【正文】 lk are the pixel edge length, camera focal length and diameter of kth transmit element (considering a circular transmitting element) respectively. The amount of concentration of the signal per pixel is also dependent on the amount of blur in the image due to the lens. Typically, lens blur is modeled as a Gaussian function [12] and the amount of blur in the image is quantified by its standard deviation (blur). The lens essentially acts like a filter with the blur function as its impulse response. Thus the image of the transmit element can be viewed as a result of the projected image convolving with the blur function over the detector area.I(:) is an indicator function indicating whether a pixel (i。VI. CONCLUSION We showed that visual MIMO can enable high data rate mobile optical wireless munication over long transmission ranges. This concept advocates that regardless of any type of modulation and transmission scheme, the system can achieve high data rates simply by exploiting some of the unique characteristics of the visual channel. The visual MIMO approach, different from that of its RF counterpart, allows adaptive design where multiplexing gains can be obtained at short distances while ranges of hundreds of meters can be achieved in a diversity mode. Our analytical results report even in the presence of signal distortion due to lens blur channel capacities of the order of Mbps at short distances and of the order of hundreds of Kbps at medium to longer ranges for an exemplary visual MIMO system with 100 LEDs in an array. We also showed similar channel capacities for the same system over wide camera view angles. These results validate the premise that the MIMO gains in an optical MIMO system such as visual MIMO is primarily dependent on receiver perspective with respect to the transmitter in contrast to the multipath fading dependent gains in RF MIMO. We inferred that a visual MIMO system will have to switch between its multiplexing and diversity mode unlike RF MIMO where they can be achieved simultaneously but follow a tradeoff in performance. The consistency in data rates over a wide range of camera viewing angles is a positive indication that visual MIMO can enable mobility in optical wireless munication.視覺MIMO特征的復用與多樣性摘要：移動無線光學迄今已受到限制高數(shù)據(jù)速率系統(tǒng)的很短的范圍。 j), characterized by hk(i。i。 j) from each transmit element k to the pixel(i。 j) representing the channel between the kth transmit element and pixel (i。本文選用 Ateml 公司的工業(yè)級 ARM 芯片 AT91SAM9G45，該處理器 BootLoader 和 Kernel 需要使用 Ateml 公司的 SAMBA 軟件通過 USB 口進行燒寫，而 Rootfs 是通過網(wǎng)口進行燒寫。 嵌入式 Linux 是在 Linux 的基礎(chǔ)演變而成的，專門應用于嵌入式設(shè)備中。將 ARM 作為節(jié)點的主控制器可全面提高節(jié)點性能。傳感器模塊通過傳感器觸頭感知外界信息，獲取傳感數(shù)據(jù)；無線通信模塊通過天線與其他節(jié)點通信完成數(shù)據(jù)交換。第16周 準備答辯。 選用ARM芯片AT91SAM9G45作為處理器， 選用AD7492作為A/D轉(zhuǎn)換器，選用FIFO CY7C4261作為緩存器，F(xiàn)PGA芯片選用XC3S500E， WIFI 芯片選用 RT3070。 3）目前技術(shù)存在的問題 ?無線傳感器網(wǎng)絡(luò)即便節(jié)點靈活，可減硬件成本，但依然受有限能量的制約，優(yōu)勢未能充分發(fā)揮。國家對傳感器網(wǎng)絡(luò)的研究也非常重視,國家自然科學基金委員會從2003年起開始設(shè)立了無線傳感器網(wǎng)絡(luò)相關(guān)研究課題,國家的“863”項目、國家自然科學基金項目、各省區(qū)的自然科學基金項目的課題中都有相當?shù)谋壤沁M行無線傳感器網(wǎng)絡(luò)研究的。組網(wǎng)不需要任何固定的網(wǎng)絡(luò)設(shè)備，傳感器節(jié)點通過分布式網(wǎng)絡(luò)協(xié)議形成自組織網(wǎng)絡(luò)，能夠自動調(diào)整來適應節(jié)點的變化，網(wǎng)絡(luò)中的節(jié)點可以快速、自動的組成一個獨立的網(wǎng)絡(luò)。長春理工大學畢業(yè)設(shè)計任務書題目名稱：基于WIFI的無線傳感器采集系統(tǒng)設(shè)計 學生姓名：華丹陽 起止日期：~題目要求(包括主要技術(shù)參數(shù)):1． 題目內(nèi)容：設(shè)計基于WIFI技術(shù)的傳感器信息采集系統(tǒng)，實現(xiàn)數(shù)據(jù)信息的網(wǎng)絡(luò)發(fā)布2． 具體要求及技術(shù)參數(shù)： ； ； 。傳感器網(wǎng)絡(luò)具有自組織功能。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,中國科技大學,西北工業(yè)大學等院校都展 了路由層、數(shù)據(jù)鏈路層方面的研究。南加州大學研究了傳感器網(wǎng)絡(luò)上的聚集函數(shù)的計算方法,提出了節(jié)省能源的計算聚集的樹構(gòu)造算法,并通過實驗證明了無線通信機制對聚集計算的性能有很大的影響。無線傳感器網(wǎng)絡(luò)節(jié)點分為核心控制模塊、外圍接口及電源管理模塊、數(shù)據(jù)采集模塊，針對各個模塊的功能進行硬件設(shè)計。第13周～第15周 數(shù)據(jù)整理，撰寫論文。 圖11 無線傳感器網(wǎng)絡(luò)節(jié)點結(jié)構(gòu)示意圖 無線傳感器網(wǎng)絡(luò)的傳感器節(jié)點內(nèi)部結(jié)構(gòu)示意圖如圖 11 所示，內(nèi)部分為四個模塊：電源模塊、傳感器模塊、信息處理模塊和無線通信模塊。在節(jié)點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。無線 AP（AP，Access Point，無線接入節(jié)點）是一個包含很廣的名稱，它包含無線接入點（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。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。 j), xk 2 R represents the transmitted optical power from kth element of the LEA and Hk 2 RIJ is the channel matrix of the kth transmit element of the LEA, with elements hk(i。 j), the channel DC gain hk(i。 j) respectively.Typically, since the pixel size is very small (order ofmicrons), the difference in distance dk。j =  as the perpendicular distance and the angle between the transmitter array and image detector planes respectively. Hence the channel between each transmit element k and each pixel (i。 j) from equation (2). I(:) is the indicator function, from equation (5). We plot the channel capacity from equation (7), for an exemplary visual MIMO system, where the transmit elements of the LEA are light emitting diodes (LEDs) and the receiver is a machine vision camera (Basler Pilot piA640), over a range of distances d (Fig. 5) and over different viewing angles (Fig. 6). The underlying parameters used in our analysis are summarized in Table I. Inferences: From the analytical capacity plots we draw few notable inferences that relate to the multiplexing and diversity characterizations in visual MIMO. The visual MIMO system with no blur can achieve capacities of the order of Mbps even at long distances of about 90m. Blurring certainly reduces multiplexing range but still medium ranges of 3040m are achievable at high data rates. The data rate gains at these distances are attributed to multiplexing where each LED sends an independent stream of bits over parallel channels. The transitions in the plot (for the multi LED cases) indicate the switch from multiplexing to diversity mode. The capacity gains due to diversity at the long distances, though may not be significant parable to the multiplexing gains at shorter distances, are still close to an order of magnitude gain pared to the single LED system.Fig. 5. Visual MIMO channel Capacity versus distance ( = 0)Fig. 6. Visual MIMO channel Capacity versus angle (d constant) A visual MIMO system will have to switch between the multiplexing and diversity modes in discrete intervals based on distance and angle unlike RF MIMO where the gains in these modes could be achieved simultaneously but follow a continuous tradeoff in performance.