>As you start to walk up the modulation line you definitely need more C/I,
but you also start to loose the ability to use full power out of the radio.

A small bit of trivial regarding this issue

With higher order modulation schemes, the EVM (Error Vector Magnitude) can
be so high that even on a perfect link (no noise) the receive chip is
incable of decoding the signal properly into the correct 64 "dots" of the
QAM modulation plot.

This QAM constellation "interference" can be represented by a grid of 8x8
dots that are being blurred by the transmitter not handling the signals with
enough linearity (e.g., the radio power amp is turned to high).  When too
much blur occurs, the adjacent dots touch each other and the receiver will
not be able to decipher the signal (it's blurred)


WiNOG Austin, TX
March 13-15, 2006

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