802 11 Enhancements and Applications 802 11 n

802. 11 Enhancements and Applications 802. 11 n, 802. 11 p, 802. 11 r, 802. 11 s, 802. 11 y

802. 11 n 802. 11

802. 11 n • • Overview Certification, Products Performance Summary

802. 11 n overview • Adds MIMO to WLAN OFDM • Operate in either UNII or ISM bands • Status: –In Ballot –May get held up by IP Streaming Home Multimedia (HDTV) • http: //arstechnica. com/news. ars/post/2007 0924 -dark-australian-patent-cloud-loomsover-802 -11 n-spec. html • CSIRO (http: //www. csiro. au/) holds some key IP, hasn’t signed letter of assurance, has history of Wi. Fi lawsuits and seeking injunctions • Last publicly available draft –Enhanced Wireless Consortium (merger of TGn. Sync and WWi. SE) –http: //www. enhancedwirelessconsortiu m. org/home/EWC_PHY_spec_V 127. pd f (PHY) –http: //www. enhancedwirelessconsortiu m. org/home/EWC_MAC_spec_V 124. pd f (MAC) Source: http: //www. tgnsync. org/products

802. 11 n PHY (in 1 slide) • MIMO evolution of 802. 11 OFDM PHY –Up to 4 antennas per device • 20 and 40 MHz channels –Fully interoperable with legacy 802. 11 a/b/g – 288 Mbps in 20 MHz and 600 Mbps in 40 MHz (64 QAM, 4 spatial streams, 1/2 guard interval) –Claim of 100 Mbps in real throughput • Optional enhancements –Transmit beamforming with negligible overhead at the client –Advanced channel coding techniques (RS) –Space Time Block Coding (Alamouti and others) – 1/2 guard interval (i. e. , 400 ns instead of 800 ns) – 7/8 rate coding http: //www. enhancedwirelessconsortium. org/home/EWC_PHY_spec_V 127. pdf

802. 11 n MAC Features • • • Supports 802. 11 e (Qo. S) Frame aggregation – Bi-directional data flow Link adaptation with explicit feedback and control of channel sounding packets Protection mechanisms – • • For seamless interoperability and coexistence with legacy devices Channel management – • Single and multiple destinations – Including management of 20/40 MHz operating modes Channel estimation and feedback Power management for MIMO receivers Data aggregation Broadcom, “ 802. 11 n: Next-Generation Wireless LAN Technology, ” White Paper, April 06

Legacy Support • • • Distributed coordination function will fail if devices cannot interpret packets Much more spectrum used by 802. 11 n Three packet modes to support legacy equipment – Legacy (all legacy) – Mixed (some legacy, some 802. 11 n) – Green Field (all 802. 11 n) 802. 11 n PLCP Format http: //www. enhancedwirelessconsortium. org/home/EWC_PHY_spec_V 127. pdf • Spectrum usage – LM – Legacy Mode – equivalent to 802. 11 a/g – HT-Mode – In HT mode the device operates in either 40 MHz bandwidth or 20 MHz bandwidth and with one to four spatial streams. – Duplicate Legacy Mode – in this mode the device operates in a 40 MHz channel composed of two adjacent 20 MHz channel. The packets to be – sent are in the legacy 11 a format in each of the 20 MHz channels. To reduce the PAPR the upper channel (higher frequency) is rotated by 90º – relative to the lower channel. – 40 MHz Upper Mode – used to transmit a legacy or HT packet in the 16 upper 20 MHz channel of a 40 MHz channel. – 40 MHz Lower Mode – used to transmit a legacy or HT packet in the lower 20 MHz channel of a 40 MHz channel. LM is mandatory and HT-Mode for 1 and 2 spatial streams are also mandatory.

Some 802. 11 performance results From IEEE 802. 11 -04/1369 r 0

Comparison with 802. 11 a/g Throughput Enhancements Peak Rates Relative Cost to Implement IEEE 802. 11 -04/1369 r 0

PHY Throughput • • Link adaptation is based on long term average SNR sub-optimum inferior bound Finer grid possible with more modes

Simulation results Mode/ Mbps SNR for PER=10 -1 180 (effect) 36 d. B 180 36 d. B 120 35 d. B 25. 5 d. B 96 27. 5 d. B 21 d. B 48 18 d. B 14 d. B 12 5 d. B 4. 5 d. B doc. : IEEE 802. 11 -04/1369 r 0 • Diversity gain for 2 streams, but not for 3 streams • 120 Mbps lowers SNR ~ 36 d. B 26 d. B

Mixed traffic handling • Capacity usage at MAC-SAP vs. Number of Vo. IP sessions – 1 TCP data flow transmitted using MIMO 3 x 3_64 QAM 2/3 (Ns=3) [144 Mbit/s] – Vo. IP: 120 -byte packets emitted every 10 ms (2 x 96 kbit/s) – n Vo. IP sessions, using either 2 x 2_64 QAM 2/3 (Ns=1) [48 Mbit/s] or 2 x 2_16 QAM 1/2 (Ns=1) [24 Mbit/s] • • MAC Efficiency between 78% and 55% 30 Vo. IP sessions + at least 65 Mbit/s of TCP traffic doc. : IEEE 802. 11 -04/1369 r 0

Delay performances • IEEE TGn Usage models : Scenario I (Home) • Traffic classification based on priority level (Vo. IP > TCP) • Delay comparison for different error rate [cdf(d>D)] • Strong Qo. S constraints of Vo. IP reached: – with a simple centralised scheduling – an efficient ARQ • Max delay below 20 ms for Qo. S traffic doc. : IEEE 802. 11 -04/1369 r 0

802. 11 n Certification • Wi-Fi Alliance Key Certification Features – Certifying to Draft 2. 0 while draft is approved – Certify to Ratified Standard when available – 22 August 2007 - Almost 70 products certified for compliance with Draft 2. 0 of the 802. 11 n • http: //www. wifiplanet. com/news/article. php/3578886 Wi-Fi CERTIFIED™ 802. 11 n draft 2. 0: Longer-Range, Faster-Throughput, Multimedia-Grade Wi-Fi® Networks

Pre-802. 11 n deployments • Belkin (pre-802. 11 n) – – • Netgear (pre-802. 11 n) – – • 802. 11 g with Speed and Range e. Xpansion (802. 11 g SRX) 8 x speed, 3 times range 3 antennas Airgo (chip vendor, “True MIMO”) – – • 7 antennas 43. 2 Mbps (measured) http: //www. theregister. co. uk/2005/06/07/review_netgear_mim o_router/page 2. html Linksys (Cisco) – – – • 8 x coverage, 6 x speed of 802. 11 g 3 antennas SOHOware, Planex Linksys Dell – Optional Pre-N with Broadcom adapter – http: //biz. yahoo. com/prnews/060717/nym 115. html? . v=38

802. 11 n Summary • By adding antenna arrays to Wi. Fi, significant improvements possible without exponential increases in complexity – Most people using it for range extension • Thin pipe into the house • High SNRs needed for peak rates • Designed to co-exist with 802. 11 a/b/g • Wi. Fi Alliance certifying to draft 2. 0 now

802. 11 p

802. 11 p • “Dedicated Short Range Communications” (DSRC) – – • Started in IEEE 1609, spun into 802. 11 p Aka (WAVE) Wireless Access for Vehicular Environment Goal – Telematics (collision avoidance a big driver) • • – 54 Mbps, <50 ms latency • • • Roadside-to-vehicle Vehicle-to-vehicle environments Possible competitor to cellular Operates in 5. 850 to 5. 925 GHz band Draft under ballot – Projected for March 2009

Broader Context • 802. 11 p part of several standards which will jointly enable widescale telematics Intelligent Transportation Systems doc. : IEEE 802. 11 -07/2045 r 0 S. Biswas, R. Tatchikou, F. Dion, “Vehicle-to-vehicle wireless communication protocols for enhancing highway traffic safety, ” IEEE Comm Mag, Jan 06, pp. 74 -82.

802. 11 p Applications • Applications – – – – Emergency warning system for vehicles Cooperative Adaptive Cruise Control Cooperative Forward Collision Warning Intersection collision avoidance Approaching emergency vehicle warning (Blue Waves) Vehicle safety inspection Transit or emergency vehicle signal priority Electronic parking payments Commercial vehicle clearance and safety inspections In-vehicle signing Rollover warning Probe data collection Highway-rail intersection warning

Example Application COLLISION IMMINENT In-Vehicle Displays and Annunciations IMMINENT LEFT ~ ~ FRONT COLLISION ~ ~ Note 1: The OBU in the vehicle recognizing the threat transmits a WARNING and COLLISION PREPARATION MESSAGE with the location address of the threat vehicle. ~ ~ Note 2: Only the OBU in the threatening vehicle processes the message because only it matches the threat address. up to Note 3: COLLISION PREPARATION includes seat belt tightening, side air bag deployment, side bumper expansion, etc. 100 m (328 ft) Car NOT Stopping Radar Threat Identification Traffic Signal OBUs on Control Ch From: IEEE 802. 11 - 04/ 0121 r 0 Available: http: //www. npstc. org/meetings/Cash%20 WAVE%20 Information%20 for%205. 9%20 GHz%20061404. pdf

Operation • Spectrum divided into 7 bands – 178 is control (safety) – 2 edge channels are reserved for future – The rest are service channels (not application specific) • IEEE 802. 11 a adjusted for low overhead operations D. Jiang, V. Taliwal, A. Meier, W. Holfelder, R. Herrtwich, “Design of 5. 9 ghz dsrc-based vehicular safety communication, “ IEEE Wireless Comm, Oct 06, pp. 36 -43

Safety Messages • Control Messaging characteristics –Most messages are single hop –Some broadcasting (e. g. , forwarding hazard warnings) –No coordination for channel access –Messages targeted based on vehicle location more so than vehicle identity –Short and mapped to a single frame –Arbitrary distances (100 m is a more practical distance) –Vehicles in constant communication –Dedicated channel • Messaging Principles –Safety communication is not application-to-application Instead, an intermediate layer is responsible for safety information distribution and aggregation among vehicles and infrastructure. –Applications work by continuously analyzing the aggregated information to look out for potential trigger conditions. –Simply put, the sender of a safety message cannot dictate how the message should be processed –“I-am-braking” vs “You have-tobrake” message. One particular advantage –Simplifies future enhancements

Reliability • If cars are being controlled wirelessly, dropping packets could cause accidents • May need to signal a long ways off • Result of studies: Free way conditions – Errors not bursty – Communications up to 1 km feasible F. Bai, H. Krishnan, “Reliability Analysis of DSRC Wireless Communication for Vehicle Safety Applications, ” IEEE ITSC 2006 Packet error distribution

Possible Deployments • • Good (though dated) schedule at http: //www. itsforum. gr. jp/Public/E 4 Meetings/P 03/schnac ke. TP 74. pdf US Do. T planning to deploy as Vehicle Infrastructure Integration project (VII) – – http: //www. networkworld. com/news/2005/111405 -vii. html Widescale deployment decision in 2008 • • GM possibly going its own route with “Vehicle to Vehicle” which leverages On. Star – • First use in intersections http: //www. gm. com/company/gmability/safety/news_issues/rele ases/sixthsense_102405. html European Effort – Car-to-Car Communication Consortium – http: //www. car-to-car. org/

802. 11 r Support for Faster Roaming

802. 11 r overview • Fast BSS Roaming/Transition within IEEE WLAN networks – Preserve security with handovers <50 ms • Fast BSS Roaming is possible only within a certain area called the mobility domain (MD), inter-MD cases are not covered – Mobility Domain (MD): Set of BSS grouped together with the same 48 bit MD Identifier – FT functionality seeks to provide handover performance for RT services • Key Issues – Resource Reservations – Security • Collapsed 5 step process down to 3 – Scanning – active or passive for other APs in the area – Authentication with a (one or more) target AP – Re-association to establish connection at target AP • Target 2008 http: //www. cs. tut. fi/kurssit/TLT 6556/Slides/Lect ure 4. pdf

Resource Reservation (optional) • Resource Reservation (RR) is to setup Qo. S resources in one or more target AP during FT transition mechanism – RR Setup only follows successful PTK derivation • RR is based on one round-trip negotiation • – STA requests certain Qo. S and t-AP provides as much or less Qo. S • • Benefits – No delay during re-association for RR (RIC) processing – Better application service quality during FT roaming – Without RR, STA may realize target AP does not have enough resources at the time of reassociation • Drawbacks – STA may reserve at multiple AP but use only one => cost – Increased AP complexity • –Mechanism – AP advertises the capability in the Beacon frame – STA has the choice to initiate the RR procedure

Security • New key hierarchy • New authentication route http: //www. cs. tut. fi/kurssit/TLT-6556/Slides/Lecture 4. pdf http: //www. networkcomputing. com/gallery/2007/0416 t tb. jhtml; jsessionid=0 CK 4 ZKR 20 HC 5 QQSNDLPCKHSCJU NN 2 JVN

Reduction in Roaming Time S. Bangolae, C. Bell, E. Qi, “Performance study of fast BSS transition using IEEE 802. 11 r, ” International Conference On Communications And Mobile Computing, 2006

802. 11 s Mesh Networking in Wi. Fi

Objectives 1 • Modify 802. 11 MAC to create dynamic self-configuring network of access points (AP) called and Extended Service Set (ESS) Mesh • Automatic topology learning, dynamic path selection • Single administrator for 802. 11 i (authentication) • Support up to 32 AP • Support higher layer connections • Allow alternate path selection metrics • Extend network merely by introducing access point and configuring SSID 1. http: //standards. ieee. org/board/nes/projects/802 -11 s. pdf IP or Ethernet

Conceptual Operation of 802. 11 s http: //ieee 802. org/802_tutorials/nov 06/802. 11 s_Tutorial_r 5. pdf • WLAN Mesh – An IEEE 802. 11 -based Wireless distribution service consisting of a set of two or more Mesh Points interconnected via IEEE 802. 11 links and communicating via the WLAN Mesh Services. • Mesh Point - A Mesh Services supporting device (bridge, access point) • Mesh AP - Any Mesh Point that is also an Access Point. • Mesh Portal - A boundary connection for the Mesh

Major Participants Wi. Mesh • http: //www. wi-mesh. org/ • Major Partners – – – Nortel Inter. Digital Phillips Mitre Naval Research Lab Thomson SEEMesh • Simple, Efficient and Extensible Mesh • No group site • Major Partners – Intel – Motorola (purchased Mesh. Networks) – Nokia – Texas Instruments 1. http: //grouper. ieee. org/groups/802/11/Reports/tgs_update. htm

Key Technologies • • Topology Formation Internetworking Routing Security

Topology Formation • Each Mesh Point may have one or more logical radio interface: – Each logical interface on one (infrequently changing) RF channel, belong to one “Unified Channel Graph” – Each Unified Channel Graph shares a channel precedence value • Channel precedence indicator – used to coalesce disjoint graphs and support channel switching for DFS http: //ieee 802. org/802_tutorials/nov 06/802. 11 s_Tutorial_r 5. pdf

Internetworking • 1. Determine if the destination is inside or outside of the Mesh – Leverage layer-2 mesh path discovery • 2. For a destination inside the Mesh, – a. Use layer-2 mesh path discovery/forwarding • 3. For a destination outside the Mesh, – a. Identify the “right” portal, and deliver packets via unicast – b. If not known, deliver to all mesh portals http: //ieee 802. org/802_tutorials/nov 06/802. 11 s_Tutorial_r 5. pdf

Default Routing: Hybrid Wireless Mesh Protocol (HWMP) • On demand routing is based on Radio Metric AODV (RM-AODV) – Based on basic mandatory features of AODV (RFC 3561) – Extensions to identify best-metric path with arbitrary path metrics – Destinations may be discovered in the mesh on-demand • Pro-active routing is based on tree based routing – If a Root portal is present, a distance vector routing tree is built and maintained – Tree based routing is efficient for hierarchical networks – Tree based routing avoids unnecessary discovery flooding during discovery and recovery http: //ieee 802. org/802_tutorials/nov 06/802. 11 s_Tutorial_r 5. pdf

RA-OLSR – Key Features (Optional Routing) • Multi Point Relays (MPRs) • – A set of 1 -hop neighbor nodes covering 2 -hop neighborhood • – Only MPRs emit topology information and retransmit packets • • Reduces retransmission overhead in flooding process in space. • (Optional) message exchange frequency control (fish-eye state routing) • – Lower frequency for nodes within larger scope • Reduce message exchange overhead in time. http: //ieee 802. org/802_tutorials/nov 06/802. 11 s_Tutor ial_r 5. pdf

Security • The MPs are no longer wired to one another • There is no intrinsic node hierarchy • MPs need to maintain secure links with many other MPs • Transport security – Mutually authenticate neighbor MPs – Generate and manage session keys and broadcast keys – Data confidentiality over a link – Detect message forgeries and replays received on a link • Authentication and Initial Key Management – Basic approach is to re-use 802. 11 i/802. 1 X – Re-use of 802. 11 i facilitates implementation http: //ieee 802. org/802_tutorials/nov 06/802. 11 s_Tutorial_r 5. pdf

Usage Models http: //ieee 802. org/802_tutorials/nov 06/802. 11 s_Tutorial_r 5. pdf

Combat Usage Case • Vehicular mounted APs interconnected via WDS (wide area data services) Dismounted troops carry client STAs APs & client STAs are communication endpoints Occasionally a STA may need to switch roles and become an AP in order to heal a bifurcated mesh Predominance of multicast applications, e. g. , situational awareness, conference mode Vo. IP, … Type 1 encryption, e. g. , Harris Sec. Net 11 Auto configuration • • • Logical View – • plug and play, or nearly so Multiple 802. 11 ESS Meshes interconnected via JTRS ELOS links Mesh AP Links – 802. 11 MAC/PHY (4 -addr data frames) Some JTRS ELOS links may belong to the WDS while others are external to the WDS, i. e. , are terminated via IP routers rather than by 802. 11 APs. 802. 11 ESS Mesh JTRS ELOS Links (Joint Tactical Radio System) (Extended Line-of-Site) ine-o f-S Picture from: IEEE 802. 11 -04/1006 r 0 Client-to-AP Links 802. 11 MAC/PHY (3 -addr data frames) Slide from: J. Hauser, D. Shyy, M. Green, MCTSSA 802. 11 s Military Usage Case

Wi. Fi Mesh Products • Motorola Mesh Networks – www. motorola. com/mesh • Tropos – www. tropos. com • Packet. Hop Communications – www. packethop. com • Mesh. Dynamics – www. meshdynamics. com • Sky. Pilot Networks – www. skypiilot. com • Proxim Networks – www. proxim. com/can/ • • Nortel Networks Wave Wireless – www. wavewireless. com • • Locust. World. com Fire. Tide Network List from: http: //www. cs. wustl. edu/~jain/cse 574 -06/ftp/j_jmesh/sld 019. htm

802. 11 y Dynamic Spectrum Access

Background • FCC issued rules for novel “lite licensing” scheme for 3650 -3700 MHz band – Licensees • pay small fee for nation-wide non-exclusive license • Pay additional fee for each high-powered base station (up to 20 W) – No need for license for clients nor operators, but devices must be “enabled” – Devices must be identifiable (to find the culprit) – Support contention based protocol to give opportunity to transmit to multiple licensees – Interference disputes between licensees must be resolved between themselves • Applications – – – – Back haul for Municipal Wi-Fi networks Industrial automation and controls Campus and enterprise networking Last Mile Wireless Broadband Access Fixed Point to point links Fixed point to mobile links Public safety and security networks

802. 11 y • Ports 802. 11 a to 3. 65 GHz – 3. 7 GHz (US Only) – FCC opened up band in July 2005 – Conditionally approved Summer 2007, to sponsor ballot, ready 2008 • • Intended to provide rural broadband access (distances up to 5 km) Incumbents – Band previously reserved for fixed satellite service (FSS) and radar installations – including offshore – Must protect 3650 MHz (radar) – Not permitted within 80 km of inband government radar – Specialized requirements near Mexico/Canada and other incumbent users • Leverages other amendments – Adds 5, 10 MHz channelization (802. 11 j) – DFS for signaling for radar avoidance (802. 11 h) • Database of existing devices – Access nodes register at http: //wireless. fcc. gov/uls – Must check for existing devices at same site Source: IEEE 802. 11 -06/0 YYYr 0

Key 802. 11 y technologies • DFS (802. 11 h) • Channelization (802. 11 j) • Contention based protocol (CBP) – geographic protection of the grandfathered satellite stations – database for users to research other users in their area – Location information • Extended channel switch announcement (ECSA) – Dependent notification of DFS – Continuous adaptation • Dependant station enablement (DSE)

Dependant station enablement • DSE controls when a dependant is allowed to transmit in licensed spectrum – enabling station need not be an access point, may be elsewhere – Need not be completed via a direct link DSE Enabling Process https: //edge. arubanetworks. com/article/ standards-corner-august-2007 -ieee 802 -11 y-3650 -3700 -mhz-operation-usa

Summary • 802. 11 is expanding into lots of applications – VOIP roaming (802. 11 r) – Cellular like ranges with dynamic spectrum access (802. 11 y) – Telematics (802. 11 p) – Mesh networks (802. 11 s) • Leverage and enhance previous amendments • Expect to see cross-pollination of technologies later.