JPL's Wireless Communication Reference Website

Chapter: Analog and Digital Transmission
Section: Diversity

Equal-Gain Combining Diversity

Various techniques are known to combine the signals from multiple diversity branches. In Equal Gain Combining, each signal branch weighted with the same factor, irrespective of the signal amplitude. However, co-phasing of all signal is needed to avoid signal cancellation.

Figure: L-branch antenna diversity receiver (L = 5). With EGC, the attenuation/amplification factor a_i is the same for all channels i.

Thus, EGC is simpler to implement than Maximum Ratio Combining (MRC). The adaptively controller amplifiers / attenuators are not needed. Moreover, no channel amplitude estimation is needed.

Figure: L-branch Equal Gain Combining antenna diversity receiver (L = 5).

The average SNR improvement of EGC is typically about 1 dB worse than with MRC, but still much better than without diversity.



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