| 摘要 |
PCT No. PCT/FI95/00390 Sec. 371 Date Jun. 20, 1996 Sec. 102(e) Date Jun. 20, 1996 PCT Filed Jul. 5, 1995 PCT Pub. No. WO96/02091 PCT Pub. Date Jan. 25, 1996A 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. |
