User's Manual Chapter 13
Table Of Contents
Chapter 7: Operational Description
AT&T Wireless Services
7-99
FCC Type Acceptance Application
10991 Rev. 1.0 7/6/99
7.2.4 PWAN Network Access Channel (NAC) Functional Description
The PWAN Network Access Channel (NAC) provides a means by
which calls can be set up between a Base and its population of RUs.
Several physical layer entities utilize the NAC for the exchange of peer-
peer information between the Base and RU over the airlink. As a result,
the NAC is subdivided into logical channels, as shown in Table 7.3—:
These logical channels are defined as follows:
7.2.4.1 BC Definition
The Broadcast Channel (BC) is a point to multipoint channel between
the serving Base and its population of RUs. The BC’s main functions
are to broadcast cell-wide provisional parameters, provide Base
identification (ID), and to provision new RUs during the RU installation
procedure. During normal operation, a fully provisioned RU rarely
requires BC updates of any kind. The downlink BC time slots are
paired with the uplink UCAC time slots. The BC is time shared with
the CLC (refer to Figure 7.14—), with one BC time slot allotted for
every four CLC time slots. In addition, the BC is deployed across base
stations in a time-reuse pattern of 32 to guarantee negligible co-channel
interference.
7.2.4.2 CLC Definition
The Common Link Channel (CLC) provides a downlink transmission
channel used by the Base during call-setup and access procedures. The
downlink CLC time slots are paired with the uplink SCAC time slots.
The CLC is time shared with the BC (refer to Figure 7.14—), with four
CLC time slots set aside for every one BC time slot. Because the CLC
Table 7.3— NAC Logical Channel Summary
Logical Channel
Link
Direction
Description
Broadcast Channel (BC) Downlink Base identification; initial RU
provisioning
Common Link Channel (CLC) Downlink Call establishment, Base-RU
Unsolicited Common Access
Channel (UCAC)
Uplink Call establishment RU-Base
Solicited Common Access
Channel (SCAC)
Uplink Call establishment, RU-Base in
response to request from Base