Adaptive equalizer
An adaptive equalizer is an equalizer that automatically adapts to time-varying properties of the communication channel.[1] It is frequently used with coherent modulations such as phase shift keying, mitigating the effects of multipath propagation and Doppler spreading.
Many adaptation strategies exist. They include:
- LMS Note that the receiver does not have access to the transmitted signal when it is not in training mode. If the probability that the equalizer makes a mistake is sufficiently small, the symbol decisions made by the equalizer may be substituted for .[2]
- RLS
A well-known example is the decision feedback equalizer,[3][4] a filter that uses feedback of detected symbols in addition to conventional equalization of future symbols.[5] Some systems use predefined training sequences to provide reference points for the adaptation process.
See also
References
- ↑ S. Haykin. (1996). Adaptive Filter Theory. (3rd edition). Prentice Hall.
- ↑ Tutorial on the LMS algorithm
- ↑ Decision Feedback Equalizer
- ↑ Warwick, Colin (March 28, 2012). "For Decision Feedback Equalizers, Beauty is in the Eye". Agilent Technologies.
- ↑ Stevens, Ransom. "Equalization: The Correction and Analysis of Degraded Signals" (PDF).
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