Method and system for demodulating communication signals in spectral domain

Abstract

The invention discloses a method and a system for demodulating communication signals in a spectral domain. The method comprises the following steps that: step 1) an estimated value processing unit of a cyclic autocorrelation function calculates a corresponding estimated value of the cyclic autocorrelation function according to one section of received continuous CDM-OFDM (code division multiplexing-orthogonal frequency division multiplexing) cyclic delay modulation signals in the length of L OFDM (Orthogonal Frequency Division Multiplexing cycles; step 2) a cyclic delay detection processing unit respectively calculates corresponding likelihood functions aiming at different cyclic delay values and obtains a corresponding cyclic delay vector according to a maximum likelihood criterion; and step 3) a cyclic modulation vector mapping processing unit maps the cyclic delay vector and obtains a cyclic modulation signal which is sent. The method and system disclosed by the invention can be applied to channel multiplexing and transmission of the spectral domain, and the capacity of the system can be simultaneously increased on the premise of not affecting the transmission of ordinary OFDM signals; and a block computing way is adopted, so that the computational complexity can be greatly reduced and processing time and resources can be saved.

Description

technical field [0001] The invention belongs to the technical field of communication, and relates to a demodulation method and a demodulation system of a spectrum domain communication signal. Background technique [0002] As a standard multi-antenna diversity technology with good compatibility, cyclic delay diversity (Cyclic Delay Diversity, CDD) has greatly enhanced the existing standard Orthogonal Frequency Division Multiplexing (OFDM) technology, making it It can obtain enough space diversity gain in the wireless environment with rich scattering. Cyclic delay processing can convert space diversity into frequency diversity, thus adding redundancy in the frequency domain of OFDM systems. Different from Space-Time Block Coding (STBC) and Space-Time Trellis Codes (STTC) technologies, the cyclic delay diversity technology can only be realized at the sending end, using this enhanced technology The system maintains compatibility with the standard. Therefore, the cyclic delay ...

AI Technical Summary

Problems solved by technology

[0006] In the existing cyclic feature detection algorithm, the simplified suboptimal algorithm is often used, the detection performance is not high, and it cannot meet the requirements of the spectral domain communication signal demodulation performance of the spectral domain channel multiplexing transmission system based on cyclic delay modulation

The original optimized detection algorithm has high computational complexity and is difficult to apply to actual signal detection or demodulation

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