TD-SCDMA system frequency offset compensating method and apparatus based on exercising sequence

Abstract

This method selects a received data array to intercept the training sequence, on different point of the frequency difference. The training sequence is processed with phase compensation and channel evaluation to determine the spread spectrum factor of the training sequence. The training sequence is processed with unspreading to obtain the unspreading mark of the training sequence on each frequency difference point. The exceptional unspreading mark is processed. The cost function of end customer is calculated. The minimum value of the cost function is calculated to determine the best frequency point and the estimated value of the time slot.

Description

technical field [0001] The invention relates to a frequency offset compensation method in the field of wireless mobile communication, in particular to a training sequence-based TD-SCDMA system frequency offset compensation method and device. Background technique [0002] In a mobile communication system, the frequency offset caused by Doppler can reach hundreds of hertz, and the maximum frequency difference introduced by the carrier can reach thousands of hertz, so frequency correction must be performed at the receiving end. The frequency correction function is completed by a frequency correction loop, and commonly used devices include automatic frequency control (AFC, AutoFrequency Control) and phase-locked loop (PLL, Phase Lock Loop). [0003] The frequency correction loop counteracts the frequency offset by adjusting the local oscillator frequency, and can effectively correct the frequency offset of subsequent burst data. But this correction will not improve the current ...

AI Technical Summary

Problems solved by technology

[0012] 1. When the frequency offset is relatively large, the user channel environment can no longer be assumed to be time-invariant within a TD-SCDMA burst time, and the channel impulse response h(t) obtained through the training sequence is no longer applicable to the entire burst, therefore, the performance of the joint detection is degraded, which leads to an increase in the bit error rate of the data after despreading

[0013] 2. Due to the increase in the data bit error rate after despreading, the demodulation performance decreases

[0014] 3. Due to the use of hard judgment demodulation, hard judgment loss is inevitably introduced

[0015] 4. When the phase changes by an integer multiple, the scheme cannot effectively compensate

[0016] 5. In some error cases, the demodulation constellation diagram appears in the dot after the hard judgment, which will bring a large error

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