Transmission method for lowering interference between code sequences and code sequence multiplexing in CDMA system

A technology of code division multiple access and transmission method, which is applied in the direction of code division multiplexing system, multi-frequency code system, multiplexing communication, etc., and can solve problems such as insufficient code sequence and code sequence interference

Active Publication Date: 2009-01-07
HARBIN INST OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0016] In order to solve the problems of interference between code sequences and insufficient code sequences in the existing CDMA system, the present invent

Method used

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  • Transmission method for lowering interference between code sequences and code sequence multiplexing in CDMA system
  • Transmission method for lowering interference between code sequences and code sequence multiplexing in CDMA system
  • Transmission method for lowering interference between code sequences and code sequence multiplexing in CDMA system

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specific Embodiment approach 1

[0023] Specific implementation mode one: combine Figure 1 to Figure 7 Describe this embodiment, the method of this embodiment is realized through the following steps:

[0024] At the transmitter end, the data source is sent to the forward transformation module after being digitally modulated and PN source spread. The forward transformation module performs four-item weighted fractional Fourier transformation on the data under the control of parameter α. After up-conversion, it is sent to the channel for transmission;

[0025] At the receiver side, the down-converted data is sent to the inverse transform module, and the four-item weighted fractional Fourier transform of demodulation, despreading and parameter-α control is performed in the inverse transform module to obtain the spread CDMA signal, and then Output after digital demodulation.

[0026] The specific steps of the forward transformation in the forward transformation module are as follows: 1. The digitally modulated ...

specific Embodiment approach 2

[0053] Specific implementation mode two: combination figure 2 Describe this embodiment, the difference between this embodiment and specific embodiment 1 is that the forward transformation module includes No. 1 inversion module 2, Fourier transform module 3, coefficient generation module 4, No. 2 inversion module 5, summation module or adder 6 and the digital carrier modulation module 1, the CDMA signal is delivered to the input end of the No. 1 inversion module 2, the input end of the Fourier transform module 3 and the first input end of the coefficient generation module 4, and the output end of the No. 1 inversion module 2 The second input end of the connection coefficient generation module 4, the output end of the Fourier transform module 3 is connected to the third input end of the coefficient generation module 4 and the input end of the No. 2 inversion module 5, and the output end of the No. 2 inversion module 5 is connected to the coefficient The fourth input end of the ...

specific Embodiment approach 3

[0054] Specific implementation mode three: combination Figure 5 Describe this embodiment, the difference between this embodiment and the specific embodiment is that the inverse transform module includes No. 1 inversion module 2, Fourier transform module 3, coefficient generation module 4, No. 2 inversion module 5, summation module or adder 6, digital carrier coherent demodulation module 11, PN source 17 and sequence synchronous module 18, data flow is input to the input end of digital carrier coherent demodulation module 11, the output end of digital carrier coherent demodulation module 11 connects sequence synchronous module 18 Input end, the output end of sequence synchronization module 18 connects the input end of Fourier transform module 3, the input end of No. 1 inversion module 2 and the first input end of coefficient generation module 4, the output end connection coefficient of No. 1 inversion module 2 The second input end of the generation module 4, the output end of ...

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Abstract

The invention relates to a transmission method for reducing interference and code sequence multiplexing among code sequences in a code division multiple access system. The transmission method relates to the technical field of communication and solves the problems of the interference and the insufficient code sequences in the code sequences in the existing CDMA system, the steps are as follows: a data source is sent to a transformation module at a transmitter end after the digital modulation and the PN source spread spectrum, the transformation module carries out the 4-th weighted fractional Fourier transform of data under the control of a parameter Alpha, and the data after the digital carrier modulation is further sent to a channel for transmission after the upper frequency conversion; the data after the lower frequency conversion is sent to a reverse transformation module at a receiver end, a CDMA signal after the spread spectrum is obtained after carrying out the demodulation, the dispread spectrum and the 4-th weighted fractional Fourier transform under the control of the parameter Alpha in the reverse transformation module, and then the CDMA signal is output to the outside through the digital demodulation work. The use of the method can reduce the interference among CDMA users and improve the capacity of the system; furthermore, the optimization and the reuse of the code sequences of the CDMA system can be realized under the condition of not occupying additional spectrum, time and code resources.

Description

technical field [0001] The invention relates to the technical field of communication, in particular to a method for multiplexing and transmitting signals in a fractional Fourier transform domain in a CDMA system. Background technique [0002] A communication system is a resource-constrained system, where "resources" mainly include space (spatial location), time (time), frequency (spectrum), and so on. How to make effective use of limited resources so that unit resources can carry more information, that is, to improve the effectiveness of the communication system. The Code Division Multiple Access (CDMA) system introduces "code resources" into the communication system by introducing (quasi) orthogonal code sequences, so that different users can use the same space, time, and frequency resources at the same time, and through different code sequences The orthogonality between them is used to distinguish each other, thereby achieving the purpose of resource reuse and improving s...

Claims

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Application Information

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IPC IPC(8): H04L27/26H04J13/02H04B1/7097
Inventor 沙学军梅林叶嘉星迟永钢吴少川高玉龙白旭
Owner HARBIN INST OF TECH
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