Continuous and discontinuous power reduced transmission of speech inactivity for the GSM system

Discontinuous transmission (DTX) or variable bit rate operation during speech inactivity is applied in various cellular speech communication systems. This is a technique in essence to turn off the transmission during periods of speech silence. The purpose is to reduce interference caused to other users concurrently transmitting on the air interface and to save battery power in the mobile stations. A major problem with this technique arises for emerging communication systems with link adaptation as both continuous channel tracking and continuous inband back channels are disabled when transmission is turned off. This paper presents a novel alternative method to conventional DTX which allows to keep the transmission continuous or almost continuous but which maintains or even exceeds the gain of the conventional method