25 dB. Even with this difference approximately 10 dB of gain is
still achievable for the BER 1E-3 target. This plot also shows us as the number of antennas, M,
increases the performance difference between MRC and SC increases. For the particular values chosen
above, the performance difference between SC and MRC for the M 4 antennas example is
approximately 3 dB. This is an alternative way to show the difference in performance between MRC
and SC increases as the number of receive antennas increases.
Lastly, an alternative form of the MRC performance is given below (continuing with the above
variable definitions)
(5.108)
The alternative form of the SC performance is given below with .
(5.109)
Earlier we discussed that the switching selection diversity receiver suffered from complexity since
only a single antenna was used at a time for the M available antennas. Next we present the results of
some work performed by [58] where more than 1 antenna is used in the demodulation process. We
will keep the same notation which was SC2 corresponds to keeping the largest 2 antenna signals while
SC3 corresponds to keeping the largest 3 antennas signals. We will first present the mathematical
BER equations and then discuss their results.
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