Adaptive equalizer
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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 x when it is not in training mode. If the probability that the equalizer makes a mistake is sufficiently small, the symbol decisions d(n) made by the equalizer may be substituted for x.[2]
- RLS
A well-known example is the decision feedback equalizer [3], a filter that uses feedback of detected symbols in addition to conventional equalization of future symbols. Some systems use predefined training sequences to provide reference points for the adaptation process.
[edit] See also
[edit] References
- ^ S. Haykin. (1996). Adaptive Filter Theory. (3rd edition). Prentice Hall.
- ^ Tutorial on the LMS algorithm
- ^ Decision Feedback Equalizer
