Implicit message sequence numbering for locomotive remote control system wireless communications

1. A method for providing wireless communications between a locomotive control unit (LCU) on board a locomotive and a portable operator control unit (OCU) for use in controlling operation of the locomotive from an off-board location comprising:

calculating a transmit bit error check value for a wireless message that includes an explicit sequence number assigned to the message so that the explicit sequence number is implicitly encoded in the transmit bit error check value; and

transmitting an encoded message between the OCU and the LCU with the transmit bit error check value and without the explicit sequence number effective to reduce a total amount information needed to be transmitted compared to a message including the explicit sequence number.

2. The method of claim 1 , wherein the bit error check value comprises a cyclical redundancy check (CRC) value.

3. The method of claim 1 , further comprising receiving, at the OCU, a relink message from the LCU comprising a relink sequence number.

4. The method of claim 3 , further comprising updating a current explicit sequence number maintained by the OCU with the relink sequence number when the relink sequence number is greater than the current explicit sequence number.

5. The method of claim 1 , further comprising receiving the encoded message at the LCU and validating the encoded message according to the transmit bit error check value and an expected sequence number for the encoded message.

6. The method of claim 5 , wherein the expected sequence number comprises a number based on an initial number provided to the OCU by the LCU during a linking procedure.

7. The method of claim 5 , further comprising, when the encoded message has been validated, incrementing the expected sequence number.

8. The method of claim 5 , further comprising, when the explicit sequence number of the encoded message is less than the expected sequence number, ignoring the message.

9. The method of claim 5 , wherein the expected sequence number is greater than a sequence number of a previously received message.

10. The method of claim 5 , further comprising establishing a plurality of expected sequence numbers incrementally extending from the expected sequence number.

11. The method of claim 5 , further comprising, when the encoded message cannot be validated according to the expected sequence number, incrementing the expected sequence number.

12. The method of claim 11 , further comprising validating the encoded message according to the transmit bit error check value and an incremented expected sequence number for the encoded message.

13. The method of claim 12 , further comprising, when a message cannot be validated after a desired number of cycles of incrementing the expected sequence number and attempting to validate the encoded message, ignoring the message.

14. The method of claim 5 , wherein validating comprises truncating the transmit bit error check value from the encoded message.

15. The method of claim 14 , further comprising appending the expected sequence number to a truncated encoded message.

16. The method of claim 15 , further comprising calculating a receipt bit error check value for the truncated encoded message and an appended expected sequence number.

17. The method of claim 16 , further comprising comparing the transmit bit error check value to the receipt bit error check value to validate the transmitted message.

18. A method for providing wireless digital communications between a locomotive control unit (LCU) on board a locomotive and a portable operator control unit (OCU) for use in controlling operation of the locomotive from an off-board location comprising:

calculating a transmit bit error check value for a wireless digital message that includes bits for an explicit sequence number assigned to the message so that the sequence number is implicitly encoded in the bit error check value;

transmitting the message from the OCU to the LCU with calculated bit error check value and without the explicit sequence number bits effective to reduce a total amount bits needed to be transmitted compared to a number of bits of a message explicitly including the sequence number;

receiving the encoded message at the OCU and validating the encoded message according to the transmit bit error check value and an expected sequence number for the encoded message.

19. The method of claim 18 , wherein validating comprises:

calculating a receipt bit error check value for the encoded message that includes the expected sequence number but does not include the transmit bit error check value; and

comparing the receipt bit error check value to the transmit bit error check value to validate the transmitted message.

20. The method of claim 18 , wherein the bit error check value comprises a cyclical redundancy check (CRC) value.

21. A system for providing wireless communications between a locomotive control unit (LCU) on board a locomotive and a portable operator control unit (OCU) for use in controlling operation of the locomotive from an off-board location comprising:

an OCU comprising:

an OCU processor;

OCU programmed logic operable with the OCU processor for calculating a bit error check value for a wireless message that includes an explicit sequence number assigned to the message and for generating an encoded message with the transmit bit error check value and without the explicit sequence number;

an OCU transceiver in communication with the OCU processor for transmission of the encoded message;

an LCU comprising:

an LCU transceiver for receiving the encoded message;

an LCU processor in communication with the transceiver; and

LCU programmed logic operable with the LCU processor for validating the encoded message according to the transmit bit error check value and an expected sequence number for the encoded message.

22. The system of claim 21 , wherein the bit error check value comprises a cyclical redundancy check (CRC) value.