WLAN 802.11 a/b/g PHY Specification and EDVT Measurement V

本文详细介绍了无线接收器在不同标准下(如IEEE 802.11b, 802.11a, 802.11g)的性能测试方法,包括最小输入电平、邻道抑制比(ACR)、非邻道抑制比(NACR)等关键指标的测试条件和流程。同时,提供了具体测试设备配置和环境设置,以及信号源、干扰源和接收器之间的功率校准方法。

Receive Minimum Input Level (Sensitivity)

测试方法:

 


Receiver Adjacent Channel Rejection (ACR)

-For IEEE802.11b 18.4.8.3 (11Mbps), For 802.11b 15.4.8.3 (2Mbps)
For 2Mbps, 8% PER Maximum of DUT, where –74dBm Input Power from Golden Unit at ideal frequency and -39dBm Power from Adjacent Channel Interface at 25Mhz away from the Ideal frequency with PSDU length 1024Bytes and 2Mbps Transmit Rate
For 11Mbps, 8% PER Maximum of DUT, where –70dBm Input Power from Golden Unit at Ideal frequency and -35dBm Power from Adjacent Channel Interface at  25Mhz away from the ideal frequency with PSDU length 1024Bytes and 11Mbps Transmit Rate
ACR (dBm) = Minimum Power at DUT Input from Modulated Interference (dBm) - Power at DUT Input from Golden Unit (dBm)
Signal from Golden and Modulated Interference is unsynchronized

For IEEE802.11a 17.3.10.2 (OFDM), For 802.11g 19.5.2 (OFDM)
For 802.11a, 10% PER Maximum of DUT, where Input Power (shown in the following table) from Golden Unit at ideal frequency and the Power from Modulated Adjacent Channel Interface (shown in the following table) 20MHz away from the ideal frequency with PSDU length 1000Bytes
For 802.11g, 10% PER Maximum of DUT, where Input Power (shown in the following table) from Golden Unit at ideal frequency and the Power from Modulated Adjacent Channel Interface (shown in the following table) at 25MHz away from the ideal frequency with PSDU length 1000Bytes
ACR (dBm) = Minimum Power at DUT Input from Modulated Interference (dBm) - Power at DUT Input from Golden Unit (dBm)
Signal from Golden and OFDM Modulated Interference is unsynchronized

 

 


Receiver Non-Adjacent Channel Rejection (NACR)

+40MhZ

 


Conductive Throughput Test

Test Condition
-Test Environment
ex DUT and AP in different shielding room or box
-Test AP
Brand : ex Netgear, Model : ex FWAG114
-Wired AP PC
Model : Dell D500, CPU Pentium 4 1.2GHz, RAM 512MB, OS Windows 2000 SP4
-Ethernet Card in Wired AP PC
Model : ex Intel(R) PRO/100 VE Network Connection
-Test Client
Project Number ex T60H881 ,
Description, ex Intel PCI 11b/g WLAN Card, Sample number 19
ECN ex Delete C869=0.5pF, Add C855 = 0.75pF and Change R68 = 121 ohm
-Test NDSI Driver of Client
Version ex 1.0.0.38 (5/13/04), TIC ex 84423
Microsoft 0 configuration
-Wireless Client PC
Model : ex HP D220m/P2, CPU : ex Pentium 4 2.6GHz , RAM : ex 256MB, OS Windows XP Professional SP1


-Test Utility
Ex Chariot Console version 4.0 Build level 850 and Endpoint version 4.0)
File Size : ex 100Kbytes
Test Time : ex 1 min

Power Calibration Condition
-Spectrum Analyzer
SA Setting, RBW = 100K, VBW =30K, Sweep=500ms, RMS Detector, MAX Hold
-Protocol Tools
Intersil LAN Evaluation,
PER Test (Broadcasting, Packet Size= 10K)
-Calibration Result :
ex 5dBm at DUT input port from SA while no attenuator set from HP 8494B/5B while LAN evaluation is running
Rx Conductive Throughput and TX Conductive Throughput
-TX Throughput share the same attenuation setting as RX, just for reference

Average RX Throughput
Around 20Mbps for 11g from (from -20dBm to –70dBm)
Around 5Mbps for 11b from (from -10dBm to –80dBm); 6Mpcs for Cisco 350 AP
Relative Precision
Normal (< 5), Warning (5~10), Danger (>10)

 

转载于:https://www.cnblogs.com/huangbaobaoi/p/10273455.html

### 802.11n 协议基础知识 #### 基本概念 IEEE 802.11n 是一种无线局域网(WLAN)标准,旨在显著提升数据传输速率和覆盖范围。该标准由 IEEE Task Group n (TGn) 制定,目标是通过改进物理层(PHY)和媒体访问控制层(MAC),实现更高的吞吐量和支持多输入多输出(MIMO)技术[^2]。 #### 工作原理 802.11n 的核心技术依赖于 MIMO 和正交频分复用(OFDM)。以下是其主要工作机制: - **MIMO 技术**:利用多个天线发送和接收信号,从而增加链路容量并减少干扰。这种技术允许多条独立的数据流在同一频率上传输,极大地提高了带宽利用率[^4]。 - **OFDM 调制**:将信道划分为若干子载波,每个子载波承载一部分数据。这种方法可以有效对抗多径效应,并提高频谱效率[^3]。 - **高级调制方案**:802.11n 支持更高阶的 QAM(如 64-QAM 或 256-QAM),这使得每单位时间内的比特数更多,进而提升了整体传输速度。 #### 技术特点 1. **高吞吐量**:相比之前的 WLAN 标准(如 802.11a/b/g),802.11n 可以达到高达 600 Mbps 的理论最大传输速率(在四根空间流的情况下)。这一性能得益于更高效的编码方式和更大的带宽支持。 2. **向后兼容性**:为了确保现有设备能够无缝迁移到新网络环境,802.11n 设计了兼容模式,允许旧版客户端(如 802.11a/b/g 用户)接入新型 AP(接入点)[^1]。 3. **增强型 MAC 层功能**:引入帧聚合技术和块确认机制,减少了开销并加快了数据交换过程。这些特性有助于降低延迟并改善实时应用的表现,比如 VoIP 或视频会议服务。 4. **双频操作能力**:支持 2.4 GHz 和 5 GHz 频段的同时运行,提供了更多的可用频道选项,降低了拥塞风险。 ```python def calculate_max_throughput(num_streams, channel_width, modulation_scheme='64-QAM'): """ 计算给定条件下802.11n的最大理论吞吐量 参数: num_streams (int): 空间流数量 channel_width (float): 通道宽度(MHz) modulation_scheme (str): 调制方式,默认为'64-QAM' 返回: float: 最大理论吞吐量(Mbps) """ base_rate = { 'BPSK': 6, 'QPSK': 12, '16-QAM': 24, '64-QAM': 54, '256-QAM': 108 } coding_efficiency = {'64-QAM': 5/6} # 示例取值 max_phy_rate_per_stream = base_rate.get(modulation_scheme, 54) * \ (channel_width / 20) * list(coding_efficiency.values())[0] total_max_throughput = max_phy_rate_per_stream * num_streams return round(total_max_throughput) # 示例计算四个空间流下使用64-QAM调制时的最大吞吐量 print(f"Max Throughput with 4 streams and 64-QAM: {calculate_max_throughput(4, 40)} Mbps") ```
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