Download Combining circuit and packet based services in converging networks

COMBINING CIRCUIT AND
PACKET BASED SERVICES IN
CONVERGING NETWORKS
Sauli Österman
[email protected]
About
•Written at TeliaSonera Finland, in the Mobile
System Planning department.
•Supervised by Prof. Raimo Kantola
•Instructed by M.Sc. Ville Helenius
Outline
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Background & Objective
3GPP release 6 network
IP Multimedia subsystem
Circuit Switched IMS Combinational
Services
• Conferencing service utilising CSICS
• Conclusion
Background & outline
• When using GERAN as access network, the experienced delay is
too much for real-time IMS services
• Using GERAN as access network is appealing, because of the large
coverage area
• The problem may be solved with utilising mobile network CS
services for real-time media and PS services for other types of
media
• For this purpose the 3rd Generation Partnership Project has
standardised Circuit Switched IMS Combinational Services (CSICS)
• The objective is:
– To study in which stage the standardization process at the moment
– What features are included in the standardised first phase solution
– To study how conferecing with this type of service might be
implemented
• The study was performed as a literature study
3GPP release 6 network
GERAN
CS domain
PSTN/PLMN
IP networks
UTRAN
PS domain
IMS
• Different domains for CS and PS services
• IMS is connected to both PS domain and
CS domain
IP multimedia subsystem
• 3GPP specified access network
independent service creation environment
• Two main signalling protocols:
– SIP for call control
– Diameter for database queries
• The signalling is always routed trough the
controlling nodes, but the user data is
routed via shortest path
CSICS phase 1
PLMN1
GERAN
PLMN2
CS domaín
CS domaín
UTRAN
UE1
UE2
AS
PS domaín
AS
PS domaín
IMS 1
IMS 2
Signalling traffic (SIP)
User data (RTP/MSRP)
Signalling traffic (SS7)
User data (CS voice)
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Standardization unfinished at the moment (included in the 3GPP release 7)
Phase 1 CSICS is a service between two users
Does not specify used medias
Main challenge is with establishing the connection
Problems with supplementary and CAMEL based services
Conferencing service utilising CSICS
approach 1
approach 2
Terminal 1
CS domain
CS domain
Terminal 1
Terminal 2
Terminal 2
IMS
IMS
Terminal 3
Terminal 3
approach 3
approach 4
CS domain
Terminal 1
CS domain
Terminal 1
Terminal 2
Terminal 2
IMS
Terminal 3
IMS
Terminal 3
Conference service
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Recognised 4 approaches with how to implement this
type of service
These were studied from the connection establishing
point of view
CS voice call
IMS session
Conclusion
• Service offers support for real-time services, even when
GERAN is only available access network
• The best approaches for implementing the CSICS
conferencing service were concluded to be approaches
3 or 4
• CSICS requires a lot from terminal. The success
depends heavily on the amount of the capable terminals
• Synchronization of two separate media streams may
cause problems to some applications
• Subjects fo further study:
– Final CSICS phase 1 functionality (when standardization is
finished)
– CSICS phase 2 (when more information is published)
– Other types of services with which the mobile operator may differ
from the service providers in the internet