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OQPSK-DSSS signal demodulation method and demodulator

A demodulation method and demodulator technology, which are applied in the field of signal demodulation methods, can solve the problem that the performance of the demodulator is greatly affected, and achieve the effects of reducing the bit error rate, improving the robustness, and reducing the influence of the initial phase.

Inactive Publication Date: 2014-11-26
SHANGHAI RES CENT FOR WIRELESS COMM +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In view of the above-mentioned shortcoming of prior art, the object of the present invention is to provide a kind of OQPSK-DSSS signal demodulation method and demodulator, be used to solve the problem that the performance of demodulator in the prior art is affected by initial phase and frequency deviation high impact issues

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  • OQPSK-DSSS signal demodulation method and demodulator

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Embodiment 1

[0027] Such as figure 1 As shown, the present invention provides a demodulation method of an OQPSK-DSSS signal. The demodulation method is mainly performed by a demodulator. Wherein, the demodulator obtains the OQPSK-DSSS signal in the frequency band receiving channel where the information of each spread spectrum chip of the OQPSK-DSSS signal is located according to the unified design with the sending end in advance, and the OQPSK-DSSS signal is passed through down-conversion, digitization, and filtering The digital baseband OQPSK-DSSS signal is obtained through processing, and then demodulated according to the method of the present invention.

[0028]In step S1, the demodulator performs frequency offset compensation processing on the digital baseband OQPSK-DSSS signal, and obtains a spread spectrum chip sequence from the compensated baseband OQPSK-DSSS signal, wherein the spread spectrum The chip sequence includes a plurality of spread spectrum chip information, and each sp...

Embodiment 2

[0038] Different from the first embodiment, the present invention further executes step Sa before executing step S2.

[0039] In step Sa, the demodulator reserves I or Q spreading chip information in the obtained spreading chip sequence according to the preset sequence number rules of the spreading chip sequence.

[0040] Specifically, the demodulator reserves the even-numbered spreading chip information in the spreading chip sequence for one channel spreading according to the preset sequence number rule of the spreading chip sequence corresponding to the signal transmitting end Frequency code chips, the spread spectrum chip information of the odd sequence number retains the Q-way spread-spectrum chip information, obtains a spread-spectrum chip sequence that is spaced between the I-way and the Q-way, and then sends the obtained spread-spectrum code sequence into the The correlation processing module in the demodulator performs the correlation processing as described in Embodim...

Embodiment 3

[0042] Such as figure 2 As shown, the present invention also provides a demodulator of OQPSK-DSSS signal. The demodulator 1 includes: a digital processing unit 11 , a frequency offset compensation sampling unit 12 , a detection unit 13 and a demodulation unit 14 .

[0043] The digital processing unit 11 includes an analog-to-digital converter 111 and a low-pass filter 112 for converting the analog baseband OQPSK-DSSS signal into a digital baseband OQPSK-DSSS signal and performing filtering.

[0044] The frequency offset compensation sampling unit 12 is used to perform frequency offset compensation processing on the baseband OQPSK-DSSS signal output by the digital processing unit 11, and obtain a spread spectrum chip sequence from the compensated baseband OQPSK-DSSS signal , wherein, the spreading chip sequence includes a plurality of spreading chip information, and each spreading chip information includes I-way and Q-way spreading chips.

[0045] In this embodiment, the fre...

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Abstract

The invention provides an OQPSK-DSSS signal demodulation method and demodulator. According to the invention provided by the invention, first frequency offset compensation is processed on digital base-band OQPSK-DSSS signals by a demodulator, and a spread spectrum code chip sequence is obtained from the compensated base-band OQPSK-DSSS signals; then correlation operation is performed on the spread spectrum code chip sequence with a plurality of preset PN sequences according to a preset probability density function and probability distribution of initial phase, a relevant estimated value of the spread spectrum code chip sequence with each PN sequence is obtained, and a largest estimated value is obtained from each estimated value; demodulation process is performed on the PN sequence corresponding to the largest estimated value, so as to obtain bit information born by the spread spectrum code chip sequence. Due to the initial phase distribution probability, influence of the initial phase is effectively minimized when the estimated value of the signals is determined to be transmitted by a decoder, and the signal demodulation method is provided with good robustness.

Description

technical field [0001] The invention relates to a signal demodulation method, in particular to a demodulation method and a demodulator of an OQPSK-DSSS signal. Background technique [0002] The IEEE802.15.4 standard has the characteristics of low speed, low power consumption and short-distance transmission, and is widely used in the communication system of the Internet of Things. In the 2.4GHz industrial scientific medical (ISM) frequency band, the IEEE802.15.4 physical layer adopts the half-sine pulse-shaped offset quadrature phase shift keying (offset quadrature phase shift keying: OQPSK) modulation method, that is, every 4 The information bits are mapped to a pseudo-noise (Pseudo-Noise: PN) sequence through direct sequence spread spectrum (direct sequence spread spectrum: DSSS) technology, so that OQPSK-DSSS signal (offset quadrature phase shift keying - direct sequence spread spectrum Signal). [0003] For example, according to the IEEE802.15.4 protocol, every four inf...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/22H04B1/7097H04B1/7073
Inventor 戴胜辰钱骅康凯
Owner SHANGHAI RES CENT FOR WIRELESS COMM