Communication method of spread spectrum modulation based OFDM system

A communication method and spread spectrum code technology are applied in the communication field based on spread spectrum code modulation OFDM system, which can solve the problem of low transmission rate, reduce computational complexity, increase the number of source bits, and improve the efficiency of system spectrum utilization. Effect

Inactive Publication Date: 2018-01-09
CHINA INFORMATION TECH DESIGNING & CONSULTING INST
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to solve the problem of low transmission rate of traditional spread spectrum OFDM communication system, propose a communication method based on spread spectrum code modulation OFDM system, improve system transmission efficiency, and take into account system transmission reliability at the same time

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  • Communication method of spread spectrum modulation based OFDM system

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Embodiment 1

[0027] This embodiment provides a communication method based on spread spectrum code modulation OFDM system, which specifically includes the following steps:

[0028] S1. Signal processing at the transmitting end: the source bit sequence is modulated by the spreading code to obtain the frequency-domain data symbols of each subcarrier, and then modulated by IFFT into a time-domain signal, and then parallel-to-serial conversion is realized, and finally the cyclic prefix is ​​inserted through RF module launch;

[0029] S2. Signal processing at the receiving end: perform decyclic prefix operation on the baseband time domain signal processed by the radio frequency module at the receiving end, then complete serial-to-parallel conversion and FFT transformation to the frequency domain signal in sequence, and then input it to the signal detection processing unit;

[0030] S3. Signal detection processing: the signal detection processing unit detects the received signal and obtains a dem...

Embodiment 2

[0045] This embodiment is similar to Embodiment 1. Further, in order to improve the reliability of system transmission and reduce the bit error rate, the above-mentioned information source bit sequence can be channel coded before entering the spreading code modulation signal processing unit. By adding a certain redundancy redundancy to enhance the reliability of information transmission, and then add channel decoding operation at the receiving end. Common channel error correction codes include convolutional codes, Turbo codes, and LDPC codes.

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Abstract

The invention relates to a communication method of a spread spectrum modulation based OFDM system. The communication method of the spread spectrum modulation based OFDM system comprises the steps of firstly grouping sub-carriers at a transmitting terminal according to a certain rule; then modulating the serial number of each spreading code, that is, selecting spreading codes by utilizing differentsignal source bit combinations, so as to realize the purpose of improving the transmission rate; and regarding each grouping block as a minimum granularity when a receiving terminal carries out signal detection. In order to reduce the calculation complexity of a maximum likelihood detection algorithm, frequency domain balancing is firstly carried out for each grouping block, then the Euclidean distance in the presence of the current spreading code is calculated, and finally a combination with the minimum Euclidean distance is selected to serve as a final detection result, so that the purposeof reducing the complexity is realized. As the signal source bit is adopted for selection of the spreading codes used by different grouping blocks, the data rate is improved efficiently.

Description

technical field [0001] The invention relates to the field of communication technology, in particular to a communication method based on spread spectrum code modulation OFDM system. Background technique [0002] Orthogonal frequency division multiplexing (OFDM) technology has been adopted as a basic access technology by many international communication standards because of its strong anti-multipath fading ability, high flexibility in resource allocation, and simple frequency domain equalization. OFDM technology divides the system channel bandwidth into several mutually orthogonal sub-carriers. At this time, the high-speed serial data flow will become a low-speed parallel data flow, which enhances the ability to resist frequency selective fading. When the channel quality is poor, the bit error rate of the system will increase rapidly, and the introduction of subcarrier spread spectrum communication technology can obtain frequency diversity gain and reduce the bit error rate. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L5/00H04L25/03H04L27/26
Inventor 郑正广袁鹏袁涛王宝俊谭路加冯必成董冰
Owner CHINA INFORMATION TECH DESIGNING & CONSULTING INST
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