《已翻译+RFTRAININGdnew1.ppt》由会员分享，可在线阅读，更多相关《已翻译+RFTRAININGdnew1.ppt（58页珍藏版）》请在三一文库上搜索。
1、天线增益和方向,dBi是用来描述天线的增益。它以100%效率的各向同性辐射器或者超于基准的各向同性分贝数作为参考。,一个100%有效的各向同性辐射器由一个平均高效点源（全部经过天线的能量都被辐射出去）组成。,当能量集中在一个单位面积， 能量密度会变得更加高， 这就代表了增益。,天线效率和增益,-天线的效率是指有多少能量进入天线而没有被辐射出去。,PowerBridgeM3 Antenna Array,-例如: 一副增益为-3dBi的天线是怎样可以成为一个各向同性天线呢？,天线系统,输入功率,输出功率（只有1/2）,一个各向同性辐射器的最好效率是0dBi, 如果这个各向同性辐射器的增益是-3dB
2、i, 这意味着这个天线的效率只有50%（只有1/2的输入能量被辐射出去）。,反射能量是输入功率的1/2（-3dB),各向同性辐射天线,一个效率为70%的复杂天线， 它必定是一个优良的设计。,效率损耗通常来自于高增益天线里的功率分配网络输送数组元素的电阻插损。,Ubiquiti 设备使用高TX 输出功率,-输出功率将有助于增加链接的距离和可靠性。 不过它必须 是“光洁”的能量（后面有更多的介绍）,-一般地说， Ubiquiti 无线设备的输出功率范围为+26dBm到+28dBm。,-10dBm,+13dBm,+28dBm,无线车锁,手提电脑,AirMax 无线设备,dBm的认知,-分贝（dB)是
3、一个比值。dBm 是一个真实的数值， 这个数值是以1毫瓦特作为参考基准。,-dBm遵照跟dB相同的对数映射到域的规则。,问题：500mW是多少dBm?0.002mW的时候是多少 dBm?,跟dB做法一样，应用相同的规则。加倍将增加+3dB. 到10的时候，将会增加+10dB. 然而， 现在是以1mW作为参考（一个真实的数值）， 所以“dBm“代表的是一个真实的数值。,Ubiquiti 设备拥有令人满意的RX灵敏度,-Ubiquiti AirMax 能够在窄频段里运行， 并且能够提高灵敏度（5Mhz频段的灵敏度有-103dBm),-Ubiquiti 无线设备使用优化的RF设计去实现接收器最大灵敏
4、度。,-85dBm,-103dBm,传统的 WIFI 设备,AirMax无线设备,Radio Sensitivity Improves with Narrow Channel 缩短路径改善无线电的的灵敏度,40MHz,20MHz,10MHz,5MHz,-Power can remain constant as channel size is varied 由于路径大小的变化，功率可以保持不变,-Thermal noise decreases as channel size decreases 由于路径大小的减少，热噪声也减少,NOISE FLOOR,-Result is an increase
5、 in Signal/Noise seen by receiver 从接收器可以看出在信号/噪音方面的显著效果,For 5MHz Channel, signal area remains the same, but noise area is now 1/8th the amount as 40MHz case,PtP Long Distance Performance Review 点对点长距离绩效评估,TX Power,RX Sensitivity,+28dBm,-103dBm,Antenna Gain,+34dbi,Antenna Gain,+34dbi,A Link Budget sh
6、ows the maximum path loss the link can sustain (this will determine the distance of the link)一个连接预算显示可以支撑的最大路径损耗（这决定了一个连接的距离） Link Budget = Antenna Gains + TX Power - RX Sensitivity 连接预算=天线增益+输出功率-接收灵敏度 = 34dBi + 34dBi + 28dBm + 103dBm “Link Budget” = 199dB,On the transmit side, TX Power and Antenna
7、 Gain define the “intensity” of the signal 在发送方面，输出功率和天线增益决定信号的“强度”,On the receive side, RX Sensitivity and Antenna Gain define the “listening ability” of the radio 在接收方面，接收灵敏度和天线增益决定无线电的“听力”,Using AirLink Simulator 使用AirLink模拟器,http:/ Equipment, Deployment Variables, and Location of Point to Point
8、Link 确定设备，安装变量和点对点连接位置,Using AirLink Simulator 使用AirLink模拟器,http:/ graph shows the terrain profile of the link and Fresnel Zone Clearance (more on this later) 这图表显示连接的地形轮廓和菲涅耳区间隙,These are the simulated results which will appear in AirOS 这些模拟结果会出现在AirOS里,Using AirLink Simulator 使用AirLink模拟器,http:/ c
9、an be simulated! Above are results of actual deployment compared to AirLink simulation 性能可以被模拟！以上实际安装结果比作为AirLink模拟,Link Performance Indicators 链路性能指示,Combined Signal Strength Receiver Hears 收听到的联结的信号强度,Signal Strength corresponding to MIMO Chains for each Antenna Polarity 信号强度相当于MIMO信道，为天线各个极化性,Noi
10、se Floor represents the environmental noise (from interference) the receiver hears on the operating frequency 本底噪声代表环境噪声（来自干扰） 接收器从工作频率中收听,AirMax Quality calculates the airtime efficiency for the client. Higher AMQ is important for hi-performance links. AirMax 特性为用户计算通话效率。 高AMQ对高性能链接很重要,AirMax Capac
11、ity takes into account AMQ AirMax 性能把AMQ考虑在内,TX/RX Rates are the Wireless Data Rates. Rates achievable depend largely on Signal Strength (next page) 发射接收比率是无线数据比率，可达到的比率很大程度取决于信号强度（下页）,Transmit CCQ is calculated 计算出传播CCQ,Signal Strength (SNR) and Data Rates,-Achievable data rates depend on signal st
12、rength. Higher Signal strength allows for faster data rates -Increasing MIMO chains to 2, effectively doubles data rates 可达到的数据比率取决于信号强度，高信号强度就高数据比率 增加MIMO信道到2，数据比率就加倍,All Rates in table are based on HT40 mode (40MHz Channel) 表格中的所有数值是基于HT40模型（40MHz信道）,Important! Real acheivable TCP/IP rates are app
13、rox. 50% of wireless air rates due to radio overhead,Fade Margin and Recommended Signal Strength,-Signal “Fading” is caused by environmental changes caused by weather or terrain movement 信号“Fading”是由天气和地质变动引起的环境变化而产生的。 -It is good practice to design in approximately 15dB of “Fade Margin” to a PtP li
14、nk 一个好的做法是设计大约15dB的“衰落边际”到一个PtP联结 -Example: If you are designing to achieve a minimum wireless date rate of 180MBps (-70dBm), then the link should be designed such that its installed signal strength is -55dBm 例如：如果你想达到一个无线数据比率的最小值180MBps(-70dBm),那么联结的信号强度就应设置到-55dBm,DAY 1,DAY 2,DAY 3,8dB signal fluc
15、tuation,Deployment and Fresnel Zones,-Portions of the transmitting signal can reflect off of obstructions and arrive at the receiver out of phase with the direct signal. 一部分传播信号能通过障碍物反射回来，异相的接收者能收到直接的信号。 -Because the path lengths are different, the out of phase signals can cancel each other out and
16、reduce the received signal power 因为路径长度是不一样的，异相的信号能互相抵消和减小收到的信号的强度 The Fresnel Zones defines the region which must be free of obstructions to ensure no significant signal reflections arrive at the receiver. Only the first Fresnel Zone is typically of concern for AirMax PtP Links. 菲涅耳波带解释为没有障碍物的区域确保重
17、要信号能反馈给接收者。只有第一个捏菲耳波带是AirMax PtP 联结的典型有利环境。,Fresnel Zone Obstruction,The “reflected signal” can add out of phase with the direct signal reducing received signal power,direct signal,reflected signal,Equation for Calculating Fresnel Zone depth at any point in line of direct link,Fn=The nth Fresnel Zon
18、e d1 = distance of P from one end in meters d2 = Distance of P from other end in meters 1 = Wavelength of the transmitted signal in meters,The Fresnel Zone required clearance becomes greater as the wavelength increases. Therefor, lower frequencies correspond to a larger Fresnel Zone clearance.,Fresn
19、el Zone example for 2.4GHz deployment. Maximum clearance is approximately 8 meters.,Installers can use AirLink to ensure their deployment has First Fresnel Zone clearance,Spectrum Analyzer 波谱分析器,-AirView is standard utility available in AirOS. It runs on all M Series AirMax products from Ubiquiti Ai
20、rView是标准效用可用在AirOS,它可运行在所有M系列来自Ubiquiti的AirView产品 -The application allows the installer to analyze the noise environment and intelligently select the optimum frequency to install a PtP AirMax link 它的应用可以让安装者去分析噪声环境和精明地选择最有利的频率去安装一个PtP AirMax 联结,In the unlicensed bands, interference can significantly
21、 impact link performance. Using AirView, we can see exactly where the interference is and what channels to select to avoid it. 用没有许可的品牌产品，干扰会明显地影响联接的性能。用AirView产品，我们可以明确地看到干扰信号在哪里和调到哪个信道可以消除它。,Spectrum Analyzer 光谱分析仪,This shows the frames per second (FPS) and total RF frames recorded. The FPS can be
22、 increased (giving a more “live” feel”) by reducing the frequency span 这表示每秒帧数（FPS）和所记录的RF总帧数。 FPS值随频率周期的降低而增加。,The Waterfall view shows frequency and RF energy as a function of time. In this case, there is a running 1 minute time window 瀑布形图像表示频率和RF能量的时间函数。此图表示1分钟间隔的情况。,This view gives the RF signa
23、ture of the noise environment. Over time, energy that appears most frequently will be filled into the graph 这是在噪声环境下RF的标识。长时间产生的大部分能量会显示在图标里。,The real-time view is similar to a RF Spectrum Analyzer screen. It shows real-time RF energy vs. frequency. It records maximum energy, average energy ,and cur
24、rent energy 实时图像与RF光谱分析仪的显示图相似，它表示RF能量与频率的实时关系，记录下最大能量，平均能量和现行能量,Channel Operation 路径的运行,Channel Flexing 路径弯曲,Noise 噪声,Signal 信号,Narrowing Channel Width increases sensitivity and improves interference immunity 缩短路径宽度可以增强敏感度和防干扰能力。,5MHz channel size is minimum supported filtering in AirMax radios; no
25、 improvement for 2MHz size 5MHz是AirMax无线电可支持的最小过滤路径宽度，2MHz的效果一样。,HT30 mode is peak performance channel size for PtP AirMax. This has to do with overhead reduction “trick” in AirMax HT30型号是点对点AirMax性能最好的路径，是AirMax降低耗损的“法子”,2412,2417,2422,2427,2432,802.11 Channels,1,2,3,4,5,AirMax allows channel opera
26、tion with 2MHz granularity. This provides both noise immunity and security advantages over standard 802.11 wifi radios,Channel Shifting,AirOS PtP Link Setup AirOS点对点链接设置,Point 1: Access Point (Master) 接入点（主机）,Point 2: Station 基站 (Slave辅助器),In the AirOs Wireless tab, select Access Point mode 在AirOS无线
27、栏中，选择接入点模式,On this device, select Station mode,The Station side will link to the AP side 基站链接AP处,In the AirOs Wireless tab, select Station mode 在AirOs无线栏中，选择基站模式,“Select” will bring up a survey of SSIDs. Select the Master SSID to connect to it “选择框”中会弹出SSID概况表。选择Mater SSID即可连接SSID。,Visual Antenna Al
28、ignment 可视天线校对,Signal Strength LEDs LED显示的强信号,Antenna Alignment Tool 天线校对功能,Physical LEDs are located on the AirMax station products for easier installation LED屏显示在AirMax基站产品表面，便于安装,AirOS also has an alignment tool available in the web UI AirOs同时具有UI网校对功能。,Audio Antenna Alignment 音频天线校对,The Aiming T
29、ool will provide a moving time window of signal strength and will produce tone sounds indicating signal increasing or decreasing in real-time 校对工具会显示一个信号强弱的时间表并发出实时的信号强弱声。,Ubiquiti Discovery Tool (available online; free download) Ubiquiti发现工具（可以在网上免费下载）,ACK Timing ACK时间选择,Packet Transmitted 数据包传输,AC
30、K Sending ACK发送,Waiting for ACK 等待ACK,Still waiting for ACK 仍等待ACK,If the ACK Timeout is too short, the transmitter will conclude packet was in error and will retransmit continuously. If the ACK Timeout is too long, airtime is wasted and system timing problems can occur. ACK Timing is very important
31、 for hi-performance outdoor deployments 如果ACK暂停时间过短，发射器会认为数据包出错并不断重复传输。如果ACK暂停时间过长，会浪费传输时间，也会造成系统时间问题。ACK时间选择对于户外高性能设备安装极为重要。,AirOS can automatically find the optimum ACK timeout setting when “Auto Adjust” is enabled,1,2,3,Applying Security 安全性应用,AP Setting AP设定,Station Setting 基站设定,Select security
32、option and set security key here. There is also an option to lock to MAC ID 选择安全选项，并设置密码。同时会有MAC ID锁选项可选。,Match Security option from AP side and enter Key 匹配AP方的安全选项并输入密码。,NOTE: For best throughput performance with AirMax, use WPA2-AES 注意：采用WPA2-AES可使AirMax流量最多,Using AirOS Speed Test 使用AiirOs 网速测试,F
33、rom either Station or AP side, speed test can be run by selecting other side IP address. 无论是在基站或AP处，只要通过选择另一方的IP地址就可以进行网速测试,-AirOS speed test allows installer to instantly test wireless link performance AirOS网速测试可以让安装者在短时间内测试无线连接的性能状况。,Select Speed Test from the Tools menu 从工具菜单中选择网速测试,Popular PtP A
34、irMax Choices 点对点AirMAx热卖产品,Radio Fundamentals 无线电原理,Information Theory & Shannons Law 信息论和Shannon定律,-Shannons Law expresses the maximum throughput of a channel Shannon定律阐释了一个路径的最大流量,Capacity_bps = f_Hertz log2 (1+Signal/Noise) 产能 bps= f_赫兹 log2 (1+信号/噪音),Rocket M5,Throughput depends on SNR and Chan
35、nel Size! 流量大小取决于信号强弱和路径大小,THROUGHPUT 流量,Channel Size 路径大小,Signal 信号,Increasing channel size and increasing Signal both allow for higher throughput 扩大路径和增强信号都可以提高流量,Thermal Noise / Bandwidth Dependent 热噪声/带宽,-Radio Sensitivity depends on 2 values: 无线电敏感度取决于2个准则： Thermal Noise (inherent noise in phys
36、ics)热噪声（物理固有噪声） 2. Noise Factor of Radio (noise added by radio receiver)干扰无线电波的噪声因素（无线电接收体产生的噪声）,-Thermal Noise determined by following: 热噪声受以下因数决定： -PdBm=10log10 (kBT f x1000) -PdBm=-174+10log10 (f),Thermal Noise depends on Bandwidth! 热噪声强弱取决于带宽,Radio Sensitivity 无线电敏感度,-Radio Sensitivity depends o
37、n 2 values: 无线电敏感度取决于2个准则： -Thermal Noise 热噪声 -Noise Factor of Radio (noise added by radio receiver) 影响无线电的噪声因素,-Noise Factor (F) is defined as how much a radio degrades SNR噪声因素（F）的定义是一束无线电波损失信号的程度,F=SNRIN/SNROUT,Radio 无线电波,Signal Processor 信号处理器,SNRIN 信号输入,SNROUT 信号输出,180,180,180,Radio Sensitivity
38、无线电波敏感度,-Noise Factor (F) is defined as how much a radio degrades SNR 噪声因素（F）的定义是一束无线电波损失信号的程度,F=SNRIN/SNROUT,Radio 无线电波,Signal Processor 信号处理器,SNRIN 信号输入,SNROUT 信号输出,LNA,FTOTAL=F1 + (F2-1)/G1 + (F3-1)/G1G2 +,LNA F=1.2dB, Gain=12dB,LNA,LNA,NOTE! Adding more amplifiers does not improve sensitivity. I
39、t is the noise factor and the gain of the first stage that is important 注意！ 增加放大器不能提高敏感度。第一阶段的噪声因素和增益起重要作用。,-Friis Formula calculates the Noise Factor (F) of a Radio through analysis of Noise Factor of individual radio stages. Frii公式通过分析影响单个无线电波阶段的噪声因素计算出噪声因素（F）,1,2,3,Radio Selectivity 无线电波选择性,-Sens
40、itivity defines how low of a signal a radio can hear敏感度指的是无线电可以接收信号的最弱程度。,-Selectivity defines how well a radio can hear when adjacent noise is present 选择性指的是无线电在邻近的噪声影响下所接收信号的效果,5.8GHz,5.3GHz,Signal 信号,Interferer 干扰因素,Radio with Good Selectivity选择性强的无线电波,Radio with Poor Selectivity 选择性弱的无线电波,-For u
41、nlicensed band wireless, selectivity is often as important as receiver sensitivity.对于非注册宽带无线，选择性与接收体的敏感度同样重要。,Selectivity defines how well a receiver can “filter” out of channel energy. For the crowded unlicensed bands, this is important. 选择性指的是接收器能“过滤”出路径能量的效能。,接收放大器 坏主意!,-从Frii的公式,在一台已含低噪声系数接收器前面加
42、多额外LNA放大器会降低接收器的灵敏度,-另外,接收放大器也会增加带外的噪声和降低无线电广播选择性.,5.8GHz,5.3GHz,信号,放大器收到的信号,无线电广播强选择性,无线电广播弱选择性,放大器将增加干扰度和降低接收器的选择性,调制 / 编码,二进制相移健控BPSK,时域,排列,1,0,优势: 很强;低信噪比,弱点: 很慢,只有1bit比特/符号.,-调制是数字通信的关键. 它能把波形变成数字符号集用于数据传递. -符号集里的符号可以是离散相位.振幅或波频移运动的任一组合. -二进制相移健控BPSK是很强的调制,只包含相移产生的两个符号.,这些点被称为符号集,调制/编码,-64QAM (
43、64 正交幅度调制) 用于802.11g 中54Mbps和802.11n 300Mbps,64 符号: 每6 bits比特/符号,优势: 6bits比特/符号. 比BPSK快6倍,弱点: 高信号要求和没有BPSK强,在64QAM中符号间隔会更紧凑,64 QAM 排列,调制补偿量,符号错误噪声容限,符号错误噪声容限,-在BPSK情况下 (2符号), 接收器很难定位错误符号.有很大误差限度,接收器运行低信号. -在64QAM情况下 (64符号),接收器必须精确定位符号. 有很小误差限度,接收器运行高信号.,BPSK 排列,64QAM 排列,0,1,接收器在噪声源后看到的符号.接收器定位回正确的符号
44、,误差矢量幅度(EVM),-不是所有高功率无线电设备有同样表现.许多弱EVM表现的高功率无线电设备不可靠.,-保持低的EVM对减少TX错误和重试很重要,-EVM表现越好,频谱越好,良好的64QAM传输信号例子.注意符号紧密性.,弱EVM的64QAM传输例子.注意凸起的噪声边缘和差的排列.,TX 马刺和谐波,-设计差的无线电设备会放大TX错误表现,引起网络干涉.,-无线电设备不是线性设备,会有TX马刺如谐波,-一般的,EVM表现越好,TX马刺越低.,在设计差的无线电中的TX马刺,良好的无线电设计,AirMax 传输率表格,HT40, 2x2 MIMO,较高数据传输率使用更复杂调制方案和会要求更高
45、信号强度,较低数据传输率使用强的调制方案和会运行较低信号强度,-独立的环境噪声,运行无误和最小传输重试连接必须满足两个条件,传输率, EVM, 和信号强度,1. 传输必须与调制方案一致的最小EVM确保无误运行 2. 接收器必须收到与已用过的调制方案一致的足够最小信号 (SNR).,TX 外部放大器- 坏主意!,-会引起更多TX错误输出,-会降低EVM 和导致更多TX错误,-在外部放大器转换TX/RX状态不够快的地方会引起调速问题.,放大器会使载波饱满和引起邻近频谱噪声凸起,TX 马刺和谐波会在非线性放大情况下出现,AirMax 使用 OFDM 和 MIMO,单独子通道更好处理多路径和干扰环境,
46、-正交频分多路复用技术(OFDM)在非视距NLOS应用中很有用,-多输入多输出(MIMO),在同样频段内多路发射端在多路技术时空内发送数据信号给多路接收端.,天线性能(回顾),-方向性对室外无线电是很重要的.方向性增加增益和过滤噪声.,-方向性取决于天线有效面积.面积越大,潜在方向性越多.,-实现天线增益涉及到电波附加相位调整. 天线阵和缝隙反射是经常被用的一种方法.,-天线的方向性和效率决定增益,天线交互性,增加无线电TX功率会改善一个方向的连接.,增加无线电RX灵敏度会改善一个方向的连接.,增加天线增益会改善两个方向的连接.,-因为天线增益是交互的,即使天线在一面配错,平衡的连接仍会保持.
47、,TX 功率 +3dB: 上行 = 相同 下行 = +3dB,RX 灵敏度 +3dB: 上行 = +3dB 下行 = 相同,天线增益+3dB 上行 = +3dB 下行 = +3dB,A,B,C,A,B,C,方向图,前后比定义为天线的主波瓣增益和背部能量泄漏之差.最小能量泄漏对减少高密度配置噪声环境很重要.好的天线设计有最小的背部能量泄漏.,旁瓣是高增益天线附加波相位调整出现的,一般的,好的定向天线设计旁瓣为主波瓣低-13dB或更低.,波瓣宽度定义为波束能量峰值和-3dB以下之间的平均值.对于载波天线,波瓣宽度定义为-6dB 以下.,例如: NanoBridgeM2 方向图(俯视),方向图表现天
48、线根据角度的增益,天线极化,-电磁波以既定的极化一致方式行进.天线极化是区分同一频段信号的一种方式.,垂直馈源,水平馈源,-在室外视距环境中, 没有多路径创造MIMO要求的时/空区分信号处理.,-然而,使用极化,我们隔离数据流和提供用于MIMO信号处理的独立信号.,-Ubiquiti AirMax 2x2 产品使用MIMO配置双极化天线,VSWR 和回波损耗,-电压驻波比(VSWR) 和回波损耗以传输线如RF电缆或天线馈源性能为特征.它代表多少能量被反射回和浪费. VSWR 性能在天线设计的效率上扮演重要角色.,在-14dB内回波损耗 (一致的 VSR为 1.5:1) 代表好的性能传输线,Na
49、noBridge M2 VSWR 驻波图,此区域显示出在2.4-2.5GHz频段间有好的 VSWR 驻波比,AirMax Antenna Types,碟状,网格,扇区,全向,板状,DISH ANTENNA,RocketDish5G-30,馈源,发射面,馈源和反射面的位置使发射波可以在适合的位置上结合在一起并产生增益.,RF In,-碟状可以提供高增益和定向的性能，但是它的体积是巨大。,Panel Antenna,-板状天线可以拥有定向的性能，且可以媲美碟状和栅抛天线，但有更小的装配要求和更好的外貌。,Panel Antennas split power to multiple metal or PCB radiating elements which combine in phase to create antenna di