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NEONet 2006

NEONet 2006. Investigating 802.16 for Aeronautical Use Steven Bretmersky Cleveland State University March 1, 2006. Background.

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NEONet 2006

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  1. NEONet 2006 Investigating 802.16 for Aeronautical Use Steven Bretmersky Cleveland State University March 1, 2006

  2. Background The airport surface is a highly dynamic environment that encompasses many diverse users with different needs. Future operations will make more use of data communications and will require a wireless link. In the technology pre-screening phase of the Future Communication Study (a joint Eurocontrol / FAA study) 802.16 was identified as one possible enabling technology for the airport surface for ATC. This technology could benefit other surface users as well. This work investigates the possible uses of 802.16 for the airport surface.

  3. Uses of a surface wireless network • As a data link to aircraft for Air Traffic Control (ATC) and Aeronautical Operational Communications (AOC) messages • As a data link for surface vehicles (fuel trucks, baggage carts, maintenance vehicles) • As a backup link for existing ATC fixed surface systems (radar sites, voice radio sites, navaid sites) • As a primary link for new surface systems located in remote or hard-to-reach areas (ASDE-X multilateration sensors, wake vortex sensors) • As a network connection for airport staff (technicians in the field)

  4. Wireless Surface Scenario RTR Weather Radar Radar Snow Removal Equipment Baggage Handlers Fuel Truck Emergency Vehicles Technicians ASDE-X Sensor Wake Vortex Sensor RWSL Aircraft ALS ILS Port Authority FAA Airlines

  5. Current Communications Systems • To Aircraft – VHF voice and character-based messaging system (ACARS) • To surface vehicles – VHF voice to ATC, mobile radios • To existing surface systems – copper, leased telco lines, microwave wireless links, and/or fiber. All existing surface systems use point-to-point analog interfaces (modems)

  6. Future System Requirements • High reliability • Pre-emption / prioritization (QoS) • Privacy / Security • Encryption • Authentication • Mobility • Operate in a protected band (safety of flight) • C-band identified as good candidate • MLS extension band (5.091 – 5.150 GHz) is unutilized and currently protected as aeronautical radionavigation

  7. 802.16 Flavors WirelessHUMAN WirelessMAN-SCa WirelessMAN-OFDM WirelessMAN-OFDMA WirelessMAN-SC Frequency 10 – 66 GHz 2 - 11 GHz 2 - 11 GHz 2 - 11 GHz 2 - 11 GHz Duplexing TDD FDD TDD FDD TDD FDD TDD FDD TDD Automatic Repeat Request (ARQ) ✔ ✔ ✔ ✔ Adaptive Antenna System (AAS) ✔ ✔ ✔ ✔ Spaced Time Coding (STC) ✔ ✔ ✔ ✔ Mobility ✔ ✔ ✔ Mesh ✔ ✔

  8. 802.16 OFDM Waveform Pilot Subcarriers Data Subcarriers • 8 Pilot Subcarriers • Used as reference for phase and amplitude • 192 Data Subcarriers • Combination of all subcarriers creates an OFDM symbol Guard Band Guard Band

  9. TDD Frame Structure Frame Downlink Subframe Uplink Subframe DL PHY PDU UL PHY PDU UL PHY PDU DL Burst 1 DL Burst i UL Burst UL Burst Preamble Frame Control Header DL-MAP, UL-MAP, DCD, UCD Burst 1 MAC PDU 1 Burst 1 MAC PDU k Burst i MAC PDU 1 Burst i MAC PDU l Transmit/Receive Turnaround Gap Initial Ranging Contention Slot BW Request Contention Slot SS 1 PHY PDU Preamble SS 1 MAC PDU 1 SS 1 MAC PDU m SS x PHY PDU Preamble SS x MAC PDU 1 SS x MAC PDU n Receive/Transmit Turnaround Gap

  10. 802.16 on High Reliability • 802.16 uses multiple modulations and FEC rates to offer best performance for link conditions. • Modulation / FEC selection is a tradeoff between robustness and data rate. • WirelessMAN-OFDM modulations: • BPSK • QPSK • 16-QAM • 64-QAM • WirelessMAN-OFDM FEC algorithms • Reed-Solomon-Convolutional Code (RS-CC) at rates of 1/2, 2/3, and 3/4 • Block Turbo Coding (BTC) at rates of 1/2, 3/5, 2/3, 3/4, 4/5, and 5/6 (optional) • Convolutional Turbo Codes (CTC) at rates of 1/2, 2/3, and 3/4 (optional) • 802.16 offers ARQ that can be enabled on a per-service-flow basis

  11. 802.16 on QoS • 802.16 offers four types of services • Unsolicited Grant Service • Real-time fixed-rate flows • Real Time Polled Service • Real-time variable rate flows • Non-Real Time Polled Service • Best Effort Service • QoS for real-time services • Priority (8 levels) • Tolerated jitter • Maximum tolerated latency • Minimum tolerated traffic rate • 802.16 scheduler is not standardized

  12. 802.16 on Privacy / Security • Key management • X.509 digital certificates • RSA public key encryption/authentication • Optional EAP authentication in 802.16e • HMAC with SHA-1 authentication • Data encryption • DES with 56-bit keys • AES with 64 and 128 bit keys • Data authentication • AES with 128-bit keys in 802.16e

  13. 802.16 on Mobility • 802.16e adds the mobility component to the base standard • Designed to accommodate vehicular speeds (< 120 km/h) • Cannot support takeoff/landing speeds (~250 km/h), although this is not a big issue since the aircraft will likely be using the terminal area data link during these periods

  14. Study Approach • Identify surface applications and scenarios • Create 802.16 OFDM model to use in OPNET simulations • Identify and implement appropriate scheduling algorithm • Evaluate scenario options and verify with simulations • Single vs. multiple systems • Channel size

  15. 802.16 Model CS SAP Scope of Standard Service-Specific Convergence Sublayer (CS) Scope of Model MAC SAP MAC Common Part Sublayer (MAC CPS) MAC Privacy Sublayer PHY SAP Physical Layer (PHY) Transmission Convergence (TC) PHY • Implementation of 802.16 P2MP protocols in progress • MAC Common Part Sublayer • Convergence Sublayer • Overhead from Privacy Sublayer • Overhead from OFDM PHY • 802.16e extensions to be added in the future • Creation of physical layer model to begin soon • Waiting for inputs from Ohio University Sounding Study

  16. Scheduling Algorithm • Must determine when to grant bandwidth to services to meet QoS requirements • minimum rate • maximum latency • maximum jitter • priority • Must poll subscribers at appropriate time • Must take into account the current modulation and FEC rate being used by the subscriber

  17. Bandwidth Options • Channel bandwidth is configurable (between 1.25 and 25 MHz, 802.16e up to 5 MHz) • Example (OFDM, G = 1/32) • 1.25 MHz channel (minimum) • BPSK with RS-CC ½ (most robust) • 524 kbps raw data rate • 64-QAM with RX-CC ¾ (least robust) • 4.7 Mbps raw data rate • 25 MHz channel • BPSK with RS-CC ½ (most robust) • 10.5 Mbps raw data rate • 64-QAM with RX-CC ¾ (least robust) • 94.2 Mbps raw data rate

  18. Scenario Options • Single system scenario • All nodes use same wireless channel(s) • Multiple system scenarios • Separate wireless channels for fixed nodes and for mobiles • Separate point-to-multipoint and mesh channels

  19. Comments?

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