Channel-estimation assisted search range narrowing high-order QAM demapping algorithm

The invention discloses a channel-estimation assisted search range narrowing high-order QAM (Quadrature Amplitude Modulation) demapping algorithm and aims to evaluate contribution of a reference constellation point to demapping by a soft-decision contribution factor and narrow a search range into the reference constellation point with larger soft-decision contribution so as to reduce complexity of high-order QAM demapping. According to the algorithm, the channel estimation information is sufficiently utilized to assist an self-adaptive selection search range, so that the search range is greatly narrowed, the complexity of high-order QAM demapping is effectively reduced, excellent balance between algorithm complexity and performance is realized, and a foundation for expanding a high-order QAM application scene is laid.