PCT No. PCT / FI96 / 00409 Sec. 371 Date Jan. 9, 1998 Sec. 102(e) Date Jan. 9, 1998 PCT Filed Jul. 11, 1996 PCT Pub. No. WO97 / 03403 PCT Pub. Date Jan. 30, 1997The invention relates to methods, transmitters and transceivers for transmitting a user
signal, particularly a speech or video
signal on a circuit-switched connection in a
cellular radio network when the
bit rate of the user
signal varies during transmission. The
transmitter comprises a source (2) of a variable
bit rate user signal, such as speech or video
encoder, and a channel
encoder (3) and a radio
transmitter unit (7) having an adjustable transmitting power. The capacity allocated for the circuit-switched connection corresponds to the
maximum rate of the user signal. The channel
encoder (3) has, for the
maximum bit rate of the user signal, a first, relatively the least efficient channel coding or no channel coding at all, and for each lower
bit rate of the user signal a relatively more efficient channel coding that utilizes the capacity of the circuit-switched connection, released by the lower transfer rate, for improving the interference tolerance of the connection. The transmitting power of the radio
transmitter unit depends on the channel coding used by the channel encoder so that the transmitting power is reduced with the increased efficiency of the channel coding, while the bit-error-rate remains substantially constant. This results in a lower average
power level and thus in a reduced interference level in the
cellular network.