User's Manual Chapter 13

Base FCC Regulatory Test Report
7-100
AT&T Wireless Services
FCC Type Acceptance Application
10991 Rev. 1.0 7/6/99
is controlled by the base, it is not subject to intra-cell contention but
RUs must accept inter-cell interference.
7.2.4.3 UCAC Definition
The Unsolicited Common Access Channel (UCAC) provides an uplink
access channel from any RU to its serving Base. Being unsolicited, the
UCAC is a slotted ALOHA access channel. It is subject not only to
collisions between RUs in the same cell but also interference from RUs
in co-channel cells. The uplink UCAC time slots are paired with the
downlink BC time slots. The UCAC is time-shared with the SCAC,
with one UCAC time slot for every four SCAC time slots (refer to
Figure 7.14—)
7.2.4.4 SCAC Definition
The Solicited Common Access Channel (SCAC) provides an uplink
transmission channel used by an RU during call-setup and channel
access procedures. The uplink SCAC time slots are paired with the
downlink CLC time slots. The SCAC is time-shared with the UCAC,
with four SCAC time slots for every one UCAC time slot (refer to
Figure 7.14—)
All four NAC logical channels employ QPSK modulation.
The CLC, SCAC and UCAC logical channels are all deployed with a
reuse factor of one.
Figure 7.14—NAC Logical Channel Timing Relationships
BC
CLC CLC CLC CLC
UCAC SCAC SCAC SCAC SCAC
15 mS
1.5 mS
Downlink
Uplink
Indicates TDMA slots reserved
for voice or data traffic
NAC Frame
NAC Slot(4 TDMA Slots)