What does RRC protocol do?

wirelessoom — Sun, 26 Jul 2009 13:59:23 +0000

RRC is the main AS control protocol.

RRC performs

1. establishment, modification and release of RRC conncetions

RRC connections are used to transfer RRC signal messages and be used to transport higher layer NAS protocol messages.

2. establishment, modification and release of RAB (radio access bearer ), user plane data connection.

3. radio mobility functions, etc.

NAS vs. AS

wirelessoom — Thu, 18 Jun 2009 18:49:53 +0000

UMTS protocols are divided into two different strata (See Fig):

1. NAS (non access stratum)

2. AS (access stratum)

UE (User Equipment) and CN (Core Network, MSC for circuit switched service, SGSN for packet switched service) need to talk!

NAS protocols support the talk between UE and CN.

It does not care below access method (could be UTRAN, GSM/GPRS).

Some examples of NAS protocols:

control plane

1. Connection management (CM), Session management (SM) – taking care of establishment and release of connection and session

2. Mobility management (MM) and GPRS mobility management (GMM) – responsible for mobility

data plane

1. IP

2. CS service

———-

AS is a group of protocols that are specific to access network:

1. Uu (radio interface between UE and Node B)

2. Iub (between Node B and RNC)

3. Iu (between RNC and CN)