IEEE 802.11 WLAN Standards for Wi-Fi Solutions Today and Tomorrow IEEE 802 Wireless Standards Educational Workshop November 30, - December 1, 2007 Al Petrick Vice-Chairman IEEE 802.11 WG
Outline IEEE 802.11 History Current Projects Industry Alliances Highlights of Key Projects 802.11n, 802.11s Questions 2
IEEE 802 Organization IEEE Standards Association Standards Activities Board Sponsor IEEE 802 Local and Metropolitan Area Networks (LMSC) Sponsor Sponsor Sponsor 802.1 Higher Layer LAN Protocols 802.3 CSMA/CD Ethernet 802.5 Token Passing Ring 802.11 Wireless WLAN 802.15 Wireless Personal Area Networks 802.17 Resilient Packet Ring 802.19 Co-existence TAG 802.21 Media Independent Handoff IEEE 802.11: ~500 Participants Voting Members ~259 www.ieee802.org/11 802.16 Broadband Wireless Broadband Access 802.18 Radio Regulatory TAG 802.20 Mobile Broadband Wireless Access 802.22 Wireless Regional Area Networks 3
History - Milestones 4 1989: ISM frequency Bands 900MHz, 2.4GHz and 5GHz 1990: IEEE 802 starts 802.11 project extension 802.3 1994: 1st wireless radios - Inventory control 1997: IEEE 802.11 standard approved (2.4GHz 1Mbps) 1998: UNII (Unlicensed National Information Infrastructure) Band - 5 GHz 1999: IEEE 802.11 standard achieved ISO/IEC approval 1999: IEEE 802.11a (5GHz 54Mbps) - approved IEEE 802.11b (2.4GHz- 11Mbps)- approved 1999: Formation of WECA (now Wi-Fi Alliance) 2001: IEEE 802.11d Regulatory Domains - approved 2003: IEEE 802.11g (Higher rate 2.4GHz PHY) approved IEEE 802.11i (Security) - approved IEEE 802.11h (Spectrum Mgmt) - approved IEEE 802.11f (interaccess point protocol) approved 2005: IEEE 802.11e (MAC enhancements QoS) approved November 2007-106 th Session!
IEEE 802.11 Standard and Amendments Since 1990 the IEEE 802.11 working group has initiated 27 Projects (Task Groups) IEEE Std 802.11, 802.11a, 802.11b, 802.11b-Cor1, 802.11d, 802.11e, 802.11F, 802.11g, 802.11h, 802.11i, 802.11j, 802.11k, 802.11m, 802.11ma, 802.11-REVma, 802.11mb, 802.11n, 802.11p, 802.11r, 802.11s, 802.11T, 802.11v, 802.11u, 802.11w, 802.11y, 802.11z, 802.11.1 and 802.11.2 5
802.11 Current Projects 6
IEEE 802.11 Key Technical Attributes Specifications for the Physical and MAC Layers Backward compatibility with legacy 802.11 standard 700 600 500 802.11 Physical layer Data Rates Mbps 600 Maximize spectral efficiency and performance 400 300 300 20/25 MHz 40 MHz Co-existence with other device sharing the 2.4GHz and 5Ghz frequency bands 200 100 0 2 11 802.11 802.11b 802.11a/g 802.11n 54 7
Example 802.11 Radio Architecture 2.4GHz 5.0GHz 3.65GHz- 3.7GHz Ant SW Filtering PA LNA RF/Mixed Signal Transceiver (MODEM) Host Processor and Display Interface MAC Processor ARM Voice MIPS - Video Physical Layer Baseband Processor MAC MAC Layer Ethernet Controller 802.11 specifies physical and MAC layer parameters PHY: Regulatory requirements, modulation, TX power, RxSense, PER, Timing and Switching parameters MAC: Protocol timing primitives, QoS, Security, and legacy control/management paramters IEEE 802.11 does NOT specify implementation, or physical interfaces 8
WI-Fi Alliance Founded in 1999 as WECA Chartered to certified multi-vendor WLAN equipment interoperability based on IEEE 802.11 standard and amendments Liaison representation from the Wi-Fi Alliance www.wifialliance.org 9
Wi-Fi Forecast Devices (millio 10 700 600 500 400 300 200 100 0 Source: In-Stat Consumer Electronics Voice 600M 2006 2010 Both Consumer Electronics and Voice (VoIP) are forecast to make a huge impact by 2010 They will enable even more use of Wi-Fi both in all market segments ~One billion chipsets is forecast by 2010 Enterprise APs Home/SOHO CE Phones PCs
Wi-Fi 802.11n Certification Observations Draft 802.11n Started June 2007 Certifications Draft 802.11n based on D2.0 Handheld and Consumer Electronics profile in 2008 Currently 82 products certified based on 802.11n draft 2.0 The market has demanded a certification on baseline 11n as as 11n closes in on ratified New Look and Feel 11
Wi-Fi Hotspot Public Access 143K+ hot spots in 132 countries Source: JiWire (12 March 2007) Other sources indicate 200k+ hot spots 500+ muni deployments in 29 countries Source: WFA 82% of US hotels offer Wi-Fi Source: American Hotel & Lodging Assn 12 Melbourne
IEEE 802.11n Current approved draft is 2.0 IEEE 802.11 WG completed draft 3.0 in Oct 2007 Wi-Fi CERTIFIED products shipping today support draft 2.0 Standard is expected to be completed early 2009 Data rate: >100Mbps Modulation: OFDM Channel BW: 20Mhz / 40MHz Support: WPA and WPA2 (AES) Security Based on MIMO technology Based using Spatial multiplexing and coding to achieve higher throughput Operates in the existing 2.4GHz and 5GHz band and is backwards compatible with 802.11g and 802.11b products 13
Driving Applications for 802.11n 802.11n WLAN systems are expected to be an upgrade to existing 802.11g WLANs Consumer electronics, Residential, SOHO, Hotspots, Enterprise networks Application Drivers DV Audio/video, SDTV, HDTV, DVD Internet Streaming video/audio VoIP, Video phone, Video Conf Content download (photo camera) Internet File transfer (email, web, chat) Interactive Gaming Media Server (( ((( 14
Higher Throughput Higher Frequencies Beyond 802.11n..for tomorrow!! Very High Throughput (VHT) Study Group Leveraging input from WFA liaison to define usage models Wireless docking In Home Distribution of HDTV and other content Rapid Upload and Download of large files to/from server Backhaul Traffic (e.g. for Meshing, Enterprise, Small Office) Frequency band options: 5GHz, 50GHz, (275GHz 3,000GHz)Terahertz? Terahertz spectrum satellite and amateur radio services Data rates => 1.5Gbps.for uncompressed streaming video 15
IEEE 802.11 n High Throughput PHY Layer Highlights 16
MIMO hh x 1 x N hh y 1 y M Tx Rx Tx Rx MIMO: multiple input (to the environment), multiple output (from the environment MIMO means has different meanings A transmit beamforming antenna array and/or multiple receive diversity antennas qualifies as MIMO by some These systems improve robustness and increase the rate at a given range, but they do not increase the maximum data rate Spatial division multiplexing (SDM): transmit independent data streams on different antennas The maximum data rate increases as a function of the number of transmit antennas The number of receive antennas is least the number of data streams with a linear equalizer 17
802.11n - High Throughput 20 & 40 MHz channelization 1 to 4 spatial streams 1 stream for Client (Mandatory) 2 stream for Access Point (Mandatory) ½GI 56 tones (in 20MHz) 5/6 coding Green Field preamble 18
Spectrum Allocation in US and Europe Existing 2.4Ghz World-Wide Spectrum Existing 5GHz Spectrum UNII lower Four 20MHz channels 5.15-5.25 GHz UNII middle Four 20MHz channels 5.25-5.35 GHz ETSI bands Ten 20MHz channels 5.5-5.7GHz 19
802.11n - 20MHz Channel Mask New 20MHz spectral mask Same as IEEE 802.11a Mask Modified signal floor at 30MHz From -40dBr to -45dBr 20
802.11n - 40MHz Channel Mask 40MHz Spectral Mask Adjacent channel interference performance is very similar between two neighboring 40MHz devices as between two neighboring 20MHz devices Adjacent channel interference between neighboring 20MHz and 40MHz devices is yet to be determined 40MHz channels best suited for 5GHz Frequency band 21
802.11a PPDU Phy - Header Short Training Field Long Training Field Signal Field Service Field Data Field 8usec 8usec 4usec 16-bits Short training field (STF) start-of-packet detection, AGC setting, initial frequency offset estimation,time synchronization Long training field (LTF) used for accurate frequency offset estimation, time synchronization, and channel estimation Signal field (SIG) contains rate and length information SIG has only one parity bit which leads to false detects A reserve bit in the signal field has been used by some manufactures for more parity First 16 bits of the data field is the service field - contains reserve bits and scrambler init. bits 22
Mixed Format High Throughput Preamble HT SIG 8 µsec L-STF L-LTF L- SIG HT- SIG1 HT- SIG2 HT- STF HT- LTF1 HT- LTFN Service Field HT Data Legacy Preamble HT Preamble Mixed Format (MF) high throughput preamble starts with the legacy 11a preamble Followed by high throughput training fields 23
High Throughput Signal Field Bit 8,9 # of Spatial Stream Modulation Code 20/40 BW (HT Length) LSB0.6 MSB 7..(LSB8 MSB23) Smoothing,LDPC, GI CRC Tail LSB0 MSB23 HT SIG1 HT SIG 8 µsec HT- SIG2 Mixed Format (MF) high throughput bit 7 of HT-SIG1 distinguishes between 20 vs 40MHz channels 24
Interoperable PPDU Format with 11a/g Legacy OFDM Devices L-STF L-LTF L- SIG High throughput training field 8usec 8usec 4usec Mixed Format (MF) preamble specified to provide PHY interoperability with legacy OFDM devices The beginning of the MM preamble consists of legacy (L) training identical to 11a Contains L-STF, L-LTF, and L-SIG field as 11a such that legacy devices can detect the preamble How do we transmit the single stream legacy part of the MM preamble with a multiple antenna device? It is desirable to transmit the legacy training from all antennas for maximum power and range However, this may cause unintentional and undesirable beamforming effects since we are transmitting the same signal from each antenna Cyclic shifts are applied to additional antennas to decorrelate transmission paths Legacy devices with cross correlation receivers are sensitive to delay spread, which will be exacerbated by long cyclic shifts Shorter shifts are used on the legacy training part of the MM preamble to conserve detection properties: maximum of 200nsec Cyclic shifts occur symbol by symbol basis 25
MCS Set One Spatial Stream PHY bit rates MCS Index Modulation R 20MHz Data rate (Mbps) 800ns GI 400ns GI 40MHz Data rate (Mbps) 800ns GI 400ns GI 0 BPSK ½ 6.5 7.2 13.5 15.0 1 QPSK ½ 13.0 14.4 27.0 30.0 2 QPSK ¾ 19.5 21.7 40.5 45.0 3 16-QAM ½ 26.0 28.9 54.0 60.0 4 16-QAM ¾ 39.0 43.3 81.0 90.0 5 64-QAM 2/3 52.0 57.8 108.0 120.0 6 64-QAM ¾ 58.5 65.0 121.5 135.0 7 64-QAM 5/6 65.0 72.2 135.0 150.0 26
Two Spatial Streams 27 MCS Index 8 9 10 11 12 13 14 15 Modulation BPSK QPSK QPSK 16-QAM 16-QAM 64-QAM 64-QAM 64-QAM R ½ ½ ¾ ½ ¾ 2/3 ¾ 5/6 20MHz Data rate (Mbps) 800ns GI 13.0 26.0 39.0 52.0 78.0 104.0 117.0 130.0 PHY bit rates 400ns GI 14.444 28.889 43.333 57.778 86.667 115.556 130.000 144.444 800ns GI 27.0 54.0 81.0 108.0 162.0 216.0 243.0 270.0 A two antenna device with optional 40MHz mode and R= ½ GI can achieve 300Mbps 40MHz Data rate (Mbps) 400ns GI 30.0 60.0 90.0 120.0 180.0 240.0 270.0 300.0
Three Spatial Streams PHY bit rates MCS Index Modulation R 20MHz Data rate (Mbps) 800ns GI 400ns GI 40MHz Data rate (Mbps) 800ns GI 400ns GI 16 BPSK ½ 19.5 21.7 40.5 45.0 17 QPSK ½ 39.0 43.3 81.0 90.0 18 QPSK ¾ 58.5 65.0 121.5 135.0 19 16-QAM ½ 78.0 86.7 162.0 180.0 20 16-QAM ¾ 117.0 130.0 243.0 270.0 21 64-QAM 2/3 156.0 173.3 324.0 360.0 22 64-QAM ¾ 175.5 195.0 364.5 405.0 23 64-QAM 5/6 195.0 216.7 405.0 450.0 28
Improved Robustness with Receive Diversity PER 130Mbps Mode; Channel Model D 1 2x2 2x3 0.1 0.01 0.001 20 25 30 35 40 SNR (db) 8 db 2x2 system, the required SNR may be beyond transmitter or receiver capability Additional receive antennas reduce required SNR Receive diversity enables signal reception of the peak two stream data rate at a feasible SNR 29
MIMO Performance Improvement with Receive Diversity Over-the-air Throughput (Mbps) 120 100 80 60 40 20 More Throughput 0 30 20MHz; Channel Model D legacy 1x1 11n 2x2 11n 2x3 0 10 20 30 40 50 60 70 Range (m) Better Range Added robustness from receive diversity enables longer ranges at a given throughput At a given range, add robustness achieves higher throughputs MIMO increases peak data rates with additional data streams At lower data rates, MIMO systems may rate adapt to single stream modes, equivalent to 1x2 receive diversity, for added robustness and increased range
Space-Time Block Coding (STBC) -x 2 (x 1 )* -x 4 (x 3 )* x 1 x 2 x 3 x 4 y 2 y 4 y 1 y 3 Space-time block coding combines signals over two OFDM symbols between multiple antennas for transmit diversity gain This provides gain equivalent to received diversity STBC has a transmit power penalty with respect to receive diversity Configurations include 2x1, 3x2, 4x2, 4x3 31
Improved Robustness with STBC Transmit Diversity PER 1 0.1 0.01 130Mbps Mode; Channel Model D 2x2 4x2 Transmit diversity gain from STBC enables high data rates at a reasonable SNR received by a device with few receive antennas Benefits clients that are size and power constrained 0.001 20 25 30 35 40 SNR (db) 32
IEEE 802.11s MESH 33
Why Mesh? What s so good about Mesh? Enables rapid deployment with lower-cost backhaul Easy to provide coverage in hard-to-wire areas Self-healing, resilient, extensible Under the right circumstances: Greater range due to multi-hop forwarding Higher bandwidth due to shorter hops Better battery life due to lower power transmission 34
802.11s Project Scope In brief, produce an amendment to the 802.11 standard to create a Wireless Distribution System with automatic topology learning and dynamic wireless path configuration. Target number of packet forwarding nodes: ~32 Support unicast and broadcast/multicast traffic Use 802.11i security or an extension thereof Extensible routing to allow for alternative forwarding path selection metrics and/or protocols Use the 802.11 four-address frame format or an extension Interface with higher layers and connect with other networks using higher layer protocols Current Draft 802.11s d1.07 35
802.11s Project Scope (cont.) 802.11s is an amendment to the 802.11 MAC No Redesign of Existing PHY (.11a/b/g/n) 36
Classic 802.11 Wireless LAN Wired Infrastructure AP AP AP STA STA STA AP BSS = Basic Service Set STA STA STA STA STA = radio link 37 ESS = Extended Service Set SSID Wireless Paradox: WLAN Access Points are Typically Wired
Unwire the WLAN with Mesh Wired Infrastructure STA Mesh AP STA Mesh Point Mesh AP Mesh AP STA STA Mesh AP STA STA STA STA = mesh radio link ESS = Extended Service Set SSID 38
Example 802.11s Mesh Networking Deployment Scenarios Office Campus/Public Access Residential Public Safety/Military 802.11s Expected to be Used Across Many Diverse Applications 39
Device Classes in a WLAN Mesh Network Mesh Point (MP): establishes peer links with MP neighbors, full participant in WLAN Mesh services Light Weight MP participates only in 1-hop communication with immediate neighbors (routing=null) Mesh AP (MAP): functionality of a MP, collocated with AP which provides BSS services to support communication with STAs Mesh Portal (MPP): point at which MSDUs exit and enter a WLAN Mesh (relies on higher layer bridging functions) Station (STA): outside of the WLAN Mesh, connected via Mesh AP STA MP AP External Network Portal MP STA Mesh Portal Station STA MP AP Mesh Point MP Mesh AP STA 40
802.11s MAC Mandatory MAC Functions Enhanced Distributed Channel Access (EDCA) Re-use of latest MAC enhancements from 802.11 (i.e. 802.11e) Compatibility with legacy devices Easy to implement, providing reasonable efficiency in simple Mesh WLAN deployments Optional MAC Enhancements Mesh Deterministic Access (MDA) Reservation-based deterministic mechanism Common Channel Framework (CCF) Multi-channel operation mechanism Intra-mesh Congestion Control Power Management 41
Mesh Data Frame Format Octets:2 2 6 6 6 2 6 2 4~16 0-tbd 4 Frame Control Dur Address 1 RA Address 2 TA Address 3 DA Seq Control Address 4 SA Qos Control Mesh Header Payload FCS Octets: 1 2 1 12 Bit 0: Address Extension (AE) Mesh Flags Bits 1-7: Reserved for future use Mesh E2E Seq Number Time To Live These fields are always present in mesh frames. (Optional) Mesh Addressing Address 5 (6 octets) Address 6 (6 octets) 42 Mesh Header
6-Address Scheme To DS From DS AE Flag Address 1 Address 2 Address 3 Address 4 Address 5 Address 6 0 0 0 RA=DA TA=SA BSSID N/A N/P* N/P 0 1 0 RA=DA TA=BSSID SA N/A N/P N/P 1 0 0 RA=BSSID TA=SA DA N/A N/P N/P 1 1 0 RA TA DA SA N/P N/P 1 1 1 RA TA Mesh DA Mesh SA DA SA * N/P = Not Present 11s MAC Header Address Address (up to Mesh TTL field) Frame Body FCS 5 6 When the AE flag = 0, all fields have their existing meaning, and there exist no Address 5 and Address 6 fields this assures compatibility with existing hardware and/or firmware. 43
6-Address Scheme Address Mapping Principle The ordering of the addresses should be from the innermost to the outermost connections Address 1 & 2 for endpoints of a link between RX and TX Address 3 & 4 for endpoints of a mesh path between a destination and a source MP Including MPPs and MAPs Address 5 & 6 for endpoints of an (end-to-end) 802 communication A series of mesh paths connected at MPPs (e.g., TBR in HWMP) or An 802 path between legacy STAs (including nodes outside the mesh) or Any mixture of them (e.g., an MP to an STA or vice versa). 802.11 STA MAP MP MPP link link link link STA mesh path End-to-end 802 communication 44
Example: 802.11 STA to External STA STA1 Address 1 Address 2 Address 3 Address 4 MAP1 STA1 STA3 N/A MAP1 Address 1 Address 2 Address 3 Address 4 Address 5* Address 6* MP2 MAP1 MPP MAP1 STA3 STA1 MP2 Address 1 Address 2 Address 3 Address 4 Address 5 Address 6 MPP MP2 MPP MAP1 STA3 STA1 MPP 45 STA3 DA STA3 SA MPP** Non-802.11 (i.e., Ethernet) frame * Intermediate MPs (here MP2) don t have to process these fields. ** Ethernet address of MPP s interface to a wired network
Some Challenges in Mesh networks Support for path selection Mobility aware Clients served Network itself (e.g. Military and Public Safety) Set of direct Neighbors Exposed & hidden nodes = Set of indirect Neighbors Interference Awareness needed Internet 46 Mesh AP Portal Station Mobile Station
Summary Wireless LAN Standards for the Physical and MAC Layers Backward compatibility with legacy 802.11 standard and maintain Co-existence (good neighbor) in current spectrum Provide mechanisms to interface to networks outside 802.11 Today 2007 802.11n 802.11s new infrastructure Existing spectrum Tomorrow 2010 New applications Higher data rates >1Gbps Protocol advancements Expand into new frequencies, 50GHz 60GHz, and Terahertz 1000 800 600 400 200 0 2 11 802.11 Physical layer Data Rates Mbps 54 300 600 1000 802.11 802.11b 802.11a/g 802.11n VHT 20/25 MHz 40 MHz 47
Thank you! Al Petrick Vice-Chairman IEEE 802.11 WG Jones-Petrick and Associates, LLC Orlando, Florida www.jpasoc.com Email: al@jpasoc.com Phone: +1.321.235.3269 IEEE 802.11 Handbook A Designer s Companion ISBN 0-7381-4449-5 48