Sampling frequency offset compensation method based on NG-DSL system

Abstract

The present invention discloses a sampling frequency offset compensation method based on a NG-DSL system. The method comprises a first step of carrying out phase deviation compensation on a received demodulated signal according to a known estimation frequency offset value and then carrying out constellation judgment, thus to obtain a primarily-compensated receiving signal R2; a second step of calculating ICI Qk of subcarriers; a third step of calculating a corrected demodulated signal Rc=R2-Qk; a fourth step of carrying out phase compensation on Rc and then carrying out constellation judgment to obtain a corrected compensation signal R3; and a fifth step of using the result of R3 as a compensation result and putting the result of R3 into the second step for further calculation of ICI, and repeating the third and fourth steps to obtain more accurate results; performing loop iteration for five times, and using the last corrected compensation result as an ultimate demodulation output signal Rr. ICI of the demodulated signal is removed by a means of loop iteration in a demodulation compensation process, thus to overcome the defect of neglect of ICI influences in a conventional frequency domain compensation method. Through simulated analysis display, performance of the method is raised by 3 to 4 orders of magnitude than the conventional frequency domain compensation method under the condition of small sample value timing synchronism deviation.

Description

technical field [0001] The present invention relates to the technical field of sampling frequency synchronization of NG-DSL systems, and more specifically, relates to a new sampling frequency deviation compensation method suitable for NG-DSL systems. Background technique [0002] With the rapid development of various high-bandwidth Internet services, people's demand for bandwidth is getting higher and higher, which requires higher-speed access technology. As a next-generation DSL technology, NG-DSL access technology can provide a two-way rate exceeding 1Gbps, and will be a key access technology for broadband access networks in the future. NG-DSL mainly adopts OFDM transmission with high carrier number and high QAM modulation level. To realize stable and effective data transmission, sampling frequency offset synchronization technology is required to guarantee. [0003] In order to achieve better sampling frequency offset synchronization, after obtaining the estimated value o...

AI Technical Summary

Problems solved by technology

This method can not only solve the phase rotation caused by the sampling frequency offset, but also eliminate the ICI influence caused by the sampling frequency offset. It is not necessary to apply in the OFDM system with small frequency offset, small number of subcarriers, and low tuning level

[0007] Since NG-DSL is a baseband OFDM system with a high number of carriers and a high modulation level, it is extremely sensitive to timing synchronization and sampling frequency synchronization. In a traditional OFDM system, the performance degradation caused by a small synchronization deviation may not be obvious. , but for a Gigabit DSL system, it will cause a sharp decline in the output signal-to-noise ratio

The traditional frequency compensation method only performs phase rotation on the constellation points, completely ignoring the impact of jitter caused by ICI, and its compensation performance cannot meet the needs of NG-DSL systems with high carrier numbers and high modulation levels.

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