Field programmable gate array (FPGA) implementation method applied to wireless sensor network to realize symbol precise timing

Abstract

The invention relates to a field programmable gate array (FPGA) implementation method applied to a wireless sensor network to realize symbol precise timing. The FPGA implementation method comprises the following steps: performing secondary quantization on a local sequence; performing a mutual correlation operation on a receipt signal and the local sequence to obtain a mutual correlation value; calculating a power value in the manner of sliding window; performing approximate treatment on the obtained mutual correlation value, and working out a module value of the mutual correlation value; performing threshold value judgment after the module value of the mutual correlation value and the power value are obtained; multiplying the obtained power value by a preset threshold value; accessing the multiplied power value and preset threshold value and the module value of the mutual correlation value to a comparator; when the module value of the mutual correlation value is greater than the multiplied power value and preset threshold value, indicating that precise capturing is successful; and finding out the position of a fast Fourier transform (FFT) window through a counting mode to complete timing synchronism. According to the FPGA implementation method, the symbol precise timing is realized in wireless sensor network applications at lower resource consumption.

Description

technical field [0001] The invention relates to the field of wireless communication, in particular to an FPGA implementation method for precise symbol timing applied in a wireless sensor network OFDM system. Background technique [0002] Wireless Sensor Network (Wireless Sensor Network, referred to as "WSN") is an "intelligent" network composed of micro-sensor nodes with wireless communication, perception and computing capabilities. Widely used in various fields such as military, agriculture, environmental detection, medical and health care, industry, intelligent transportation, etc. Orthogonal Frequency Division Multiplexing ("OFDM") technology is one of the core technologies in wireless sensor networks. It can be regarded as a modulation technique and a multiplexing technique. With the advantages of high spectrum utilization and strong anti-multipath fading ability, it has become a popular technology in modern wireless communication and is widely used in the field of high...

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Problems solved by technology

[0003] Timing synchronization algorithms are usually divided into synchronization algorithms based on non-assisted data and synchronization algorithms based on auxiliary data. Currently, the most widely used pilot-based timing and frequency offset estimation algorithm is proposed by Schmidl. This algorithm uses the same two stages The training sequence is used for timing. This method uses a recursive formula for calculation, and the implementation complexity is very low. It is widely used in OFDM systems. However, there is an error platform in the timing decision function of this method, which will cause a large timing deviation.

In order to reduce the influence caused by the error platform of the timing decision function, Minn made certain improvements to Schmidl's method. Minn's timing decision function is a peak, which eliminates the influence of the error platform to a certain extent. Park proposed a The timing decision function has a sharper waveform, but due to the existence of the cyclic prefix, the decision function of this method has a large side lobe. When the cyclic prefix is ​​long, it is almost the same as the height of the main lobe. When the signal-to-noise ratio is low situation, it is difficult to get correct timing results

The cross-correlation between the training sequence and the local PN code has an obvious single peak, but in the case of a large frequency offset, the timing decision function will be seriously deformed, causing a large timing error

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