1 / 21

PTC Radio and System Architecture

PTC Radio and System Architecture. Date: 2011-07-14. Authors:. Abstract.

sitara
Télécharger la présentation

PTC Radio and System Architecture

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. PTC Radio and System Architecture Date: 2011-07-14 Authors: Jia-Ru Li, Lilee Systems

  2. Abstract • Mandate : United States President George Bush signed the railway safety bill [1] into law on October 16, 2008 after the collision of a Metrolink passenger train and a Union Pacific freight train in Los Angeles, California, resulted in the deaths of 25 and injuries to more than 135. The bill mandates the implementation of Positive Train Control (PTC)[2]. • Equipment : PTC involves four components • Equipment deployed on the locomotive • Equipment deployed at trackside houses • Equipment deployed at the control center • A bi-directional wireless data link • Deadline : The United States Congress set a • deadline of Dec 31, 2015 for the implementation of PTC technology. • Estimated 20,000 locomotives and 100,000 miles of track would need to be equipped with PTC [7] Jia-Ru Li, Lilee Systems

  3. System Architecture Office segment Dispatch System Back office Server Communication segment Locomotive segment Wayside segment Jia-Ru Li, Lilee Systems

  4. System Architecture (4 Segments) • Central Traffic Segment: • Dispatching service, central monitoring, back office servers • Locomotive Segment: • On-board train control computer, braking curve, movement authority • Wayside Segment: • Track switches, railroad crossing, signals • Communication Segment: • Mission critical radio that requires a standards committee to select “best of the breed” technology and a common air interface • IEEE LMSC has track records in creating standards for millions of devices to interoperate. (Bluetooth, WIFI, WIMAX, etc) Jia-Ru Li, Lilee Systems

  5. Comm for Office/Locomotive/Wayside Back Office Server Temp Speed Restriction Network Mgmt Service Database Maintenance Dispatcher Metro Ether Router Office Field Loco-motive BS BS BS BS BS BS WS WS WS fiber Jia-Ru Li, Lilee Systems

  6. Real World Validation in Rain & Fog Mobile (3 watt) Base station Mobile (10 watt) 10 miles 10 miles 19.2 miles 19.2 miles Both uses 3 dbi Omni Antenna(5ft), cable 15 ft Jia-Ru Li, Lilee Systems

  7. PTC Radio Interface Requirement • Supports various modulation (ex: GMSK, QPSK ….) • Supports Forward Error Correction (FEC) • Supports different channel spacing, different carrier • Supports link layer fragmentation • Supports • QoS (11e) • Link Layer Security (11i) • Supports higher mobility speed than conventional WIFI • Supports 64 time slot/sec (optional to support 128 slots/sec) • Supports priority-based association (Hi/Lo contention slots) • Supports Asymmetric uplink/downlink speeds • Handover (Pre-auth) • Link measurement (11k) Jia-Ru Li, Lilee Systems

  8. PHY using GMSK Jia-Ru Li, Lilee Systems

  9. PHY using QPSK Jia-Ru Li, Lilee Systems

  10. Low MAC protocol (CSMA/TDMA hybrid) 1 second 16 slots 16 slots 16 slots 16 slots 16 9 13 5 16 2 9 6 13 5 10 2 9 14 6 13 3 10 2 7 14 6 11 3 4 10 15 7 1 14 11 3 8 12 4 15 7 1 1 5 11 16 8 12 4 15 8 12 5 16 9 13 2 6 10 14 3 7 1 11 4 15 8 12 data slot Beacon contention slot # show basestation ptc station_table station slot type tx/rx self cast CRC error time to expired (ms) ========================================================================================= beacon 00-00 0 T 1 1 0 never 01 01-01 3 T 1 0 0 47258 02 02-02 3 T 1 0 0 57852 …… 30 30-30 3 T 1 0 0 48584 brdcst 31-31 3 T 1 1 0 never Reg-Hi 32-32 3 R 1 0 0 never 01 33-33 3 R 1 0 0 41474 02 34-34 3 R 1 0 0 53135 …… 28 60-60 3 R 1 0 0 48179 29 61-61 3 R 1 0 0 56440 30 62-62 3 R 1 0 0 52599 Reg-Lo 63-63 3 R 1 0 0 never ========================================================================================= TransAir mode Jia-Ru Li, Lilee Systems

  11. High MAC protocol CRC-16 implementation • High MAC support • Beacon • Probe request/response • Association/Authentication • Hand off request/response • Action Frame • Support MIB & PICS • Station table • Based on Std 802.11-2007 Association State Machine Jia-Ru Li, Lilee Systems

  12. Link Level Fragmentation 1500 byte = 13 fragment takes 27s for round trip 56 byte = 1 fragment takes 500 ms for round trip 1500 bytes (or bigger) IP/TCP Session Payload crc # ping -s 1500 10.3.10.1 PING 10.3.10.1 (10.3.10.1) 1500(1528) bytes of data. 1508 bytes from 10.3.10.1: seq=0 ttl=255 time=26728 ms 1508 bytes from 10.3.10.1: seq=1 ttl=255 time=26152 ms 1508 bytes from 10.3.10.1: seq=2 ttl=255 time=26024 ms 1508 bytes from 10.3.10.1: seq=3 ttl=255 time=26772 ms 1508 bytes from 10.3.10.1: seq=4 ttl=255 time=26966 ms 1508 bytes from 10.3.10.1: seq=5 ttl=255 time=26724 ms 1508 bytes from 10.3.10.1: seq=6 ttl=255 time=26952 ms 1508 bytes from 10.3.10.1: seq=7 ttl=255 time=26956 ms 1508 bytes from 10.3.10.1: seq=8 ttl=255 time=26238 ms 1508 bytes from 10.3.10.1: seq=9 ttl=255 time=26384 ms 1508 bytes from 10.3.10.1: seq=10 ttl=255 time=26466 ms # ping –s 56 10.3.10.1 PING 10.3.10.1 (10.3.10.1) 56(84) bytes of data. 64 bytes from 10.3.10.1: seq=0 ttl=255 time=420 ms 64 bytes from 10.3.10.1: seq=1 ttl=255 time=435 ms 64 bytes from 10.3.10.1: seq=2 ttl=255 time=492 ms 64 bytes from 10.3.10.1: seq=3 ttl=255 time=539 ms 64 bytes from 10.3.10.1: seq=4 ttl=255 time=535 ms 64 bytes from 10.3.10.1: seq=5 ttl=255 time=404 ms 64 bytes from 10.3.10.1: seq=6 ttl=255 time=494 ms 64 bytes from 10.3.10.1: seq=7 ttl=255 time=496 ms 64 bytes from 10.3.10.1: seq=8 ttl=255 time=516 ms 64 bytes from 10.3.10.1: seq=9 ttl=255 time=528 ms 64 bytes from 10.3.10.1: seq=10 ttl=255 time=542 ms Jia-Ru Li, Lilee Systems

  13. Standards based Security – 802.1x (11i) Jia-Ru Li, Lilee Systems

  14. Standardization Drives Volume • History tells us the 2nd hump comes from standardization • It helps the customer to gain confidence in a given technology and willing to invest engineering resources • Standardization helps other industries to adopt the same technology and drive more usage cases • It usually happens 2-3 years after initial usage Jia-Ru Li, Lilee Systems

  15. ERTMS (European Rail Traffic Management System)http://en.wikipedia.org/wiki/European_Rail_Traffic_Management_System • The two main components of ERTMS • ETCS (European Train Control System) - a standard for on-board train control( http://en.wikipedia.org/wiki/European_Train_Control_System) •  GSM-R – GSM standard modified for railway operations • Specification • Modulation is GMSK . FDD duplex • TDMA frames with a period of 4.615 ms. Each TDMA frame is divided in 8 time-slots (577 µs each), carrying 148 bits • Frequency Band • In Europe — 876 MHz — 880 MHz: data transmission (uplink) — 921 MHz — 925 MHz: data reception (downlink) • In China: a 4 MHz of the E-GSM band (900 MHz-GSM) • In Australia, it is being implemented using 1800MHz band Jia-Ru Li, Lilee Systems

  16. Radio Interoperability Requirement[6] • Interoperability is achieved through an open, peer reviewed process • IEEE selects best of breed technology with cost maturity in mind • IEEE provides long term spec maintenance & administration • Interoperable mechanisms • By single vendor – Limited competition. High risk and high cost • By closed industry consortium – Not enough radio experts or researchers • By open Industry consortium (eg. ERTMS[4]) – allow peer reviews • By standards body(eg. IEEE) – allow diff industry to share spec (rail & sensor) • By national body(ANSI, ITU) – allow countries to adopt as national standard • Ultimate Goal: Interchangeability – allows end users to select different vendors’ products based on the same industry standards. • Interchangeability supports free market response Jia-Ru Li, Lilee Systems

  17. Why IEEE and LMSC? • Rail related standards AREMA/AAR/ITC[5] (similar to ETCS) Radio related standard  IEEE (similar to GSM-R) • Reuse mature technology from IEEE LMSC WGs • Association, Beacon, Information Element, interface MIB • Authentication, security (802.1x, 802.11i), 4-way handshake • PICS (Protocol Implementation Conformance Statement proforma) • Small modification to low MAC and PHY • CSMA+TDMA hybrid • BPSK/QPSK with GMSK for backward compatibility • Full duplex or half duplex • TDD (similar to WIFI) • Meets different FCC subpart rules Jia-Ru Li, Lilee Systems

  18. Relationship with existing TG/WG • S1G: Study Group Sub 1 GHz Operation • Study to determine if PTC requirement is already included in S1G • If not, add PTC requirement into PAR and 5C • TGaf : TV White Spaces • meet the legal requirements for channel access and coexistence in the TV White Space • TGae:  Prioritize 802.11 management frames  • Defines mechanisms for sending the PTC management frame using existing mechanisms for medium access • Decide if new SG/Adhoc group should be established to facilitate the Congressional mandate (RSIA’08) Jia-Ru Li, Lilee Systems

  19. Straw Poll #1 • Do you think 0WNG should invite various industry experts in railroad and others (eg. sensor) to provide more information about requirements? • Agree: • Disagree: • Abstain: Jia-Ru Li, Lilee Systems

  20. Straw Poll #2 • Assuming the results of Straw Poll #1 are affirmative, do you agree that the IEEE 802.11 WG should form a study group to pursue this task? • Agree: • Disagree: • Abstain: Jia-Ru Li, Lilee Systems

  21. References • RSIA’08 - Summary of the Rail Safety Improvement Act of 2008 http://www.fra.dot.gov/downloads/RSIA%20Overview%20031009.pdf • PTC - Positive train control http://en.wikipedia.org/wiki/Positive_train_control • ACSES - Advanced Civil Speed Enforcement System http://en.wikipedia.org/wiki/ACSES • ERTMS - European Rail Traffic Management system http://en.wikipedia.org/wiki/European_Rail_Traffic_Management_System • ITC Draft Standards http://aar-x.arinc.net • Interoperable Positive Train Control http://www.billpetit.com/Papers/2009%20AREMA%20Conf/Petit_2009_AREMA_ICBS_Paper_V2.pdf • Signal and Train Control http://www.fra.dot.gov/downloads/research/PTC_Technical.pdf Jia-Ru Li, Lilee Systems

More Related