Radio channel structure is the division and coordination of a radio communication channel (wireless information transfer) into logical channels, frames (groups) of data, and fields within the frames that hold specific types of information.

The radio channel is divided into frames with 8 time slots per frame (0 through 7) and time slots are divided into field dependent on the purpose of the time slot. A forward (downlink) radio channel is paired with a reverse (uplink) radio channel to provide simultaneous two-way (duplex) voice communication.

Several logical channels can exist on a time slots on the physical radio channels. When a radio channel has a control channel, time slot 0 of the frame is used. The other time slots are used for user data. For normal (full rate) voice communication, a time slot in each frame is dedicated for the entire duration of the call. For efficient (half rate) voice communication, a time slot in every other frame is dedicated for the duration of the call. For packet data communication (using GPRS), the time slots are dynamically assigned.

Figure 1.16 shows that the GSM system uses a single type of radio channel. Each radio channel in the GSM system has a frequency bandwidth of 200 kHz and a data transmission rate of approximately 271 kbps. This example shows that each radio communication channel is divided into 8 time slots (0 through 7). This diagram shows that a simultaneous two-way voice communication session requires at least one radio...