What is RRC re establishment?

The purpose of RRC CONNECTION RE-ESTABLISHMENT procedure is to re-establish the RRC connection, which involves the resumption of SRB1 operation and the re-activation of security (without changing algorithms). The UE shall only initiate this procedure when AS security has been activated.

What is RRC connection setup?

LTE: RRC Connection Setup The RRC CONNECTION SETUP message is used to establish SRB1. It contains configuration information for SRB1. This allows subsequent signaling to use the DCCH logical channel. The configuration for SRB1 can be a specific configuration or the default configuration.

How can I improve my RRC setup success rate?

T302 should be increased to limit the RRC signalling load. When a UE gets a RRC Reject from eNB, it has to wait for T302 seconds before sending another RRC Connection Request. So, increasing T302 will increase the interval between such RRC Connection Requests and therefore, reduce the signalling load on the eNB.

What to do when RRC Connection is re-established?

UE in RRC Connected state can initiate RRC Connection Re-Establishment procedure in order to keep the RRC connection while security is activated. Once this procedure is initiated, the UE will perform below steps: 2.

When does UE send RRC Connection establishment request?

After a paging message has been sent by eNB, then RRC Connection setup request will be sent by the UE. RRC Connection Establishment Procedure is used to configure SRB1. RRC Connection Establishment Procedure is a 3 way handshake procedure. It has below 3 messages. RRC Connection Establishment is a part of Random Access Procedure.

How is the establishment cause of a RRC request determined?

 The establishment cause within the RRC Connection Request message is determined by the Non-Access Stratum (NAS) procedure for which the connection is being established. The relationship between establishment cause and NAS procedure is specified by 3GPP TS 24.301. This relationship is presented in Table 131.

When does RRC establishment procedure fail on LTE?

LTE uses the T300 timer to define how long the UE waits for a response to the RRC Connection Request message. The establishment procedure fails if T300 expires before receiving an RRC Connection Setup message.