ARQ combining holdoff system and method

• US 20030177429A1
• Filed: 03/18/2002
• Published: 09/18/2003
• Est. Priority Date: 03/18/2002
• Status: Active Grant

• Current Assignee: North South Holdings Incorporated (Spherix Incorporated)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Voglewede, Paul E., Hessel, Clifford
• Granted Patent: US 7,036,065 B2
• Time in Patent Office: Days
• US Class Current: 714/751
• CPC Class Codes: H03M 13/33 Synchronisation based on error coding or decoding
• CPC Class Codes: H03M 13/3769 using symbol combining, e.g. Chase combining of symbols received twice or more
• CPC Class Codes: H03M 13/3961 Arrangements of methods for branch or transition metric calculation
• CPC Class Codes: H03M 13/41 using the Viterbi algorithm or Viterbi processors
• CPC Class Codes: H03M 13/6306 Error control coding in combination with Automatic Repeat reQuest [ARQ] and diversity transmission, e.g. coding schemes for the multiple transmission of the same information or the transmission of incremental redundancy H03M13/3761, H03M13/3769 and H03M13/635 take precedence
• CPC Class Codes: H03M 13/6325 Error control coding in combination with demodulation
• CPC Class Codes: H04L 1/0047 Decoding adapted to other signal detection operation in conjunction with sequence estimation or equalization H04L25/03286
• CPC Class Codes: H04L 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/1845 Combining techniques, e.g. code combining

Abstract

A system and method for demodulating a data packet in an automatic repeat request communication system is disclosed. Specifically, in a communication system that combines the energy of an initially transmitted data packet with the energy of a retransmitted version of the data packet, the inventive system and method measures the “usability” of the initially transmitted data packet that fails an error-checking procedure and the “usability” of a retransmitted version of the data packet. If the initially transmitted version and the retransmitted version of the data packet are both “usable”, the energies of the data packets are combined. The combined data packet is then subjected to the error-checking procedure. If the combined data packet fails the error-checking procedure, the energy of either the combined packet or the retransmitted packet is stored for later combination with a subsequently-retransmitted version of the data packet.

Claims

1. A method of receiving a signal containing an encoded data packet in an ARQ-enabled communication system transmitting packetized data from a transmitter to a receiver comprising the steps of:

(a) receiving, demodulating, and error checking said signal;

(b) performing a usability check on said encoded data packet in said signal in response to an error condition in the error-checking step;

(c) storing said encoded data packet in response to a positive usability condition;

(d) receiving a retransmission of the encoded data packet;

(e) combining the stored data packet with the retransmitted data packet; and

(f) demodulating the combined data packet to thereby receive said signal containing the encoded data packet.

2. The method of claim 1 wherein the usability check comprises a comparison of minimum and maximum path metrics of a short viterbi decoder.

3. The method of claim 1 wherein the step of combining data packets comprises coherently adding the data packets.

4. The method of claim 1 wherein the ARQ-enabled communication system is a traceback system.

5. The method of claim 1 wherein the ARQ-enabled communication system is a stop-and-wait system.

6. The method of claim 1 wherein step (a) includes the following step:

(i) in response to a no error condition in the error-checking step of said encoded data packet, sending an acknowledgement signal from the receiver to the transmitter.

7. The method of claim 6 replacing step (f) with the following steps:

(f) demodulating the combined data packet; and

(g) repeating steps (b) through (f) using the combined data packet as the encoded data packet until an acknowledgment signal is sent from the receiver to the transmitter to thereby receive said data packet at the receiver.

8. The method of claim 1 wherein steps (b) and (c) are replaced with the following steps:

(b) in response to an error condition in the error-checking step of said encoded data packet, performing the following steps;

(i) sending a negative acknowledgment signal from the receiver to the transmitter; and

(ii) performing a usability check on said encoded data packet;

(1) in response to a positive usability condition in the usability-checking step of said encoded data packet, storing said encoded data packet at the receiver to thereby create a first stored data packet if no first stored data packet exists, otherwise storing said second stored data packet from step (e) as said first stored data packet; and

(2) in response to a non-positive usability condition in the usability-checking step of said encoded data packet, discarding said encoded data packet.

9. The method of claim 8 wherein step (e) comprises the following steps:

(i) copying said retransmitted encoded data packet and storing said copy of said retransmitted encoded data packet to thereby create a second stored data packet; and

(ii) combining said retransmitted encoded data packet with said first stored data packet to thereby create a combined data packet if said first stored data packet exists, otherwise using said retransmitted data packet as said combined data packet.

10. The method of claim 1 wherein steps (b) and (c) are replaced with the following steps:

(b) in response to an error condition in the error-checking step of said encoded data packet, performing the following steps;

(i) sending a negative acknowledgment signal from the receiver to the transmitter; and

(ii) performing a usability check on said encoded data packet;

(1) in response to a positive usability condition in the usability-checking step of said encoded data packet, storing said encoded data packet at the receiver to thereby create a first stored data packet; and

(2) in response to a non-positive usability condition in the usability-checking step of said encoded data packet, discarding said encoded data packet.

11. The method of claim 10 wherein step (e) comprises the following steps:

(i) receiving at the receiver a retransmission of said encoded data packet contained in said signal in step (a) in response to receipt at the transmitter of said negative acknowledgement signal; and

(ii) combining said retransmitted encoded data packet with said first stored data packet to thereby create a combined data packet if said first stored data packet exists, otherwise using said retransmitted data packet as said combined data packet.

12. A receiver for receiving a signal containing an encoded data packet in an ARQ-enabled communication system transmitting packetized data from a transmitter to a receiver comprising:

(a) a demodulator and error checking means for demodulating and error checking a received signal containing an encoded data packet;

(b) usability checking means for performing a usability check on said encoded data packet in response to an error condition output from said error-checking means;

(c) memory for storing said encoded data packet in response to a positive usability condition; and

(d) combining means for combining the stored data packet with a received retransmitted data packet,

whereby the demodulator demodulates the combined data packet to thereby receive said signal containing the encoded data packet.

13. The receiver of claim 12 wherein the usability checking means includes a short viterbi decoder.

14. The receiver of claim 13 wherein the short viterbi decoder compares the minimum and maximum path metrics.

15. The receiver of claim 12 wherein the step of combining data packets comprises coherently adding the data packets.

16. The receiver of claim 12 wherein the ARQ-enabled communication system is a traceback system.

17. The method of claim 12 wherein the ARQ-enabled communication system is a stop-and-wait system.

18. A method of communicating a signal containing an encoded data packet in an ARQ-enabled communication system transmitting packetized data from a transmitter to a receiver comprising the steps of:

(a) receiving said signal containing an encoded data packet at the receiver;

(b) demodulating said received signal;

(c) performing an error check on said encoded data packet;

(i) in response to a no error condition in the error-checking step of said encoded data packet, sending an acknowledgement signal from the receiver to the transmitter;

(ii) in response to an error condition in the error-checking step of said encoded data packet, performing the following steps;

(1) sending a negative acknowledgment signal from the receiver to the transmitter;

(2) performing a usability check on said encoded data packet;

(A) in response to a positive usability condition in the usability-checking step of said encoded data packet, storing said encoded data packet at the receiver to thereby create a first stored data packet if no first stored data packet exists, otherwise storing said second stored data packet from step (c)(ii)(4) as said first stored data packet;

(B) in response to a non-positive usability condition in the usability-checking step of said encoded data packet, discarding said encoded data packet;

(3) receiving at the receiver a retransmission of said encoded data packet contained in said signal in step (a) in response to receipt at the transmitter of said negative acknowledgement signal;

(4) copying said retransmitted encoded data packet and storing said copy of said retransmitted encoded data packet to thereby create a second stored data packet;

(5) combining said retransmitted encoded data packet with said first stored data packet to thereby create a combined data packet if said first stored data packet exists, otherwise using said retransmitted data packet as said combined data packet;

(6) demodulating said combined data packet;

(d) repeating step (c) using the combined data packet as the encoded data packet until an acknowledgment signal is sent from the receiver to the transmitter to thereby communicate said data packet from the transmitter to the receiver.

19. A method of communicating a signal containing an encoded data packet in an ARQ-enabled communication system transmitting packetized data from a transmitter to a receiver comprising the steps of:

(a) receiving said signal containing an encoded data packet at the receiver;

(b) demodulating said received signal;

(c) performing an error check on said encoded data packet;

(i) in response to a no error condition in the error-checking step of said encoded data packet, sending an acknowledgement signal from the receiver to the transmitter;

(ii) in response to an error condition in the error-checking step of said encoded data packet, performing the following steps;

(1) sending a negative acknowledgment signal from the receiver to the transmitter;

(2) performing a usability check on said encoded data packet;

(A) in response to a positive usability condition in the usability-checking step of said encoded data packet, storing said encoded data packet at the receiver to thereby create a first stored data packet;

(B) in response to a non-positive usability condition in the usability-checking step of said encoded data packet, discarding said encoded data packet;

(3) receiving at the receiver a retransmission of said encoded data packet contained in said signal in step (a) in response to receipt at the transmitter of said negative acknowledgement signal;

(4) combining said retransmitted encoded data packet with said first stored data packet to thereby create a combined data packet if said first stored data packet exists, otherwise using said retransmitted data packet as said combined data packet;

(5) demodulating said combined data packet;

(d) repeating step (c) using the combined data packet as the encoded data packet until an acknowledgment signal is sent from the receiver to the transmitter to thereby communicate said data packet from the transmitter to the receiver.

20. A method of communicating a signal containing an encoded data packet in an ARQ-enabled communication system transmitting packetized data from a transmitter to a receiver comprising the steps of:

(a) receiving, demodulating, and error checking said signal;

(b) performing a usability check on said encoded data packet in said signal in response to an error condition in the error-checking portion of step (a);

(c) storing said encoded data packet in response to a positive usability condition;

(d) receiving and error checking a retransmission of the encoded data packet;

(e) combining the stored data packet with the retransmitted data packet in response to an error condition in the error checking portion of step (d), otherwise transmit an acknowledgement from the receiver to the transmitter;

(f) error checking the combined data packet;

(g) performing a usability check on said combined data packet in response to an error condition in step (f), otherwise transmit an acknowledgement from the receiver to the transmitter; and

(h) repeating steps (d) through (g) until an acknowledgement is sent thereby transmitting said encoded data packet from the transmitter to the receiver.

21. The method of claim 20 wherein one of the usability checks comprises a comparison of minimum and maximum path metrics of a short viterbi decoder.

22. The method of claim 20 wherein the step of combining data packets comprises coherently adding the data packets.

23. The method of claim 20 wherein the ARQ-enabled communication system is a traceback system.

24. The method of claim 20 wherein the ARQ-enabled communication system is a stop-and-wait system.

25. A communication system for transmitting a signal containing an encoded data packet in an ARQ-enabled communication system transmitting packetized data from a transmitter to a receiver comprising:

(a) a receiver for receiving, demodulating, and error checking said signal;

(b) usability checking means for performing a usability check on said encoded data packet in said signal in response to an error condition in the error-checking portion of step (a);

(c) memory for storing said encoded data packet in response to a positive usability condition;

(d) said receiver for receiving and error checking a retransmission of the encoded data packet;

(e) combining means for combining the stored data packet with the retransmitted data packet in response to an error condition in the error check of the retransmission of the encoded data packet;

(f) transmitter means at the receiver for transmitting an acknowledgement from the receiver to the transmitter in response to a no-error condition in the error check of the retransmission of the encoded data packet;

(g) said error checking means for error checking the combined data packet;

(h) said usability checking means for performing a usability check on said combined data packet in response to an error condition in step (g);

(i) said transmitter means for transmitting an acknowledgement from the receiver to the transmitter in response to a no-error condition in the error check of the retransmission of the encoded data packet; and

(j) means for repeating steps (d) through (g) until an acknowledgement is sent thereby transmitting said encoded data packet from the transmitter to the receiver.

26. The receiver of claim 25 wherein the usability checking means includes a short viterbi decoder.

27. The receiver of claim 26 wherein the short viterbi decoder compares the minimum and maximum path metrics.

28. The receiver of claim 25 wherein the step of combining data packets comprises coherently adding the data packets.

29. The receiver of claim 25 wherein the ARQ-enabled communication system is a traceback system.

30. The method of claim 25 wherein the ARQ-enabled communication system is a stop-and-wait system.

31. A method of communicating a signal containing an encoded data packet in an ARQ-enabled communication system transmitting packetized data from a transmitter to a receiver comprising the steps of:

(a) receiving said signal containing an encoded data packet at the receiver;

(b) demodulating said received signal;

(c) performing an error check on said encoded data packet;

(i) in response to a no error condition in the error-checking step of said encoded data packet, sending an acknowledgement signal from the receiver to the transmitter;

(ii) in response to an error condition in the error-checking step of said encoded data packet, performing the following steps;

(1) sending a negative acknowledgment signal from the receiver to the transmitter;

(2) performing a usability check on said encoded data packet;

(A) in response to a positive usability condition in the usability-checking step of said encoded data packet, storing said encoded data packet at the receiver to thereby create a first stored data packet;

(B) in response to a non-positive usability condition in the usability-checking step of said encoded data packet, discarding said encoded data packet;

(3) receiving at the receiver a retransmission of said encoded data packet contained in said signal in step (a) in response to receipt at the transmitter of said negative acknowledgement signal;

(4) copying said retransmitted encoded data packet and storing said copy of said retransmitted encoded data packet to thereby create a second stored data packet;

(5) performing an error check on said retransmitted encoded data packet;

(A) in response to a no error condition in the error-checking step of said encoded data packet, sending an acknowledgement signal from the receiver to the transmitter;

(B) in response to an error condition in the error-checking step of said encoded data packet, performing the following steps;

(I) determining if said first stored data packet exists;

(II) sending a negative acknowledgement from the receiver to the transmitter if no first stored data packet exists;

(III) performing the following steps if said first stored data packet exists;

(aa) combining said retransmitted encoded data packet with said first stored data packet to thereby create a combined data packet;

(bb) performing an error check on said combined data packet;

(AA) in response to a no error condition in the error-checking step of said combined data packet, sending an acknowledgement signal from the receiver to the transmitter;

(BB) in response to an error condition in the error-checking step of said combined data packet, sending a negative acknowledgement signal from the receiver to the transmitter;

(IV) performing a usability check on said combined data packet;

(aa) in response to a positive usability condition in the usability-checking step of said combined data packet, storing said second stored data packet as said first stored data packet;

(bb) in response to a non-positive usability condition in the usability-checking step of said combined data packet, discarding said combined data packet;

(6) repeating steps (3) through (5) until an acknowledgement signal is sent from the receiver to the transmitter to thereby communication said data packet from the transmitter to the receiver.

32. A method of communicating a signal containing an encoded data packet in an ARQ-enabled communication system transmitting packetized data from a transmitter to a receiver comprising the steps of:

(a) receiving said signal containing an encoded data packet at the receiver;

(b) demodulating said received signal;

(c) performing an error check on said encoded data packet;

(i) in response to a no error condition in the error-checking step of said encoded data packet, sending an acknowledgement signal from the receiver to the transmitter;

(ii) in response to an error condition in the error-checking step of said encoded data packet, performing the following steps;

(1) sending a negative acknowledgment signal from the receiver to the transmitter;

(2) performing a usability check on said encoded data packet;

(A) in response to a positive usability condition in the usability-checking step of said encoded data packet, storing said encoded data packet at the receiver to thereby create a first stored data packet;

(B) in response to a non-positive usability condition in the usability-checking step of said encoded data packet, discarding said encoded data packet;

(3) receiving at the receiver a retransmission of said encoded data packet contained in said signal in step (a) in response to receipt at the transmitter of said negative acknowledgement signal;

(4) performing an error check on said retransmitted encoded data packet;

(A) in response to a no error condition in the error-checking step of said encoded data packet, sending an acknowledgement signal from the receiver to the transmitter;

(B) in response to an error condition in the error-checking step of said encoded data packet, performing the following steps;

(I) determining if said first stored data packet exists;

(II) sending a negative acknowledgement from the receiver to the transmitter if no first stored data packet exists;

(III) performing the following steps if said first stored data packet exists;

(aa) combining said retransmitted encoded data packet with said first stored data packet to thereby create a combined data packet;

(bb) performing an error check on said combined data packet;

(AA) in response to a no error condition in the error-checking step of said combined data packet, sending an acknowledgement signal from the receiver to the transmitter;

(BB) in response to an error condition in the error-checking step of said combined data packet, sending a negative acknowledgement signal from the receiver to the transmitter;

(IV) performing a usability check on said combined data packet;

(aa) in response to a positive usability condition in the usability-checking step of said combined data packet, storing said second stored data packet as said first stored data packet;

(bb) in response to a non-positive usability condition in the usability-checking step of said combined data packet, discarding said combined data packet;

(5) repeating steps (3) through (5) until an acknowledgement signal is sent from the receiver to the transmitter to thereby communication said data packet from the transmitter to the receiver.

33. In a method for communicating a signal containing an encoded data packet in an ARQ-enabled communication system transmitting packetized data from a transmitter to a receiver, the improvement wherein a usability check is performed on the received encoded data packet to determine whether the energy of the received encoded data packet is to be used to demodulate the packet.

34. The method of claim 33 wherein the usability check comprises a comparison of minimum and maximum path metrics of a short viterbi decoder.

35. The method of claim 33 wherein the ARQ-enabled communication system is a traceback system.

36. The method of claim 33 wherein the ARQ-enabled communication system is a stop-and-wait system.