【正文】 的目的、意義；國(guó)內(nèi)外研究現(xiàn)狀；擬采取的研究路線；進(jìn)度安排； 社會(huì)信息化日新月異,新技術(shù)層出不窮。微型化、多功能化、網(wǎng)絡(luò)化和智能化乃大勢(shì)所趨,無線傳感器網(wǎng)絡(luò)則詮釋了這些優(yōu)勢(shì)。傳感器網(wǎng)絡(luò)覆蓋范圍大。傳感器網(wǎng)絡(luò)具有自組織功能。可以動(dòng)態(tài)拓?fù)?，無線傳感器網(wǎng)絡(luò)中可以隨時(shí)添加或減少節(jié)點(diǎn)而并不影響網(wǎng)絡(luò)其他節(jié)點(diǎn)數(shù)據(jù)的正常傳輸。本文根據(jù)傳感器網(wǎng)絡(luò)發(fā)展?fàn)顩r，設(shè)計(jì)出基于WIFI的無線傳感器網(wǎng)絡(luò)，相比于傳統(tǒng)的無線傳感器網(wǎng)絡(luò)，能夠非常容易的與現(xiàn)有網(wǎng)絡(luò)進(jìn)行無縫的連接，相對(duì)降低組網(wǎng)成本和功耗。 1）國(guó)內(nèi)的研究現(xiàn)狀 山東省科學(xué)院與沈陽(yáng)自動(dòng)化研究所等研究單位及多所高校（如哈爾濱工業(yè)大學(xué)、北京郵電大學(xué)等）在無線傳感器網(wǎng)絡(luò)網(wǎng)絡(luò)協(xié)議的研究與優(yōu)化等方面也進(jìn)行了大量的工作。比如中科院寧波軟件所和上海微系統(tǒng)所研究出自己的開發(fā)平臺(tái),中國(guó)科技大學(xué),西北工業(yè)大學(xué)等院校都展 了路由層、數(shù)據(jù)鏈路層方面的研究。 2）國(guó)外的研究現(xiàn)狀 在傳感器網(wǎng)絡(luò)方面,加州大學(xué)伯克利分校提出了應(yīng)用網(wǎng)絡(luò)連通性重構(gòu)傳感器位置的方法,并研究出一個(gè)專門用于傳感器網(wǎng)絡(luò)節(jié)點(diǎn)的操作系統(tǒng)TinyOS。南加州大學(xué)提出了在生疏環(huán)境部署移動(dòng)傳感器的方法、傳感器網(wǎng)絡(luò)監(jiān)視結(jié)構(gòu)及其聚集函數(shù)計(jì)算方法、節(jié)省能源的計(jì)算、聚集的樹構(gòu)造算法等。在傳感器網(wǎng)絡(luò)通信協(xié)議方面,人們首先對(duì)已有的因特網(wǎng)和自組織無線網(wǎng)絡(luò)的通信協(xié)議進(jìn)行了研究,發(fā)現(xiàn)這些協(xié)議不適用于傳感器網(wǎng)絡(luò)應(yīng)用場(chǎng)合。南加州大學(xué)研究了傳感器網(wǎng)絡(luò)上的聚集函數(shù)的計(jì)算方法,提出了節(jié)省能源的計(jì)算聚集的樹構(gòu)造算法,并通過實(shí)驗(yàn)證明了無線通信機(jī)制對(duì)聚集計(jì)算的性能有很大的影響。?無線傳感器網(wǎng)絡(luò)壽命長(zhǎng)短與節(jié)點(diǎn)功耗大小息息相關(guān)，應(yīng)致力于降低功耗。④通信能力有限，傳輸距離不夠長(zhǎng)，受環(huán)境變化干擾。充分研究，并通過 WIFI 組網(wǎng)技術(shù)設(shè)計(jì) WIFI 無線傳感器網(wǎng)絡(luò)的結(jié)構(gòu)。無線傳感器網(wǎng)絡(luò)節(jié)點(diǎn)分為核心控制模塊、外圍接口及電源管理模塊、數(shù)據(jù)采集模塊，針對(duì)各個(gè)模塊的功能進(jìn)行硬件設(shè)計(jì)。然后進(jìn)行軟件設(shè)計(jì)，了解嵌入式Linus系統(tǒng)的開發(fā)環(huán)境，再進(jìn)行基于FT245 USB芯片Linus驅(qū)動(dòng)系統(tǒng)的設(shè)計(jì)，配置內(nèi)核，使系統(tǒng)支持 USB 接口的 WIFI 無線網(wǎng)卡。第1周～第4周 資料收集，完成開題報(bào)告的撰寫，英文資料的翻譯。第7周～第9周 電路設(shè)計(jì) 電路制作 程序編寫。第13周～第15周 數(shù)據(jù)整理，撰寫論文。5. 文獻(xiàn)綜述（2000字以上，列出主要參考文獻(xiàn)） 無線傳感器網(wǎng)絡(luò)的三個(gè)基本要素包括：無線傳感器網(wǎng)絡(luò)節(jié)點(diǎn)、覆蓋環(huán)境感知對(duì)象和接收數(shù)據(jù)觀察者。無線傳感器網(wǎng)絡(luò)節(jié)點(diǎn)按照?qǐng)?zhí)行功能的不同又可劃分為傳感器節(jié)點(diǎn)和匯聚節(jié)點(diǎn)，傳感器節(jié)點(diǎn)完成數(shù)據(jù)的采集和通信鏈路的續(xù)傳，而匯聚節(jié)點(diǎn)只完成收發(fā)無線網(wǎng)絡(luò)數(shù)據(jù)和上傳給接收數(shù)據(jù)觀察者。接收數(shù)據(jù)觀察者是無線傳感器網(wǎng)絡(luò)的終端用戶，完成采集數(shù)據(jù)的應(yīng)用。 圖11 無線傳感器網(wǎng)絡(luò)節(jié)點(diǎn)結(jié)構(gòu)示意圖 無線傳感器網(wǎng)絡(luò)的傳感器節(jié)點(diǎn)內(nèi)部結(jié)構(gòu)示意圖如圖 11 所示，內(nèi)部分為四個(gè)模塊：電源模塊、傳感器模塊、信息處理模塊和無線通信模塊。 無線傳感器網(wǎng)絡(luò)組成形式如圖 12 所示，其工作原理：首先分布于監(jiān)控區(qū)域的眾多傳感器節(jié)點(diǎn)通過無線通信的方式自組織成一個(gè)有傳播梯度的多跳網(wǎng)絡(luò)，接著某個(gè)傳感器節(jié)點(diǎn)采集接收到覆蓋范圍感知對(duì)象的有效數(shù)據(jù)，此節(jié)點(diǎn)將數(shù)據(jù)發(fā)送給周圍選擇的鄰居節(jié)點(diǎn)，鄰居節(jié)點(diǎn)再傳遞給自身周圍的鄰居節(jié)點(diǎn)，數(shù)據(jù)經(jīng)過多跳傳遞給匯聚節(jié)點(diǎn)（sink），匯聚節(jié)點(diǎn)最后再傳遞給接收數(shù)據(jù)觀察者，從而完成整個(gè)無線網(wǎng)絡(luò)的通信功能。它是一種短程無線傳輸技術(shù)，能夠在數(shù)百米范圍內(nèi)支持互聯(lián)網(wǎng)接入的無線電信號(hào)。輻射小， 規(guī)定的發(fā)送功率是 100mW，而一般的WIFI 設(shè)備只要60~70mW。在節(jié)點(diǎn)核心控制模塊硬件結(jié)構(gòu)中，ARM 作為一種嵌入式處理器，具有高性能、低功耗、低成本、體積小等優(yōu)點(diǎn)。本設(shè)計(jì)中，處理器選用 Ateml 公司的ARM芯片AT91SAM9G45，主頻達(dá)400MHZ。在節(jié)點(diǎn)外接口與電源管理模塊中，電源管理芯片，選用 LM2596 和 LM1084，為系統(tǒng)提供 5V 和 電壓。數(shù)據(jù)采集系統(tǒng)由傳感器、AD 轉(zhuǎn)換器、FPGA 組成，它的主要任務(wù)是把傳感器采集到的模擬信號(hào)轉(zhuǎn)換成數(shù)字信號(hào)。無線 AP（AP，Access Point，無線接入節(jié)點(diǎn)）是一個(gè)包含很廣的名稱，它包含無線接入點(diǎn)（無線 AP）和無線路由器（含無線網(wǎng)關(guān)、無線網(wǎng)橋）等類設(shè)備的統(tǒng)稱。Linux 是開放源代碼的，不存在黑箱技術(shù)，全球有眾多 Linux 愛好者，對(duì) Linux 發(fā)展提供強(qiáng)大技術(shù)支持。Linux 是完全免費(fèi)，與其它昂貴操作系統(tǒng)如 Vxworks 相比，容易普及。Linux 內(nèi)核的結(jié)構(gòu)在網(wǎng)絡(luò)功能完善，支持包括百兆、千兆以太網(wǎng)絡(luò)以及無線網(wǎng)絡(luò)。這三部分需要寫到嵌入式系統(tǒng)的 NandFlash 中，不同的處理器，其燒寫方式有所不同。 驅(qū)動(dòng)程序設(shè)計(jì)好后，需要將其編譯生成二進(jìn)制文件，驅(qū)動(dòng)程序不同于應(yīng)用程序的編譯，由于驅(qū)動(dòng)程序是 Linux 內(nèi)核的一部分，所以需要將驅(qū)動(dòng)程序源碼放到 Linux 內(nèi)核源碼中。所以要配置內(nèi)核，使內(nèi)核支持 ，對(duì)內(nèi)核進(jìn)行相關(guān)的配置后，系統(tǒng)就完全支持 USB 接口的 WIFI 無線網(wǎng)卡了。 in section III we detail the visual MIMO channel model followed by the perspective dependent MIMO characterizations in section IVC. In section V we plot the analytical channel capacity in visual MIMO and follow up with key inferences about the multiplexing and diversity characterization in visual MIMO based on the capacity plots.II. RELATED WORKPrior work in optical wireless using visible light that use photodiode receivers or imaging receivers are either limited to short ranges or require plex processing at the receiver [17], [21], [22]. Though photo diodes can convert pulses at very high rates, they suffer from large interference and background light noise. This results in very low SNRs and thus short munication ranges. We showed analytically in [6], based on the visual MIMO concept, that a camera receiver outperforms photodiode receivers in terms of its channel capacity at medium to long ranges. Recently, a few sporadic projects have begun to investigate cameras as receivers, particularly for intervehicle munications [21] and traffic light to vehicle munications [8]. Their analytical results show that munication distances of about 100m with a BER  10??6 are possible. Other work has investigated channel modeling [18] and multiplexing [7]. While earlier work has also used cameras to assist in steering of FSO transceivers [25], the visual MIMO approach differs by directly using cameras as receiver to design an adaptive visual MIMO system that uses multiplexing at short distances but still can achieve ranges of hundreds of meters in a diversity mode.Only a few projects till now have investigated MIMO techniques for optical wireless. For shorter range systems [15], [26] show a MIMO approach for indoor optical wireless munication, [13] studied the capacity of a optical MIMO system and [19] details some work on spacetime codes for optical MIMO. Earlier work by Kahn [23] investigates the use of multibeam transmitters and imaging receivers in InfraRed systems very similar to MIMO in concept. Very recently the PixNet project [20] presents an implementation of an LCD camera munication system that can deliver high data rates of the order of Mbps over distances of about 16m and wide view angles. PixNet uses OFDM to transmit between the LCDcamera pair similar to the pixelated MIMO system proposed by Hranilovic and Kschischang [13]. In this paper we will emphasize that regardless of any type of modulation and transmission scheme, visual MIMO can still achieve significantly high data rates by exploiting some of the uniquecharacteristics of the visual channel.III. VISUAL MIMO MODELIn the visual MIMO munications system, the optical transmit element generates a light beam (optical signal) whose output power is proportional to the electrical input power of the modulating signal, limited by the emitter’s peak transmission power [14], [18], [22]. While RF channels are typically characterized by their impulse response that reflects the multipath environment, this aspect differs significantly for optical channels. Since the rate of change of the channel impulse response is very slow pared to the frequency of the optical signal, it is usually sufficient to use a static parameter (channel DC gain) [16] to represent the channel. For the same reason intersymbol interference and multipath fading can be neglected in optical wireless channels. Similarly Doppler shift is negligible pared to the frequency as well. Consider the visual MIMO munication system model as shown in Fig. 1 where an optical transmitter consisting of an array of K transmitting elements municates to a camera receiver with an array of I J pixels. The channel model for the visual MIMO system is given as, where Y 2 RIJ is the image current matrix with eac