Technology Blog

More Power More Problems

by on ‎10-21-2015 07:51 AM - last edited on ‎10-21-2015 07:52 AM by Chief Airhead Chief Airhead

In the wireless world we often think more power is good. The louder the signal surely higher the performance gain. I am sorry to say that is not true in most cases. RF power is like a delicate flower and should be treated with respect. Simply choosing a higher power output and not properly tuning your radios could cause you more pain than you really know. In this quick blog post, I share a pair of static bridges being bench tested 70 feet apart. The only difference in configuration is simply changing the RF power. While I only share the capacity values, the throughput values have been excluded to keep the focus on power.

 

Example #1 - (HOTTEST)

In this example we pump up the power @ 30 dBm.

(1) Link @ -17 dBm

(2) Modulation at 16 / 64 QAM

(3) TX Power 30 dBm

(4) Capacity Link TX 205, RX 200

 

gs1.png

 

 

 

Example #2 - (HOT)

In this example we power down to @ 24 dBm.

(1) Link @ -22 dBm

(2) Modulation at 256 / 256 QAM

(3) TX Power 24 dBm

(4) Capacity Link TX 396, RX 391

 

GS2.png

 

 

 

Example #3 - (PEACHY)

In this example we power down to @ 18 dBm.

(1) Link @ -27 dBm

(2) Modulation at 1024 / 1024 QAM

(3) TX Power 18 dBm

(4) Capacity Link TX 482, RX 469

 

gs3.png

 

Modulate Gain: 16 vs 1024 and 64 vs 1024

Capacity Link Gain: TX 205 vs 481, RX 200 vs 469

 

Why excessive power gain is bad is because it increases noise and distortion at the receiver’s radio. In Example #1, both radios can hear each other at -17 dBm! Think of it this way, imagine having someone in your ear with a megaphone yelling today’s lunch specials at you. You can’t hear so well, can you ? Take away the megaphone and step back a few feet and all is peachy.

My quick less-techy blog post for today! 

 

Cheers!

 

 

Comments
JerryD

Can you tell me what program you are using?

Thanks JerryD

Hi Jerry,

 

This is the onboard software Ubiquiti uses. 

JerryD

Can this software work with say some smb cisco for example: WAP321 AP?

This software is specific to Ubquiti only.

JerryD

Nice feature.....

 

Thanks

JerryD

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