OFDMA Receiver Channel Estimation via Multipath Delay Rotation

The patent applies preliminary action by estimating the time delay of multipath components before performing channel estimation. The receiver first obtains time delay information through correlation processing or other delay estimation techniques, then uses this information to pre-process the received signal (e.g., aligning multipath components or compensating for delay effects) before conducting channel estimation. This preliminary delay estimation and compensation action improves channel estimation performance by reducing the harmful frequency selectivity effects caused by large time delays, without requiring complex receiver structures.

The patent implements feedback by using the estimated channel impulse response to determine appropriate modulation and coding schemes adaptively. The receiver performs channel estimation using the improved method, obtains accurate channel state information, and feeds this information back to the transmitter or uses it locally to adjust the modulation order and code rate. This feedback mechanism ensures that high-order modulation schemes are only used when channel conditions are good, while automatically switching to more robust lower-order schemes when channel estimation reveals poor conditions, thus maintaining both high data rates when possible and transmission reliability when needed.