Method of header compression over channels with out-of-order delivery
View Patent ↗For use in packet-switched networks, a method is provided for using external information regarding the degree of misordering of packets, to make header compression more robust against such misordering.
1. A method comprising:
determining, at a source external to a packet compressor, a degree of packet misordering occurring for packets being transmitted over a communications channel;
selecting an interpretation interval parameter for a packet-header compression algorithm, the interpretation interval parameter being configurable to correspond to the determined degree of packet misordering; and
compressing the headers of the packets being transmitted over the communications channel in accordance with the interpretation interval parameter.
2. The method of claim 1 , wherein the packet-header compression algorithm is of a kind in which a portion of an original field value is transmitted and the original field value is recovered by interpreting the transmitted portion within an interpretation interval about a previously received field value v ref ; and
the interpretation interval parameter to be selected comprises the position of the interpretation interval relative to v ref .
3. The method of claim 1 , wherein the packet-header compression algorithm is of a kind in which a variable number of consecutive packets are transmitted with full headers to establish a context before transmitting packets with compressed headers; and
the number of consecutive packets to be transmitted with full headers is varied as a function of the determined degree of packet misordering.
4. The method of claim 1 , further comprising controlling the delivery of late-arriving packets as input to a decompression algorithm.
5. The method of claim 4 , wherein the controlling step comprises determining a degree of lateness of packets that can be tolerated by the decompression algorithm.
6. The method of claim 4 , wherein the controlling step comprises withholding late-arriving packets from delivery if they are later that a specified amount.
7. The method of claim 4 , wherein the controlling step comprises delivering each of at least some late-arriving packets together with an indication that the packet is late.
8. The method of claim 4 , wherein the controlling step comprises delivering each of at least some late-arriving packets together with an indication of how late the packet arrived.
9. The method of claim 8 , wherein the indication of how late the packet arrived is based on a gap in sequence numbers of arrived packets.
10. A method comprising:
obtaining a determined degree of packet misordering occurring for packets being transmitted over a communications channel;
selecting an interpretation interval parameter for a packet-header compression algorithm, the interpretation interval parameter being configurable to correspond to the determined degree of packet misordering; and
compressing the headers of the packets being transmitted over the communications channel in accordance with the interpretation interval parameter.
11. The method of claim 10 , wherein the packet-header compression algorithm is of a kind in which a portion of an original field value is transmitted and the original field value is recovered by interpreting the transmitted portion within an interpretation interval about a previously received field value v ref ; and
the interpretation interval parameter to be selected comprises the position of the interpretation interval relative to v ref .
12. The method of claim 10 , wherein the packet-header compression algorithm is of a kind in which a variable number of consecutive packets are transmitted with full headers to establish a context before transmitting packets with compressed headers; and
the number of consecutive packets to be transmitted with full headers is varied as a function of the determined degree of packet misordering.
13. The method of claim 10 , further comprising controlling the delivery of late-arriving packets as input to a decompression algorithm.
14. The method of claim 13 , wherein the controlling step comprises determining a degree of lateness of packets that can be tolerated by the decompression algorithm.
15. The method of claim 13 , wherein the controlling step comprises withholding late-arriving packets from delivery if they are later that a specified amount.
16. The method of claim 13 , wherein the controlling step comprises delivering each of at least some late-arriving packets together with an indication that the packet is late.
17. The method of claim 13 , wherein the controlling step comprises delivering each of at least some late-arriving packets together with an indication of how late the packet arrived.
18. The method of claim 17 , wherein the indication of how late the packet arrived is based on a gap in sequence numbers of arrived packets.
19. A method comprising:
receiving, from a source external to a packet compressor, a determined degree of packet misordering occurring for packets being transmitted over a communications channel;
selecting an interpretation interval parameter for a packet-header compression algorithm, the interpretation interval parameter being configurable to correspond to the determined degree of packet misordering; and
compressing the headers of the packets being transmitted over the communications channel in accordance with the interpretation interval parameter.
20. The method of claim 19 , wherein the packet-header compression algorithm is of a kind in which a portion of an original field value is transmitted and the original field value is recovered by interpreting the transmitted portion within an interpretation interval about a previously received field value v ref ; and
the interpretation interval parameter to be selected comprises the position of the interpretation interval relative to v ref .
21. The method of claim 19 , wherein the packet-header compression algorithm is of a kind in which a variable number of consecutive packets are transmitted with full headers to establish a context before transmitting packets with compressed headers; and
the number of consecutive packets to be transmitted with full headers is varied as a function of the determined degree of packet misordering.
22. The method of claim 19 , further comprising controlling the delivery of late-arriving packets as input to a decompression algorithm.
23. The method of claim 22 , wherein the controlling step comprises determining a degree of lateness of packets that can be tolerated by the decompression algorithm.
24. The method of claim 22 , wherein the controlling step comprises withholding late-arriving packets from delivery if they are later that a specified amount.
25. The method of claim 22 , wherein the controlling step comprises delivering each of at least some late-arriving packets together with an indication that the packet is late.
26. The method of claim 22 , wherein the controlling step comprises delivering each of at least some late-arriving packets together with an indication of how late the packet arrived.
27. The method of claim 26 , wherein the indication of how late the packet arrived is based on a gap in sequence numbers of arrived packets.