面向智慧农业的大田图像无线传输系统设计与MATLAB仿真

Design and MATLAB Simulation of Field Image Wireless Transmission System for Smart Agriculture

摘要: 随着智慧农业、农业物联网以及无线通信技术的快速发展，大田图像实时采集与远距离可靠传输已成为农业智能监测系统的重要基础。针对复杂农业无线传播环境下图像传输可靠性和通信性能不足的问题，设计了一种面向智慧农业的大田图像无线传输系统，并基于MATLAB建立完整通信链路模型。系统以真实大田作物图像为输入，依次完成JPEG图像压缩、16QAM数字调制、OFDM基带传输、无线衰落信道传播、接收端同步解调及图像重构，分别构建AWGN、Rayleigh和Rician三种典型无线信道，对系统通信性能进行仿真分析。实验从JPEG压缩性能、16QAM星座特性、OFDM时域波形、功率谱密度、多帧频谱稳定性、时频能量分布、误码率、图像重构质量以及系统有效吞吐率和传输时延等方面进行了综合评价。仿真结果表明，JPEG质量因子取75时能够兼顾图像恢复质量与数据压缩效率；随着信噪比提高，系统误码率显著下降，星座点逐渐收敛，图像重构质量持续改善，其中AWGN信道具有最佳传输性能，Rician信道优于Rayleigh信道；同时，OFDM信号具有良好的频谱利用率和时频稳定性，在保证较高图像恢复质量的同时能够获得较高有效吞吐率和较低传输时延。研究结果验证了所设计系统在智慧农业图像无线传输中的可行性与有效性，可为农业无线图像通信系统设计及性能优化提供参考。

Abstract: With the rapid development of intelligent agriculture, agricultural Internet of Things and wireless communication technology, real-time acquisition and long-distance reliable transmission of field images have become an important foundation of agricultural intelligent monitoring system. Aiming at the problem of insufficient reliability and communication performance of image transmission in complex agricultural wireless communication environment, a wireless transmission system of field image for smart agriculture is designed, and a complete communication link model is established based on MATLAB. The system takes real field crop images as input, and completes JPEG image compression, 16QAM digital modulation, OFDM baseband transmission, wireless fading channel propagation, synchronous demodulation and image reconstruction in turn. Three typical wireless channels, AWGN, Rayleigh and Rician, are constructed respectively, and the communication performance of the system is simulated and analyzed. The experiment comprehensively evaluates JPEG compression performance, 16QAM constellation characteristics, OFDM time domain waveform, power spectral density, multi-frame spectrum stability, time-frequency energy distribution, bit error rate, image reconstruction quality, effective system throughput and transmission delay. The simulation results show that the JPEG quality factor of 75 can give consideration to both image restoration quality and data compression efficiency. With the improvement of signal-to-noise ratio, the bit error rate of the system decreases significantly, the constellation points gradually converge, and the quality of image reconstruction continues to improve. AWGN channel has the best transmission performance, and Rician channel is better than Rayleigh channel. At the same time, OFDM signals have good spectrum utilization and time-frequency stability, and can obtain high effective throughput and low transmission delay while ensuring high image restoration quality. The research results verify the feasibility and effectiveness of the designed system in the wireless transmission of intelligent agricultural images, which can provide reference for the design and performance optimization of agricultural wireless image communication system.