Variable rate CDMA transmitter-receiver and transmission method

A CDMA transmitter-receiver comprising:

• a plurality of error correcting encoders for carrying out error correcting coding of input data, said plurality of error correcting encoders having different error correcting capabilities;
• a selector for selecting one of said plurality of error correcting encoders;
• a controller for generating transmission rate information indicative of a number of transmitted bits;
• a transmitting stage for generating a sequence of transmitted bits which contains bits having undergone the error correcting coding, and transmitting said sequence of transmitted bits;
• and
• a transmission power controller for reducing transmission power in accordance with the number of transmitted bits indicated by said transmission rate information when the number of transmitted bits is reduced,
• wherein said selector selects one of said plurality of error correcting encoders in accordance with the number of transmitted bits indicated by said transmission rate information and brings the selected error correcting encoder into operation.

A method of transmitting data at a variable transmission rate comprising performance of the following steps in a CDMA transmitter-receiver:

• generating transmission rate information indicative of a number of transmitted bits;
• coding a voice signal on a sample by sample basis;
• selecting, from among bits of a coded voice signal, a set of bits to be subjected to error correcting coding in accordance with the number of transmitted bits indicated by said transmission rate information, said set of bits being selected in order of precedence beginning from an MSB of said bits of said coded voice signal;
• carrying out error correcting coding of said set of bits;
• transmitting a sequence of transmitted bits which contains bits having undergone the error correcting coding and bits not selected in the step of selecting;
• and
• reducing transmission power in accordance with the number of transmitted bits indicated by said transmission rate information when the number of transmitted bits is reduced.

A method of transmitting data at a variable transmission rate comprising performance of the following steps in a CDMA transmitter-receiver:

• varying a number of bits of transmitted data by varying a number of redundant bits by selecting one of a plurality of error correcting encoders with different error correcting capabilities when carrying out error correcting coding of said transmitted data;
• transmitting a sequence of transmitted bits which contains bits having undergone said error correcting coding;
• generating transmission rate information indicative of a number of transmitted bits;
• and
• reducing transmission power in accordance with the number of transmitted bits indicated by said transmission rate information when the number of transmitted bits is reduced,
• wherein said selecting is carried out in accordance with the number of transmitted bits indicated by said transmission rate information.