Call Overview
|
The following diagram provides a single sheet
overview of the message interactions. Interaction details and remarks are
omitted from the diagram.
 Inter
MSC Handover Call Flow Overview
pdf
Inter
MSC Handover Collaboration Overview
pdf |
Mobile - GSM Network Interactions
|
This diagram treats the whole GSM network as
a black box and focuses on the interactions between the Mobile
and the network.
Inter
MSC Handover (Network-Mobile Interactions)
pdf |
Mobile, Target MSC and Source MSC
Interactions
|
The following diagram adds more details.
Interactions between the UE, Target and Source networks are covered. The
individual networks are treated as black boxes.
Subscriber
and MSC Interactions in Inter-MSC Handover
pdf |
Mobile Role
|
The mobile involved in an inter-MSC handover
performs the following steps:
- The mobile is at the edge of coverage
for the Rockville cell and is reporting poor signal quality in its
periodic repports.
- The controlling BSC commands the UT
to tune to the new channel on another cell.
- The mobile tunes to the new channel
and accepts the handover.
- The BSC controlling the new cell
sends a timing correction to the UT.
- The Mobile establishes an RR
connection and switches to the new voice path.
Mobile
Role Call Flow
pdf Mobile
Role Collaboration Diagram
pdf |
Source BSC Role
|
The source BSC is responsible for:
- Analyzing the measurement reports
from the mobile and triggering a handover with the MSC.
- Receiving the handover command from
the BSC handling the target cell and passing it on the the mobile.
- Releasing local radio resources when
the call has been successfully handed over.
Source
BSC Call Flow
pdf Source
BSC Collaboration Diagram
pdf |
Source MSC Role
|
The source MSC performs the following steps
in an inter-MSC handover:
- Identify and route the handover
request to the target MSC.
- Route the handover command from the
target MSC to the source BSC.
- Obtain a handover number and use it
to setup a voice call towards the target MSC.
- Release the radio resources on the
source BSC after a successful handover has been confirmed.
- Release the voice call between the
source and target MSCs when the handed over call is released.
Source
MSC Call Flow
pdf Source
MSC Collaboration Diagram
pdf |
Target MSC Role
|
The target MSC takes the following actions in
an inter-MSC handover:
- Receive the handover request from the
source MSC and route it to the target BSC.
- Route the handover command back to
the source MSC.
- Assign a handover number and
participate in a voice call between the source and target MSCs.
- Notify the source MSC when the
handover has been completed successfully.
Target
MSC Call Flow
pdf Target
MSC Collaboration Diagram
pdf |
Target BSC Role
|
The target BSC role in inter-MSC handover is:
- Receive the handover request,
allocate radio resources for the call and then reply back to the target
MSC.
- Receive the handover request from the
user terminal and setup an RR connection.
- Notify the target MSC about the
completion of the handover.
Target
BSC Call Flow
pdf Target
BSC Collaboration Diagram
pdf |
