Specifications

Capacity Enhancements
Dispatch Call Processing
August 08, 2000 68P81095E55-E 4-7
Capacity Enhancements
One of the limiting factors to the capacity in a large sector/cell is control channel
traffic and the ability of the Primary Control Channel (PCCH) to handle system
messages. When the capacity of a site is increased, the number of messages per
control channel may become high enough to require additional control channels. The
use of a Secondary Control Channel solves this problem by allowing one or more RF
link timeslots to be assigned as Secondary Control Channels. Secondary Control
Channels are configured on a per-cell basis.
Dispatch Call Types
The iDEN system supports the several Dispatch Call types, some of which are
optional and require the purchase of additional hardware and software. They are:
• Private Call - Individual dispatch call between 2 users
• Talkgroup Call - Subfleet dispatch call across 1 or more sites and include:
Local Area
Wide Area
Selected Service Area
• Call Alert - Alert message sent from 1 user to another
• Emergency Call - A high priority subfleet dispatch call across 1 or more sites
• MS Status - Alert message with additional field sent from 1 user to another
Dispatch Private Call
A Private Call is similar to a one-to-one call. One user enters another user’s
designation (Fleet Member ID) and the call connection is one-way and exclusive.
Other members of the fleet and group are not involved in the conversation.
A private dispatch call was limited to another member of the same fleet in the same
region. There are specific limitations to cross-fleet calling. These limitations are
discussed in greater detail in Dispatch Provisioning of this chapter.
The caller enters the called MSs Fleet Member ID and presses the talk button on the
MS to hail the iDEN system. The hail sends a request for service over the radio link
control channel to the EBTS then to the DAP.
During call setup, the DAP validates the MS (caller), the request, and the target
(authentication). After validation, the DAP sends a location request to the called MS
unit. If resources are not available to either the caller or called MS, the call is queued.
If resources are available and the called party is available, a call establishment
indicates to the originator that the called party has been located and is ready for the
call.
The called MS activates the audio. The caller’s Fleet Member ID is sent to the called
MS during the set-up process for display on the called user’s MS or for returning
another call. The called MS may display the caller’s alias if it has the feature and is
programmed to display the alias.