add the radio power of your access point and the antenna dBi to get total output power. This should not be stronger than the weakest wireless client you have.

Look at RF Math under section 2.
http://www.overclock.net/networking-security/917186-wireless-information-troubleshooting.html
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post #10 of 10
802.11 G tests do not show degraded throughput as TX power increases. It also does not show a reduced S/N.

Laptop: Lenovo T400
NIC: Intel 5100 AGN (Configured for G only at Lowest Power setting. Intel drivers does not give dBm level.)
Testing software: IPERF (Using 8 parallel streams.)
AP: Cisco 1242
Antenna: Cisco AIR-ANT4941 (2.1 dBi)
Distance from AP: 10 feet line of site.
Specturm Analyzer:Airmagnet Specturm XT
Wireless Analyzer:Airmagnet WiFi Analyzer

Spectrum XT shows no interference before test.
Signal strength of Laptop at AP = -61 dBm

Test #1
AP power: cck -1 dBm / ofdm -1 dBm / EIPR 1.2 mW
Wifi signal @ client is -62 dBm / SNR 27
Throughput 19.1 Mbits/sec
Throughput 18.2 Mbits/sec
Throughput 19.0 Mbits/sec

Test #2
AP power: cck 8 dBm / ofdm 8 dBm / EIPR 10.23 mW
Wifi signal @ client is -53 dBm / SNR 36
Throughput 19.0 Mbits/sec
Throughput 19.1 Mbits/sec
Throughput 19.1 Mbits/sec

Test #3
AP power: cck 14 dBm / ofdm 14 dBm / EIPR 40.73 mW
Wifi signal @ client is -49 dBm / SNR 39
Throughput 19.2 Mbits/sec
Throughput 18.8 Mbits/sec
Throughput 19.3 Mbits/sec

Test #4
AP power: cck 20 dBm / ofdm 20 dBm / EIPR 162.18 mW
Wifi signal @ client is -40 dBm / SNR 49
Throughput 19.4 Mbits/sec
Throughput 19.2 Mbits/sec
Throughput 19.3 Mbits/sec


Please show me documentation that makes you belive the statement you made below.

" If you increase the transmit power so that you get "good" s/n in the farthest corner of your house, your throughput closer to the router is going to drop. Stronger signal = stronger noise = slower connection."


I can google too... biggrin.gif

http://www.cisco.com/en/US/docs/solutions/Enterprise/Mobility/emob41dg/emob41dg-wrapper.html

Chapter 3 pg. 16 of the PDF document.
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