4. cpp based products

vainclamInternet and Web Development

Dec 14, 2013 (3 years and 7 months ago)

82 views

Connectivity Packet Platform in the GSM/WCDMA Network



Denis Duka

Ericsson Nikola Tesla

Split, Croatia

e
-
mail:
denis.duka@ericsson.com



Abstract

-

The telecommunications community is migrating toward a new network architecture based on horizontal layer
s.
The separation of the network functionality into independent layers is a key principle in modern networking in the tele
-

and
datacom industry today. The layered thinking is also a very fundamental and visible aspect in a number of standardization
initia
tives and industry forums, such as the Multiservices Switching Forum, led by several of the largest operators and
manufacturers.

This paper presents the short overview of Connectivity Packet Platform as a carrier
-
class technology that has been
positioned
for access and transport products in mobile and fixed networks based on layered design.



Keywords

-

CPP, MGW, WCDMA


1.
INTRODUCTION



As mobile communications evolve, mobile end
-
users
will be offered wideband multimedia capabilities. The
associated
multimedia streams require that the networks
should be more flexible than networks that are based on
time
-
division multiplexing (TDM)


at providing bandwidth
on demand.


Today's tele
-

and data communications environment
consists of a variety of networ
ks. Most of these networks are
highly specialized, designed and optimized to serve a
specific purpose as illustrated in Figure 1 (left part). To a
large extent these networks can also be described as
vertically integrated

in the sense that they combine ver
y
different functionality (for example, transport, control,
services etc.) in one and the same network element
[1]
. For
historical reasons the networks in this vertically integrated
multi
-
network world have evolved independently of one
another and therefor
e differ in many ways. This, of course,
reduces the possibilities for operators to create synergies
among their networks as a means to reduce costs, provide
service portability and so on
[2]
. The architecture in the
right part of Figure 1 illustrates a way

to evolve this multi
-
network situation in order to overcome some of its
deficiencies. The solution is based on a horizontal structure
of the network into a number of independent layers, which
gives a more flexible system. The open architecture of the
UMTS

(Universal Mobile Telecommunication System)
network ensures a smooth migration from the existing
systems to the new technologies
[3]
.






The rapid convergence of telecom and datacom
technologies has lead to the integration of vertical networks
into mu
lti
-
service (or next
-
generation) networks that
provide reliable and real
-
time communications for all
service types
[4]
.


Fig. 1.

Vertically versus horizontally integrated networks




To simplify backbone network design and enable
incremental upgrad
e as new technologies are
commercialized, a layered approach has been taken to the
design of the next
-
generation networks. By layering the
design of the network and providing open, standard
interfaces, each part of the network can evolve at its own
pace i
ndependent of changes in other parts of the network
[5]
. The layering means in practice that the different levels
in network hierarchy are separated, and communicate over
well
-
specified interfaces; thus different applications can
share the resources in the

lower level of the network.
Networks designed on this layered principle are described as
horizontally integrated
. All network functionality is split
between the connectivity layer, the control layer and the
application layer
[6]

(see Figure 2).






Fig. 2.

Horizontally integrated network


2.

BACKGROUND

TO

THE

DEVELOPMENT

OF

THE

CPP



When Ericsson first began designing Wideband Code
Division Multiple Access (WCDMA) products for third
-
generation cellular systems based on layered architecture, i
t
lacked a system platform that could support the multimedia
services that will characterize these systems. Designers also
perceived that the new radio network products would have
to be cost effective enough to compete with mature GSM
products of the futur
e. Thus CPP was selected, mostly
because it demonstrated the best cost
-
to
-
performance ratio.


CPP (Connectivity Packet Platform) is a carrier
-
class
technology that has been positioned for access and transport
products in mobile and fixed networks. It
is an execution
and transport platform with specified interfaces for
application design. The
execution part consists of support
for the design of application hardware and software. The
transport part, which can be seen as an internal application
on the exe
cution platform, consists of several protocols for
communication, signaling, and transmission.


CPP was first developed for asynchronous transfer mode
ATM (
Asynchronous Transfer Mode
) and TDM transport.
Later, support is being added for IP (
Internet P
rotocol)

transport
[7]
.


The keywords when designing CPP have been and are
flexibility, scalability, modularity and user friendliness.





Flexibility
-

CPP can be implemented in different nodes
and networks. The transport technique in CPP is based on
the Asynchronous Transfer Mode (ATM) protocol. ATM
is well suited for a lot of different applications spanning
from low intensive constant bi
t rate applications such as
voice requiring short and predictable delay to bursty
packet data applications that asks for reliable and high
performing transfer capabilities.


Scalability
-

The scalability feature of CPP comprises
both execution resources as

well as communication
interfaces. It is possible to change the size of a node
during its duty task with very small or non disturbance.


Modularity


Using CPP it is possible to create nodes
with different configurations, functionality, capacity, cost,
an
d reliability and performance levels.


User Friendliness


CPP can be managed by what is
called a ‘thin client’. That is a web browser that for a
dedicated task and by utilizing HTTP will fetch a
management application from the node. CPP contains a
number

of such applications. The users can also develop
their own applications utilizing the management
application support provided by CPP.


CPP also contains a generic object browser that is used
to manage the node by directly accessing and manipulating
th
e managed objects defined by CPP and the node
application
[8]
.


3.

CPP

NODE

ARCHITECTURE



The term "CPP based node" is used when talking about a
node that includes the CPP platform and the applications
that run on top of the platform. The term node is

thus used
to describe any type of network node that switches ATM
cells, regardless of its purpose or complexity.


The CPP Application Development Environment
(CADE) is used during the design of node applications. The
CPP Platform and CADE together inc
lude all the physical
equipment and associated software that is required so that
the ATM network node can be created.


Figure 3. shows the CPP platform and the application
part.




Fig. 3.

CPP platform and application part


4.

CPP

BASED

PRODUCTS




CPP is a platform product from which it is possible to
develop a switching network node such as a small to
medium sized ATM switch. The present day design of CPP
emphasizes WCDMA products, for example the Radio
Network Controller (RNC) in the UMTS Terre
strial Radio
Access Network (UTRAN) (Figure 4). Nonetheless, it is a
generic platform that can be used for several different
applications such as IP routers, and the RNC and Base
Transceiver Station (BTS) for CDMA2000
[9]
. Code
Division Multiple Access (CD
MA) 2000 is the evolution
from CDMA1, which is the narrowband CDMA system in
the United States today. CDMA stands for Code Division
Multiple Access.



Fig. 4.

WCDMA CPP based products



4.1. CPP Media Gateway



The CPP MGW (Media Gateway), as shown o
n Figure 5,
can contain a full set of speech and data resources for
performing manipulation and additions to the connectivity
layer. It also contains transport resources for performing
protocol and connectivity layer conversions between
different networks
and it provides Signaling Gateway
functionality for performing conversions of lower layer
control protocols. An incoming connection on a physical
line interface with a standardized bearer protocol is
connected to the appropriate function. On the outgoing s
ide,
the connection is connected to an outgoing standardized
bearer. Therefore, an incoming bearer is switched to an
outgoing bearer even if the stream is modified and the
bearers are changed.




Fig. 5.

CPP MGW





As part of this process, conversion b
etween different bearers
and formats can be made. This conversion can, for example,
mean converting a compressed voice to a non
-
compressed
format and changing the bearer from ATM to STM
(
Synchronous Transfer Mode
)
, or terminating the packet
data traffic re
ceived from the Gn interface in the GTP
(Gateway Tunneling Protocol) tunnels and re
-
tunneling the
IP packets into IPsec or L2TP tunnels towards external IP
networks (Gi interface)
[10]
. All MGW application
functions during a connection are initiated from t
he
Gateway Control Protocol (GCP) that provides a direct link
to the controlling
Mobile Switching Center

(MSC) server(s).
The platform provides the physical line interfaces and most
of the bearer layer interfaces including bearer control
signaling, for exa
mple, AAL2 with Q.AAL2.


For packet based traffic functions such as tunneling
(GTP, IPSec and L2TP), re
-
tunneling (of GTP packets to
IPSec encapsulation and vice versa), translation of IP
address to IMSI (Individual Mobile Subscriber Identity)
address
, volume based charging, security functions QoS
(Quality of Service) handling is performed in the Media
Gateway [11]. The external control interface is the
Gateway
Control Protocol

used by the MSC Server to request the
Media Gateway to add and remove media

stream functions
into a speech and data connection. The Gateway Control
Protocol also includes commands to establish and release a
through connection with the requested media stream
functions included. In the process to establish and release a
connection
to other network nodes the relevant bearer
signaling is included. A Media Gateway can lend its
resources to any MSC Server and an MSC Server can use
the resources of any Media Gateway. That way UMTS Core
Network architecture allows an
m:n

relation between
Servers and Media Gateways
[12]
.



5.

CONCLUSION



The layered architecture is being deployed in third
-
generation mobile networks


that is universal mobile
telecommunication system.
The
enhanced platform
architecture
, today generally pursued by most
s
tandardization forums, provides an inherent flexibility,
which allows operators to build scalable and cost effective
multi
-
services solutions in the new telecom world. At the
same time the layered architecture offers a pragmatic way to
rationalize legacy n
etworks, allowing them to run over state
-
of
-
the
-

art, cost effective transport solutions.


The modular nature CPP base nodes means it is possible
to create nodes with different configuration, functionality,
capacity, cost, reliability and performance l
evel. MGW
based on CPP represents the base for supporting the
multimedia services associated with UMTS making the


convergence of telecom and data in mobile communications
possible.


CPP is uniquely scalable. It can be used in small
applications and l
arge RNC and media gateway nodes.
Virtually every aspect of scalability is covered by CPP:
high
-
end and low
-
end nodes, pay
-
load capacity, processing
capacity, number of routes, route updating capacity, number
of physical links, link capacity and cost.



RE
FERENCES


[1]

Antun Caric, Kristian Toivo
:
New Generation Network
Architecture and Software Design
, IEEE
Communication Magazine, vol. 38, no 2, Feb 2000, pp.
108
-

114.

[2] Ramje Prasad, Marian Ruggieri:
Technology Trends in


Wireless Communic
ations, 2
n
edition,
Artech House,


London, 2003.

[3]
Gene Robinson:
Communication Networks

with


Layered Architecture
, IEEE802, N


West Standards


meeting for Broadband

Wireless Access Systems,


March 1999
.

[4] R.C. M
aier:
Strategic Aspects of Core Network


Migration
, First International Conference
on 3G


Mobile Communication Technologies, Conf. Publ. No.


471.

[5]
D. Medhi, S. Jain, T. Srinivasa Rao, D. Shenoy, M.


Saddi, and

F. S
umma:

A
Network

Management


Framework for Multi
-
Layered
Network

Survivabilit
y
,


Technical Report, Computer Science Telecommunic.


University of Missouri
-

Kansas City (July 1999).

[6]
J.S. DaSilva, D. Ikonomou and H. Erben:
Eu
ropean R


& D programs on third
-
generation
mobile communic.


systems
, IEEE, Personal Commun. (February 1997).

[7] L. O. Kling, A. Lindholm, L. Marklund and G.B.


Nilsson:
CPP


Cello Packet Platform
,
Ericsson


Review
No.2, 2002, pp. 68
-
75
.


systems
, IEEE, Personal Commun. (February 1997).

[8] Denis Duka:
Layered Network Architecture
,


Conference of Software, Telecommunications and


Computer Networks, SoftCOM 2003, pp. 122
-
126.

[9] De
nis Duka, L. Hribar and Damir Buric:
Adopting the


Horizontal Layering in the GSM/UMTS Network
,


Conference of Software,

Telecommunications and



Computer Networks, SoftCOM 2004, pp. 66
-
71.

[10] Denis Duka, Lovre Hribar
and Damir Buric:


Horizontal Layering


an Essential
Aspect in Modern


Networking
, MIPRO 2004, pp. 347
-
351.

[11] Fyro, Heikkinen, Petersen and Wiss: Media gateway


for mobile networks, Ericsson Review No.4, 2000,



pp. 216
-
233.

[12] Mpirical:
http://www.mpirical.com/companion/mpirical_compani
on.html#http://www.mpirical.com/compa
nion/Multi_Te
ch/Media_Gateway.htm