Reference Models

1
Reference Models
THE OSI TCP/IP REFERENCE MODELS
2
Public Switched Telephone Network (PSTN)

• The PSTN includes a number of transmission links
  and nodes
• Customer Premises Equipment (CPE) the
  equipment that is located at the customer site to
  transmit and receive user information and
  exchange the control information with the
  network, it includes PBXs key telephone systems,
  and single line telephones.
• Switching nodes interconnect transmission
  facilities at various locations and route traffic
  through a network.

3
Public Switched Telephone Network (PSTN)
(Continued..)

• Transmission nodes provide communication paths
  that carry user traffic and network control
  information between the nodes in the network,
  include the transmission media, transport
  equipment, amplifiers and/or repeaters,
  multiplexers and
• Service nodes handle signaling, which is the
  transmission of information to control the setup,
  holding, charging, and releasing of connections,
  as well as the transmission of information to
  control network operations and billing (SS7)

4
PSTN Architecture
International Gateway
Long-haul Network
Central Office
Central Office
PBX
Central Office
Individual User station lines, or Extensions
Toll switch (For routing calls to or from other
cities)

• Each phone user (subscriber) has a direct
  connection to a switch in the central office.
  This is called the local loop
• The local loop has a length of 1 10 km
• The switches in the central office are called
  (local) exchange
• A company which provides local telephone service
  is called a local exchange carrier (LEC)

5
How is voice transmitted?

• Voice can be transmitted in two ways
• Analog voice transmission each voice channel is
  allocated a bandwidth of 3.5 kHz
• Digital voice transmission analog voice stream
  is converted in a digital stream
• Standard scheme for voice call Obtain 8000
  samples per second, each with length 8 bit

6
How is voice transmitted?

• Until 1960s
• Entire telephone network is analog
• Frequency division multiplexing
• Today
• The local loop is analog.
• The rest of the network is digital (based on TDM)
• All digital When do we get an all digital
  network?
• ISDN (Integrated Services Digital Network ) is an
  all digital circuit-switching technology. ISDN is
  available since the early 1990s (in Europe) or
  mid-1990s (US). No wide deployment in US
• Another all digital but not circuit switched -
  telephony solution is IP telephony.

7
All Analog telephone network
Sub- scriber
Sub- scriber
Telephone Switch
Telephone Switch
Sub- scriber
Sub- scriber

• The telephone switch bundles (multiplexes)
  multiple voice calls on a high-bandwidth link
• The multiplexing method is FDM

8
Analog local loop / digital network
Sub- scriber
Sub- scriber
Telephone Switch
Telephone Switch
1-byte voice samples
Sub- scriber
Sub- scriber

• The first telephone digitizes a voice call (8000
  8-bit samples per second)
• Switching method is TDM.
• - Switch bundles multiple calls, by interleaving
  samples in time. Each receives one 8-bit slot
  every 125µs

9
PBX
Long-haul Network
Central Office
Central Office
PBX
Central Office
Toll switch

• A PBX (Private Branch Exchange) is telephone
  system within an enterprise that switches calls
  within the enterprise on local lines, while
  allowing all users to share a certain number of
  external lines to the central office.
• The main purpose of a PBX is to save the cost of
  requiring a line for each user to the telephone
  companys central office.

10
The long-haul network
Long-haul Network
Central Office
Central Office
PBX
Central Office
Toll switch

• Toll or backbone switches provide long-distance
  connectivity over long distance trunks.
• There are only about 500 toll switches in the
  united states. Each toll switch can run more than
  100,000 simultaneous phone calls

11
Signaling

• Signaling exchange of messages among network
  entities
• to enable (provide service) to connection /
  call
• Or the communication necessary to set up a call
  from one
• subscriber to another

• Before, during, after connection/call
• call setup and tear down
• call maintenance
• measurement, billing
• Between
• end user lt-gt network
• network element lt-gt network element
• end user lt-gt end user

12
Telephone network services

• point-to-point POTS calls
• special telephone numbers
• 800 (888) number service free call to customer
• numbers for life
• caller ID
• calling card / third part charging
• call routing (to end user) prespecified, by
  time-of-day
• follow me service allows you to select a
  temporary alternate phone on campus to receive
  your forwarded calls.
• incoming/outgoing call restrictions
• support for cellular roaming home number
  routed to current cell location

13
Intelligence in the network

• Telephone companies are looking for providing
  intelligent services to their subscribers
  forward, block, reverse the call charges and
  record messages.
• Network programmability.
• Competence by delivering value-added services
• This competence led to the standardization of
  intelligent network architecture.
• SS7 Metanetwork for signaling.

14
SS7 Network Elements

• Signaling points (SPs) network equipment that
  can send or receive signaling messages.
• Signaling Links (SLs) links that carry
  signaling messages ( 56-Kbps or 64-Kbps)
• Signaling Transfer points (STPs) intermediate
  nodes that route signaling messages from one
  place to another.

15
SS7 Network Elements
SP
SP
SL
SL
SL
STP
STP
SL
SL
STP
STP
SP
SP
Bearer Connection
Network 1
Network 2
16
SS7 Protocol Stack
Telephony User Part (TUP)
ISDN User Part (ISUP)
IN Application Part (INAP)
Mobile Application Part (MAP)
Orientation, Administration, and Management Part
(OAMP)
Transaction Capabilities Application Part (TCAP)
Signaling Connection Control Part (SCCP)
Message Transfer Part (MTP) 3
Message Transfer Part (MTP) 2
Message Transfer Part (MTP) 1
17
(No Transcript)
18
SS7 Protocol Stack (Cont.)

• Message Transfer Part 1 (MTP1) Contains
  hardware and firmware resources (Network Cards,
  Transceivers, and Cables).
• Message Transfer Part 2 (MTP2) Responsible for
  secure transaction of messages between two
  signaling points.
• Message Transfer Part 3 (MTP3) Responsible for
  routing (Through STP).
• Telephony User Part (TUP) Describes the
  signaling messages for the setup of calls and
  connections in analog telephony networks.
• ISDN User Part (ISUP) Describes the signaling
  messages for the setup of calls and connections
  in Digital networks.

19
SS7 Protocol Stack (Cont.)

• Signaling Connection Control Part (SCCP) Sets
  up and manages signaling connections, using MTP3
  to route messages reliably from one node to
  another.
• Supports both Connection-Oriented and
  Connectionless signaling contexts.
• Carries the information that STPs need to
  perform global title translation. (800 numbers,
  and number portability)
• Transaction Capabilities Application Part
  (TCAP) allows signaling nodes to do
  transactions. (e.g. Database access). It contains
  two types of information 1. Transaction Portion
  (starting and ending transactions maintains the
  state of the dialog).
• 2. Component portion (carries the actual protocol
  queries and responses).

20
SS7 Protocol Stack (Cont.)

• A TCAP message can carry the signaling message of
  other protocols in the component portion
• Operation, Administration, and Management Part
  (OAMP) verification network routing Database and
  diagnosing link problems.
• Mobile Application Part (MAP) Responsible for
  Mobility management, GSM networks.
• IN Application Part (INAP).

21

• SS7 provides a secure data network for signaling
  messages.
• It is easy to add special processing nodes for
  call processing.
• SCP service control points allows an operator
  to install and manage services like call
  forwarding, and call blocking

22
IN Standardization Implementation

• Problems
• 1. Framework expanding all the time by nature.
• 2. Telephony switches offer more and more
  features with every release and new network.
• 3. Technology such as GSM and the Internet are
  constantly changing the environment that IN
  operates in.
• Assumptions
• Upward compatibility
• IN collection of dedicated computers that
  perform special control functions.
• IN software architecture that runs services.
• IN set of nodes as it is a software framework.

23
IN Standardization Implementation (Cont.)
ITU -gt INCM look for the IN from different
angles.
2. Global Functional Plane (GFP) Identify the
building blocks out of which to construct
services. (Looks at services from the providers
point of view). Describes the software components
that a service providers must deploy to assemble
services.
1. Service Plane (SP) Describes what features a
service is composed of. E.g. the freephone
service consists of two features 1. One
number feature routes incoming calls to a single
external number from different telephones. 2.
Reverse Charging The owner of the freephone
number Pays instead of the caller.
3. Distributed Functional Plane (DFP) Reflects
the distribution of functions. It is the result
of interactions between switches that use
protocols to decide how to route the call from
source to destination
4. Physical Plane (PP) Allocates functions to
physical locations or machines. E.g. 1. SSP
contains the switch, CCF, and SSF. 2. SCP
contains SCF. 3. SMP contains SMF. 4. SDP cont.
DB, SDF. 5. IP impl. SRF.
24
IN Standardization Implementation (Cont.)
Alcatel SCP Architecture
Memory Channel
BEP
BEP
BEP
BEP
BEPs Run the actual service software
FEPs Terminate the SS7 connections and run the
SS7 Protocols
Ethernet
DB
FEP
FEP
Service Control Point
SS7 Network
FEP BEP selected for three reasons 1.
Performance
2. Scalability 3. Reliability
25
IN and the Internet

• Many operators and manufacturers already started
  making their IN platforms Internet ready with
  proprietary solutions.

1. IP, the Internet, and the Web
2. Routers and Gateways hubs, bridges, routers,
   gateways, firewalls.
3. Connecting to the Internet using modems via an
   ISPs.
4. ISDN
5. ADSL, VDSL, and DHN
6. Satellite Networks, LEO
7. Cellular Networks GSM, GPRS

26
IN and The Internet
Intelligence on the Internet

• The internet is a network of networks.
• Not administered by a central operator
• Invented for data communication not for voice
  communication
• Communications achieved by the routing packets
  of data
• IP addresses and telephone numbers are differ on
  format, scope, and the way that they are
  assigned.
• IP Networks have almost the intelligence on the
  application layer
• The Features in IN are centralized and
  controlled from the SCF. In the Internet they are
  completely distributed through the network.
• Some IN features do not make sense in the
  Internet freephone, calling card calls
• All of this changes when we use the Internet
  Infrastructure for telephony.

27
IN and The Internet
Intelligence on the Internet
Voice, Video, and Multimedia over the Internet

• TCP/IP Designed for communicating data (files,
  e-mail, web pages) between servers and clients.
  It breaks the data up into packets and routs them
  to their destination, where they are reassembled
  and passed to the receiving application.
• Voice and video could be translated into bits
  using codecs, IP routers should be able to deal
  with it as they do the routing of a file or a web
  page.
• H323 is the standard for providing Voice and
  Multimedia services over packet networks. Can
  involve the following components
• Gateways, Gatekeepers (address translation, call
  authorization, accounting and billing, call
  management), Multipoint Control Units.

28
The Mobile Dimension

• Three types of mobility in telecommunications
• Terminal mobility the terminal is connected to
  the network via radio interface and can move
  around freely (e.g. cordless and cellular phones)
• User mobility the user can move from one
  terminal to another and register for incoming and
  outgoing calls to be made to and from this
  terminal. (e.g. calling cards)
• Service mobility the portfolio of services that
  a user has subscribed to follows the user as he
  or she roams to different networks (the concept
  of exporting content and service to visited
  location)

29
The Mobile Dimension
Cellular Networks

• Types of Terminal Mobility Networks
• Cordless DECT, CT2,
• Cellular GSM, DAMPS,
• Satellite LEO EUTELSAT,
• GEO SKYBRIDGE,

A cellular network employs many radio cells of
limited coverage to cover a large area that gives
the following advantages 1. A mobile phone is
always close to a network transceiver, needs less
transmission power. 2. channels can be reused in
different cells, the capacity of network
increases as the cell size shrinks.
30
The Mobile Dimension
Cellular Networks Generations
First Generation (1G) 1980 analog cellular
networks (e.g. AMPS USA, NMT Scandinavia,
C-450 Germany, RTMS - France). Second
Generation (2G) 1990 digital transmission,
higher capacity, Better standardization (e.g.
GSM, D-AMPS, IS-95, PDC) . Third Generation (3G)
2000 Multimedia communications, Mobile
Internet, Capacity services (e.g. GPRS, UMTS)
31
The Mobile Dimension
GSM
GSM radio interface is a mix of Time- and
Frequency-division Multiple Access (TDMA and
FDMA) with Frequency Division Duplex (FDD).
Frequency Channel
0.58ms

200kHz
94
1001 0101 1101
93
1111 1100 0110
92
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4


Time Slot
Time
32
The Mobile Dimension
GSM Architecture

• A GSM network consists of three components
• Mobile Station (MS) GSM network terminals, they
  connect to the network through a radio interface
  and require processing power.
• Base Station Subsystem (BSS) consists of a base
  station controller (BSC) and base transceiver
  stations (BTS).
• Network Switching Subsystem (NSS) the core
  network part of the GSM, the key component in NSS
  is the Mobile Switch Center (MSC) A Visited
  Location Register database (VLR) holds the
  subscriber data for visiting subscribers A home
  Location Register database (HLR) holds the
  essential subscriber information including
  information about the VLR to which a subscriber
  is currently attached.

33
The Mobile Dimension
GSM Architecture (Cont.)
MS
HLR
BSC
BTS
BTS
MSC
To other MSC or other Networks
BSC
BTS
VLR
BTS
Base Station Subsystem
Network Switching Subsystem
34
The Mobile Dimension
Mobility Management and Handover

• Procedures that enable mobile terminal when a
  call arrives.
• GSM is divided into location areas, each area
  covers several radio cells and has a unique
  identifier transmitted on a special channel in
  all the cells it contains.
• Each mobile monitors this channel. When it
  detects a change in the broadcast location area
  identifier (LAI), the mobile terminal knows it
  has crossed into another location areas radio
  cell. at that time it requests a location update
  from the network.

35
The Mobile Dimension
Mobility Management and Handover (Continued)

• Two ways that a location update can take
  place
• If the new location area is served by the same
  MSC and VLR, then the VLR registers the move.
• If the new location area is served by the
  another MSC and VLR, then the mobile subscriber
  information is moved from the old to the new VLR.
  The HLR is also updated so that it can rout all
  incoming calls to the new MSC and VLR as follows
  

36
The Mobile Dimension
Mobility Management and Handover (Continued)

1. The mobile terminal moves into a new cell, notice
   that the location identifier for this cell is
   different, and requests a location update.
2. The VLR requests the subscriber information from
   the HLR.
3. The HLR sends the subscriber information to the
   VLR and registers that the subscriber is now
   attached to the new VLR.
4. The HLR informs the old network of the move and
   orders the old VLR to remove the record for this
   subscriber.

37
The Mobile Dimension
Mobility Management and Handover (Continued)
4
Location Area A
MSC
VLR
BSC
HLR
3
1
VLR
MSC
BSC
2
Location Area B
Location Update
38
The Mobile Dimension
Mobility Management and Handover (Continued)
Handover When the network and the mobile
terminal perceive a decline in quality of the
current connection, the network will look for a
better channel in a neighboring cell. The mobile
terminal must be detached in real time from the
radio channel of the old cell and attached to the
new channel in the new cell.
39
The Mobile Dimension
GSM Security

• A subscriber identity module (SIM) stores the
  GSM subscription.
• Each subscription has a unique identifier, the
  international mobile subscriber identity (IMSI).
• The dialed number is called the mobile station
  ISDN number (MS-ISDN).
• The HLR stores the mapping from MS-ISDN to IMSI.
• The network authenticates the SIM in the mobile
  terminal using a secret key algorithm. The
  visited network will request a location update by
  sending the mobile station roaming number (MSRN)
  to the HLR.

40
The Mobile Dimension
GSM Security (Continued)

• The MSRN is an identifier composed of the IMSI
  and the LAI of the cell where the mobile terminal
  is located.
• The VLR assigns a temporary identifier for the
  mobile terminal that is locally unique, the
  temporary mobile station identifier (TMSI). It is
  much shorter than IMSI and prevents the IMSI from
  being sent over the air frequently.
• The VLR stores the relationship between IMSI and
  TMSI, and also keep track of the location area of
  the mobile terminal in the form of the MSRN
• when the call is established, the exchange of
  the digital voice is encrypted using the same
  secret key as for authentication, but using a
  different algorithm.

41
The Mobile Dimension
GSM Security
HLR
VLR
MS-ISDN IMSI MSRN
IMSI TMSI MSRN
IMSI SIM
BSC
MSC
BTS
TMSI
MS
Visited Network
Home Network
Use of Identifiers in GSM
42
The Mobile Dimension
GSM Connection Services

• GSM provides the following services
• Basic voice (using 13 kbps codec)
• Half - rate voice (using 6.5 kbps codecs)
• Circuit Switched data connection (9.6 kbps)
• SMS (Store-and-forward Messages of 160
  characters)
• Cell broadcast (93 characters)
• USSD transfer of service data between mobile
  terminal and HLR.

43
The Mobile Dimension
General Packet Radio Service (GPRS)

• GPRS deployed by operators that already have a
  GSM network it is implemented as an extension of
  the existing GSM infrastructure.
• GPRS Radio Interface
• GPRS occupies free time slots only when a packet
  is sent or received in a dynamic way.
• The maximum number of time slots that a terminal
  can handle is called mutlislot class of the
  terminal. It depends on the processing power and
  radio interface hardware in the terminal.

44
The Mobile Dimension
GPRS Radio Interface
Frequency Channel
0.58ms

200kHz
94
1001 0101 1101
93
1111 1100 0110
92
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4


Time Slot
Time
Mobile 1 sends on channel 93 in time slot 4
Mobile 2 sends on channel 92 in time slot 2
GPRS packet transmission in free time slots
45
The Mobile Dimension
GPRS Radio Interface (continued)

• Many terminals support more slots for the
  downlink than for the uplink.
• Most terminal multislot classes commercially
  available are 41, 31, , and 22.
• The data rate depends on the number of slots and
  the coding scheme employed to map the data
  packets on the channel bit stream.
• The most frequently used scheme offers 13.4 kbps
  per time slot.

46
The Mobile Dimension
GPRS Architecture
PTSN, ISDN, or GSM
MSC
GMSC
Circuit
Switched
VLR
BSC
HLR
BTS
PCU
MS
SGSN
Internet
GGSN
IP
GPRS-Specific infrastructure
47
The Mobile Dimension
GPRS Architecture

• Installing GPRS requires software updates in the
  BTS, MSC, VLR, and HLR.
• The BSC needs to extend with a Packet Control
  Unit (PCU), which inserts the packet data traffic
  into the GSM channel structure.
• GPRS core network contains
• The serving GPRS support node (SGSN), which routs
  the packets to and from the mobile terminals.
• The Gateway GPRS support node (GGSN), which acts
  as the gateway to the external packet network.

48
The Mobile Dimension
GPRS Mobility Management

• The GPRS network is divided into routing areas,
  to find a compromise between notifying the
  network of each cell change and the broadcasting
  of packets for each subscriber to the whole
  network.
• The routing area is the same as, or a subset of
  , a location area. This gives the following
  advantages to the GSM-GPRS subscribers
• GSM updates automatically imply routing area
  updates.
• An incoming GSM call can be paged in the GPRS
  routing area. Which is smaller than a location
  area that means less use of radio resources for
  paging.

49
The Mobile Dimension
GPRS Mobility Management

• ATTACHMENT AND DETACHMENT PROCEDURE
• Before a mobile station can use GPRS services,
  it must register with an SGSN of the GPRS
  network. The network checks if the user is
  authorized, copies the user profile from the HLR
  to the SGSN, and assigns a packet temporary
  mobile subscriber identity (P-TMSI) to the user.
  This procedure is called GPRS attach.
• For mobile stations using both circuit switched
  and packet switched services it is possible to
  perform combined GPRS/IMSI attach procedures. The
  disconnection from the GPRS network is called
  GPRS detach. It can be initiated by the mobile
  station or by the network (SGSN or HLR).

50
The Mobile Dimension
GPRS Connection model

• A GPRS subscriber can be in one of the following
  states

State model of a GPRS mobile station.
51
The Mobile Dimension
GPRS Connection model (Continued)

• In IDLE state the MS is not reachable.
  Performing a GPRS attach, the MS gets into READY
  state. With a GPRS detach it may disconnect from
  the network and fall back to IDLE state. All PDP
  contexts will be deleted.
• The STANDBY state will be reached when an MS
  does not send any packets for a longer period of
  time, and therefore the READY timer (which was
  started at GPRS attach) expires.
• An MS in READY state informs its SGSN of every
  movement to a new cell.

52
The Mobile Dimension
GPRS Connection model (Continued)

• For the location management of an MS in STANDBY
  state, a GSM location area (LA) is divided into
  several routing areas (RA). In general, an RA
  consists of several cells. The SGSN will only be
  informed when an MS moves to a new RA cell
  changes will not be disclosed. To find out the
  current cell of an MS in STANDBY state, paging of
  the MS within a certain RA must be performed.

53
The Mobile Dimension
GPRS Connection model (Continued)

• For MSs in READY state, no paging is necessary.
  Whenever an MS moves to a new RA, it sends a
  routing area update request to its assigned
  SGSN. The message contains the routing area
  identity (RAI) of its old RA. The base station
  subsystem (BSS) adds the cell identifier (CI) of
  the new cell, from which the SGSN can derive the
  new RAI.

54
The Mobile Dimension
GPRS Connection model (Continued)
To exchange data packets with external PDNs after
a successful GPRS attach, a mobile station must
apply for one or more addresses used in the PDN,
e.g., for an IP address in case the PDN is an IP
network. This address is called PDP address
(Packet Data Protocol address). For each session,
a so-called PDP context is created, which
describes the characteristics of the session. It
contains the PDP type (e.g., IPv4), the PDP
address assigned to the mobile station (e.g.,
129.187.222.10), the requested QoS, and the
address of a GGSN that serves as the access point
to the PDN. This context is stored in the MS, the
SGSN, and the GGSN. With an active PDP context,
the mobile station is visible for the external
PDN and is able to send and receive data packets.
The mapping between the two addresses, PDP and
IMSI, enables the GGSN to transfer data packets
between PDN and MS. A user may have several
simultaneous PDP contexts active at a given time.
55
Distributed Intelligence
Parlay OSA

• Intelligent networks were originally designed
  for telephony networks.
• Services are controlled and managed centrally by
  the network operator.
• The IN model doesnt seem prepared to deliver
  value-added services in an environment that is
  becoming heterogeneous and competitive.
• Several industry initiatives sought to develop
  more state-of-the art software architectures for
  service deployment and operation.

56
Distributed Intelligence
Parlay OSA (cont.)

• Parlay OSA appear to be the technologies that
  are leading the way in the evolution of IN the
  key concept in both is the distribution of
  service control.

Parlay Concept

• The network provider is responsible for
  deploying, operating, and managing services.
• The idea of Parlay is to open this interface to
  third parties, so that others beside the network
  operator can create and deploy services.

57
Parlay Concept
Parlay
SMF
Third-party application
Intelligent network
Proprietary interface
Public interface
SCF
Proprietary interface
SSF
PSTN operator
58
Distributed Intelligence
Parlay Concept (cont.)

• The Parlay interface also allows access to other
  network functionalities, such as messaging,
  charging, QoS negotiation, and mobility
  management.
• Network access to third-party applications is
  subject to authentication and authorization.
• Parlay allow the network provider to set
  different privilege levels (e.g. some third-party
  applications can be allowed to receive only
  notifications from the network while others can
  control calls and connections)
• Parlay also provides facilities for
  nonrepudiation.

59
Distributed Intelligence
Parlay Business Model
Subscription
QoS Connectivity Management
Enterprise Administration
Trust and Security management Discovery Integrity
management
Call Control User Interaction Messaging Mobility
Client Application
Parlay Service
Parlay framework
Service Provider
Framework provider
Service factory
Registration
(Not in specified Parlay)
60
Distributed Intelligence
Parlay Business Model

• Client Application the third-party application
  that accesses network features through Parlay
  interface. (deployed and operated by the
  enterprise administration)
• Framework Interfaces offer all support
  functions for Parlay, in particular security and
  management features (administered by the service
  provider)
• Service Interfaces offer access to network
  features, such as call control, messaging, and
  mobility management (administered by the service
  provider)

61
Distributed Intelligence
Parlay Business Model

• Parlay wanted to ensure complete flexibility in
  mapping Parlay business roles into real-world
  physical entities.
• Parlay allows the provider of the framework
  interface to be different from the provider of
  the service interface.

From Parlay to OSA

• At the same time that Parlay began gaining
  momentum, 3GPP and ETSI were working on the OSA
  interfaces for UMTS.

62
Distributed Intelligence
From Parlay to OSA

• Because Parlay and OSA are so similar, most
  manufacturers have been combining both interfaces
  in one product.
• There remains some differences between the two
• Parlay specifies only a business model and a set
  of interfaces.
• Parlay very explicitly refrains from specifying
  any requirements on the implementation of the
  interfaces.
• Parlay is generic and stand-alone interface
  specification. While
• OSA Specifies more than just an interface and
  must be seen as a service architecture.
• ETSI makes recommendations for mapping OSA
  interface to network protocols like MAP CAP.
• OSA is an integral part of the service
  architecture for UMTS.

63
Distributed Intelligence
OSA interfaces

• OSA and Parlay consist of 10 main interface
  groups

Interface Short description
Framework Overall security, integrity, and management framework
Call control Setting up, releasing, and managing calls, conferences, and multimedia connections notifications of call- and connection-related events.
Data session control Setting up, releasing and managing data sessions
User interaction Play or display messages and retrieve user input
Mobility Notifications of user location and user status
Generic messaging E-mails, voice mails, SMS
Terminal capabilities Interrogating a terminal for its capabilities
Connectivity management Negotiation and management of QoS and service Lev agr IP
Account management Creating, deleting, and modifying subscriber accounts
Charging Reservation and charging of units of volume or money
64
Distributed Intelligence
OSA interfaces

• Parlay offers two extra interfaces that are not
  parts of OSA
• a. Policy Management allows for the creation
  and management of policy classes and their
  parameters to provide application service
  providers with the possibility of defining
  service-level agreements (SLAs)
• b. PAM. Allows subscribers and terminals in the
  network to exchange information about presence
  and availability (buddy lists and instant
  messaging).
• OSA interfaces are defined as a set of object
  types (classes) class definitions follow an
  inheritance hierarchy.

65
Distributed Intelligence
OSA interfaces

• Each of the OSA interfaces is specified (in UML
  and IDL) in four parts
• 1. Class diagrams. Provide an overview of the
  inheritance structure of the interface, its
  classes and operations.
• 2. Sequence diagrams. Show key examples of use of
  the interface in the form of UML message sequence
  charts.
• 3. Interface specifications. Provide the formal
  definition of the interface
• 4. Data definitions. Provide formal data-type
  definition in IDL.

66
Distributed Intelligence
General Interface Structure

• OSA defines two object classes for each
  interface on the network side
• IpltInterfacegt - is the actual interface that
  offers operations to control resources in the
  network.
• IpltInterfacegtmanager - is a management interface
  that that contains the operation to start and
  manage an instance of IpltInterfacegt. Its also
  used to request server-related event
  notifications like overload conditions.
• The client application also has to implement two
  object classes for each interface
• 1. IpAppltInterfacegt - is a client-side
  interface that contains operations for receiving
  results and notifications from the IpltInterfacegt
  interface.
• 2. IpAppltInterfacegtmanager - is an interface for
  receiving results and notifications from the
  IpltInterfacegtmanager interface.

67
Distributed Intelligence
OSA Interface Structure
OSA server
Application
IpltInterfacegtManager
IpAppltInterfacegtManager
Notifications
Creates, manages
IpltInterfacegt
IpAppltInterfacegt
Notifications, results
68
Distributed Intelligence
General Interface Structure

• These client-side interfaces are often called
  callback interfaces they are just like
  procedure calls in programming languages such as
  Pascal, operations on objects are synchronous a
  client application that requests an operation on
  an object has to wait for this operation to
  finish and send back the result.
• By putting a callback interface on the client it
  is possible to decouple the delivery of the
  result from the request.
• Callbacks are used to allow asynchronous
  communication with synchronous operations.

69
Distributed Intelligence
OSA call-control interface

• OSA offers several interfaces for call control,
  some of these interfaces consist of several
  classes with an inheritance relation.
• The figure below shows the inheritance structure
  (the main classes defined at the server side)
• A new object class is defined in a terms of an
  existing one by inheriting and extending the
  operations of the parent class

70
Distributed Intelligence
OSA call-control interface (Server side)
0n
1
IpMultiPartyCall
IpCallLeg
0n
1
1
IpMultiMediaCall
IpMultiMediaCallLeg
0n
0n
0n
IpMultiMediaCallLeg
1
1
IpConfCall
1
0n
IpSubConfCall
71
Distributed Intelligence
OSA call-control interface

• There are three main types of call defined in
  OSA
• Multiparty calls calls with zero or more
  parties. The connections set up within a call are
  represented by call-leg objects (connect and
  disconnect call parties within the scope of a
  call)
• Multimedia calls multiparty calls that allow for
  multimedia connections between parties. (can
  create and delete multimedia call legs each of
  which can have several streams)
• Conference calls multimedia calls in which there
  exists the possibility of defining additional
  relationships between the parties (the chair
  party has privileges to add parties, drop
  parties, give a party to turn a speak, and
  interrupting a speaking party). It is possible to
  create subconferences, and to move parties from
  one subconference to another

72
Distributed Intelligence
Using OSA

• The complete cycle for using an OSA service
  consists of three phases
• Authentication before using OSA services, the
  application and the OSA framework authenticate
  each other (prevents unauthorized access)
• Service selection the application selects the
  service interface. Request the signing of
  agreement before using the interface.
• Service use only after the authentication and
  service selection the application start using the
  actual service.

73
Application
OSA Framework
Initiateauthentication
(1)
Specify an authentication method (e.g., challenge
response)
authentication method
authenticationFramework
(2)
Compute authentication response
Evaluate authentication response
authentication response
authenticationSucceeded
authenticate Client
(3)
Compute authentication response
authentication response
Evaluate authentication response
authenticationSucceeded
obtainDiscoveryInterface
(4)
Create
Discovery
Interface reference
DiscoverServices
Get Profile
Services
74
Using OSA Service Selection Service Agreement
Distributed Intelligence
Application
OSA Framework
Select Service
(5)
Prepare service agreement
SignServiceAgreement
Evaluate agreement
(6)
Signature
SignServiceAgreement
(7)
Evaluate agreement
Signature
Create
Create
(8)
(8)
IpAppCallControlManager
IpCallControlManager
setCallback
(9)
75
Using OSA Call Setup
Distributed Intelligence
IpAppCallControlManager
IpCallControlManager
Create
IpAppCall
(10)
createCall
(11)
Create
IpCall
routeReq
(12)
Party A rings Party A answers
routeRes
(13)
routeReq
(14)
Party B rings Party B answers
routeRes
(15)
76
Distributed Intelligence
OSA Applications

• OSA can bring the following added value
• Third-party service control. Allow the
  integration of network features with applications
  external to the network. (OSA needed to securely
  access the networks features)
• Roaming interface. Current roaming agreements
  require a high level of trust between the roaming
  partners. OSA has a security framework, it offers
  roaming between parties that dont have an
  established trust relationship.

77
Distributed Intelligence
OSA Applications (Continue)

1. Protocol replacement. OSA can provide a standard
   programming interface for these network
   functions OSA also provides a framework for
   features that might be added in the future.
2. Content billing. The OSA charging interface can
   be used to dynamically establish relations
   between volume and value.

78
Distributed Intelligence
OSA Applications Example Taxi Dispatcher

• The idea is that when a client calls, his mobile
  terminal is automatically located and a program
  automatically alerts the nearest taxi. To
  implement this service, the taxi dispatcher
  subscribes to the following three OSA service
  interfaces offered by the mobile network
  operator
• Call control to automatically notify the taxi
  dispatcher of requests for taxis
• Mobility to determine the position of the
  calling customer and the taxis
• Generic messaging to send a notification to the
  nearest taxi.

79
Distributed Intelligence
OSA Applications Example Taxi Dispatcher
(Cont.)

• OSA supports two ways of locating taxis (mobile
  terminals)
• To ask for the position of all taxis whenever a
  customer calls.
• To have the network send periodic positioning
  information for each taxi, for example every 5
  minutes.
• The taxi dispatcher develops an application that
  automatically receives a notification when a
  customer calls, then locates the customer and
  finds the nearest taxi, the program send a short
  message to alert the taxi to pick up the client.
  This includes the following steps
• A customer dials a special number to request a
  taxi.

80
Distributed Intelligence
OSA Applications Example Taxi Dispatcher
(Cont.)

1. The OSA interface notifies the taxi dispatcher
   application of the customers call. Identifies
   the calling-party number.
2. The taxi dispatcher requests location of the
   calling party or the (taxis) through the OSA
   interface. Forwards it to the MLC.
3. The network locates the calling party or the
   taxis (this may be done periodically).
4. Receiving the callers coordinates, it looks up
   the geographic location in a database and
   determines the nearest taxi.
5. The application sends a short message to the
   nearest taxi through the OSA interface to pick up
   the customer at the indicated location.

81
Distributed Intelligence
OSA Applications Example Taxi Dispatcher
(Cont.)
Taxi
Taxi
Taxi
Taxi Dispatcher
GMLC
(3)
(4)
(2)
Application
OSA
MSC
(6)
(5)
(6)
SMSC
(1)
Database
Mobile network
82
Telecommunications Information-Networking
Architecture (TINA)
Telecommunications Middleware

• Middleware is software that runs between
  machines operating system and the applications.
• TINA Business Model
• TINA architecture
• Session model
• TINA Service Architecture
• Computational objects
• Access session
• Service session
• TINA network-resource Architecture
• Computational objects
• Connection establishment
• Federation

83
Telecommunications Middleware
TINA Architecture
Retailer
Service
Service
Service
Consumer
Service Architecture
Terminal Application
Resource Management Architecture
ATM Switch
ISDN Switch
IP Router
Connectivity Provider
84
Telecommunications Middleware
Service session graph
Service Session graph
Contains
Session member
Session relation
Is-a
Is-a
Stream binding
Control relation
Party
resource
85
Telecommunications Middleware
Access session

• The procedure for starting an access session
• When the user requests an access session, the PA
  (provider agent) in the terminal contacts the
  IA(initial agent) in the network. The address of
  the IA is always known to any TINA network.
• The IA consults the subscription database,
  authenticates the user, and finds the UA(user
  agent) for this user. (UA can be in a remote
  network).
• The UA activates an access session for the user.
  The PA in the terminal is linked to the UA for
  the duration of the access session and the user
  can start using the services.

86
Telecommunications Middleware
Access session

• Through the access session, the user can do any
  of the following
• Request a list of available services. The UA will
  list the services that the user is subscribed to.
  
• Request the start of a service session. The
  access session is always the window through which
  services are started.
• Receive invitations from other users to join a
  service session.
• Join a service session that is already active.
• Register remotely at terminals. A user can
  request to be registered on a remote terminal for
  incoming invitations to join sessions.

87
Telecommunications Middleware
Service session graph

• The TINA service session offers the following
  features that allow parties to modify the session
  graph
• Basic features such as starting, stopping, and
  suspending a session
• Multiparty features adding or dropping a party
  in a session
• Stream-binding features adding or dropping a
  stream binding to a party in the session
• Voting features voting among parties in the
  session (permission of a new party to join the
  session)
• Control features for modifying control relations
  between parties (transferring chairmanship of a
  videoconference).

88
Telecommunications Middleware
TINA network-resource Architecture

• TINA sets up connections in three main steps
• Negotiation. The communication session queries
  all involved terminals and network entities for
  their capabilities, and selects a set of common
  capabilities that will allow the connection to be
  set up.
• Reservation. The communication session asks all
  involved terminals and network entities to
  reserve the selected capabilities.
• Commitment. If all involved terminals and
  networks confirm the reservation of the necessary
  resources, the communication session will then
  order them to commit the resources and the
  connection is set up.

89
Telecommunications Middleware
TINA network-resource Architecture
Service session
Retailer
Terminal Application
Consumer
Negotiate
TCSM
CSM
Connectivity provider
CC
M
Reserve and commit
TLA IP
LNC IP
Terminal resources
Network resources
90
Telecommunications Middleware
Connection Establishment

• The negotiation phase consists of the following
  steps
• The CSM queries the TCSM of each terminal for the
  terminal capabilities. The terminals respond by
  giving a list of capabilities they can support (4
  slot GPRS)
• The CSM matches the terminal capabilities listed
  by each terminal, and defines the common set of
  capabilities that will allow the requested
  connection to be established.
• The CSM tells the TSCM which capabilities are
  needed and asks the TSCM to select the necessary
  resources in the terminal.
• The TCSM asks the TLA to identify the terminal
  end points that correspond to the requested
  capabilities. (GSM channels, IP addresses)
• The selected end-point coordinates are propagated
  back to the CSM.

91
Telecommunications Middleware
Negotiation phase in TINA connection setup
TCSM
TLA
TCSM
TLA
CSM
Query capabilities
(1)
Terminal capabilities
Query capabilities
Terminal capabilities
CSM selects common capabilities
(2)
Select capabilities
Select end points
Select capabilities
Select end points
(4)
(3)
TLA selects terminal end points that fit the
requested capabilities
TLA selects terminal end points that fit the
requested capabilities
End points
End points
End-point address
End-point address
(5)
Terminal A
Terminal B
92
Telecommunications Middleware
Connection Establishment

• The reservation phase consists of the following
  steps
• The CC contacts the LNC for each subnetwork
  involved, and asks them to set up the necessary
  connections within their domain.
• The LNC asks the terminal to reserve the
  resources negotiated in the previous steps. The
  LNC also reserves the necessary network
  resources.
• If the selected terminal end-points are
  available, the LNC asks the TLA to associate them
  with physical resources in the terminal.
• The TLA asks the TCSM to link the terminal
  applications to the physical ports in the
  terminal that will terminate the connection.

93
Telecommunications Middleware
Reservation phase in TINA connection setup
TCSM
TLA
TCSM
TLA
LNC
CC
LNC
Set up connection
(1)
Set up connection
(2)
Reserve resources
Reserve resources
(2)
Terminal reserve resources
Network reserve resources
Network reserve resources
Terminal reserve resources
Terminal end-point settings
Terminal end-point settings
Associate end points
Associate end points
(3)
(3)
Associate end points
(4)
Associate end points
(4)
The TLA associates end points with terminal
ports, and the TCSM links the application to them
The TLA associates end points with terminal
ports, and the TCSM links the application to them
OK
OK
OK
OK
Terminal A
Terminal B
Network A
Network B
94
Service Creation
From SIBs to Objects

• The key issue is how to conduct business with
  the new architectures.
• Telecommunications business is determined by the
  services and offered and their price.
• Service creation is all about software
  engineering.
• Telecommunications software is complex,
  concurrent, must be reliable and deliver high
  performance.
• The INCM recognizes the need for efficient
  creation of new services. It defines services as
  compositions of features, which are composed out
  of elementary building blocks, SIBs.
• An IN service-creation environment allows even
  inexperienced service engineers to create
  services by clicking together elementary building
  blocks in a plug-and-play fashion.

95
Service Creation
From SIBs to Objects
Begin
Play announcement Get calling card ID from user
(1)
User Interaction
Look up calling card in database
Service data management
(2)
Play announcement Get PIN from user
User Interaction
(3)
No match
Validate PIN against card data
Compare
(4)
Play error announcement
Charge communication to calling card
Charge
User Interaction
(5)
(6)
Return to BCP Release call
Return to BCP Continue setting up the
call
Continue
Clear call
96
Service Creation
From SIBs to Objects

• The calling card service shows the SIB flow and
  performs the following steps
• A message is played to the user, asking for the
  calling-card ID, and user input is received in
  the form of DTMF tones.
• The calling card data is retrieved from the
  database using the calling-card ID input by the
  user in the previous step.
• A message is played to the user, asking for the
  PIN code, and user input is received in the form
  of DTMF tones.
• The PIN provided by the user is verified against
  the PIN on the card.
• If the PIN is correct, the call is charged to the
  calling card and the call setup continues.
• If the PIN incorrect (card number or PIN
  invalid), an error message is played to the user
  and the call is cleared.