TIA TIA-102.BAAD-1

This supplement defines sample operational procedures for basic conventional radio systems. A conventional radio system is one that does not include any controlling entity in the infrastructure to assign radio channels. It is different from a trunking system which includes some means of assigning radios to channels, i.e. a trunking controller. The sample operational procedures defined in this supplement are, in the whole, not mandatory requirements. However, some of the procedures are mandatory for this supplement, and others may be specified as mandatory for other portions of the Project-25 set of standards even though they are not specified as mandatory here.

A basic conventional radio system is one which meets the minimum requirements for this supplement. Additional functions or features may be added to a basic system as they are required. The operation of these additional functions is not discussed in this supplement, but it is expected that they will be compatible with the basic operation as described here. Basic procedures covered in this supplement are further restricted to the lower 2 OSI layers of the radio system. Operation of the encryption function, vocoder function, or user data applications is not explicitly defined here. Operation of trunking control is also not included.

There are several different types of conventional radio system, depending on whether or not a repeater is used. These are diagrammed Figure 1-1.

For the purposes of this document, basic conventional systems can be classed as either repeater systems or direct systems. Repeater systems make use of a full duplex base station that is configured so that all of the signals that are received are re-transmitted. Direct systems simply transmit directly from one unit to another without the assistance of any intervening repeater. Radio units in a system consist of mobile or portable units, and base stations. The mobile or portable units are represented as MR elements. The base station is represented as a BR element in Figure 1-1. The communication paths are represented as arrows. They are intended to show a simplex (i.e. one direction only) path. Generally, the radios may be capable of operating half duplex, which is to say that they can transmit or receive, but not both at the same time. The repeater is always full duplex. Full duplex operation for portables or mobiles is not discussed for a basic conventional system.

Addressing for the mobiles, portables, and base stations is covered in Sections 2 and 3. Section 2 contains some mandatory requirements. Mobiles, portables, and base stations also generate Status Symbols, and this subject is covered in Section 4 with some mandatory requirements.

From the stand point of the originating unit, the message is broadcast to all other radio units that are within range of the signal. Those units that are within range may choose to unmute and listen to the signal, or remain muted. The procedures for the originating unit and destination units are covered in Sections 5, 6, 8, and 9. Sections 5, 8, and 9 contain some mandatory requirements. For the purposes of direct systems, either an MR or a BR can be the origination or destination unit. Three representative cases are given in Figure 1-1. Multiple arrows from the originating unit are intended to show communication paths to multiple destination units, of which only a single destination unit is shown.

For repeater systems, the base station is the repeater, and mobile / portable units are the origination and destination units. Multiple destination units can listen to the repeater transmission, but only the repeater is configured to listen to the originating unit. The operation of the repeater is a special case of operation of the units in direct mode, and some aspects of its operation are defined in Sections 2 and 7, with both sections containing mandatory requirements.

The procedures for data transmission and reception are given in Sections 8 and 9. Portions of the procedures are mandatory for interoperability with the Common Air Interface, and these portions are indicated in those sections.