IEEE 802.11n标准：提升无线网络传输速度

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"IEEE 802.11n 是一个重要的无线网络标准，旨在显著提升无线局域网（WLAN）的数据传输速率。该标准由电气和电子工程师协会（IEEE）制定，其目标是通过引入多项技术改进，如多输入多输出（MIMO）天线技术和频道绑定，实现高达600Mbps的理论最大速度，实际应用中通常可达到几十兆比特每秒的速率。此标准在2009年被正式采纳，是802.11系列标准中的一个重要里程碑，为家庭、办公室和公共场所的高速无线连接奠定了基础。" 详细内容: IEEE 802.11n 是802.11标准家族中的一员，它的主要目的是提升无线网络的性能和效率，特别是在传输速率方面。在802.11a/b/g等早期标准之后，802.11n的出现极大地提高了无线网络的速度，使其可以与有线网络相媲美。 1. **多输入多输出（MIMO）技术**：这是802.11n的一个关键特性，它使用多个天线同时发送和接收数据，通过空间多重载波和分集技术提高信号质量和吞吐量。MIMO能够利用反射和散射来创建多个独立的数据流，从而显著提高无线连接的带宽。 2. **频道绑定**：802.11n支持40MHz的频道宽度，比传统的20MHz翻了一倍。这允许更多的数据在同一时间内传输，进一步提升了数据传输速率。 3. **帧聚合**：802.11n引入了帧聚合功能，将多个较小的数据包组合成一个大帧进行传输，减少了协议开销，提高了传输效率。 4. **高级编码技术**：使用更高效的编码方式，如高阶调制（例如64-QAM），在相同的时间内可以传输更多的数据位。 5. **兼容性与向后兼容**：802.11n标准设计时考虑了与前代标准的兼容性，比如802.11a/b/g，这意味着802.11n设备可以在旧的标准下工作，但速度会降级到较低的标准支持的最大速率。 6. **应用范围**：802.11n的高速率使得高清视频流媒体、在线游戏和其他对带宽要求较高的应用成为可能，不仅适用于家庭环境，也广泛应用于企业网络和公共Wi-Fi热点。 7. **物理层（PHY）和介质访问控制（MAC）层的改进**：除了物理层的增强，802.11n也对MAC层进行了优化，以提高网络的并发性能和整体效率。 IEEE 802.11n标准的实施极大地推动了无线通信技术的发展，为现代无线网络提供了坚实的基础，也为后来的802.11ac和802.11ax等更高速度的标准铺平了道路。

IEEE

P802.11n/D1.04 September 2006

This is an unapproved IEEE Standards Draft, subject to change.

Figures

Figure 18—MAC frame format..................................................................................................................... 10

Figure n1—HT Control field ......................................................................................................................... 13

Figure n2—Link Adaptation Control field .................................................................................................... 13

Figure n4—ASELC subfield ......................................................................................................................... 14

Figure n3—MAI field.................................................................................................................................... 14

Figure n5—Block Ack Starting Sequence Control field ............................................................................... 20

Figure n6—BAR Information field (MTBAR) ............................................................................................. 21

Figure n7—Per TID Info field ....................................................................................................................... 21

Figure 33—BlockAck frame ......................................................................................................................... 21

Figure 34—BA Control field......................................................................................................................... 22

Figure n8—BA Information field (BlockAck) .............................................................................................. 23

Figure n9—BA Information field (Compressed BlockAck) ......................................................................... 24

Figure n10—BA Information field (MTBA)................................................................................................. 25

Figure n11—A-MSDU structure ................................................................................................................... 26

Figure n12—A-MSDU Subframe structure................................................................................................... 26

Figure n13—QoS Null envelope carrying Management Action Body.......................................................... 27

Figure n14—Secondary Channel Offset element format ..............................................................................31

Figure n15—HT Capabilities element format. .............................................................................................. 32

Figure n16—HT Capabilities Info field......................................................................................................... 33

Figure n18—Supported MCS Set field.......................................................................................................... 35

Figure n17—A-MPDU Parameters field ....................................................................................................... 35

Figure n19—HT Extended Capabilities field ................................................................................................ 36

Figure n20—TxBF Capability field............................................................................................................... 37

Figure n21—Antenna Selection Capability field........................................................................................... 39

Figure n22—HT Information element format ............................................................................................... 40

Figure n23—PSMP Parameter Set format..................................................................................................... 46

Figure n24—STA Info field format............................................................................................................... 47

Figure n25—Transmit Beamforming Control field....................................................................................... 48

Figure n26—Complex coefficient representation.......................................................................................... 49

Figure n27—Encoding of MIMO Channel Measurement Report (40 MHz) ................................................ 50

Figure n28—Encoding of MIMO Channel Measurement Report (20 MHz) ................................................ 50

Figure n29—Encoding of the Reciprocity Correction Vector (40 MHz)...................................................... 51

Figure n30—Encoding of the Reciprocity Correction Vector (20 MHz)...................................................... 51

Figure n31—CSI Matrices Control field ....................................................................................................... 52

Figure n32—A-MPDU format....................................................................................................................... 62

Figure n33—A-MPDU subframe format....................................................................................................... 63

Figure n34—A-MPDU parsing ..................................................................................................................... 64

Figure n35—HT-immediate BlockAck architecture ..................................................................................... 79

Figure n36—Basic Concept of L-SIG TXOP Protection .............................................................................. 92

Figure n37—Example of L-SIG Duration Setting......................................................................................... 94

Figure n38—Example of LongNAV operation with implicit Block Ack request ......................................... 97

Figure n39—Example of TXOP truncation................................................................................................... 98

Figure n40—Example of RD exchange sequence showing response burst................................................... 99

Figure n41—PSMP sequence ...................................................................................................................... 102

Figure n42—Different Service Intervals of different STAs ........................................................................102

Figure n43—Multiple RA packet transmission with RIFS or SIFS ............................................................ 103

Figure n44—Multi-phase PSMP showing additional resource allocation................................................... 105

Figure n45—Multi-Phase PSMP showing retransmission as well as additional resource allocation ......... 106

Figure n46—Frame exchange sequence for transmit beamforming with implicit feedback....................... 111

Figure n47—Calibration procedure ............................................................................................................. 113

Figure n48—Frame exchange for transmit beamforming with explicit feedback....................................... 115

IEEE

P802.11n/D1.04 September 2006

xvii

This is an unapproved IEEE Standards Draft, subject to change.

Figure n49—Frame exchange sequence of transmit antenna selection....................................................... 117

Figure n50—Frame exchange sequence of receive antenna selection......................................................... 118

Figure n49—Phased Coexistence Operation ............................................................................................... 144

Figure n50—PLCP packet format ............................................................................................................... 158

Figure n51—Transmitter block diagram ..................................................................................................... 160

Figure n52—Timing boundaries for PPDU fields ....................................................................................... 166

Figure n53—Non-HT SIGNAL field .......................................................................................................... 173

Figure n54—Format of HT-SIG1 and HT-SIG2 ......................................................................................... 177

Figure n55—Data tone constellations in the non-HT SIGNAL field (L-SIG) and the HT SIGNAL field (HT-

SIG) in an HT mixed mode PPDU .............................................................................................................. 179

Figure n56—HT-SIG CRC calculation ....................................................................................................... 179

Figure n57—Generation of Data HT-LTFs ................................................................................................. 183

Figure n58—Generation of the Extension HT-LTFs................................................................................... 184

Figure n59—Puncturing at rate 5/6 ............................................................................................................. 191

Figure n60—Examples of cyclic-permutation matrices with Z=8. The matrix Pi is produced by cyclically

shifting the columns of the identity matrix to the right by i places. ............................................................ 193

Figure n61—LDPC PPDU encoding padding and puncturing of a single codeword ................................. 195

Figure n62—The beamforming MIMO channel model .............................................................................. 209

Figure n63—Example of an NDP used for sounding ..................................................................................214

Figure n64—Transmit spectral mask for 20 MHz transmission.................................................................. 217

Figure n65—Transmit spectral mask for a 40 MHz channel....................................................................... 218

Figure n66—Packet alignment example (Greenfield packet with short GI) ............................................... 219

Figure n67—PLCP transmit procedure (HT Mixed Mode packet format) ................................................. 225

Figure n68—PLCP transmit procedure (Greenfield packet format)............................................................ 225

Figure n69—PLCP transmit state machine ................................................................................................. 226

Figure n70—PLCP receive procedure for HT Mixed Mode PLCP format ................................................. 228

Figure n71—PLCP receive procedure for Greenfield format PLCP........................................................... 228

Figure n72—PLCP receive state machine ................................................................................................... 229

Figure n73—PMD layer reference model ................................................................................................... 237

IEEE

P802.11n/D1.04 September 2006

This is an unapproved IEEE Standards Draft, subject to change.

Tables

Table 4—QoS Control Ffield ........................................................................................................................ 11

Table n3—Link Adaptation Control subfields .............................................................................................. 13

Table n4—Subfields of the MAI field........................................................................................................... 14

Table n7—Feedback Request values............................................................................................................. 15

Table n5—The ASEL Command and ASEL Data parts of the ASELC subfield.......................................... 15

Table n6—Calibration Control subfields....................................................................................................... 15

Table n9—NDP Announcement values......................................................................................................... 16

Table n10—AC Constraint values................................................................................................................. 16

Table n8—CSI/Steering values ..................................................................................................................... 16

Table n11—RDG/More PPDU values........................................................................................................... 17

Table n12—BAR Ack Policy / BA Ack Policy fields for HT-delayed BlockAck........................................ 19

Table n13—BlockAckReq frame variant encoding....................................................................................... 19

Table n14—BlockAck frame variant encoding ............................................................................................. 22

Table n15—Address fields for unicast MPDU containing A-MSDU ........................................................... 26

Table 39—Access Policy Subfield ................................................................................................................ 32

Table n16—Subfields of the HT Capabilities Info field................................................................................ 33

Table n17—Subfields of the A-MPDU Parameters field ..............................................................................35

Table n18—Subfields of the HT Extended Capabilities field .......................................................................36

Table n19—Subfields of the TxBF Capability Field..................................................................................... 37

Table n20—Subfields of the Antenna Selection Capability Field................................................................. 40

Table n21—HT Information element ............................................................................................................ 41

Table n22—HT Action field values............................................................................................................... 44

Table n23—Notify Channel Width................................................................................................................ 45

Table n24—SM Power Save.......................................................................................................................... 45

Table n26—Format of the PSMP Management Action field ........................................................................ 46

Table n25—Set PCO Phase ........................................................................................................................... 46

Table n27—MIMO Channel Measurement................................................................................................... 48

Table n28—Use of transmit beamforming control fields (MIMO Channel measurement) .......................... 49

Table n29—Reciprocity Correction............................................................................................................... 50

Table n30—Use of transmit beamforming control fields (Reciprocity Correction)...................................... 51

Table n31—MIMO CSI Matrices.................................................................................................................. 52

Table n32—Use of CSI Matrices Control field (MIMO CSI Matrices frame).............................................. 53

Table n33—Explicit Feedback Format field for CSI Matrix Feedback ........................................................ 53

Table n34—Matrix coding............................................................................................................................. 54

Table n35—CSI Matrices Report for 20 MHz .............................................................................................. 54

Table n36—CSI Matrices Report for 40 MHz .............................................................................................. 55

Table n37—Number of matrices (MIMO CSI Matrices) .............................................................................. 55

Table n38—MIMO Non-compressed Steering.............................................................................................. 55

Table n39—Use of CSI Matrices control field (MIMO Non-compressed Steering)..................................... 56

Table n40—Explicit Feedback Format Field for MIMO Non-compressed Steering .................................... 56

Table n42—Non-compressed Steering Matrices Report for 20 MHz ........................................................... 57

Table n41—V Matrix coding (MIMO Non-compressed Steering) ............................................................... 57

Table n43—Non-compressed Steering Matrices Report for 40 MHz ........................................................... 58

Table n44—Number of matrices (MIMO Non-compressed Steering) .......................................................... 58

Table n45—MIMO Compressed Steering..................................................................................................... 59

Table n46—Use of CSI Matrices Control fields (MIMO Compressed Steering) ......................................... 59

Table n48—Order of angles in the Quantized Steering Matrices Feedback Information field..................... 60

Table n47—Explicit Feedback Format field (MIMO Compressed Steering) ............................................... 60

Table n49—Antenna Selection Indices Feedback ......................................................................................... 62

Table n50— MPDU Delimiter fields............................................................................................................. 63

Table n51—A-MPDU contents using HT-immediate BlockAck.................................................................. 65

IEEE

P802.11n/D1.04 September 2006

xix

This is an unapproved IEEE Standards Draft, subject to change.

Table n52—A-MPDU contents using HT-delayed BlockAck ...................................................................... 65

Table n53—A-MPDU contents MPDUs using MTBA/PSMP...................................................................... 66

Table n54—Dual CTS rules .......................................................................................................................... 70

Table n55—Non-HT reference rate ............................................................................................................... 74

Table 76—Attributes applicable to frame exchange sequence definition ..................................................... 84

Table n56—TxBF support required with implicit feedback........................................................................ 111

Table n57—Response frame format in 20/40 MHz BSS ............................................................................ 120

Table n58—TSPEC contained PSMP scheduling parameters..................................................................... 135

Table n59—TSPEC contained PSMP reservation parameters ................................................................... 136

Table n60—AP Mode definitions................................................................................................................ 140

Table n61—Operating modes according to band and BSS capability......................................................... 141

Table n62—STA operation according to BSS capability and STA width capability.................................. 142

Table n63—TXVECTOR parameters ........................................................................................................ 150

Table n64—RXVECTOR parameters ......................................................................................................... 154

Table n65—Timing related constants.......................................................................................................... 164

Table n66—Frequently used parameters ..................................................................................................... 165

Table n67—Number of tones in each HT PLCP field.................................................................................168

Table n68—Cyclic shift for non-HT portion of the packet .........................................................................171

Table n69—Generation of the Non-HT SIGNAL field............................................................................... 174

Table n70—Cyclic shift values of HT portion of the packet.......................................................................175

Table n71—Fields of HT SIGNAL field..................................................................................................... 176

Table n72—Modulation of the HT SIGNAL field in an HT Mixed Mode packet...................................... 178

Table n73—Determining the number of space time streams ...................................................................... 182

Table n74—Number of DLTFs required for data space-time streams ........................................................ 182

Table n75—Number of ELTFs required for extension spatial streams....................................................... 182

Table n76—LDPC parameters..................................................................................................................... 192

Table n77—PPDU encoding parameters..................................................................................................... 194

Table n78—Number of rows and columns in the interleaver...................................................................... 197

Table n79—Constellation mapper output to spatial mapper input for STBC ............................................. 200

Table n80—pilot values for 20 MHz transmission...................................................................................... 201

Table n81—Pilots values for 40 MHz transmission.................................................................................... 201

Table n83—40 MHz channel allocation in the 5 GHz band ....................................................................... 216

Table n82—40 MHz channel allocation in the 2.4 GHz band..................................................................... 216

Table n84—Allowed relative constellation error versus constellation size and code rate .......................... 220

Table n85—Receiver minimum input level sensitivity ............................................................................... 222

Table n86—HT PHY MIB attributes........................................................................................................... 230

Table n87—MIMO PHY characteristics ..................................................................................................... 236

Table n88—PMD_SAP peer-to-peer service primitives ............................................................................. 238

Table n89—PMD_SAP sublayer-to-sublayer service primitives................................................................ 238

Table n90—List of parameters for the PMD primitives.............................................................................. 239

Table n91—Symbols used in rate dependent parameter tables ................................................................... 249

Table n92—Rate dependent parameters for mandatory 20 MHz, NSS =1 modes, NES = 1 ...................... 249

Table n93—Rate-dependent parameters for optional 20 MHz, NSS = 2 modes, N

= 1.......................... 250

Table n94—Rate-dependent parameters for optional 20 MHz, NSS = 3 modes, N

= 1.......................... 250

Table n95—Rate-dependent parameters for optional 20 MHz, NSS = 4 modes, N

= 1.......................... 251

Table n96—Rate-dependent parameters for optional 40 MHz, NSS = 1 modes, N

= 1.......................... 251

Table n97—Rate-dependent parameters for optional 40 MHz, NSS = 2 modes, N

= 1.......................... 252

Table n98—Rate-dependent parameters for optional 40 MHz, NSS = 3 modes......................................... 252

Table n99—Rate-dependent parameters for optional 40 MHz, NSS = 4 modes......................................... 253

Table n100—Rate-dependent parameters for optional 40 MHz HT duplicate mode, NSS = 1, NES = 1 .. 253

Table n101—Rate-dependent parameters for optional 20 MHz, NSS = 2 modes, NES = 1....................... 253

Table n102—Rate dependent parameters for optional 20 MHz, NSS = 3 modes, N

= 1 ........................ 254

Table n103—Rate-dependent parameters for optional 20 MHz, NSS = 4 modes, N

= 1 ....................... 255

Table n104—Rate-dependent parameters for optional 40 MHz, NSS = 2 modes, NES = 1....................... 256

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