Wireless signal transmission system with random access

Claim 2

A mobile digital communication apparatus for transferring a data message between a plurality of terminal stations (1) and a central station (2) with random access, whereby said data message is divided into a plurality of burst signals for transmission in a number required by the length (W) of the data message and of which the first burst signal contains data (44) indicating the length (W) of the message, characterized in that the apparatus comprises means for preparing and transmitting, in the central station (2), data of a transmission format including an I/B bit (37) indicating permission or inhibition of a new data message transmission at a next transmission timing of the terminal stations, in accordance with the number of the burst signals required by the length (W) of the data message that has been received from the terminal station (1) at the central station (2), an R/N bit (38) indicating reception or non-reception of burst signals from the terminal stations (1) at the central station (2), and partial data (39) produced from data received at the central station (2) in accordance with a predetermined rule based on the signals received from the terminal stations (1); means for preparing data (44) indicating the length (W) of a data message to be transmitted from each terminal station and starting the new data message transmission of the burst signal or burst signals containing the data (44) indicating the length of the message, from one or plural of the terminal stations (1) to the central station (2) when the I/B bit (37) indicates the permission of the new data message transmission; means for determining and transmitting, in the central station, the I/B bit (37), the R/N bit (38) and the partial data (39) in accordance with the reception of the data (44) indicating the length (W) of the message and the rest of the first burst signal transmitted from one of the terminal stations (1) if it was the first burst signal, or in accordance with the reception of the burst signal transmitted from one of the terminal stations (1) if it was not the first burst signal; means for determining, in the one or plural of the terminal stations which have been transmitting, whether or not the burst signal has been correctly been transmitted, whether or not the burst signal has been correctly received at the central station, in accordance with the R/N bit (38) and the partial data (39) from the central station, and determining whether or not the I/B bit (37) permits or inhibits a further burst signal; and means for suspending transmission of burst signals from the one or plural of the terminal stations, for a predetermined period of time, when it is determined that the burst signal has not been correctly received at the station.