Overview of Previous Analysis for WAVE Month 2002 doc.: IEEE 802.11-02/xxxr0 January 2004 Overview of Previous Analysis for WAVE Justin McNew jmcnew@technocom-wireless.com Justin McNew, TechnoCom John Doe, His Company

Traditional Scanning Passive scanning Active scanning Month 2002 doc.: IEEE 802.11-02/xxxr0 January 2004 Traditional Scanning Passive scanning Requires waiting for Beacon reception Beacons are not required for WAVE communications (see 11-04-0135-00-wave) Introduces excessive latency for public safety applications that require immediate access to information transmitted in mobile environments Active scanning Requires excessive transmissions by mobile units Clogs communications channels with densely populated OBU (mobile stations) Justin McNew, TechnoCom John Doe, His Company

Authentication & Association January 2004 Authentication & Association Authentication and association also affect latency of critical public safety applications (see 11-04-0135-00-wave) Not utilized for most public safety applications Requires Beaconing mechanism Joining a network is not required to communication with WAVE devices Justin McNew, TechnoCom

Channelization 10 MHz versus 20 MHz channels Month 2002 doc.: IEEE 802.11-02/xxxr0 January 2004 Channelization 10 MHz versus 20 MHz channels 75 MHz allocation results in excessive unused bandwidth with 20 MHz channels Seven 10 MHz channels provides ability to dedicate more channels to specific applications Leftover 5 MHz reserved for future FCC allocation of spread spectrum ISM band below 5.85 GHz Licensing of channels more robust (less overlap) Utilize half-rate solution consistent with 802.11j Consistent with expected delay spreads in outdoor and mobile environments Justin McNew, TechnoCom John Doe, His Company

January 2004 Basic MAC Simulations Altered existing simulation models to represent WAVE environment and 10 MHz channels No Beacons or association 6 Mbps data rate (QPSK modulation) Simple simulation used to confirm 802.11 can work for WAVE Justin McNew, TechnoCom

PHY Parameters January 2004 Characteristics Value Comments aSlotTime Calculated as aCCATime + aRxTxTurnaroundTime + AirPropagationTime + aMACProcessingDelay aSIFSTime 32 s Doubled from standard 802.11a value aCCATime  8 s aRxTxTurnaroundTime  2 s Same as standard 802.11a value aRxTxSwitchTime  1 s aAirPropagationTime  4 s Quadrupled to support up to 1200 meter range aMACProcessingDelay aPreambleLength 40 s aPLCPHeaderLength 8 s aCWmin 15 aCWmax 1023 Justin McNew, TechnoCom

Basic Simulation Results (cont’d) January 2004 Basic Simulation Results (cont’d) Generic simulation Randomly distributed nodes. 10, 30, 50, 70, and 90 OBUs with 1 RSU Network traffic Unicast traffic sent from OBUs destined to RSU Each OBU starts in different time (exponentially distributed with mean of 10 sec.) Exponentially distributed inter-arrival time with mean of 0.1 sec Average payload size of 64 bytes (smaller than anticipated) Justin McNew, TechnoCom

Basic Results January 2004 Justin McNew, TechnoCom

Realistic Simulation Case January 2004 Realistic Simulation Case OBU enter communication zone of an RSU at a reasonably consistent rate OBU service table (OST) sent in response to periodically broadcast RSU service table (RST) Single Exchange represented by Exchange Success Rate (ESR): RSU OBU RST Broadcast Delay Unicast OST Justin McNew, TechnoCom

January 2004 System Stability An excessive number of OBU entering a communication zone will result in significant exchange failures E.g. if 5 new OBUs enter the zone, the total number of OBUs that must be processed is the number of new OBUs plus the number of OBUs that failed for the last RST transmission Failures can result from collisions of RSTs and/or OSTs Realistically, not more than around 10 to 15 OBU can arrive in a communication zone on a large freeway within a 100 ms period Justin McNew, TechnoCom

Simulation Parameters January 2004 Simulation Parameters Packet characteristics RST Size: 490 bytes Unicast OST size: 490 bytes Vehicle to Vehicle: Broadcast OST size: 250 bytes Broadcast OST period: 100 ms Randomly distributed over 100 ms interval (uniform) 6 Mbps data rate Justin McNew, TechnoCom

January 2004 Simulation Results RST Period Justin McNew, TechnoCom

Summary 802.11 can support WAVE applications January 2004 Summary 802.11 can support WAVE applications Requires disabling various MAC features in certain instances Beacons, authentication & association 10 MHz channels used in WAVE frequency band Simulations indicate adequate capacity is available Note: Resulting recommendations presented in 11-04-0135-00-wave Justin McNew, TechnoCom