Method for header compression in packet-based telecommunication systems

1 . A method for transmitting compressed data packets via a packet-based communications path extending between a compressing node and a decompressing node, the method comprises transmitting groups of one or more compressed packets wherein each two consecutive groups are separated from each other by single partially compressed packets, and wherein

the compressed packets being data packets each having a compressed header and comprising a first compression context ID (CID) for further decompression of the compressed data packets, and

the partially compressed packets being data packets each having a partially compressed header and a second CID.

2 . The method according to claim 1 , comprising

a) obtaining the compressed packets from uncompressed packets of a packet stream, and

b) obtaining the partially compressed packets from uncompressed packets of the packet stream, wherein

for obtaining each of the compressed packets, the method includes:

a1) reducing, from a full header of an uncompressed packet of the packet stream, said constant and/or inferable fields and also context fields defining said packet stream,

a2) introducing said first CID,

a3) inserting a compressed packet's mark, and for obtaining each of the partially compressed packets, the method includes:

b1) reducing such fields of a full header of an uncompressed packet of the packet stream, that are constant and/or inferable in packets of a particular packet type to which the packet stream belongs,

b2) introducing said second CID,

b3) inserting a partially compressed packet's mark.

3 . The method according to claim 1 , wherein said first CID is essentially identical to said second CID.

4 . The method according to claim 2 , further comprising inserting, in each of the partially compressed packet, a field indicating the packet type.

5 . The method according to claim 1 , comprising determining packet types to be supported and actions to be executed per packet type by carrying out a negotiation step between said compressing node and said decompressing node, or by pre-configuring said compressing node and said decompressing node.

6 . The method according to claim 1 , wherein a number of the compressed packets separating two consecutive partially compressed packets is defined according to a selected function.

7 . The method according to claim 1 , further comprising transmitting one or more interface-related fields (I/F-related fields) from the compression node to the decompression node by periodically appending said I/F-related fields to a partially compressed packet.

8 . The method according to claim 1 , further comprising either pre-configuring the compression node and the decompression node, or carrying out a negotiation step between the compression node and the decompression node for performing compressed transmission of interface-related fields (I/F-related fields).

9 . A system comprising at least a compressing node and a decompressing node and a packet-based communications network path extending there-between, the system being capable of performing the method according to claim 1 .

10 . A software product comprising software implementable instructions and/or data for carrying out the method according to claim 1 .

11 . A carrier medium comprising the software product according to claim 10 , suitable for being installed in the compressing node and the decompressing node of the packet-based network.