Combined timing and frequency synchronization method based on conjugated structure preamble

Abstract

The invention provides a combined timing and frequency synchronization method based on a conjugated structure preamble. The method comprises following steps: 1. calculating a correlated signal r0(n, d) of a reception signal r(n) and a preamble signal c(n); 2. obtaining a difference correlation signal p(m, d) through calculation; 3. performing weighted accumulation on the difference correlation signal p(m, d) so as to obtain a weighted correlation function P(d); 4. normalizing the weighted correlation function P(d) by the use of the energy of the reception signal in a sliding window so as to obtain a normalized timing metric value M(d); 5. working out the maximum of the normalized timing metric value M(d) so as to obtain a timing offset estimated value epsilon-hat according to a formula shown in the description; 6. calculating a carrier wave frequency offset estimated value xi-hat of a decimal part; 7. compensating the reception signal by the use of the carrier wave frequency offset estimated value xi-hat of the decimal part so as to obtain the compensated reception signal r1(n, epsilon-hat); 8. calculating a carrier wave frequency offset estimated value q-hat of an integer part by the use of the reception signal compensated according to decimal frequency offset; and 9. working out the carrier wave frequency offset estimated value according to a formula that v-hat = q-hat + xi-hat. By employing the method, only one preamble signal having the conjugated structure is employed for combined signal timing and carrier wave frequency synchronization, and signal timing synchronization is not influenced by the frequency offset.

Description

technical field [0001] The invention belongs to the technical field of digital wireless communication transmission, and in particular relates to a joint timing and frequency synchronization method based on a conjugate structure preamble. Background technique [0002] Orthogonal Frequency Division Multiplexing (OFDM) can effectively combat the multipath effect of the channel, has a high spectrum utilization rate, and can provide high-speed data transmission under a wireless fading channel. The OFDM system has been applied in the fields of digital video broadcasting (DVB) and the new generation of terrestrial mobile communication and has become an international and industry standard. In the field of satellite communication, OFDM is suitable for high-speed data transmission under broadband satellite communication channels. For example, the European satellite standard DVB-SH has designed a hybrid ground-satellite communication system using OFDM or TDM technology. [0003] Assum...

AI Technical Summary

Problems solved by technology

However, the pseudo-random sequence weighting process on the preamble will deteriorate the power spectrum of the OFDM signal, resulting in serious out-of-band leakage, which will affect adjacent frequency band signals

Therefore, in view of the poor performance of traditional symbol timing and carrier frequency synchronization algorithms in OFDM receivers under multipath fading channels

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