Method and apparatus for low-complexity ISI estimation using sparse discontinuous time-domain pilots

A receiver comprising:

• a processor;
• and
• a non-transitory computer readable storage medium storing programming for execution by the processor, the programming including instructions to:
• receive a first frame and a second frame of a signal, wherein the first frame and the second frame are communicated during different time intervals;
• extract a first noise vector from at least one pilot carried by the first frame and a second noise vector from at least one pilot carried by the second frame;
• store the first noise vector and the second noise vector in a buffer;
• perform spectral estimation on at least the first noise vector and the second noise vector to obtain a first set of tap coefficients;
• and
• perform inter-symbol interference ISI equalization on the second frame in accordance with the first set of tap coefficients to remove residual ISI from symbols in the second frame.

A method for dynamically activating or deactivating an equalizer, the method comprising:

• receiving a signal carrying at least a leading symbol and a trailing symbol;
• extracting a noise vector from at least one pilot carried by the signal;
• performing spectral estimation on the noise vector to obtain at least a first tap coefficient and a second tap coefficient, wherein the first tap coefficient corresponds to an energy level of a leading symbol in the signal, and wherein the second tap coefficient corresponds to an amount of energy that leaks from the leading symbol to the trailing symbol as a result of inter-symbol interference (ISI);
• and
• activating an ISI equalizer when a ratio of the second tap coefficient to the first tap coefficient exceeds a first threshold, wherein the ISI equalizer is configured to perform ISI equalization on the signal when activated.