Research On Channel Model And Related Technologies Based On Internet Of Things

Internet of Things (IOT) is a new technology system which is combined by a lot of information technologies. It’s known as the third revolution of IT industry after the computer and internet. As the ubiquitous network which contains kinds of object-object connections, IOT is still in the concept stage. There’re already some mature technologies available for reference. However, little research work in this area has been started. Therefore, the research of channel model, cooperative diversity and data compression are all of great importance, and are critical for realizing the practical stage of IOT. The main contributions of this thesis are as below:1. An improved Clarke model is proposed for the urban environment in the IOT. The theoretical Clarke model can accurately describe the channel, but need large quantity of calculation. And the Jakes model has less calculation but with bad statistical properties. These shortcomings are improved in the new model. The caculation of statistical properties indicates that the improved model is wide-sense stationary while reducing nearly half of the computation. And with a finite value of N (number of sinusoids), it has a better high-order statistics. The simulation result shows that the new model’s first-order and second-order statistics are closer to the theoretical values than Wu model (an imprved Jakes model). Its performance of independence is good.2. An improved Rician model is proposed for the suburban enviroment in the IOT. The derivation and simlution results prove that this new model matches the Rician distribution, and is wide-sense stationary. It is also simulated with different values of Rician factor for checking the statistical properties. Its cross-correlation value is very small, especially for the adjacent channels, which insures a good performance of independence.3. We study the technique of cooperative diversity, and caculate the SNR and BER of direct transmission, AF (Amplify and Forward) and DF (Decode and Forward) with cooperation. The Matlab simulation platforms for the embedded channel, the improved Rayleigh channel in 1 and the improved Rician channel in 2 are all created to validate their BER performance. Simulation results prove the credibility and effectiveness of this improved model, which indicates that cooperative diversity is more suitable for the environment of IOT.4. Two types of improved Huffman compression algorithms (ⅠandⅡ) for PML file in the IOT are proposed. TypeⅠcompresses the whole element part based on the Huffman coding and is most optimized. TypeⅡis designed for the insufficient memory situation, by seperating the weight assignment for element and data parts, and its memory requirement is lessen with increasement of average code word length. With comparison of standard Huffman coding, the improved typeⅠand typeⅡalgorithm’performance of handling different size files, we prove the compression ratios of these two modified algorithms are much bigger than the standard Huffman coding, and can provide transmission efficiency for IOT. Besides these, the improved algorithms make up the Huffman coding’s defect of no error checking. Without increasing the amount of data transmission, new algorithms provide error detection function for the decompression and decoding.