ISDN user part
Part of SS7 protocol for telephone call setup.
In UMTS, part of this is being used for CS call.
IAM: Initial Address Message
ACM: Address Complete Message
ANM: Answer Message
REL: Release message
RLC: Release complete Message
Why do we have a cellular network?
To make a call or do data connection. (something useful)
Here, I post brief step for Mobile Originated call setup.
Detailed call flow can be found at here
What is AN (Access Network, UTRAN)’s role ?
Provide simple connectivity to the core network (CN) – whether it is a CS or PS.
Remember that UE wishes to make a call or data connection to do some useful and helpful thing.
AN just helps it in the middle between UE and CN.
In connected mode, the GTP-U can be established between GGSN and AN (without SGSN), which is more efficient.
I drew some figure to clarify the definition of RB, SRB and RAB.
Among many, in this post, we focus on signal level perspective.
Suitable cell is defined:
Srxlev > 0
Squal > 0
Then, questions arise: what is Srxlev and Squal?
Srxlev = Qrxlev_meas – Qrxlevmin – Pcompensation
Qrxlevmin is the minimum received signal level defined for the cell (broadcast information). Qrxlevmin ranges from -115dBm to -25dBm.
Here, we use RSCP (power measured by [...]
“B” party number means called number.
It could be landline, mobile, and same or other PLMN.
The device periodically wakes up and check if there is page for me or not.
The below diagram shows when the device wakes up to check its page. (Only at a particular PI location, otherwise in sleeping.)
related posts: here here
here here
