WLAN IEEE 802.11ac Wide bandwidth high speed 802.11ac technology and testing Hagen Heggenberger Regional Manager Customer Solutions Wireless Terminals
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WLAN IEEE 802.11ac
Wide bandwidth high speed 802.11ac technology and testing
Hagen HeggenbergerRegional Manager Customer Solutions Wireless Terminals
November 2012 | 802.11ac | 2
Agenda
l What is behind WLAN IEEE 802.11ac
l What has to be measured (Transmiter Specification)
l Market View
l Rohe&Schwarz testing solution
November 2012 | 802.11ac | 3
Facts about WLAN 802.11ac
l Backwards compatible to 802.11a and 802.11n and coexistence with11a and 11n
l Frequency band: 5 GHzl RF bandwidths: 20 MHz, 40 MHz, 80 MHz and 160 MHzl Modulation types: BPSK, QPSK, 16QAM, 64QAM, 256QAMl MIMO antenna support: 2x2, 4x4, 8x8
(new, compared to 802.11n)
à Check out the R&S technology introduction white paper 1MA192 (written by Lisa Ward)
November 2012 | 802.11ac | 4
Facts about WLAN 802.11ac – OFDM
l OFDM Subcarriers
l Subcarrier Rotation reduces Peak to Average Power RatioPAPR
-122 to -2 and 2 to 122, 16 Pilots256 per 80MHz Chan80+80
-250 to-130, -126 to -6,6 to 126 and 130 to 250, 16 Pilots
512160-122 to -2 and 2 to 122, 8 Pilots25680-58 to -2 and 2 to 58, 6 Pilots12840-28 to -1 and 1 to 28, 4 Pilots6420Subcarriers Transmitting SignalNumber of SubcarriersBandwidth (MHz)
Same as 80MHzSame as 80 MHz80+80180 degrees (-1)-192 to -1 and ≥64160180 degrees (-1)≥-648090 degrees (j)≥040
N/A20Rotation ValueRotated SubcarriersBandwidth
(MHz)
November 2012 | 802.11ac | 5
Facts about WLAN 802.11ac – Channelization
l Support of 20, 40, 80 MHz, 160 MHz channel bandwidth l The 80MHz channel will consist of two adjacent, non-overlapping
40MHz channels. l The 160MHz channels will be formed by two 80MHz channels
l adjacent (contiguous)l non-contiguous
l Europe, Japan and Global Operating Class Channel Allocation
140
136
132
128
124
120
116
112
108
104
100
6460565248444036IEEE channel #20 MHz40 MHz80 MHz
5170MHz
5330MHz
5490MHz
5710MHz
160 MHz
November 2012 | 802.11ac | 6
Facts about WLAN 802.11ac – Frame Format
l All 802.11 devices (L= Legacy) to synchronize to the signall L-STF (Short Training Field)l L-LTF (Long Training Field)l L-SIG (Signal).
l New for 802.11ac: VHT (Very High Throughput.)l VHT-SIG-A field contains two OFDM symbols (BPSK, 90° rotated BPSK)l VHT-STF l VHT-LTFs.’. l The VHT-SIG-B is the last field in the preamble
VHT auto-detection
November 2012 | 802.11ac | 7
Facts about WLAN 802.11ac –Modulation and Coding Schemes
l 802.11ac will use the 802.11n modulation, interleaving and coding architecture.
l 802.11ac adds an optional 256 QAM
5/6256-QAM93/4256-QAM85/664-QAM73/464-QAM62/364-QAM53/416-QAM41/216-QAM33/4QPSK21/2QPSK11/2BPSK0
Coding RateModulationMCS
November 2012 | 802.11ac | 8
XLow Density Parity Check (LDPC)XSpace Time Block Coding (STBC)X400 ns short guard intervalXMulti-User MIMO (MU-MIMO)X2 to 8 spatial streamsX80+80 MHz, 160 MHz channelsX256QAM
XBPSK, QPSK, 16QAM, 64QAMX1 spatial streamX20 MHz, 40 MHz, 80 MHz channels
OptionalMandatoryProperties
Peak Data Rate ~293 Mbps ~3.5 Gbps
Facts about WLAN 802.11ac – Optional/Mandatory
November 2012 | 802.11ac | 9
Facts about WLAN 802.11ac –Calculation of Data Rate
l Mandatoryl 242 carrier – 8 pilot carriers = 234 carriersl Sample Frequency 80 MHzl Guard Interval 800 nsl FFT 256 l MCS7, 64 QAM (6 bits), Coding 5/6l Symbol time: 256/80 MHz + 800 ns = 4 µsl Number of bits 6 x 234 x 5/6 = 1170 bits/symboll Maximum data rate: 1170 bits/symbol / 4 µs /symbol =l 292.5 Mbit/s
November 2012 | 802.11ac | 10
Facts about WLAN 802.11ac –Transmiter Specifications
l Spectral Mask for 20, 40, 80 and 160 MHz Channels
240 MHz160 MHz81 MHz79 MHz160 MHz120 MHz80 MHz41 MHz39 MHz80 MHz60 MHz40 MHz21 MHz19 MHz40 MHz30 MHz20 MHz11 MHz9 MHz20 MHz
DCBAChannel Size
November 2012 | 802.11ac | 11
Facts about WLAN 802.11ac –Transmiter Specifications
l 80 + 80 MHz Non Contiguous Channel Mask When the 80 MHz Channels Center Frequencies are separated by 160 MHz
November 2012 | 802.11ac | 12
Facts about WLAN 802.11ac – Market View
l Chips are planned by end of this year and beginning of next year
l First wave of chips will support:l 80 MHz bandwidthl 256 QAM support expectedl MIMO support plans vary for customers
– Some start with 2x2, some plan 3x3 initially l Some plan MU-MIMO initially with 2 streams for 2 users
l Next wave will support 160 MHzl Planned for end of this year to mid of next yearl Some indicating plans for 4x4 MIMO
November 2012 | 802.11ac | 13
Signal GeneratorsIEEE 802.11ac
l Support for all mandatory physical layer modesl 80 MHz, 80+80 MHz, 160 MHz
l For 80 MHz a SMBV100A can be usedl For 80+80 MHz two SMBV100A with an external coupler can be usedl For 160 MHz and 80+80 MHz the SGS100A and AFQ100A are ideal
l Combination of SGS100A and AFQ100A provides excellent EVM performance of -47 dBc
November 2012 | 802.11ac | 14
R&S Signal Generator SolutionSignal Generator Setup
Instrument: SMBV100AAFQ + SGS or SMBV
802.11ac bandwidth: 80 MHz + 80 MHzMode: contiguous
Instrument: SMBV100A802.11ac bandwidth: 80 MHz + 80 MHzMode: non-contiguous
Instrument: AFQ + SGS or SMBV802.11ac bandwidth: 160 MHz Mode: contiguous
November 2012 | 802.11ac | 15
R&S Signal Generator SolutionFeatures of –K86 and –K286
l Support for all mandatory physical layer modes (VHT Preambles, Signal Fields, …)
l Very High Throughput (VHT) frames with 20, 40 and 80 MHz transmission bandwidth
l Frame Block Sequencer for alternating legacy (11a/b/g), 11n or 11ac frames within one ARB waveform
l Binary Convolutional Coding (BCC)
l Space Time Block Coding
l Cyclic Shift Diversity (CSD)
l MIMO modes with 4 transmit antennasl BPSK, QPSK, 16-QAM, 64-QAM and 256QAM modulation
Additional features supported since October 2011
l 80+80 MHz and 160 MHz modes
l MIMO modes with up to 8 transmit antennasl Multi-user (MU)-MIMO modes
November 2012 | 802.11ac | 16
Signal Analysis with Signal Analyzers
Max. bandwidth 80 MHz
Max. bandwidth 160 MHz
R&S FSQ
R&S FSW
November 2012 | 802.11ac | 17
WLAN 802.11ac Analysis with R&S FSWResults available
l Result list EVM, IQ offset etcl Power versus time l Magnitude capturel EVM versus symbol & EVM versus carrierl Spectrum & spectrum masksl ACPl FFT spectruml Spectrum flatness & group delayl Constellation diagram & constellation versus carrierl Signal content and statistics, signal field, bit stream
NASM 2012 17
November 2012 | 802.11ac | 18
l Spectral Mask for 20, 40, 80 and 160 MHz Channels
WLAN 802.11ac Analysis with R&S FSWTransmiter Specifications – Spectrum Measurements with R&S FSW
November 2012 | 802.11ac | 19
l Transmitter Constellation Error
-325/6256-QAM9-303/4256-QAM8-275/664-QAM7-253/464-QAM6-222/364-QAM5-193/416-QAM4-161/216-QAM3-133/4QPSK2-101/2QPSK1-51/2BPSK0
RCE (dB)Coding RateModulationMCS
For error < 1dB a residual EVMof < -38 dB for T&M is needed
WLAN 802.11ac Analysis with R&S FSWModulation Analysis
November 2012 | 802.11ac | 20
WLAN 802.11ac Analysis with R&S FSWModulation Analysis – R&S FSW-K91/91ac
Bandwidth 160 MHz
November 2012 | 802.11ac | 21
WLAN 802.11ac Analysis with R&S FSWModulation Analysis – R&S FSW-K91/91ac
Constellation diagram R&S FSW-K91acResidual EVM < -45 dB at 5 GHz
DUT EVM: -33 dBWith -45 dB res. EVM, the result is -32.7 dB
R&S FSW quality is needed, becausewith e.g. -35 dB res. EVM, the result is -30.9 dB,which does not meet the spec.
November 2012 | 802.11ac | 22
802.11ac MIMOSignal Analysis
Simultaneous Analysis:l Each Analyzer captures one MIMO streaml Better analysis of interferences and dynamic scenarios
November 2012 | 802.11ac | 23
l MIMO is supportedl Sequential MIMOl Sequential MIMO using OSP boxl Support of more analyzers
Signal Source
Application firmware R&S FSQ-K91ac
November 2012 | 802.11ac | 24
802.11ac MIMOSignal Analysis
l One Analyzer (Master) displays all results
November 2012 | 802.11ac | 25
802.11ac MIMOSequential Analysis
l Different antennas are routed automatically by R&S®OSP Switch Box to the analyzer
l Analyzer combines results to form a „quasi-simultaneous“reception
l Automatic switching control by analyzer
R&S®OSP Switch Box
RF
Switching Control
R&S®FSW
Tx Rx
LAN
November 2012 | 802.11ac | 26
WLAN 802.11ac – Test Solutions Signal Generation
l 802.11ac (80 MHz) is supported by all vector signal generators of R&S
l For 160 MHz a combination of R&S AFQ100A/B and vector signal generator is neededl R&S SGS100A shows the best performancel WinIQSIM2 (2.20.230.162) is neededl Calibration of generator setup is recommended to get EVM < -40 dB
– SMx RF and Baseband Correction Toolkit
DUT
IQ
RF
November 2012 | 802.11ac | 27
Max. bandwidth 80 MHz
Max. bandwidth 160 MHz
R&S SMU
R&S SMBV
R&S FSQ
R&S FSW
Test Solutions for 80MHz and 160 MHz
R&S SMU
R&S SMBV
R&S FSW +R&S FSW-B160R&S AFQ100A/B
+
R&S SGS
November 2012 | 802.11ac | 28
R&S Signal Generator Solution Application note 1GP94
l Solution overview
l Capabilities of 11ac options
l Step by step guidelines
l Signal quality optimization for AFQ setups
l Measurement examples
R&S 11ac technology introduction white paper 1MA192
YouTube: WLAN 802.11ac measurements using the R&S®FSW signal and spectrum analyzer
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