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CDMA spread and despread-spectrum method and its transmitter, receiver and communication system

A code division multiple access, transmitter technology, applied in the direction of code division multiplexing system, multiplexing communication, transmission system, etc.

Inactive Publication Date: 2004-08-18
PEKING UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The present invention proposes a key technology designed for the fourth generation mobile communication (4G)——discrete spread spectrum method, aiming at the defects of existing spread spectrum methods

Method used

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  • CDMA spread and despread-spectrum method and its transmitter, receiver and communication system
  • CDMA spread and despread-spectrum method and its transmitter, receiver and communication system
  • CDMA spread and despread-spectrum method and its transmitter, receiver and communication system

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Embodiment Construction

[0026] First refer to figure 1 A CDMA mobile communication system according to the prior art will be described.

[0027] On the transmitter 14 side, the data packets to be transmitted are sequentially read from the data packet memory 11 . Modulation is performed in the modulator 12, and the modulation mode can be BPSK\QPSK or QAM mode. The modulated data is sent to the frequency spreader 13, and in the frequency spreader 13, the PN code is used for CDMA spreading. It is then sent out via an antenna (not shown). The signal sent by the transmitter is received by the receiver 16 after undergoing multi-path channel, and the original data packet is obtained after the despreader 17 and decision demodulation 18 . Thereby completing a process of communication.

[0028] see now figure 2 . In the discrete spread spectrum communication system of the present invention, in the transmitter 23, a device 21 for setting a prefix is ​​added between the existing data packet memory 11 and ...

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Abstract

The present invention relates to a method of spread and de-spread spectrum for code division multiple access and relevant transmitter in order to eliminate the multipath disturbance. The continuous spread spectrum mode of each symbol in the information symbol flow, which is used in the orthogonal spread spectrum code on the spreading steps of the conventional CDMA is replaced by the discrete mode in the present invention. But the information of the different user is still in the format of the CDMA. From the viewpoint of the receiver, the invented transmitting technique converts the multiple addresses interfere, which caused by the multi-path happened in the conventional CDMA system, into the symbol overlapping (so called the cross talk between symbols in the conventional technique) in each user completely. Based on the elimination of the multiple addresses interfere, the symbol information of each user can be obtained from the overlapped symbols by using the method of solving the equation.

Description

technical field [0001] The present invention relates to a spread spectrum and despread method based on code division multiple access and a transmitter, a receiver and a communication system realized by using the method. Background technique [0002] In the existing CDMA system, the information transmission of multiple users is distinguished by codes, so it is a parallel multi-channel structure under a certain bandwidth. In a high-quality synchronous direct spread spectrum CDMA system, the above-mentioned parallel multi-channels are assigned to multiple users, and the user's information symbols are spread with orthogonal spread spectrum codes. The receiver obtains certain user information by means of correlation calculation. While other user signals are canceled due to orthogonality. [0003] However, in a multipath environment, the above technology cannot maintain the orthogonality of the spreading codes of each user. The reason is that the synchronous modulation technolo...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04B1/707
Inventor 焦秉立肖灯伟
Owner PEKING UNIV
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