Systems and methods for interoperability positive train control

• US 20110075641A1
• Filed: 09/23/2010
• Published: 03/31/2011
• Est. Priority Date: 09/25/2009
• Status: Active Grant

• Current Assignee: MeteorComm LLC (Berkshire Hathaway Incorporated)
• Original Assignee: MeteorComm LLC (Berkshire Hathaway Incorporated)
• Inventors: Siriwongpairat, Wipawee, Himsoon, Thanongsak
• Granted Patent: US 8,340,056 B2
• Time in Patent Office: Days
• US Class Current: 370/337
• CPC Class Codes: B61L 27/70 Details of trackside communication
• CPC Class Codes: H04W 4/12 Messaging; Mailboxes; Announcements

Abstract

A method for implementing communications in a railroad communications system having a base station radio and remote radios, the remote radios including a mobile radio and a wayside radio. The method includes assigning a common radio communications channel for allowing a remote radio to connect with the base station radio using a carrier sense multiple access (CSMA) communications protocol and assigning a local channel for allowing communications between the radio base station and the remote radios and between the remote radios, wherein communications on the local channel utilizes a selected one of fixed time division multiple access (FTDMA) and dynamic time division multiple access (DTDMA) communications protocols.

Claims

1. A method for implementing communications in a railroad communications system having a base station radio and remote radios, the remote radios including a mobile radio and a wayside radio, comprising:

assigning a common radio communications channel for allowing a remote radio to connect with the base station radio using a carrier sense multiple access (CSMA) communications protocol; and

assigning a local radio communications channel for allowing communications between the base station radio and the remote radios and between the remote radios, wherein communications on the local channel utilizes a selected one of fixed time division multiple access (FTDMA) and dynamic time division multiple access (DTDMA) communications protocols.

2. The method of claim 1, wherein communications on the local channel are organized as superframes, wherein each superframe includes a FTDMA cycle comprising a plurality of time slots each for transmitting a packet and at least one DTDMA cycle comprising a plurality of slots each for transmitting a packet.

3. The method of claim 2, wherein a DTDMA cycle comprises:

at least one control slot for transmitting a control packet from the base station radio for controlling the slot assignments in the DTDMA cycle;

a selected number of slots assigned by the base station radio in the control packet for transmitting packets from the base station; and

a selected number of slots assigned by the base station radio in the control packet for transmitting packets from a selected one of the remote radios.

4. The method of claim 3, wherein the DTDMA cycle further comprises a selected number of CSMA slots for allowing a selected remote radio to transmit packets to the base station radio using a CSMA communications protocol.

5. The method of claim 4, wherein at least some of the CSMA slots are assigned for transmission of packets carrying high priority information.

6. The method of claim 2, wherein the FTDMA cycle is utilized for transmitting periodic information.

7. The method of claim 6, wherein the periodic information is selected from the group consisting of base station timing signals transmitted by the base station radio and wayside status information transmitted from the wayside radio.

8. The method of claim 2, wherein the superframe includes a plurality of DTDMA cycles, wherein a first DTDMA cycle is controlled by a first base station radio and a second DTDMA cycle is controlled by a second base station radio.

9. The method of claim 4, wherein a selected remote radio utilizes a selected number of the CSMA slots to obtain slot assignments in a DTDMA cycle from the base station radio by transmitting a queue status packet.

10. The method of claim 9, wherein the queue status packet indicates an amount and priority of information for transmission by a corresponding remote radio.

11. A method of messaging in a railroad communications system comprising:

generating a message with at an application layer implemented in a message processing system, the message associated with a message handling code;

passing the message and the message handling codes to a transport layer implemented within the message processing system;

fragmenting the message into a least one fragment at the transport layer;

passing the fragmented message and message handling codes to a network layer implemented within the message processing system;

selectively segmenting the fragmented message at the network layer as indicated by the message handling code;

passing the selectively segmented message and the message handling code to a link layer implemented within the message processing system;

forming a packet from the selectively segmented at the link layer, the packets including packet type information and data parts;

passing the packet to a physical layer implemented within the message processing system;

adding a preamble to the packet at the physical layer; and

transmitting the preamble and packet with a radio forming a part of the message processing system.

12. The method of messaging of claim 11, wherein:

the application layer is implemented on a host processor forming a part of the message processing system;

the transport layer is implemented with a link manager running on an associated processor forming a part of the message processing system; and

the network, link, and physical layers are implemented by the radio.

13. The method of messaging of claim 11, wherein the transport layer further provides time slot configuration information for use by the link layer for forming the packet.

14. The method of messaging of claim 11, wherein the link layer is further operable to perform forward error correction encoding on the data parts of the packet in response to the message handling code.

15. The method of messaging of claim 11, wherein the preamble includes a bit synchronization pattern and a frame synchronization pattern.

16. The method of messaging of claim 11, wherein transmitting comprises selectively transmitting using a selected one of fixed time division multiple access, dynamic time division multiple access, and carrier sense multiple access protocols in response to the message handling code.

17. The method of messaging of claim 11, further comprising:

receiving the preamble and the packet with a destination radio;

detecting the preamble with a physical layer implemented on the destination message processing system;

passing the packet to a link layer implemented on the destination message processing system;

validating the packet at the link layer implemented on the destination message processing system;

selectively performing forward error correction decoding on the data part of the validated packet in response to the packet type information at the link layer on the destination message processing system;

passing the selectively decoded data part of the validated packet and data handling information from the packet type information to a network layer implemented on the destination message processing system, wherein the decoded part of the packet comprises a data fragment at the network layer;

selectively routing the data fragment and the data handling information to a transport layer implemented on a selected processor at a selected destination node;

forming a message at the transportation layer implemented on the selected processor at the selected destination node to form a message; and

passing the message to an application layer running on a selected processor at the destination node.

18. The method of claim 16, wherein:

the physical, link, and transport layers implemented at the destination message processing system are implemented within the destination radio;

the transport layer is implemented by a link management processor; and

the application layer is implemented on a host processor at the destination node.

19. The method of claim 16, wherein validating the radio transmission packets comprises performing a cyclic redundancy check (CRC) on CRC data transmitted with each packet.

20. The method of claim 14, wherein performing forward error correction encoding comprises performing forward error correction encoding on the data parts of the radio frequency packets and interleaving resulting encoded data blocks.

21. The method of claim 16, wherein selectively performing forward error correction decoding on the data part of the radio transmission packets comprises de-interleaving encoded blocks within each radio transmission packet and decoding resulting de-interleaved encoded blocks.

22. The method of claim 16, wherein the link layer of the destination message processing system passes decoded data to the network layer of the destination message processing system and the network layer of the destination message processing system assembles the segments into the data fragment.

23. The method of claim 11, wherein generating a message with at an application layer implemented in a message processing system further comprises associating the message with a priority code.

24. The method of claim 23, wherein the time domain multiple access protocol is selected from the group consisting of fixed time division multiple access (FTDMA) and dynamic time division multiple access (DTDMA) communications protocols.

25. The method of claim 23, wherein transmissions on the common radio frequency channel are implemented using a carrier sense multiple access (CSMA) communications protocol.

26. The method of claim 23, wherein the remote radio connects with the base station radio across a local channel by:

periodically transmitting a base beacon packet from the base station radio on the common channel;

counting a number of base beacon packets received by the remote radio;

measuring a signal strength of a signal transmitting the base beacon packets with the remote radio; and

connecting the remote radio to the base station radio when at least one of a count of the number of base beacon packets received by the remote radio and the signal strength exceeds a predetermine threshold.

27. The method of claim 24, further comprising maintaining a connection between the base station radio and the remote radio when a ratio between the signal strength and a number of acknowledgement packets received by the remote radio from the base station radio exceeds a predetermined threshold.

28. The method of claim 23, wherein the system comprises a plurality of base station radios each assigned a corresponding local channel and each broadcasting a base beacon signal on a selected on of the corresponding local channel and the common channel, wherein the plurality of base station radios coordinate transmissions on the common channel to mitigate interference and wherein the remote radio selects a base station to connect to via the corresponding local channel in response to the base beacon signals transmitted on the common channel.

29. The method of claim 23, wherein the remote radio is selected from the group consisting of a mobile radio on a locomotive and a wayside radio.

30. The method of claim 24, wherein the remote comprises a wayside radio and the method further comprises periodically sending wayside status messages in the corresponding assigned cycles using the FTDMA protocol.

31. The method of claim 24, wherein the system comprises a plurality of remote radios including a locomotive radio and a wayside radio and the method further comprises:

selectively transmitting a request for status from the locomotive radio to the wayside radio on the local radio communications channel using the CSMA protocol; and

in response to the request for status, transmitting a wayside status message from the wayside radio to the locomotive radio on the local radio communications channel using the CSMA protocol.

32. The method of claim 30, further comprising repeating the wayside status messages with a selected one of another base station or another wayside radio.

33. The method of claim 30, wherein the wayside radio is operable to filter out received wayside status messages.

23-1. A method for implementing communications in a railroad communications system having a base station radio and remote radio, comprising:

assigning a common radio communications channel for allowing a remote radio to connect with the base station radio; and

assigning a local radio communications channel allowing the base station radio and the remote radio to transmit in corresponding assigned cycles under a time domain multiple access protocol.

34. A system for implementing railroad communications comprising:

a base station radio and a plurality of remote radios communicating via a local channel controlled by the base station, wherein the base station radio is operable to;

dynamically assign a selected number of slots within a dynamic time division multiple access (DTDMA) cycle for transmission of packets by the base station radio and by selected ones of the remote radios, the slot assignments being transmitted to the remote radios by a control packet transmitted at the start of the DTDMA cycle; and

receiving a request for slots in a DTDMA cycle from a selected one of the remotes using carrier sense multiple access (CSMA) transmissions within CSMA slots dynamically assigned in the DTDMA cycle by the base station.

35. The system of claim 34, wherein the DTDMA cycle is one of a plurality of DTDMA cycles organized in a superframe, the superframe including a fixed time division multiple access (FTDMA) cycle of a fixed number of slots for implementing periodic transmissions by a selected one of the remote radios.

36. The system of claim 34, wherein the base station and the remote radios are further operable to communicate using CSMA via a common channel.

37. The system of claim 36, wherein selected remote radios are operable to implement peer-to-peer communications using CSMA via the common channel.

38. The method of claim 36, wherein a selected remote is operable to establish a connection with the base station radio by:

receiving base beacon signals on a selected one of the local channel and a common channel;

selecting the base station radio from a plurality of base station radios in response to information carried by the base beacon signals; and

transmitting a queue status packet to the base station radio in the local channel.

39. The method of claim 35, wherein the base station radio controls the DTDMA cycle within the superframe and another base station radio controls another DTDMA cycle within the superframe.

40. The method of claim 34, wherein the base station radio dynamically assigns slots in the DTDMA cycle by:

receiving queue status packets from selected remote radios, a queue status packet from a selected one of the remote radios indicating a number of segments and priority of each segment in a transmit queue at that remote radio; and

selectively increasing and decreasing a number of slots assigned to the remote radio based on the number of segments and the priority of each segment in the transmit queue of each of the selected remote radios.

41. The method of claim 40, wherein selected remote radios having assigned slots transmit queue status packets in corresponding assigned slots in the DTDMA cycle.

42. The method of claim 40, wherein selected remote radios having segments to transmit and without currently assigned slots transmit queue status packets using CSMA transmissions in the CSMA slots provided by the base station radio in the DTDMA cycle to request slots.

43. The method of claim 42, wherein selected remote radios having high priority segments to transmit and without currently assigned slots transmit queue status packets using CMSA transmissions in ones of the CSMA slots provided by the base station radio in the DTDMA cycle for high priority requests for slots.

44. The method of claim 34, wherein the remote radios comprise a locomotive radio and a wayside radio, wherein said base station, locomotive, and wayside radios receive packets using a waveform selected from the group consisting of 4 FM and Pi/4 DQPSK waveforms.

45. The method of claim 44, wherein said base station and locomotive radios transmit packets using a selected one of the 4 FM and Pi/4 DQPSK waveforms and the wayside radio transmits using the 4 FM waveforms.

46. The method of claim 34, wherein the remote radios comprise a multiple channel wayside radio operable to:

set a selected wayside radio channel to a common channel;

receive base beacon signals from a plurality of base station radios via the common channel;

in response to information carried by the base beacon signals, selecting the base station radio for establishing a connection; and

a setting another radio channel to the local channel controlled by the base station radio to establish the connection.

47. The method of claim 34, wherein the remote radios comprise a multiple channel locomotive radio operable to:

set a selected locomotive radio channel to a common channel;

set other locomotive radio channels to default local channels;

receive base beacon signals from a plurality of base station radios via the common channel;

in response to information carried by the base beacon signals, selecting the base station radio for establishing a connection; and

setting a locomotive radio receive channel to the local channel controlled by the base station radio to establish the connection; and

setting remaining locomotive radio receive channels to neighbor base station radio channels identified by the information carried by the base beacon signal for the base station radio.

48. The method of claim 34, wherein the base station radio is operable to:

set a selected base station radio channel to a common channel;

set another selected base station radio channel to the radio base station local channel; and

set remaining base station radio channels to local channels of neighbor base station local channels.