10.1 Overview

3GPP44.018GSM/EDGE Radio Resource Control (RRC) protocolMobile radio interface Layer 3 specificationRelease 17TS

Within the RR protocols defined in 3GPP TS 44.018, every message with the exception of the messages sent on the BCCH, downlink CCCH, SCH, EC-SCH, RACH and the HANDOVER ACCESS message, is a standard L3 message as defined in 3GPP TS 24.007. This means that the message consists of the following parts:

a) protocol discriminator;

b) skip indicator;

c) message type;

d) other information elements, as required.

This organization is illustrated in the example shown in figure 10.1.1.

8

7

6

5

4

3

2

1

Skip Indicator

Protocol discriminator

octet 1

Message type

octet 2

Other information elements as required

etc.

Figure 10.1.1: General message organization example

Messages sent on the EC-AGCH are formatted as described in sub-clause 9.1.30c. Messages sent on the EC-BCCH and EC-CCCH use a short message type as described in sub-clause 10.4. All messages sent on the EC-CCCH consist of the following fields in the order listed:

– Message Type field (4 bits)

– Used DL Coverage Class (2 bits)

– EC Page Extension (5 bits, except for the EC Dummy message in which case this field is excluded)

Additional fields (message specific)A mobile station that has enabled EC operation and receives an RR message on downlink EC-CCCH with a message type it does not understand shall still read the Used DL Coverage Class and EC Page Extension fields while ignoring the remaining part of the message.

Unless specified otherwise in the message descriptions of sub-clause 9, a particular information element shall not be present more than once in a given message.

The term "default" implies that the value defined shall be used in the absence of any assignment, or that this value allows negotiation of alternative values in between the two peer entities.

When a field extends over more than one octet, the order of bit values progressively decreases as the octet number increases. The least significant bit of the field is represented by the lowest numbered bit of the highest numbered octet of the field.

When a message is coded using CSN.1 notation, the definition of the CSN.1 syntax in CSN.1 Specification, Version 2.0, shall be used.