Method and apparatus for speech transmission in a mobile communications system
DCFirst Claim
1. A method for speech transmission of a speech in a telecommunications system, said method comprising the steps of:
- compressing a speech signal of the speech to a small number of speech coding bits by speech coding method,channel encoding the speech coding bits, andusing, in transmitting the speech as a transmitted signal by a transmitter, N different speech coding methods, all of which operate at different transmission rates S1, S2, . . . , and SN kbit/s, respectively, where N≧
2 and S1 ≧
S2≧
. . . ≧
SN, including;
employing with each speech coding method a first channel encoding method specific for the respective said speech coding method, said first channel encoding method comprising adding error-detecting and error-correcting first channel coding bits to the speech coding bits, and producing a constant transmission rate S1 which is independent of the speech coding method employed, so that the transmission rate of the first channel coding bits added to the speech coding bits during the first channel encoding its, depending on the speech coding method employed, 0 S1-S2, . . . , S1-SN kbit/s, respectively, andafter the first channel encoding, performing a second channel encoding, in which error-detecting and error-correcting second channel coding bits are added to the signal generated by the first channel encoding, the transmission rate of said second channel coding bits being C kbit/s, whereby, after the second channel encoding, the total transmission rate is a constant S1+C kbit/s irrespective of the selected speech encoding method.
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Abstract
A method and apparatus for speech transmission in a telecommunications system in which a speech signal is compressed to a small number of speech coding bits by a speech coding method, and the speech coding bits are subjected to channel coding. Several different speech coding methods, which may all operate at different transmission rates, are involved in the speech transmission. The method is based on the use of two-stage channel coding. The first channel coding is dependent on the speech coding method, and it is performed in connection with the speech coding in such a manner that the total transmission rate provided by the speech coding and the first channel coding is always constant irrespective of the speech coding method. The second channel coding performed thereafter is always exactly the same regardless of the speech coding method and the first channel coding method, and it is used with all speech coding methods. The second channel coding may be, for example, the original channel coding in an existing telecommunications system.
13 Citations
14 Claims
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1. A method for speech transmission of a speech in a telecommunications system, said method comprising the steps of:
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compressing a speech signal of the speech to a small number of speech coding bits by speech coding method, channel encoding the speech coding bits, and using, in transmitting the speech as a transmitted signal by a transmitter, N different speech coding methods, all of which operate at different transmission rates S1, S2, . . . , and SN kbit/s, respectively, where N≧
2 and S1 ≧
S2≧
. . . ≧
SN, including;employing with each speech coding method a first channel encoding method specific for the respective said speech coding method, said first channel encoding method comprising adding error-detecting and error-correcting first channel coding bits to the speech coding bits, and producing a constant transmission rate S1 which is independent of the speech coding method employed, so that the transmission rate of the first channel coding bits added to the speech coding bits during the first channel encoding its, depending on the speech coding method employed, 0 S1-S2, . . . , S1-SN kbit/s, respectively, and after the first channel encoding, performing a second channel encoding, in which error-detecting and error-correcting second channel coding bits are added to the signal generated by the first channel encoding, the transmission rate of said second channel coding bits being C kbit/s, whereby, after the second channel encoding, the total transmission rate is a constant S1+C kbit/s irrespective of the selected speech encoding method. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A transmitter apparatus for a telecommunications system transmitting digital speech on a transmission channel, said apparatus comprising:
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speech means for coding a speech signal by a speech coding method to provide a speech encoded signal, channel encoding means for channel-encoding the speech-encoded signal to a signal whose transmission rate is equal to a total transmission rate on the transmission channel, the speech encoding means employing two or more speech coding methods, which provide speech-encoded signals have mutually different transmission rates (S1, S2, . . . , SN), the channel encoding means being arranged to provide the channel encoding in two steps comprising first channel encodings which are specific for each speech encoding method and which, from the encoded speech signals having different transmission rates, generate first channel-encoded signals having a same constant transmission rate (S1) which is independent of the speech coding method, and a second channel encoding which is independent of the speech coding method and which, from a selected first channel-encoded signal, generates a second channel-encoded signal having a constant transmission rate (S1+C) which is independent of the speech coding method and which is the same as said total transmission rate. - View Dependent Claims (10, 11)
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12. A receiver apparatus in a telecommunications system transmitting digital speech on a telecommunications channel at a total transmission rate, comprising:
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channel decoding means for decoding a received channel-coded speech signal, speech decoding means for speech-decoding a channel-decoded speech signal by a speech decoding method, the channel decoding means being arranged to provide channel decoding two steps comprising; a second channel decoding which is independent of the speech coding method and which, from said received channel-encoded speech signal, sharing a constant transmission rate (S1+C), which is independent of the speech coding method and is the same as the total transmission rate used in the telecommunications channel, produces a first signal having a lower constant transmission rate (S1) which is independent of the speech coding method, and first channel decodings which are specific for each speech coding method and which channel-decode said first signal, producing encoded speech signals which are specific for each speech coding method and which have mutually different transmission rates (S1, S2, . . . , S3), and the speech decoding means employ two or more speech decoding methods for decoding said speech-coded speech signals produced by two or more speech encoding methods and having mutually different transmission rates (S1, S2, . . . , SN). - View Dependent Claims (13, 14)
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Specification