Diversity Combining is the technique applied to combine the multiple received signals of a diversity reception device into a single improved signal. In electronics, diversity reception refers to a method for improving reception of a radio signal, typically achieved by the use of dual receivers whose antennas are located in physically distinct locations (which can be less than a metre apart). ...
Various Diversity Combining techniques can be distinguished:
selection combining: Of the N received signals, the strongest signal is selected. On an AWGN channel, the maximum achievable diversity gain is log_10(N) dB.
maximum ratio combining.
In communications, the additive white Gaussian noise (AWGN) channel is one in which the only impairment is the linear addition of wideband Gaussian noise with a constant spectral density (expressed as watts per hertz of bandwidth). ...
Because of this problem, it is possible for the output of the diversitycombiner to be of poorer usability than that of one of the individual branches.
Thus, the diversitycombiner processes the received signals using a diversitycombining algorithm that includes the weighting factor for each of the reception paths, to provide a resultant signal that more likely represents a signal as originally transmitted from the common point of transmission than any of the received signals alone.
The diversitycombiner 212 uses the weighting factors 209 to perform a modified form of max-ratio combining to obtain estimates, D, of the data symbols.
A diversity system could involve frequency diversity which is implemented by transmitting identical information on two or more separate carriers that are separated enough in frequency for the fading of each carrier to be uncorrelated with the others.
In another aspect of the present invention, spatially diverse received signals are directly summed or combined without the need to estimate the phase of the signals from each receiving element, thus eliminating the requirements of the prior art apparatus and methods to obtain phase information and perform phase adjustments prior to combining.
The method comprises perturbing the phase of the carrier of a received signal from a diversity receiving element such that the perturbation of the phase of the carrier is periodic with a period equal to, or a multiple of, the symbol rate.
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