Method for spread spectrum modulation and demodulation of code element grouping time-shifting position

A technology of spread spectrum modulation and symbol position, applied in the field of information transmission, can solve the problems of limited transmission rate and lack of flexibility

Active Publication Date: 2013-08-28
中国人民解放军海军航空大学航空作战勤务学院
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  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

The multi-ary orthogonal spread spectrum modulation technology is based on the orthogonality of the spread spectrum code, and has strict requirements on the selection of the spread spectrum code, and is more severely constrained by the sequence set of the orthogonal spread spectrum code; the cyclic code shift keying The system transmission rate of the modulation technology is directly determined by the length of the spreading code, the transmission rate is limited and lacks flexibility

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  • Method for spread spectrum modulation and demodulation of code element grouping time-shifting position
  • Method for spread spectrum modulation and demodulation of code element grouping time-shifting position
  • Method for spread spectrum modulation and demodulation of code element grouping time-shifting position

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Embodiment 1

[0072] The preset binary data stream is "...1110101011110101010...", each 6bit is divided into a frame, and the first frame of preset data is "111010", here is an exemplary analysis of its modulation and demodulation process. symbol time T s =7ms, spreading code length n=7, spreading code chip period T c =1ms, the modulation symbol grouping duration is 2T s (may as well make the time interval of symbol grouping be [0,14ms)), the number of spreading modulation symbols in the symbol grouping is b=2, the time shifting interval T that spread spectrum modulation symbol time-shifting position modulation adopts g =T c , the modulation position interval between adjacent time-shifted position modulation symbols is T b =T c , a direct spread modulation adopts binary BPSK modulation, M=2.

[0073] The specific implementation process of the modulation part is as follows:

[0074] ① Data grouping:

[0075] The frame preset data is grouped, and the data "111010" is divided into two p...

Embodiment 2

[0101] For embodiment 1, the m-sequences with lengths of 63, 127, and 255 are respectively used as spreading codes to replace the original spreading codes with a length of 7 for modulation and demodulation processing. Except that the frame data length is adjusted accordingly, other modulation The parameters are unchanged.

[0102] The specific transmission rate and bit error performance will be described below.

[0103] ①Transmission rate

[0104] The transmission rate of the traditional BPSK-based direct sequence spread spectrum modulation system is: 1 / 7×10 3 b / s;

[0105] The transmission rate of the time-shift position spread spectrum modulation system using 63-bit long m-sequence as the spread code is: 6 / 7×10 3 b / s is 6 times that of the original modulation system; when the 127-bit long m-sequence is used as the spreading code, the transmission rate is 1k b / s, which is 7 times that of the original system, and the 255-bit long m-sequence is used as the spreading code co...

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Abstract

The invention provides a method for spread spectrum modulation and demodulation of code element grouping time-shifting position. A method for the spread spectrum modulation is on the basis of a good autocorrelation characteristic of a direct spread code. On the basis of primary direct sequence spread spectrum modulation, secondary time-shifting position modulation is conducted on spread spectrum modulation code elements and the spread spectrum modulation code elements after the secondary time-shifting position modulation are overlaid to a route of signals to be output; the secondary time-shifting position modulation of the spread spectrum modulation code elements is added by the method for the spread spectrum modulation, so that the transmission rate of a system is greatly improved; specific positions of the spread spectrum modulation code elements are detected firstly by a method for the spread spectrum demodulation and information carried by the positions is demodulated, so that position demodulating data are obtained, information carried by the spread spectrum modulation code elements is modulated on this basis until direct spread demodulating data are obtained, and finally the demodulated data are output according to a prior data stream format.

Description

technical field [0001] The invention relates to a communication system in radio communication, in particular to a code element grouping time-shift position spread spectrum modulation and demodulation method, which belongs to the technical field of information transmission. Background technique [0002] A typical feature of the spread spectrum system is that the bandwidth occupied by the transmitted signal energy must be greater than the corresponding bandwidth of the information bit rate (generally much greater than), and it is generally considered that the transmission bandwidth has nothing to do with the information bit rate, and the U.S. published patent "METHOD AND This view is clearly mentioned in documents such as "APPARATUS FOR SELECTING A SPREADING CODE IN A SPECTRUM SPREAD COMMUNICATION SYSTEM" (see U.S. Patent 5515396) and Roger L's classic "Introduction to Spread Spectrum Communications". [0003] Direct Sequence Spread Spectrum System (DSSS) is a typical spread s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B1/707
Inventor 王红星康家方刘传辉赵志勇钟佩琳陈昭男刘锡国
Owner 中国人民解放军海军航空大学航空作战勤务学院
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