Specifications

Unassigned Channel
Radio Frequency Channel Types
B-8 68P81095E55-E August 08, 2000
Associated Control Channel
The Associated Control Channel is for Interconnect Calls only and is sub-set of the
Traffic Channel and is used to pass radio link status, handover, and control
information. Short Message Service Data is also sent on the ACH when an MS is
busy (DCCH when idle). Since the TCH does not require the full data stream of the
TDMA timeslots, a small portion of the timeslot may contain bits of data that are
used to manage the communications during a call (Figure B-4). The passed
parameters are summarized in Table B-8.
Table B-8 Associated Control Channel Contents
Figure B-4 Elements of the Traffic Channel
Unassigned Channel
When a timeslot on a carrier becomes available, or is reassigned as unused by the
system, it is designated as an Unassigned Channel (UCH). The UCH is a data stream
from the system that the MS recognizes as something to avoid. When the UCH data
stream is detected, the MS will re-synchronize or re-tune to reestablish contact. By
avoiding the UCH, the MS can more easily attach to the correct carrier and timeslot
and does not attempt to communicate on channels that may be re-assigned.
Channel Contents
Inbound (downlink) Handover requests
metrics (measurement reports)
call control (handover commands)
SMS acknowledge
Outbound (uplink) Handover target cell
call control (handover commands)
SMS data
0.266 kbs (Associated Control Channel - ACCH)
3.175 kbs - Forward Error Correction
(provides 99.98% accuracy)
4.26 kbs VSELP
(Voice and data)
Traffic Channel
6:1 Interleave
(Dispatch,
Non-Enhanced Interconnect)
0.532 kbs (Associated Control Channel - ACCH)
6.35 kbs - Forward Error Correction
(provides 99.98% accuracy)
8.0 kbs VSELP
(Voice and data)
Traffic Channel
3:1 Interleave
(Enhanced Interconnect)