Method for decreasing the frame error rate in data transmission in the form of data frames

• US 6,430,721 B2
• Filed: 12/05/2000
• Issued: 08/06/2002
• Est. Priority Date: 04/10/1997
• Status: Expired due to Term

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Vainio, Janne, Kajala, Matti
• Primary Examiner(s): Decady, Albert
• Assistant Examiner(s): Chase, Shelly A
• Application Number:
  US09/730,288
• Publication Number:
  US 20010000543A1
• Time in Patent Office: 609 Days
• Field of Search: 714/752, 714/758, 714/786, 714/746
• US Class Current: 714/752
• CPC Class Codes: H03M 13/35 Unequal or adaptive error protection, e.g. by providing a different level of protection according to significance of source information or by adapting the coding according to the change of transmission channel characteristics
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/0068 by puncturing
• CPC Class Codes: H04L 1/007 Unequal error protection for format H04L1/0078; for codes per se H03M13/35
• CPC Class Codes: H04L 2001/0098 Unequal error protection

Abstract

The invention relates to a method for decreasing the frame error rate of information to be transmitted in the form of data frames in a data transmission system, in which the information to be transmitted is divided into data frames. The data frame is supplemented with error correction data generated by using part of the information to be transferred. At least part of the information to be used in the generation of error correction data is protected by error correction coding, by which an error correction coded data frame is obtained, in which different parts of the protected information have different error rates (BER). The error correction coded data frames are transferred in the data transmission channel from the transmitter to the receiver. The error rates of at least one part of the protected information are levelled out by shaping at the transmission stage that information part which is protected by error correction coding and which is used in the generation of the error correction data.

Claims

1. A method for decreasing frame error rate of information to be transmitted in the form of data frames in a data transmission system, in which

the information to be transmitted is divided into data frames,

the data frame is supplemented with error detection data generated by using part of the information to be transferred, at least part of the information to be used in the generation of error detection data is protected by error correction coding, by which an error correction coded data frame is obtained, in which at least some parts have different error correction capability, and

the error correction coded data frames are transferred in the data transmission channel from the transmitter to the receiver,

wherein the error correction capability of at least part of the protected information is levelled out.

2. A method according to claim 1, in which the information to be transmitted is in binary form, wherein the data frames (102, 202) consist of bits, and the error rates of the bits in said information part (207) is adjusted to be substantially equal at the transmission stage.

3. A method according to claim 2, wherein the mutual order of bits in the part of the data frame which contains those bits to be protected by error correction coding that are to be used in error detection coding, can be placed in said part of the data frame freely, irrespective of the mutual order of importance of said bits.

4. A method according to claim 1, in which the information to be transmitted is in binary form, wherein the data frames (102, 202) consist of bits, and some of the bits in the error correction coded data frame (207) are removed during the shaping.

5. A method according to claim 4, and the error correction coding is convolutional coding, and the error detecting coding is parity checking coding (CRC).

6. A method according to claim 5, and the convolutional coding is 1/3 convolutional coding, and that one third of the convolutional coded data frame is removed during the shaping.

7. A method according to claim 5, wherein the information part (207) to be used in the generation of error detecting data is placed either at the beginning or at the end of the protected information part in the data frame (212) to be transmitted to the data transmission channel.

8. A method according to claim 5, where the shaping is implemented by unevenly removing bits of the error correction coded data frame.

9. A method according to claim 8, wherein relatively more bits are removed at the beginning of the convolutional code.

10. A method according to claim 8, wherein more bits are removed in data not used in the error detection coding.

11. A data transmission system, in which information is transmitted in the form of data frames, the data transmission system comprising:

means (101, 201) for distributing the information to be transmitted into data frames (102, 202),

means (105, 205) for adding error detection data into the data frame (102, 202), and

means (107, 206) for protecting at least part of the information to be used in the generation of error detection data with error correction coding in order to achieve an error correction coded data frame (108, 207), in which at least some parts have different error correction capability,

wherein the data transmission system further comprises means (208) for levelling out error correction capability of at least one part of the protected information.

12. Data transmission system according to claim 11, wherein the means (208) for levelling out error rates of at least one part of the protected information comprise means (208) for shaping at the transmission stage at least part of the information part (207) protected with error correction coding and which is used in the generation of the error detection data.

13. A data transmission system according to claim 11, wherein the data transmission system is a GSM mobile communication system, and that the information to be transmitted is information of the speech channel.

14. A mobile station comprising:

means (101, 201) for dividing the information to be transmitted into data frames (102, 202),

means (105, 205) for adding error correction data into the data frame (102, 202), and

means (107, 206) for protecting at least part of the information to be used in the generation of error detection data with error correction coding in order to achieve an error correction coded data frame (108, 207), in which at least some parts have different error correction capability,

wherein the mobile station comprises further means (208) for levelling out error correction capability of at least one part of the protected information.