IEEE WLAN Standards for Wi-Fi Solutions Today and Tomorrow IEEE 802 Wireless Standards Educational Workshop November 30, - December 1, 2007

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1 IEEE 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 WG

2 Outline IEEE History Current Projects Industry Alliances Highlights of Key Projects n, s Questions 2

3 IEEE 802 Organization IEEE Standards Association Standards Activities Board Sponsor IEEE 802 Local and Metropolitan Area Networks (LMSC) Sponsor Sponsor Sponsor Higher Layer LAN Protocols CSMA/CD Ethernet Token Passing Ring Wireless WLAN Wireless Personal Area Networks Resilient Packet Ring Co-existence TAG Media Independent Handoff IEEE : ~500 Participants Voting Members ~ Broadband Wireless Broadband Access Radio Regulatory TAG Mobile Broadband Wireless Access Wireless Regional Area Networks 3

4 History - Milestones : ISM frequency Bands 900MHz, 2.4GHz and 5GHz 1990: IEEE 802 starts project extension : 1st wireless radios - Inventory control 1997: IEEE standard approved (2.4GHz 1Mbps) 1998: UNII (Unlicensed National Information Infrastructure) Band - 5 GHz 1999: IEEE standard achieved ISO/IEC approval 1999: IEEE a (5GHz 54Mbps) - approved IEEE b (2.4GHz- 11Mbps)- approved 1999: Formation of WECA (now Wi-Fi Alliance) 2001: IEEE d Regulatory Domains - approved 2003: IEEE g (Higher rate 2.4GHz PHY) approved IEEE i (Security) - approved IEEE h (Spectrum Mgmt) - approved IEEE f (interaccess point protocol) approved 2005: IEEE e (MAC enhancements QoS) approved November th Session!

5 IEEE Standard and Amendments Since 1990 the IEEE working group has initiated 27 Projects (Task Groups) IEEE Std , a, b, b-Cor1, d, e, F, g, h, i, j, k, m, ma, REVma, mb, n, p, r, s, T, v, u, w, y, z, and

6 Current Projects 6

7 IEEE Key Technical Attributes Specifications for the Physical and MAC Layers Backward compatibility with legacy standard Physical layer Data Rates Mbps 600 Maximize spectral efficiency and performance /25 MHz 40 MHz Co-existence with other device sharing the 2.4GHz and 5Ghz frequency bands b a/g n 54 7

8 Example 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 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 does NOT specify implementation, or physical interfaces 8

9 WI-Fi Alliance Founded in 1999 as WECA Chartered to certified multi-vendor WLAN equipment interoperability based on IEEE standard and amendments Liaison representation from the Wi-Fi Alliance 9

10 Wi-Fi Forecast Devices (millio Source: In-Stat Consumer Electronics Voice 600M 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.

11 Wi-Fi n Certification Observations Draft n Started June 2007 Certifications Draft n based on D2.0 Handheld and Consumer Electronics profile in 2008 Currently 82 products certified based on n draft 2.0 The market has demanded a certification on baseline 11n as as 11n closes in on ratified New Look and Feel 11

12 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.

13 IEEE n Current approved draft is 2.0 IEEE 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 g and b products 13

Driving Applications for 802.11n 802.11n WLAN systems are expected to be an upgrade to existing 802.

14 Driving Applications for n n WLAN systems are expected to be an upgrade to existing g 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 ( , web, chat) Interactive Gaming Media Server (( ((( 14

15 Higher Throughput Higher Frequencies Beyond n..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

16 IEEE n High Throughput PHY Layer Highlights 16

17 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

18 802.11n - 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

19 Spectrum Allocation in US and Europe Existing 2.4Ghz World-Wide Spectrum Existing 5GHz Spectrum UNII lower Four 20MHz channels GHz UNII middle Four 20MHz channels GHz ETSI bands Ten 20MHz channels GHz 19

20 802.11n - 20MHz Channel Mask New 20MHz spectral mask Same as IEEE a Mask Modified signal floor at 30MHz From -40dBr to -45dBr 20

21 802.11n - 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

22 802.11a 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

23 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

24 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

25 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

26 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 QPSK ½ QPSK ¾ QAM ½ QAM ¾ QAM 2/ QAM ¾ QAM 5/

27 Two Spatial Streams 27 MCS Index 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 PHY bit rates 400ns GI ns GI A two antenna device with optional 40MHz mode and R= ½ GI can achieve 300Mbps 40MHz Data rate (Mbps) 400ns GI

28 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 QPSK ½ QPSK ¾ QAM ½ QAM ¾ QAM 2/ QAM ¾ QAM 5/

29 Improved Robustness with Receive Diversity PER 130Mbps Mode; Channel Model D 1 2x2 2x 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

30 MIMO Performance Improvement with Receive Diversity Over-the-air Throughput (Mbps) More Throughput MHz; Channel Model D legacy 1x1 11n 2x2 11n 2x 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

31 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

32 Improved Robustness with STBC Transmit Diversity PER Mbps 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 SNR (db) 32

33 IEEE s MESH 33

34 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

35 802.11s Project Scope In brief, produce an amendment to the 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 i security or an extension thereof Extensible routing to allow for alternative forwarding path selection metrics and/or protocols Use the four-address frame format or an extension Interface with higher layers and connect with other networks using higher layer protocols Current Draft s d

36 802.11s Project Scope (cont.) s is an amendment to the MAC No Redesign of Existing PHY (.11a/b/g/n) 36

37 Classic 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

38 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

39 Example s Mesh Networking Deployment Scenarios Office Campus/Public Access Residential Public Safety/Military s Expected to be Used Across Many Diverse Applications 39

40 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

41 802.11s MAC Mandatory MAC Functions Enhanced Distributed Channel Access (EDCA) Re-use of latest MAC enhancements from (i.e e) 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

42 Mesh Data Frame Format Octets: ~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: 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

43 6-Address Scheme To DS From DS AE Flag Address 1 Address 2 Address 3 Address 4 Address 5 Address RA=DA TA=SA BSSID N/A N/P* N/P RA=DA TA=BSSID SA N/A N/P N/P RA=BSSID TA=SA DA N/A N/P N/P RA TA DA SA N/P N/P 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

44 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) STA MAP MP MPP link link link link STA mesh path End-to-end 802 communication 44

45 Example: 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 (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

46 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

47 Summary Wireless LAN Standards for the Physical and MAC Layers Backward compatibility with legacy standard and maintain Co-existence (good neighbor) in current spectrum Provide mechanisms to interface to networks outside Today n s new infrastructure Existing spectrum Tomorrow 2010 New applications Higher data rates >1Gbps Protocol advancements Expand into new frequencies, 50GHz 60GHz, and Terahertz Physical layer Data Rates Mbps b a/g n VHT 20/25 MHz 40 MHz 47

48 Thank you! Al Petrick Vice-Chairman IEEE WG Jones-Petrick and Associates, LLC Orlando, Florida Phone: IEEE Handbook A Designer s Companion ISBN

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