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apta 2006 rail conference

The Train-to-Wayside Air Gap. . Over-the-Air Issues. Throughput and speedLatencyHardware cost and market availabilityInterference sensing capabilitiesChoice of frequency band Interference and interference sensing. 2006 APTA RAIL CONFERENCEInvesting Today for a Brighter Tomorrow. . Design Trade Offs.

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apta 2006 rail conference

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    1. APTA 2006 RAIL CONFERENCE Ted Woods ARINC Senior Program Manager

    2. The Train-to-Wayside Air Gap

    3. Over-the-Air Issues Throughput and speed Latency Hardware cost and market availability Interference sensing capabilities Choice of frequency band Interference and interference sensing

    4. Design Trade Offs Functional and performance requirements Speed versus range System size and scalability Network architecture and topology Safety and security

    5. Types of Protocols - Proprietary Direct sequence (spreading techniques) Good multi-path discrimination Limited power density Frequency hopping Better interference resistance Orthogonal frequency-division multiplexing (OFDM) Similar to frequency hoping but with higher throughput on multiple channels simultaneously

    6. Types of Protocols - Open IEEE 802.11b 2.4 GHz, 11 Mb/sec Direct sequence spread spectrum (DSSS) IEEE 802.11a More recent for 5.3 GHz, 54 Mb/sec Orthogonal frequency-division multiplexing (OFDM) IEEE 802.11g 802.11b functionality, 2.4 GHz, 54 Mb/sec, DSSS Bluetooth

    7. Multi-Point Operation

    8. Multi-Point Operation:TDMA versus CSMA/CD

    9. Open Protocol Advantages Lower cost, more available HW and SW Less engineering on the project Flexibility, adaptability, scalability Upgrades and product evolutions Easier to share with non-CBTC applications

    10. Proprietary Protocol Advantages More customizable Potentially higher throughput Lower, more predictable latency Can be adapted more specifically to tunnel and other railroad propagation issues A multi-band approach may be possible

    11. Security Threats System integrity Confidentiality Non-repudiation Availability (Denial of Service)

    12. Threat Prevention Authentication Authorization Accounting Manual Automatic

    13. Living with Interference Increased noise floor in a public band Illegal interference Native versus application-based interference management

    14. Interference Management Techniques

    15. Implementation Considerations Product development plans Interoperability and standardization Radio routing: unicast vs. broadcast Priority management in the air gap

    16. More on Implementation Propagation and other RF issues Testing and commissioning Allow for future upgrades, radio replacement, and even frequency changes

    17. Procurement Strategies To attain reasonable competition, allow either an open or proprietary approach. If a proprietary approach is proposed, it still must meet certain requirements, such as: Commercial off-the-shelf hardware components and chip sets Modular hardware and software components available from multiple vendors Air gap protocol is documented and made available to other qualified suppliers

    18. Concluding Remarks The industry may be moving toward an open standards approach for the air gap, but it is not there yet. Open standards (e.g. TCP/IP or similar) are already accepted for most wire-line interfaces in rail transit. For more info: twoods@arinc.com

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