本文選題：射線跟蹤 + 路徑損耗��； 參考：《河南工業(yè)大學(xué)》2017年碩士論文

【摘要】：2016年糧食安全成為國家“一號戰(zhàn)略”。糧情檢測能夠及時發(fā)現(xiàn)倉儲糧堆內(nèi)出現(xiàn)的溫度熱點、霉變、異物等異常糧情信息,提前做好糧食安全預(yù)警和政策調(diào)控。現(xiàn)有的有線傳感器糧情檢測存在難于布設(shè)、監(jiān)測參數(shù)單一、覆蓋范圍小、難升級等問題。因此,必須盡快研發(fā)快速有效的非入侵無損檢測方法,提高糧情檢測效率,節(jié)約檢測成本。糧堆是一種與倉型和糧食種類密切相關(guān)的散粒體多層結(jié)構(gòu),大型糧堆儲糧高度較高,糧堆各層密度、濕度、溫度等分布呈現(xiàn)非均勻性,這導(dǎo)致糧情無線探測技術(shù)應(yīng)用于非均勻糧食介質(zhì)中時首先要準確估計射頻探測信號傳輸鏈路的特性,這也是糧堆介質(zhì)無線數(shù)據(jù)傳輸?shù)奈锢韺咏?jīng)典問題。針對此問題,本文深入研究了糧倉信道的電磁特性、糧堆信道的仿真平臺的搭建以及糧堆信道的確定性建模等關(guān)鍵技術(shù)。主要成果和創(chuàng)新包括如下幾個方面:1.從無線信道相關(guān)理論出發(fā)研究糧堆介質(zhì)中電波傳播的特殊性。根據(jù)糧堆溫度、濕度和密度與糧食介質(zhì)介電特性的關(guān)系,深入分析電波頻率和介質(zhì)介電特性對糧堆電波傳播衰減的影響。通過實測數(shù)據(jù)和理論分析表明了糧堆濕度和頻率是影響電波傳播路徑損耗的主要因素。2.對比分析統(tǒng)計性、確定性以及半確定性信道建模理論,采用確定性方法中高效精確的射線跟蹤算法作為糧倉無線信道的研究方法。提出正向和反向兩種射線跟蹤信道建模方法,并對糧食介質(zhì)中各條傳輸路徑上的接收功率、路徑損耗、時延和到達角進行定量計算。結(jié)果表明兩種算法都能較好的反映糧堆中電波的衰減特性,誤差范圍基本相同。相比復(fù)雜度較低效率較高的正向算法,反向算法不僅能得到路徑損耗特性,且能獲取不同傳輸路徑的相位、時延和極化等信息。3.建立了兩種糧倉無線信道仿真平臺,能夠?qū)崿F(xiàn)糧倉模型和仿真參數(shù)的靈活設(shè)置�；贛ATLAB反向射線跟蹤信道建模平臺,研究了糧堆頻率、濕度和收發(fā)距離對射線幅度分布的影響,并得到平房倉糧堆介質(zhì)中只需考慮直射徑和一次反射徑的重要結(jié)論�；陔姶欧抡孳浖⺈ireless InSite正向射線跟蹤信道建模平臺,得到了與反向射線跟蹤算法一致的糧堆介質(zhì)路徑損耗模型。
[Abstract]:Food security in 2016 became a national "strategy number one." The detection of grain condition can detect the abnormal grain information such as temperature hot spot, mildew, foreign body and so on in the storage grain pile in time, and make the food security early warning and policy control well in advance. The existing wired sensors are difficult to set up, single monitoring parameters, small coverage, difficult to upgrade and so on. Therefore, it is necessary to develop a fast and effective noninvasive nondestructive testing method as soon as possible to improve the efficiency of grain condition detection and save the testing cost. The grain heap is a multilayer structure of bulk grain which is closely related to the type and type of grain. The grain storage height of large grain heap is relatively high, and the distribution of density, humidity and temperature in each layer of grain heap is non-uniform. This leads to the accurate estimation of the characteristics of the radio frequency detection signal transmission link when the grain condition wireless detection technology is applied to the non-uniform grain medium, which is also a classical problem in the physical layer of the wireless data transmission in the grain heap medium. In order to solve this problem, the electromagnetic characteristics of granary channel, the construction of simulation platform and the deterministic modeling of grain stack channel are studied in this paper. Major achievements and innovations include the following: 1. Based on the theory of radio channel correlation, the particularity of radio wave propagation in the medium of grain heap is studied. According to the relationship between the temperature, humidity and density of grain stacks and the dielectric properties of grain media, the effects of wave frequency and dielectric properties on the attenuation of electric wave propagation in grain heaps are analyzed in depth. Based on the measured data and theoretical analysis, it is shown that the humidity and frequency are the main factors affecting the propagation path loss of the electric wave. Compared with the statistical, deterministic and semi-deterministic channel modeling theory, the high-efficient and accurate ray tracking algorithm in deterministic method is used as the research method of granary wireless channel. In this paper, forward and reverse ray tracing channel modeling methods are proposed, and the received power, path loss, delay and arrival angle of each transmission path in grain medium are calculated quantitatively. The results show that the two algorithms can well reflect the attenuation characteristics of the electric wave in the grain heap, and the error range is basically the same. Compared with the forward algorithm with lower complexity and higher efficiency, the reverse algorithm can not only obtain the path loss characteristics, but also obtain the phase, delay and polarization information of different transmission paths. Two kinds of silo wireless channel simulation platform are established, which can realize the flexible setting of granary model and simulation parameters. Based on the MATLAB reverse ray tracking channel modeling platform, the effects of grain stack frequency, humidity and receiving distance on the ray amplitude distribution are studied. The important conclusions are obtained that only direct and primary reflection diameters should be considered in the medium of grain bunker. Based on the electromagnetic simulation software Wireless InSite forward ray tracking channel modeling platform, a grain stack dielectric path loss model is obtained, which is consistent with the reverse ray tracing algorithm.
【學(xué)位授予單位】：河南工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN92

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本文編號：1820626