Data compression on a data connection

• US 6,434,168 B1
• Filed: 12/07/1998
• Issued: 08/13/2002
• Est. Priority Date: 06/07/1996
• Status: Expired due to Fees

• Current Assignee: Nokia Solutions and Networks US LLC (Nokia Corporation)
• Original Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Inventors: Kari, Hannu
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): PHAM, BRENDA H
• Application Number:
  US09/202,203
• Time in Patent Office: 1,345 Days
• Field of Search: 370/521, 379/93.08, 710/68, 709/247, 348/439.1, 348/14.13, 348/568
• US Class Current: 370/521
• CPC Class Codes: H03M 7/30 Compression speech analysis-synthesis for redundancy reduction G10L19/00; for image communication H04N; Expansion; Suppression of unnecessary data, e.g. redundancy reduction
• CPC Class Codes: H04L 69/04 Protocols for data compression, e.g. ROHC
• CPC Class Codes: H04L 69/24 Negotiation of communication capabilities
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365

Abstract

The invention relates to compressing and transmitting data on a connection between two parties in a telecommunication system comprising at least one slow transmission channel, such as the air interface Um of the radio network. The data to be transmitted are assembled into frames (F) comprising a header section (1) and a data section (2). Prior to transmission, at least the header (1) or the data section (2) of at least some of the frames (F) are compressed. The transmitting party has available at least two different compression algorithms and the receiving party has available at least two different decompression algorithms. The transmitting party compresses at least one section (1, 2) of at least some of the frames (F) with at least two different algorithms, and transmits the frame (F) compressed with the algorithm that produced the best compression ratio.

Claims

1. A method for compressing and transmitting data on a connection between two parties in a telecommunication system comprising at least one slow transmission channel (Um), the method comprising:

assembling the data to be transmitted into frames (F) which contain at least a header section (1) and a data section (2), and

compressing at least one section (1, 2) of at least some of the frames (F) prior to transmission,

making at least two different compression algorithms available to the transmitting party,

making at least two different decompression algorithms available to the receiving party,

characterized in that the transmitting party;

compresses at least one section (1, 2) of at least some of the frames (F) with at least two different compression algorithms;

selects the compression algorithm that yielded the best compression ratio; and

transmits the frame (F) over the slow transmission channel (Um) to the receiving party, compressed with said selected compression algorithm.

2. A method as claimed in claim 1, characterized in that the parties negotiate the compression algorithms to be used on the connection at least at the beginning of the connection.

3. A method as claimed in claim 2, characterized by the first party sending to the second party an inquiry concerning the available algorithms, to which the second party responds by sending a list containing information on the algorithms available to the second party.

4. A method as claimed in claim 2, characterized by the second party selecting the algorithms that both the parties support from the list sent by the first party.

5. A method as claimed in claim 2, characterized by the second party transmitting a list of the algorithms available to it regardless of which algorithms the first party has available.

6. A method as claimed in claim 2, characterized by the first party transmitting a brief test message compressed separately with each algorithm being tested, and the second party responding with an affirmative acknowledgment if it is capable of decompressing the message, and if not, with a negative acknowledgment.

7. A method as claimed in claim 2, characterized in that both parties have a decompression algorithm available for substantially each compression algorithm.

8. A method as claimed in claim 2, characterized in that at least one of the parties may have available a decompression algorithm without a corresponding compression algorithm or vice versa, and that the parties negotiate separately the compression and decompression algorithms available to them.

9. A method as claimed in claim 2, characterized in that the negotiation between the parties is transmitted on an encrypted channel.

10. A method as claimed in claim 2, characterized in that the identifiers of the compression algorithms are changed between successive connections and/or during one connection.

11. A method as claimed in claim 1, characterized by

compressing the header sections (1) of the frames (F) with an algorithm which is substantially the same between two successive frames (F), and

compressing the data sections (2) of the frames (F) with at least two different algorithms of which the one is selected that yields the best compression result.

12. A method as claimed in claim 1, characterized by transmitting, with each compressed frame (F), an identifier indicative of the compression algorithm used.

13. A method as claimed in claim 1, characterized in that when the compression algorithm changes the transmitting party separately transmits information on the change to the receiving party.

14. A method as claimed in claim 1, characterized by

compressing a frame (F), which is advantageously the first one representing a specific type of data, with substantially all the algorithms known to both parties,

compressing the subsequent frames (F) first with the algorithm that at the previous frame (F) produced the best result,

discontinuing to carry out the other algorithms if the length of the frame (F) compressed with the algorithm in question exceeds the length of the frame (F) compressed with up to that point the best algorithm.

15. A method as claimed in claim 1, characterized by the transmitting party being assigned a restricted time for the compression, such as the time between two successive transmit turns in time division multiple access systems.

16. A method as claimed in claim 15, characterized in that at the end of the restricted time the transmitting party discontinues testing the compression algorithms and transmits the frame (F) compressed with the algorithm that up to that point has yielded the best compression result.

17. A method as claimed in claim 16, characterized by

maintaining, for the different compression algorithms, a parameter indicating efficiency, advantageously a sliding average of the compression ratio,

compressing each frame (F) or a section (1, 2) thereof with a few, advantageously 1-3 of the best compression algorithms up to that point, in an order determined by the parameter indicating efficiency, and

testing, in the remaining part of the restricted time, the remaining algorithms alternately so that at successive frames (F) different algorithms are tested.