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OFDM (Orthogonal Frequency Division Multiplexing) system signal sending method, receiving method and device

A transmission method and system signal technology, applied in the field of digital information transmission, can solve the problems of physical layer encryption and no confidential communication, and achieve the effects of enhancing security, eliminating the possibility of deciphering keys, and deteriorating demodulation performance.

Inactive Publication Date: 2010-10-20
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, at present, my country's terrestrial digital TV standard does not have the function of secure communication, which limits the application of TDS-OFDM, an original technology that requires high security, especially in the field of military communications.
[0006] The next-generation terrestrial digital television transmission standard DVB-T2 promulgated by Europe in 2009 adopts the rotated constellation technology, which is to rotate all the constellation points on the constellation in the OFDM system by a fixed angle to combat fading channels and obtain High diversity performance gain, but this technique cannot be used for physical layer encryption

Method used

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  • OFDM (Orthogonal Frequency Division Multiplexing) system signal sending method, receiving method and device
  • OFDM (Orthogonal Frequency Division Multiplexing) system signal sending method, receiving method and device
  • OFDM (Orthogonal Frequency Division Multiplexing) system signal sending method, receiving method and device

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Embodiment 1

[0069] This embodiment takes the CP-OFDM system as an example to illustrate the method and device of the present invention, the application of the method and device of the present invention, and the improved encryption type and reliability of the system.

[0070] The data frame structure of CP-OFDM system is as follows: image 3 As shown, the data frame is composed of CP and OFDM data. During specific implementation, the frame body OFDM data undergoes the pseudo-random constellation diagram rotation and the addition of weak artificial noise in the method of the present invention, while the frame header CP prefix does not undergo these processes.

[0071] like Figure 4 Shown is a block diagram of the CP-OFDM system of this embodiment applying the method of the present invention. The method for sending and receiving signals by the system includes the steps of:

[0072] S101. Carry out constellation modulation after performing serial / parallel conversion on the input signal;

...

Embodiment 2

[0096] This embodiment takes the TDS-OFDM system as an example. As mentioned in the background technology, the current terrestrial digital television standard in my country has no encryption function, and the physical layer encryption method of the OFDM system proposed by the present invention can also be used in the TDS-OFDM system , so as to improve the security of my country's digital TV standards in military applications and other aspects.

[0097] The data frame structure of the TDS-OFDM system of this embodiment is as follows Figure 7 As shown, the guard interval can be filled with either a single-carrier time-domain PN sequence or a multi-carrier frequency-domain PN sequence (PN-MC, multi-carrier PN). The domain PN sequence is subjected to IDFT transformation to obtain the time domain sequence, and the single-carrier time-domain PN sequence or the multi-carrier PN-MC sequence can be used as the guard interval of OFDM frame body data.

[0098] In this embodiment, the PN...

Embodiment 3

[0108] The method of this embodiment can support constellation modulation modes such as QPSK, 16QAM, and 64QAM. In the method of this embodiment, 2000 input symbols are taken, and it is assumed that the sending end cannot perform channel estimation, but uses a method of randomly adding weak noise. The schematic diagram of the process of pseudo-random constellation rotation and superposition of artificial weak noise is as follows: Figure 9(a)-9(d) , Figure 10(a)-10(d) , Figure 11(a)-11(d) As shown in , the results of adding artificial weak noise according to different signal-to-noise ratios can be seen in the figure.

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Abstract

The invention relates to OFDM (Orthogonal Frequency Division Multiplexing) system signal sending method, receiving method and device. The methods comprise the steps of: carrying out serial / parallel conversion on an input signal for constellation modulation; encrypting the signal subjected to the constellation modulation, wherein the encrypting operation includes the steps of: implementing paseudorandom constellation diagram rotation on the signal subjected to the constellation modulation, and adding weak artificial noise in the signal subjected to paseudorandom constellation diagram conversion, wherein each constellation point rotates a random angle which is appointed by a system sending end and a legal receiving end; and emitting after carrying OFDM modulation. The methods and the device can obtain higher safety and confidentiality by using the randomness of the constellation diagram rotating angle and the inconvertibility of the weak artificial noise, and can ensure the compatibility with the traditional communication system.

Description

technical field [0001] The present invention relates to the technical field of digital information transmission, in particular to an OFDM system signal sending method, receiving method and device based on pseudo-random constellation diagram rotation and adding weak artificial noise. Background technique [0002] With the rapid development and comprehensive deployment of various wireless communication systems and the extensive coexistence of various wireless networks, users have increasing requirements for the transmission performance (effectiveness and reliability) of wireless communication systems, and the security of communication Performance also puts forward higher and higher requirements, especially wireless communication systems involving national security, military information and commercial secrets, which have higher requirements for communication security performance and transmission performance. At the same time, with the significant increase in the computing power...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/26H04L1/06H04L9/00
Inventor 王昭诚马瑞丰戴凌龙王军潘长勇
Owner TSINGHUA UNIV
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