Datenübertragungsverfahren

摘要

A disadvantage of known discontinuous transmission methods in a GSM mobile phone system is that dummy bursts transmitted on the downlink on the frequency of the broadcasting channel (BCCH) cause disturbing responses in a mobile phone when frequency hopping of the speech channel is used and the hopping frequencies include the BCCH frequency. To prevent such disturbances, dummy bursts transmitted on the BCCH frequency are encoded in a manner so that after decoding in the mobile phone receiver, the dummy bursts are not interpreted as speech and the mobile phone responds with noise when the dummy bursts are received. The encoding may be by use of a training sequence which is different to that used in the normal state (Fig.5), so that the mobile can identify the dummy bursts as bad frames, or a stealing bit may be set at a value identifying dummy bursts as signalling rather than data, so that the mobile receiver directs the bursts to the signalling channel where they are rejected (Fig.6). The method may be applied to other communications systems and also to any data transmitted in digital form.