Sony Ericsson Mobile Communications Japan, Inc.

Hiroaki Nagaoka

Katsutoshi Itoh

Taku Nagase

Noboru Oki

Disclosed is a method and an apparatus for controlling transmission electric power capable of minimizing a decrease in the amount of maximum transmission electric power without degrading an adjacent channel leakage power ratio when code-multiplexing additional control information with data and main control information. A mobile device checks values of gain factors &#x3b2;d and &#x3b2;c when performing code multiplexing to transmit signals from channels DPDCH to transmit data, DPCCH to transmit main control information, and HS-DPCCH to transmit additional control information. A maximum transmission electric power is decreased at a plurality of levels based on the check result and a ratio (&#x394;hs) between the gain factors &#x3b2;c and &#x3b2;hs. It may be preferable to check the presence or absence of transmission data instead of the gain factor &#x3b2;d. In this case, when no transmission data is available, the maximum transmission electric power is decreased at a plurality of levels based on &#x394;hs. When transmission data is available, the maximum transmission electric power is decreased at a plurality of levels based on the gain factor &#x3b2;c and &#x394;hs.

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Saitama, Japan

Hiroaki Nagaoka