What is the Meaning of Critical Extension, Non critical extension , message class extension in RRC Messages.

Question

What is the importance of these types in RRC messages ...

Comments

Good question,even i am interested for the answer to this question

Answer 1

RRC messages may be extended in future versions of the standard, either by adding values for choices, enumerated types, and size constrained types, or by adding information elements. Two kinds of protocol extensions are defined:

• Non-critical extensions – New values for choices, enumerated types, and size constrained types may be added where “reserved” values have been allocated in the current protocol version. New information elements may be added to the end of a message. If a message includes non-critical extensions not supported by the receiver, the receiver processes the message as if the extensions were absent.

• Critical Extensions – For all critical extensions, a new version of the message is defined and indicated at the beginning of the message. These messages may be modified completely, e.g., IEs may be inserted at any place, and IEs may be removed or redefined. If a message includes critical extensions, which are not supported by the receiver, the receiver rejects the entire message.

Comments

message class extension??

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I will try to make an complete article with example on this but currently to give u a answer on message class extension

message class extension is nothing but way of showing critical extension,so that in later release if u want to complete change the message structure then old stack equipment will take old messages structure and new equipment will take the new message structure which u will add in place of  message class extension .

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How does the sender know the RRC protocol version of the UE? For the DL-CCCH messages, the network must choose the correct version to send, so how does it know the UE's supported RRC protocol version?