Header compression

1. A method for communicating a message over a data path, the method comprising:

forming a plurality of individual data segments together representing the message, each data segment having control data;

estimating a quality of the data path;

calculating, based on the estimated quality, an interval between data segments that are to be communicated over the data path in a first segment format that includes a first amount of control data, the interval decreasing when the estimated quality decreases;

for each data segment, if the calculated interval has passed, selecting the first segment format, and otherwise selecting a second segment format, the second segment format including a second amount of control data, the second amount being less than the first amount; and

transferring the data segments over the data path.

2. A method as claimed in claim 1 , wherein the interval is a number of data segments between zero and infinity.

3. A method as claimed in claim 1 , wherein the data segments are packets.

4. A method as claimed in claim 3 , wherein the control data is comprised in a header and/or trailer of each packet.

5. A method as claimed in claim 4 , wherein the first format is a format having a non-compressed header and the second format is a format having a compressed header.

6. A method as claimed in claim 1 , wherein the quality of the data path is estimated by means of one or more of the following measures: signal to interference ratio, bit error rate, power loss over the data path, required transmission power over the data path, delay over the data path.

7. A method as claimed in claim 1 , wherein the data path includes a portion over which no bit error correction protocol is applied.

8. A method as claimed in claim 1 , wherein the data path includes a portion constituted by a radio link.

9. A method as claimed in claim 1 , wherein the data segments are formed and transferred according to one or more of the following protocols: TCP, IP, UDP, RTP.

10. A method as claimed in claim 1 , wherein each packet includes message data representing at least part of the message.

11. A method as claimed in claim 10 , wherein the available segment formats do not differ in their ability to comprise message data.

12. A method as claimed in claim 10 , wherein the control data of each segment includes first control data for permitting control of the transmission and/or reception of the segment and second control data for permitting detection and/or correction of errors in the first control data.

13. A method as claimed in claim 12 , wherein the available segment formats including greater amounts of first control data include greater amounts of second control data.

14. A communication system for communicating a message over a data path, comprising:

data forming apparatus configured to form a plurality of individual data segments together representing the message, each data segment having control data;

path quality estimation apparatus configured to estimate a quality of the data path;

segment format determining apparatus configured to calculate based on the estimated quality an interval between data segments that are to be communicated over the data path in a first segment format that includes a first amount of control data, the interval decreasing when the estimated quality decreases;

segment format selecting apparatus configured to select, for each data segment, the first segment format if the calculated interval has passed, and otherwise selecting a second segment format, the second segment format including a second amount of control data, the second amount being less than the first amount; and

data transfer apparatus configured to transmit the data segments over the data path.

15. A communication system as claimed in claim 14 , wherein the interval is a number of data segments between zero and infinity.

16. A communication system for communicating a message over a data path, comprising:

means for forming a plurality of individual data segments together representing the message, each data segment having control data;

means for estimating a quality of the data path;

means for calculating based on the estimated quality an interval between data segments that are to be communicated over the data path in a first segment format that includes a first amount of control data, the interval decreasing when the estimated quality decreases;

means for selecting for each data segment the first segment format if the calculated interval has passed, and otherwise selecting a second segment format, the second segment format including a second amount of control data, the second amount being less than the first amount; and

means for transferring the data segments over the data path.

17. A transmission apparatus for transmitting a message over a data path, comprising:

means for forming a plurality of individual data segments together representing the message, each data segment having control data;

means for estimating of a quality of the data path;

means for calculating based on the estimated quality an interval between data segments that are to be communicated over the data path in a first segment format that includes a first amount of control data, the interval decreasing when the estimated quality decreases;

means for selecting for each data segment the first segment format if the calculated interval has passed, and otherwise selecting a second segment format, the second segment format including a second amount of control data, the second amount being less than the first amount; and

means for transferring the data segments over the data path.

18. A transmission apparatus as claimed in claim 17 , wherein the transmission apparatus is a mobile terminal.

19. A transmission apparatus as claimed in claim 17 , wherein the transmission apparatus is a base station.

20. An apparatus for transmitting a message over a data path, comprising:

data forming apparatus configured to form a plurality of individual data segments together representing the message, each data segment having control data;

path quality estimation apparatus configured to estimate a quality of the data path;

segment format determining apparatus configured to calculate based on the estimated quality an interval between data segments that are to be communicated over the data path in a first segment format that includes a first amount of control data, the interval decreasing when the estimated quality decreases;

segment format selecting apparatus configured to select for each data segment, the first segment format if the calculated interval has passed selecting and otherwise selecting a second segment format, the second segment format including a second amount of control data, the second amount being less than the first amount; and

data transfer apparatus configured to transmit the data segments over the data path.