This is based on the Slotted Aloha Protocol.
The dedicated CCH (DCCH) are used in the following manner:
??? Used for both uplink and downlink
??? Sends/receives SDCCH for system signaling and call setup
??? Sends/receives SACCH for measurement reporting and cell info
??? Sends/receives FACCH for exchange info for rates higher than SACCH. The 20-msec speech is
deleted and FACCH is inserted into the frame.
For us to define the time-slot structures, we will present the normal burst and synchronization burst
time-slot structures (see Fig. 1.10).
Normal Time Slot. The training sequence is a known 26-bit pattern that can be used for a variety
of signal processing reasons, for example, training of the equalizer and timing recovery. The guard
WIRELESS TOPICS 7
Logical Channels
Traffic Channel (TCH)
- Full Rate
- Half Rate
Control Channel (CCH)
- Broadcast Control Channel (BCCH)
- Common Control Channel (CCCH)
- Dedicated Control Channel (DCCH)
FIGURE 1.9 Logical channel partitioning.
Normal Time Slot
1 2 3 4 5 6 7 8
Frame = 4.615 msec
Data
57
Tail
Bits 3
SF
1
Training
26
SF
1
Data
57
Tail
Bits 3
Time Slot = 0.577 msec = 156.25 Bits
FIGURE 1.10 Normal burst time-slot structure.
period is equal to 156.
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