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Method for constructing spread-spectrum code with low interference window from LAS code

A spread spectrum code, low interference technology, applied in the field of constructing spread spectrum codes with low interference windows, can solve problems such as limiting performance, and achieve the effects of overcoming multipath interference, reducing multi-user interference, and reducing ICI interference

Inactive Publication Date: 2007-07-04
FOUNDER BROADBAND NETWORK SERVICE
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Problems solved by technology

However, it is relatively sensitive to ICI (inter-subcarrier interference) caused by frequency offset or Doppler spread, which becomes the main factor limiting its performance.

Method used

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Embodiment Construction

[0018] The low-interference window spreading code referred to in the present invention means that the correlation value of its acyclic autocorrelation and acyclic cross-correlation sequences near zero offset is relatively small, for example, less than a predetermined value. Let the code word sequence be C n =(c 1 n , c 2 n ,... c N n ), n=1, 2, ..., M, N is the codeword length, M is the number of codewords, and the acyclic correlation sequence defining the codeword sequence is

[0019] R ij (n)=c 1 i c 1+n j +c 2 i c 2+n j +...+c N-n i c N j n=-N+1,-N+2,...,N-1

[0020] For spreading codes with low interference window characteristics, when -Wij {|R ij (n)|} is closer to zero (R ii (0)=N, so R is not considered when considering the low-interference window characteristics ii (0)).

[0021] The low interference window spread spectrum code can be used in the time domain spread spectrum communication system. Using low interference window spread codes f...

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Abstract

A method uses LAS code to construct low interference window expanding frequency code, in which, the non-cyclic self-related and non-cyclic inter-related sequences of the low interference window expanding frequency code are less than the predetermined values in the vicinity of zero-offset, and the LAS code comprises compound LA code and LS code. The method includes the following steps: step one: choose two or more LS expanding frequency codes Cln and Csn with zero interference windows of [-W, W]; step two: combine the said expanding frequency codes Cln and Csn chosen from the first step, remove the protective interval on the side or in the center of the low interference expanding frequency code Cn, and obtain the low interference window expanding frequency code Cn. The low interference window expanding frequency code of the invention is used for OFDM communication system, and processes frequency domain expanding frequency modulation in the OFDM frequency domain, and it can reduce ICI interference due to frequency shift or Doppler expansion.

Description

technical field [0001] The invention relates to a method for constructing a spreading code with a low interference window, which belongs to the technical field of mobile communication. Background technique [0002] The difficulty of wireless communication mainly comes from the frequency selective fading and time selective fading of wireless channels. At present, the modulation methods with better performance under wireless channel conditions mainly include CDMA spread spectrum modulation and OFDM orthogonal frequency division multiplexing modulation. [0003] For the CDMA spread spectrum modulation method, the fading and interference caused by the multipath of the wireless channel can be better overcome by using the good correlation characteristics of the spread spectrum code. At the same time, in the actual communication system, the channel bandwidth is relatively wide, and the spread spectrum gain is not It is very large, and the time occupied by one information bit symbo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B1/707H04B1/711H04L27/26
Inventor 康良川
Owner FOUNDER BROADBAND NETWORK SERVICE
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