THESIS
PRESENTATION
Real Time Transport Protocol Processing
in a Voice over IP Network
SUPERVISORS
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Supervisor: Sven-Gustav Häggman

Instructor:
Tapio Savunen
(Head of R&D, Nokia Networks)
FACTS ABOUT THESIS

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Work done in year 2001 (for Nokia
Networks) with almost 6-8 months of
full-time (and more) effort
Thesis report completed in 2005
FACTS ABOUT THESIS


A VoIP prototype system
implemented
Workd done from implementation
specifications to code development,
module testing and successful
demonstration of voice calls
(individual and group).
PROTOTYPE ARCHITECTURE

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Architecture consists of Control Plane
server, User Plane server, and LAN
client (simulating Nokia Mobile
terminals.
Specifications for interface between
Terminal, Control plane server, User
plane server have been finalized in
advance
PROTOTYPE ARCHITECTURE


Desktop PCs used with Linux OS
(RedHat) as control plane and user
plane servers
Laptop used as LAN client, with
Wireless LAN in order to simulate
”air-interface” feeling
PROTOTYPE ARCHITECTURE


SIP protocol used as interface between
User Terminal and Control Plane server
(and between Control Plane servers). SIP
works with Control Plane (identify and
manage calls by contexts)
RTP protocol used as interface between
User Terminal and User Plane server (and
between User Plane servers). RTP works
with User Plane (identify and manage calls
by IP)
PROTOTYPE ARCHITECTURE


MEGACO protocol used as interface
between Control Plane server and
User Plane server
IPv4 Network
PROTOTYPE ARCHITECTURE
SIP
SIP
U-CPF
P-CPF
G-CPF
SIP
MS
IPV4 Network
MEGACO
U-UPF
RTP P-UPF
MEGACO
RTP
G-UPF
RTP
MS = User Terminal
U-UPF, G-UPF = User Plane Servers
U-CPF, G-CPF = Control Plane Servers
POC CONCEPT



POC is Push to Talk (PTT) over
Cellular
User must always press PTT (pushto-talk) button in order to talk
This prototype demonstrates POClike service using VoIP
WHAT USER CAN DO WITH THIS
PROTOTYPE?



User(s) can login into ”system”
User can make individual call to
another user
User can make group call
WHAT USERS CAN DO WITH
THIS PROTOTYPE?

User(s) can join to a predefined
”Talk-Group”

User can talk/listen in a ”Talk-Group”

User can log-off
USE CASE: USER LOGIN



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MS sends SIP message to Control Plane with
terminal information
Control Plane does basic checkings, remembers
this data and sends MEGACO message to User
Plane
User Plane memorizes terminal information and
sends MEGACO reply to Control Plane
Control Plane sends SIP message back to MS
informing successful login (if so!)
USE CASE: INDIVIDUAL CALL


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MS (caller) sends RTP call setup (with
callee info) message to User Plane
User Plane does necessary checking and
informs control plane (MEGACO)
Caller’s Control plane contacts Callee’s
Control plane (SIP) to find if callee is able
to accept call
USE CASE: INDIVIDUAL CALL


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After positive acknowledgment,
Caller’s control plane informs Caller’s
User-plane (MEGACO)
Caller’ user-plane sends RTP
(positive acknowledgement) to MS
MS can now press PTT and start
sending audio
THESIS WORK


There are 31 Use-cases implemented
in this prototype
Actual Thesis Work = Implementing
these 31 Use-cases for USER PLANE
server (in addition to specifying such
use cases + testing & bug-fixing +
demonstration)
THESIS WORK


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Other teams were involved in
developing counter-part use-cases
for Control Plane server, MS (LAN
client)
MS Word used for documentation
Linux, C, C++, GNU Tools for SW
development
WORK CONTINUES...
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
This prototype served as first ”proof
of concept” to demonstrate POC-like
service using VoIP
Full scale network is now running in
some of major Mobile Operators
worldwide who now provide PoC
sevice to consumers
THANK YOU