Diversity gain is the increase in signal-to-interference ratio due to some
diversity scheme, or how much the transmission power can be reduced when a diversity scheme is introduced, without a performance loss. Diversity gain is usually expressed in
decibels, and sometimes as a power ratio. An example is
soft handoff gain. For
selection combining N signals are received, and the strongest signal is selected. When the N signals are independent and
Rayleigh distributed, the expected diversity gain has been shown to be
, expressed as a power ratio.