【正文】 between the transmitter and receiver, each transmitting element of the LEA looks clearly focused on a unique set of pixels and the images of these elements can be detected from the plete image. In contrast, at a large distance between the transmitter and receiver, the image of each transmit element looks clearly unfocused and thus the signal from all the transmitting elements of the LEA is directed to typically one or few pixels. This suggests that at short distances, the system can offer large ”multiplexing” gains by using the transmitting elements to signal independent bitstreams or equivalently realizing ”parallel” channels. On the other hand, at large distances, there can only be a ”diversity” gain where by the same bits are signaled on each of the transmit elements. These distance dependent gains in visual MIMO is in contrast to the RF MIMO channel, where the rich scattering channel matrix typically allows a continuous tradeoff between diversity and multiplexing gains [24], [27].Fig. 4. Distance dependent Multiplexing and Diversity modesV. VISUAL MIMO CHANNEL CAPACITYTo quantify the perspective dependent multiplexing and diversity gains in visual MIMO we use the channel capacity of the visual MIMO channel as a metric which is given as, where W is the receiver sampling rate (camera framerate), d is the threshold multiplexing distance from equation (6). SNRcam。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(fù)用與多樣性摘要：移動(dòng)無線光學(xué)迄今已受到限制高數(shù)據(jù)速率系統(tǒng)的很短的范圍。 j) from equation (3) and AWGN noise nk(i。 j) which can expressed as,where, s, f, 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。i。i。 viewing angle between each transmit element kand receiving pixel (i。i。 j) represents the concentration ratio of the kth transmit element of an LEA on pixel (i。 j) of the noise matrix N representing the noise current at each pixel is given aswhere q is the electron charge, R is the responsitivity of the receiver characterized as the optical power to current conversion factor, Pn is the background shot noise power per unit area, s is the square pixel side length and W is the sampling rate of the receiver (equates to the frame rate of the camera).The optical signal from the kth transmit element (k =1。 j) in each pixel with image coordinates (i。Linux 內(nèi)核是支持 WIFI 無線網(wǎng)絡(luò)通信的，但是需要對(duì)其進(jìn)行配置，才能使用。Linux 操作系統(tǒng)至少具有三部分：BootLoader（引導(dǎo)系統(tǒng)）、Kernel（內(nèi)核）、Rootfs（根文件系統(tǒng)）。Linux 的內(nèi)核小、執(zhí)行效率高，非常容易裁剪定制，其系統(tǒng)內(nèi)核最小只有約幾百 KB。本文設(shè)計(jì)的系統(tǒng)所使用的 WIFI 無線網(wǎng)卡是 TOTOLINK 公司的 N200UA，這款 WIFI無線網(wǎng)卡的優(yōu)點(diǎn)在于外置天線，我們可以根據(jù)需要選用特殊形狀以及高增益的天線。動(dòng)態(tài)存儲(chǔ)器，選用 National Semiconductor 公司 64M DDR2 存儲(chǔ)器，工作溫度在系統(tǒng)中使用兩片，總?cè)萘窟_(dá) 128M，大幅提高 ARM 處理器的運(yùn)算效率。而且易擴(kuò)展，傳輸可靠，組網(wǎng)便捷。 WIFI 全稱 Wireless Fidelity[14]，又稱 標(biāo)準(zhǔn)，是由一個(gè)名為“無線以太網(wǎng)相容聯(lián)盟”（Wireless Ethernet Compatibility Alliance, WECA）的組織所發(fā)布的業(yè)界術(shù)語，中文譯為“無線相容認(rèn)證”。接收數(shù)據(jù)觀察者一般為終端計(jì)算器或者其它監(jiān)控設(shè)備，甚至是連接外部世界的萬維網(wǎng)，數(shù)據(jù)采集觀察者通過主動(dòng)查詢或者被動(dòng)接收的方式分析無線傳感器網(wǎng)絡(luò)的數(shù)據(jù)信息，并最終完成數(shù)據(jù)的分析、應(yīng)用。無線傳感器網(wǎng)絡(luò)節(jié)點(diǎn)是無線傳感器網(wǎng)絡(luò)最基本、最核心的組成部分，網(wǎng)絡(luò)節(jié)點(diǎn)主要集成相應(yīng)微型傳感器、數(shù)字信號(hào)處理器、無線通信模塊等功能單元。第10周～第12周 調(diào)試測(cè)試 電路調(diào)試 軟件調(diào)試。進(jìn)行基于RT3070芯片的網(wǎng)卡驅(qū)動(dòng)移植，最后設(shè)計(jì)WIFI的驅(qū)動(dòng)程序，進(jìn)行WIFI聯(lián)網(wǎng)。然后設(shè)計(jì) WIFI 無線傳感器節(jié)點(diǎn)的硬件結(jié)構(gòu)。?通信協(xié)議依然廣泛，網(wǎng)絡(luò)協(xié)議標(biāo)準(zhǔn)化較低。加州大學(xué)伯克利分校研究了傳感器網(wǎng)絡(luò)的數(shù)據(jù)查詢技術(shù),提出了實(shí)現(xiàn)可動(dòng)態(tài)調(diào)整的連續(xù)查詢處理方法和管理傳感器網(wǎng)絡(luò)上多查詢方法,并研制了一個(gè)感知數(shù)據(jù)庫(kù)系統(tǒng)TinyDB。加州大學(xué)洛杉肌分校開發(fā)了一個(gè)無線傳感器網(wǎng)絡(luò)和一個(gè)無線傳感器網(wǎng)絡(luò)模擬環(huán)境,用于考察傳感器網(wǎng)絡(luò)各方面的問題。除此之外，國(guó)家 863 計(jì)劃、973 計(jì)劃也對(duì)無線傳感器網(wǎng)絡(luò)的研究進(jìn)行了相關(guān)規(guī)劃。功耗小，電池供電，網(wǎng)絡(luò)節(jié)點(diǎn)一般都能工作3年左右，甚至更長(zhǎng)。能根據(jù)實(shí)際情況設(shè)計(jì)無線傳感器網(wǎng)絡(luò)的規(guī)模，有利于應(yīng)用范圍的擴(kuò)展。而傳感器技術(shù)在科技發(fā)展中卻舉足輕重。 指導(dǎo)教師簽字 系主任簽字 年 月 日 開題報(bào)告本課題研究的目的、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。傳感器網(wǎng)絡(luò)覆蓋范圍大。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。 1）國(guó)內(nèi)的研究現(xiàn)狀 山東省科學(xué)院與沈陽自動(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。 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。在傳感器