System and method for compressing data using field-based code word generation

• US 20030009595A1
• Filed: 07/09/2001
• Published: 01/09/2003
• Est. Priority Date: 07/09/2001
• Status: Abandoned Application

• Current Assignee: Good Technology Incorporated (Blackberry Limited)
• Original Assignee: Good Technology Incorporated (Blackberry Limited)
• Inventors: Collins, Roger
• Application Number:
  US09/902,515
• Publication Number:
  US 20030009595A1
• Time in Patent Office: Days
• US Class Current: 709/247
• 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: H03M 7/3084 using adaptive string matching, e.g. the Lempel-Ziv method
• CPC Class Codes: H03M 7/40 Conversion to or from variable length codes, e.g. Shannon-Fano code, Huffman code, Morse code
• CPC Class Codes: H03M 7/42 using table look-up for the coding or decoding process, e.g. using read-only memory H03M7/4006 takes precedence
• CPC Class Codes: H04L 51/066 Format adaptation, e.g. format conversion or compression
• CPC Class Codes: H04L 51/58 Message adaptation for wireless communication
• CPC Class Codes: H04L 69/04 Protocols for data compression, e.g. ROHC
• CPC Class Codes: H04L 69/22 Parsing or analysis of headers
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A method for compressing a message is described comprising: identifying a first field and a second field within the message; applying a first set of code words to encode data in the first field; and applying a second set of code words to encore data in the second field.

Claims

1. A method for compressing a message comprising:

identifying a first field and a second field within said message;

applying a first set of code words to encode data in said first field; and

applying a second set of code words to encore data in said second field.

2. The method as in claim 1 further comprising:

generating said first set of code words based on the frequency with which character strings represented by said code words are found within said first field; and

generating said second set of code words based on the frequency with which character strings represented by said code words are found within said second field.

3. The method as in claim 2 wherein character strings which are relatively more common within said first field are represented by relatively shorter code words in said first set of code words and character strings which are relatively more common within said second field are represented by relatively shorter code words in said second set of code words.

4. The method as in claim 1 wherein said first field is an email header field and said second field is an email text field.

5. The method as in claim 1 wherein said first field is an address book field and said second field is an email message field.

6. The method as in claim 1 further comprising:

encoding ASCII text in said message in a 6-bit character format.

7. The method as in claim 6 further comprising:

providing one or more 6-bit escape sequences indicating that code following said sequence represents data compressed using a particular compression technique.

8. The method as in claim 6 wherein relatively common characters are encoded using 6 bits and relatively uncommon characters are encoded using two successive sequences of 6 bits.

9. A method comprising:

generating a first code word table containing code words for a plurality of character strings found in a first message field;

generating a second code word table containing code words for a plurality of character strings found in a second message field; and

encoding character strings in said first field using said first code word table and character strings in said second field using said second code word table.

10. The method as in claim 9 further comprising:

initially performing a statistical analysis of character strings found in said first message field and said second message field to determine a frequency of occurrence of each of said character strings.

11. The method as in claim 10 wherein character strings occurring relatively more frequently in said first field and said second field are associated with relatively shorter code words in said first code word table and said second code word table, respectively.

12. The method as in claim 9 wherein said first field is an email address field.

13. The method as in claim 12 wherein said second field is an address book address field.

14. The method as in claim 9 further comprising:

encoding said message further using one or more alternate compression techniques.

15. The method as in claim 14 wherein one of said alternate compression techniques comprises converting ASCII characters into a 6-bit character format.

16. The method as in claim 14 wherein one of said techniques comprises identifying strings in said first or second fields based on a location of said strings in a spell-check dictionary.

18. The method as in claim 17 wherein said message is an email message.

19. The method as in claim 17 further comprising:

using one or more alternate compression techniques to further compress said message.

20. The method as in claim 19 wherein one of said alternate compression techniques is a Huffman coding technique.

21. The method as in claim 19 wherein one of said alternate compression techniques comprises converting ASCII text to a 6-bit character format.

17. A method for compressing a message comprising:

replacing character strings within said message with data identifying a location of said character strings within a spell check dictionary stored on a data processing device.

22. A machine readable medium having program code stored thereon which, when executed by a machine, causes said machine to perform the operations of:

identifying a first field and a second field within said message;

applying a first set of code words to encode data in said first field; and

applying a second set of code words to encore data in said second field.

23. The method as in claim 22 comprising additional program code to cause said processor to perform the operations of:

generating said first set of code words based on the frequency with which character strings represented by said code words are found within said first field; and

generating said second set of code words based on the frequency with which character strings represented by said code words are found within said second field.

24. The machine-readable medium as in claim 23 wherein character strings which are relatively more common within said first field are represented by relatively shorter code words in said first set of code words and character strings which are relatively more common within said second field are represented by relatively shorter code words in said second set of code words.

25. The machine-readable medium as in claim 22 wherein said first field is an email header field and said second field is an email text field.

26. The machine-readable medium as in claim 22 wherein said first field is an address book field and said second field is an email message field.

27. The machine-readable medium as in claim 22 comprising additional program code to cause said processor to perform the operations of:

encoding ASCII text in said message in a 6-bit character format.

28. The machine-readable medium as in claim 27 comprising additional program code to cause said processor to perform the operations of:

providing one or more 6-bit escape sequences indicating that code following said sequence represents data compressed using a particular compression technique.

29. The machine-readable medium as in claim 27 wherein relatively common characters are encoded using 6 bits and relatively uncommon characters are encoded using two successive sequences of 6 bits.