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Demodulation method and device for flexible sub-carrier modulation system

A technology of carrier modulation and demodulation method, which is applied in the field of digital information transmission, can solve the problems of not using pilot frequency and being unable to use it, and achieve the effect of good demodulation data and channel estimation results

Inactive Publication Date: 2009-05-13
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] Since the training sequence is not used to fill the guard interval between data frames in the flexible subcarrier system, and the pilot frequency is not used at the same time, therefore, the channel estimation method using the training sequence or the pilot frequency commonly used cannot be used

Method used

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  • Demodulation method and device for flexible sub-carrier modulation system
  • Demodulation method and device for flexible sub-carrier modulation system
  • Demodulation method and device for flexible sub-carrier modulation system

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Embodiment 1

[0059] The embodiment of the present invention provides a flexible subcarrier demodulation system implementation method and implementation device. The flexible subcarrier modulation system workflow applicable to this demodulation method is as follows: figure 1 As shown, first, the data to be transmitted is subjected to OFDM modulation, the number of effective subcarriers is K, the number of total subcarriers is M, the number of virtual subcarriers is M-K, and the guard interval is filled with the cyclic prefix of the OFDM data frame body , forming a CP-OFDM data frame, wherein the number and position of effective subcarriers are configured by the information adjustment module to complete the variable bandwidth or frequency modulation function; secondly, according to the CP-OFDM data frame, use the training sequence to generate a CP-OFDM training frame, The training sequence is used to modulate the CP-OFDM data frame body, the number of effective subcarriers is L, the number of...

Embodiment 2

[0080] The time slot frame structure adopted by the modulation system in the second embodiment of the method of the present invention is as follows: image 3 shown. A signal frame consists of a 2048-symbol OFDM data body and its 256-symbol cyclic prefix. The total number of sub-carriers in the OFDM data volume is 2048, among which the effective sub-carriers are continuously distributed and filled with data to be transmitted, and the number varies with the required bandwidth, and the remaining sub-carriers are virtual sub-carriers. The signal frame does not contain any known information such as pilot frequency. The training frame filled with the slot header consists of 2048-symbol OFDM known data body and its 256-symbol cyclic prefix. The total number of subcarriers in the training frame is 2048, and the PN sequence with a length of 2047 is selected to be zero-filled to obtain a PN sequence with a length of 2048; each subcarrier position corresponds to a PN sequence position ...

Embodiment 3

[0150] The slot frame structure adopted by the modulation system according to the third embodiment of the method of the present invention is as follows: the signal frame is composed of OFDM data body of 2048 symbols and cyclic prefix of 256 symbols. The total number of sub-carriers in the OFDM data body is 2048, among which, the effective sub-carriers are divided into one or more parts and distributed continuously, filling the data to be transmitted, the central position can change with time, and the total number remains unchanged, and the remaining sub-carriers are virtual sub-carriers . Frequency hopping is realized by changing the central position of the effective subcarrier. The signal frame does not contain any known information such as pilot frequency. The training frame filled with the slot header consists of 2048-symbol OFDM known data body and its 256-symbol cyclic prefix. Since the actual bandwidth occupied by the frequency hopping system exceeds the total bandwidt...

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Abstract

The invention relates to a demodulation method for active subcarrier modulation system comprising following steps: digital base band signal acquired by receiving terminal is subject to combined rough frame synchronization, timing frequency synchronization and front carrier frequency synchronization to acquire rough frame synchronization position and preliminarily synchronized signal by two-dimensional short-sliding self-correlation method; and then combined fine frame synchronization, back carrier frequency synchronization, and timing phase deviation compensation are performed to acquire signal corrected by synchronization parameter; then frame mode identification is performed to acquire signal frame structure information; preliminary channel estimation is performed to acquire preliminary channel estimation result; every data frame is subject to data guide channel estimation to acquire estimation result of channel impact response and OFDM demodulated data. In the demodulation method and demodulation device of the invention, digital base band signal acquired by receiving terminal can be effectively demodulated, and synchronization and channel estimation task during demodulation course are completed, good demodulated data and estimation result are acquired.

Description

technical field [0001] The invention relates to the technical field of digital information transmission, in particular to a demodulation method and device for a flexible subcarrier modulation system. Background technique [0002] In digital communication systems, OFDM (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiplexing) modulation technology has gradually been widely developed due to its advantages in anti-interference and improving frequency band utilization. OFDM technology assigns high-speed data streams to several sub-channels with relatively low transmission rates for transmission through serial-to-parallel conversion, so as to improve channel utilization. [0003] In the OFDM modulation process, if some subcarriers are modulated with zero symbols, these subcarriers can be called virtual subcarriers, and correspondingly, the subcarriers modulated with the data to be transmitted are called effective subcarriers. When the center positi...

Claims

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Application Information

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IPC IPC(8): H04L27/26
Inventor 宋健董雪符剑张彧王劲涛
Owner TSINGHUA UNIV