KDB 662911 多天线讲义-FCC认证

1、 October 31, 2013 Emissions Testing of Transmitters with Multiple Outputs in the Same Band (e.g., MIMO, Smart Antenna, etc) 什么是MIMO?MIMO有哪些技术？MIMO(Multiple-Input Multiple-Output)技术指在发射端和接收端分别使用多个发射天线和接收天线，使信号通过发射端与接收端的多个天线传送和接收，从而改善通信质量。它能充分利用空间资源，通过多个天线实现多发多收，在不增加频谱资源和天线发射功率的情况下，可以成倍的提高系统信道容量，显示出明显

2、的优势、被视为下一代移动通信的核心技术。MIMO技术的应用上行传输对于R8/R9的LTE终端，主要配置为双天线，但是采用单发双收的工作模式。上行链路MIMO的工作方式主要包括以下几种：单天线传输：采用上行单天线传输方式，使用固定天线发送（端口0）。开环发送天线选择分集：采用上行单天线传输方式，终端选择天线进行上行传输。闭环发送天线选择分集：网络侧通过下行物理控制信道上承载的下行控制信息通知终端采用特定天线进行上行传输。上行MU-MIMO：网络侧能够根据信道条件变化自适应地选择多个终端共享相同的时频资源进行上行传输下行传输LTER8/R9版本中下行引入了8种MIMO传输模式，其中LTEFDD常用

3、的MIMO传输模式为模式1到模式6（TM1TM6），而模式7（TM7）和模式8（TM8）主要应用于TDLTE系统中，下面是不同传输模式的简要说明。模式1：单天线端口传输（端口0）。模式2：开环发射分集。模式3：大延迟CDD空间复用与开环发射分集自适应。模式4：闭环空间复用与开环发射分集自适应。模式5：多用户MIMO与开环发射分集自适应。模式6：单层闭环空间复用与开环发射分集自适应。模式7：单流波束赋形（端口5）与开环发射分集或单天线端口传输（端口0）自适应。模式8：双流波束赋形（端口7和端口8）或单流波束赋形（端口7或端口8）与开环发射分集或单天线端口传输（端口0）自适应。A) SCOPE T

4、his document provides guidance for measurement of conducted output emissions of devices or composite systems that employ a transmitter with multiple outputs in the same band or multiple transmitters operating in the same band, with the outputs occupying the same or overlapping frequency ranges. It a

5、pplies to EMC compliance measurements on devices and systems (including hosts with multiple modular transmitters) that transmit on multiple antennas simultaneously in the same or overlapping frequency ranges through a coordinated process. Examples include, but are not limited to, devices and systems

6、 employing beamforming or multiple-input and multiple-output (MIMO.) This guidance applies to both licensed and unlicensed devices wherever the FCC rules call for conducted output measurements or where conducted output measurements are combined with directional antenna gain to demonstrate compliance

7、 with a radiated limit. Guidance is provided for in-band, out-of-band, and spurious emission measurements. KDB 662911工作在同一频段的多发设备处理方法，适用于如下测试项：带内发射带外发射杂散发射1. 传导输出设备独立设备多个输出多个设备多个输出2. 符合系统设备独立设备多个输出多个设备多个输出For devices having two outputs driving a cross-polarized pair of antennas, see Attachment 66291

8、1 D02 of this publication for additional guidance. 对于具有水平极化天线对的双输出设备，请参阅KDB 662911 D02以获取更多指导。备注：Cross-Polarization水平极化 一般与Co-Polarization垂直极化相对.极化是指在最大辐射方向上辐射电波的极化，其定义为在最大辐射方向上电场矢量端点运动的轨迹，由于天线本身物理结构等原因，天线辐射远场的电场矢量除了有所需要方向的运动外，还在其正交方向上存在分量，这就指的天线的交叉极化。B) PURPOSE This document addresses two issues as

9、sociated with conducted testing of emissions from transmitters with multiple outputs in the same band: 1) Summing emissions. 发射求和The FCCs emission limits apply to the total of emissions from all outputs of the transmitter or of composite system transmitters. Thus, emission measurements from the tran

10、smitter outputs must be summed before comparing measured emissions to the emission limit. FCC的发射限值适用于发射器或复合系统发射器的所有输出的发射总量。 因此，在将测量的发射与发射限制进行比较之前，必须对来自发射机输出的发射测量求和。 Accounting for array gain. 阵列增益计算Correlation between signals transmitted from different antennas can lead to array gain, which increase

11、s the directional gain of the device and leads to higher radiated levels in some directions. The contribution of array gain to the directional gain of the transmitter must be considered in rule parts where conducted in-band emission limits vary with directional gain, or in situations in which conduc

12、ted measurements are combined with directional antenna gain to determine compliance with in-band radiated limits. 根据不同天线发射的信号之间的相关性可以引出阵列增益，这增加了设备的定向增益并且导致在一些方向上的较高辐射水平。 在传导带内发射限制随着方向增益变化的规则部分中或者在传导测量与定向天线增益组合以确定符合带内发射限制的情况下，必须考虑阵列增益对发射机的定向增益的贡献 辐射极限。 These issues are unique to conducted emissions m

13、easurements. In most cases, radiated measurements automatically combine the power emitted from multiple outputs and include the effects of directional gain if the measurements are performed in the direction of maximum response of the transmitter.传导发射测量：需要计算定向增益辐射测量：不需要计算，因为辐射测试会自动组合从多个输出发射的功率，并且包括方向

14、增益的影响 C) LIMITATIONS This document provides guidance only with respect to summing of emission measurements from multiple outputs and performing directional gain computations. It makes no change in other aspects of measurements and compliance, such as the type of power or power spectral density measu

15、rement to be made (e.g., peak or average) or the methods for making those measurements (e.g., spectrum analyzer setup parameters). 这个文档只对多天线设备发射测量和定向增益计算，不涉及其他测试方法和设置方面D) DEFINITION Measure-and-sum technique. The conducted emission level (e.g., transmit power or power in specified bandwidth) is meas

16、ured at each antenna port. The measured results at the various antenna ports are then summed mathematically to determine the total emission level from the device. Summing is performed in units that are directly proportional to power (e.g., mW or microvolts-squarednot dBm or microvolts). 测量与求和技术。在每个天

17、线端口处测量传导发射功率（例如，指定带宽中的发射功率或功率）。 然后在各个天线端口处的测量结果在数学上求和以确定来自设备的总发射功率。 以与功率成正比的单位（例如，mW或微伏平方 - 不是dBm或微伏）执行求和。E) GUIDANCE FOR SUMMING EMISSION MEASUREMENTS FROM MULTIPLE OUTPUTS OF A TRANSMITTER OR FROM MULTIPLE TRANSMITTERS 发射器或多个发射器的多个输出的发射测量的指导Acceptable methodologies for summing emission measurement

18、s from multiple transmitter outputs depend on the type of emission measurement being performed. Three types of emission measurements are considered: in-band power measurements; in-band power spectral density measurements; and out-of-band and spurious emissions measurements. 考虑三种类型的发射测量：带内功率测量; 带内功率谱

19、密度测量; 带外和杂散发射测量。1) In-Band Power Measurements The measure-and-sum technique shall be used for measuring in-band transmit power of a device. Total power is the sum of the conducted power levels measured at the various output ports 总功率是在各个输出端口处测量的传导功率的总和2) In-Band Power Spectral Density (PSD) Measurem

20、ents When performing measurements for compliance with PSD limits within the band of operation of a transmitter, any of the three techniques below may be used to combine the emission measurements from multiple outputs prior to comparing to the emission limit. The first is the most accurate method. Th

21、e second and third techniques are offered as simpler alternatives, but they may lead to overestimates of the total PSD when emission levels differ between outputs; consequently, if measurements performed using methods b) or c) exceed the emission limit, the test lab may wish to retest using method a

22、) before declaring that the device fails the emission test. With any of the methods, existing rules and guidance shall be applied in performing the measurements on the individual outputs and in determining the maximum permitted PSD for the device. 当在发射器的操作频带内执行符合PSD限制的测量时，下面的三种技术中的任一种可以用于在与发射限度比较之前组

23、合来自多个输出的发射测量。 第一种是最准确的方法。第二和第三技术被提供为更简单的替代但是当输出之间的发射水平不同时，它们可能导致总PSD的过高估计; 因此，如果使用方法b）或c）进行的测量超过发射限值，则测试实验室可能希望在声明设备未通过发射测试之前使用方法a）重新测试。 使用任何方法，在执行各个输出的测量和确定设备的最大允许PSD时，应应用现有规则和指导。a) Measure and sum the spectra across the outputs. With this technique, spectra are measured at each output of the devic

24、e at the required resolution bandwidth. The individual spectra are then summed mathematically in linear power units. Unlike in-band power measurements, in which the sum involves a single measured value (output power) from each output, measurements for compliance with PSD limits involve summing entir

25、e spectra across corresponding frequency bins on the various outputs i.e., for a device with NANT transmitter outputs, if the spectrum measurements of the individual outputs are all performed with the same span and number of points, the spectrum value (in watts or milliwatts) in the first spectral b

26、in of output 1 is summed with that in the first spectral bin of output 2 and that from the first spectral bin of output 3, and so on up to the NANTth output to obtain the value for the first frequency bin of the summed spectrum. The summed spectrum value for each of the other frequency bins is compu

27、ted in the same way). 举个例子：对于具有N个发射机输出的设备，如果各个输出的频谱测量都使用相同的Span和扫描点数：测量出第1端口的第一段频谱图（以瓦特或毫瓦为单位）测量出第2端口的第一段频谱图测量出第3端口的第一段频谱图直到测量出第N端口的第一段频谱图, 以相同的方式计算每个端口第一段频谱图相加b) Measure and sum spectral maxima across the outputs. With this technique, spectra are measured at each output of the device at the require

28、d resolution bandwidth. The maximum value (peak) of each spectrum is determined. These maximum values are then summed mathematically in linear power units across the outputs. These operations shall be performed separately over frequency spans that have different out-of-band or spurious emission limi

29、ts计算最大值：在标准要求的RBW内，线性计算所有的输出端口的最大值的总和c) Measure and add 10 log(NANT) dB, where NANT is the number of outputs. With this technique, spectrum measurements are performed at each output of the device, but rather than summing the spectra or the spectral peaks across the outputs, the quantity 10 log(NANT)

30、 dB is added to each spectrum value before comparing to the emission limit. The addition of 10 log(NANT) dB serves to apportion the emission limit among the NANT outputs so that each output is permitted to contribute no more than 1/NANTth of the PSD limit specified in the rules. (Note that the 10 lo

31、g(NANT) term in this calculation is not related to that used in array gain calculations, to be discussed later in this document.) 在与发射限值比较之前，将10 log（N）dB的量加到每个端口的测试值上。将10log（N）dB分配到N跟发射输出天线上，每个输出允许的值不超过标准规定的PSD限值的1 / N。 （请注意，此计算中的10 log（N）项与阵列增益计算中使用的术语无关，本文档后面将对此进行讨论。）3) Out-of-Band and Spurious Em

32、ission Measurements a) Absolute Emission Limits （绝对限值）When performing measurements outside of the band of operation of a transmitter (i.e., out-of-band and spurious emissions), any of the three techniques below may be used to combine the emission measurements from multiple outputs prior to comparing

33、 to the emission limit. The first is the most accurate method. The second and third techniques are offered as simpler alternatives, but they may lead to overestimates of the total emission level when emission levels differ between outputs; consequently, if measurements performed using methods (ii) o

34、r (iii) exceed the emission limit, the test lab may wish to retest using method (i) before declaring that the device fails the emission test. With any of the methods, existing rules and guidance shall be applied in performing the measurements on the individual outputs and in determining the maximum

35、permitted emission level for the device. 当在发射机的操作频带外（即，带外和杂散发射）执行测量时以下三种技术中的任一种可用于在与发射限度比较之前组合来自多个输出的发射测量。第一种是最准确的方法。第二和第三技术被提供为更简单的替代法(i) Measure and sum the spectra across the outputs as described in sectionE)2)a). Note that the summation must be performed in linear power units, or the equivalent.

36、 For example, if measurement units are microvolts or microvolts/meter, the values shall be squared before summing, and then a square root shall be applied to the sum in order to achieve the equivalent of summing in power units. 如E）2）a）部分所述测量和求和输出的光谱。注意，求和必须以线性幂单位或等效量来执行。例如，如果测量单位是微伏或微伏/米，则在求和之前将该值平方

37、，然后对该和应用平方根，以便实现功率单位求和的等效值。为什么要先平方后开方呢,标准差的原理是什么?因为标准差只取正值,先平方后开放就能保证这一点.另外,也能说明方差与标准差的关系,习惯上就这样描述了.标准差 ,也称均方差是各数据偏离平均数的距离的平均数,它是离均差平方和平均后的方根,用表示.标准差是方差的算术平方根.标准差能反映一个数据集的离散程度.平均数相同的,标准差未必相同.(ii) Measure and sum spectral maxima across the outputs as described in sectionE)2)b). Note that the summatio

38、n must be performed in linear power units, or the equivalent. For example, if measurement units are microvolts or microvolts/meter, the values shall be squared before 测量和总和输出两端的频谱最大值。(iii) Measure and add 10 log(NANT) dB, where NANT is the number of outputs, as described in section E)2)c). 各加10 log(

39、N) dBb) Relative Limits 相对限值When testing out-of-band and spurious emissions against relative emission limits, tests may be performed on each output individually without summing or adding 10 log(NANT) if the measurements are made relative to the in-band emissions on the individual outputs.For example

40、, if a rule states that out-of-band emissions in a 100 kHz bandwidth must be at least 20dB below the 100 kHz bandwidth in-band that contains the highest power, compliance may be established by confirming that the maximum total out-of-band emission is at least 20 dB below the maximum total in-band PS

41、D, as determined by the “measure and sum the spectra” technique in both instances; alternatively, compliance may be demonstrated by confirming that the maximum out-of-band emission on each individual output is at least 20 dB below the maximum in-band PSD (in 100 kHz bandwidth) on that output. Simila

42、rly, if a rule states that out-of-band emissions in a 1MHz bandwidth must be at least X dB below the transmit power (where X does not vary with transmit power), compliance may be established by confirming that the maximum total out-of-band emission, as determined by the “measure and sum the spectra”

43、 technique, is at least X dB below the total transmit power; alternatively, compliance may be demonstrated by confirming that the maximum out-of-band emission on each individual output is at least X dB below the maximum transmit power on that output. Emission limits specified as X + 10 log(P) dB bel

44、ow the transmit power (where P is the transmit power) are absolute limits and are not considered “relative limits” for purposes of this guidance. Outof-band and spurious emissions must be tested against absolute limits using techniques described in section a) above. 当针对相对发射限制测试带外和杂散发射时，可以单独对每个输出执行测试

45、，而不求和或增加10个对数（N）如果测量是相对于单个输出上的带内发射进行的。例如，如果规则规定在100kHz带宽中的带外发射必须比包含最高功率的带内100kHz带宽低至少20dB，则可以通过确认最大总输出功率带外发射比最大总带内PSD低至少20 dB，如在这两种情况下通过“测量和求和频谱”技术所确定的;或者，可以通过确认每个单独输出上的最大带外发射比该输出上的最大带内PSD（在100kHz带宽中）低至少20dB来证明顺应性。类似地，如果规则规定1MHz带宽中的带外发射必须至少比发射功率低X dB（其中X不随发射功率而变化），则可以通过确认最大总输出 - 由“测量和总和频谱”技术确定的带外发射至

46、少比总发射功率低X dB;或者，可以通过确认每个单独输出上的最大带外发射比该输出上的最大发射功率低至少X dB来证明顺应性。指定为低于发射功率X + 10 log（P）dB的发射限值（其中P是发射功率）是绝对限值，为本指南的目的不被认为是“相对限值”。带外和杂散发射必须使用上述a）节中描述的技术针对绝对限制进行测试。F) GUIDANCE ON DIRECTIONAL GAIN CALCULATIONS 定向增益计算Some rule parts define a limit on output power or power spectral density that is a functio

47、n of the directional gain of the antenna system. There may also be cases in which conducted measurements are combined with directional antenna gain to determine compliance with radiated limits. In such cases, the effect of array gain must be included in the calculation of overall directional antenna

48、 gain for devices that transmit on multiple outputs simultaneously in the same band, in the same or in overlapping frequency ranges. 有一些标准会定义：天线系统的定向增益的函数的输出功率或功率谱密度的限制。 还可能存在其中进行的测量与定向天线增益组合以确定与辐射限制的符合性的情况。在这种情况下，阵列增益的影响必须包括在针对在相同频带中，在相同或重叠的频率范围中同时在多个输出上发射的设备的总定向天线增益的计算中。 Array gain results when th

49、e signals transmitted on different antennas are positively correlated when viewed from a specific direction. In most cases, beamforming systems attempt to achieve 100 percent correlation between the transmitted signals when viewed from the intended beam direction, though actual correlation may be sl

50、ightly lower. A transmitter that transmits correlated signals from its multiple antennas has the potential to create array gain even when that is not the intent. 当从特定方向观看时，在不同天线上发射的信号是正相关的时，得到阵列增益。在大多数情况下，当从预期波束方向观察时，波束成形系统尝试实现发射信号之间的100相关，但实际相关可能略低。从其多个天线发射相关信号的发射机具有产生阵列增益的潜力，即使这不是意图。For simplicity

51、, the guidance presented here categorizes transmissions as correlated (i.e., correlation exists between the signals on at least two antennas) or completely uncorrelated. Unless the transmitted signals are categorized as completely uncorrelated based on the guidance provided below, the signals must b

52、e considered correlated for the purposes of computing directional gain. In the case of correlated signals, array gain will be computed based on 100 percent correlation even if the actual correlation is lower except in certain cases involving cyclic delay diversity or multiple spatial streams. 为了简单起见

53、，这里给出的指导将传输分类为相关的（即，在至少两个天线上的信号之间存在相关）或完全不相关。除非基于以下提供的指导，所发送的信号被分类为完全不相关的，否则为了计算定向增益的目的，信号必须被认为是相关的。在相关信号的情况下，将基于100相关性来计算阵列增益，即使实际相关性较低，除了在涉及循环延迟分集或多个空间流的某些情况下。1) Categorization as Correlated or Completely Uncorrelated分类：相关或完全不相关For the purposes of this guidance, transmitter output signals are cons

54、idered correlated if any of the following are true: 以下情况被视为是相关性的 The same digital data are transmitted from two or more antennas in a given symbol period, even with different coding or phase shifts; Correlation between two transmitted signals exists at any frequency and time delay; or, Multiple tran

55、smitter outputs serve to focus energy in a given direction or to a given receiver; The operating mode combines correlated techniques with uncorrelated techniques. 在给定符号周期中，即使具有不同的编码或相移，从两个或更多个天线发送相同的数字数据;两个发射信号之间的相关性存在于任何频率和时间延迟; 或者多个发射器输出用于在给定方向或给定接收器聚焦能量;操作模式将相关技术与不相关技术相结合。Otherwise, the output si

56、gnals are considered completely uncorrelated. 否则就是无相关性的产品Correlated signals include, but are not limited to, signals transmitted in any of the following modes: 以下产品均为相关性的 Any transmit beamforming mode, whether fixed or adaptive (e.g., phased array modes, closed loop MIMO modes, Transmitter Adaptive

57、Antenna modes, Maximum Ratio Transmission (MRT) modes, and Statistical Eigen Beamforming (EBF) modes). beamforming 模式 Cyclic Delay Diversity (CDD) modes, also known as Cyclic Shift Diversity (CSD) (including modes for 802.11n and later devices to communicate with legacy 802.11 devices). In CDD modes

58、, the same digital data is carried by each transmit antenna, but with different cyclic delays. The signals are highly correlated at any one frequency, though not necessarily at zero time delay. In particular, correlations tend to be high over the bandwidths specified for in-band PSD measurements in FCC rule parts that requi