A Position Modulation and Soft Demodulation Method in Spread Spectrum Communication

Abstract

The invention discloses a location modulation and soft demodulation method in spread spectrum communication, belongs to the wireless communication technical field. The method comprises two parts of a transmitting terminal algorithm and a receiving terminal algorithm; at the transmitting terminal, multiple different cyclic shift duplications are taken as a spread spectrum sequence; the multiple different cyclic shift duplications are obtained through shifting a certain original spread spectrum sequence; at the receiving terminal, a soft demodulation method is adopted; correlation is carried out to cyclic shifts of a receiving sequence and a local sequence; amplitude modulated data bit amplitude modulation value and location bit soft demodulation value are calculated according to correlation values at different locations and a demodulation algorithm; and decoding data are obtained through matching with the soft decision of the a decoder. According to the method of the invention, the traditional modulation mode and C band sequence location modulation are combined; the data carried by each modulation symbol can be improved by log2c bits; the spectrum efficiency is improved; the location bits are obtained through the soft demodulation method in the location demodulation; the method of the invention can be combined with a coded soft demodulation method; and the system error rate is reduced.

Description

technical field [0001] The invention relates to a position modulation and soft demodulation method in spread spectrum communication, belonging to the technical field of wireless communication. Background technique [0002] In the spread spectrum communication system, the transmitter uses a high-speed pseudo-random code whose bandwidth is much larger than the signal bandwidth to modulate, so that the bandwidth of the original data signal is expanded, and then modulated by the carrier and sent out. The receiving end uses exactly the same pseudo-random code for correlation processing with the received bandwidth signal, and replaces the broadband signal with the narrowband signal of the original information data, that is, despreading, to realize information communication. [0003] Common sequences in spreading codes include m-sequence and Gold sequence. The m-sequence is generated by an n-stage linear shift register with a period of 2 n The code sequence of -1 is an abbreviati...

AI Technical Summary

Problems solved by technology

However, this hard demodulation method cannot be used in conjunction with the encoded soft decision. If the correlation peak position is affected by noise and changes, the position data obtained by hard demodulation will inevitably be wrong, and the position bits that control the shift number may be all wrong.

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