More Power More Problems

By George Stafanick, Blog Contributor
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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



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




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


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!