mansoor2
2008-10-03, 09:04 AM
<i>Introduction</i>
Customised Applications for Mobile network
Enhanced Logic also known as CAMEL was developed as a standard for
mobile intelligence across different vendor equipments for GSM network.
What this means is that the end user should be able to roam between
different networks (maybe in different countries) and be reachable at
the same number and should receive only one bill from the original
service provider (Home Operator).
Before CAMEL, the GSM networks used INAP
(Intelligent Network Application Part) for injecting intelligence in
GSM networks. The limitations of INAP was that it did not support
mobility management. CAMEL solved the mobility management problem and
provided with much more functionality. With the evolution of 3G
standards, CAMEL has evolved to provide new functionalities that will
be discussed later.
CAMEL has been divided into Phases. The last
section in this primer lists the functionality of each phases. The
latest Phase is Phase 4. If an IPLMN (Interrogating PLMN) or VPLMN
(Visiting PLMN) supports CAMEL Phase 4, it shall also provide the
functionality of all previous CAMEL phases. The first commercial implementation of CAMEL
(phase 1) was in August 2000 by France Telecom Mobiles (France),
Mobistar (Belgium) and Dutchtone (The Netherlands). <i>NOTE: CAMEL feature is a network feature and not a supplementary service. It is a tool to help the network operator </i>
<br><i>Applicability of CAMEL procedures</i>
<ul><li>The CAMEL feature is applicable to Mobile Originated and Mobile
Terminated Call Related Activities. CAMEL procedures are applicable to
all circuit switched basic services without distinction (except
Emergency calls).
</li><li>The CAMEL feature is applicable to Supplementary Services Invocation
</li><li>CAMEL procedures are applicable to GPRS sessions and PDP contexts
</li><li>CAMEL procedures are applicable to Mobile
Originating/Terminating short message service through both circuit
switched and packet switched serving network entities
</li><li>CAMEL procedures are applicable to IP multimedia services (except Emergency calls) to support legacy services
</li><li>CAMEL shall support IPMM sessions which are based on the same
charging paradigm as CS/PS calls. This applies most probably to VoIP
and Video over IP.
</li><li>CAMEL procedures are applicable to IP multimedia sessions addressed by either E.164 numbers or SIP URLs.
</li></ul>
<br><i>Example of CAMEL procedure</i>
Before we proceed further and use more technical
terms, it would be wise to understand CAMEL procedure with the help of
some examples.
<center>
<img src="http://www.3g4g.co.uk/Tutorial/ZG/Camel/Logic.jpg">
</center>
Take a simple scenario of a voice call being made.
When a subscriber starts to make a call, this request is received by
the network's Mobile Switching Centre (MSC). The MSC then sends a
message that 'queries' the SCP's database. Note that the essential
element of any CAMEL solution is a Service Control Point (SCP). This
unit effectively hosts a database which holds the instructions needed
for an intelligent application. The SCP processes that query, comes up with an
appropriate response and then sends a message back to the MSC telling
what action it should take with the subscriber’s request for a specific
service. The call is then connected in the most appropriate manner, a
process which is transparent to the customer. A very good example of
this process in action is short code dialling over a VPN (Virtual
Private Network) where the user calls a colleague’s internal extension
telephone number but is, in fact, routed to that person’s mobile phone
which is roaming abroad.
The main addition in CAMEL phase 2 which phase
1 omitted is support for a Specialised Resource Function (SRF) a
component most often found in Voice Response Units (VRUs). For example,
when an account balance reaches zero for a pre-paid customer under
phase 1, the customer will simply be cut off. With phase 2 thanks to
support for SRF, the customer will hear automatically generated
messages from the Voice Response Unit warning that the balance is
dangerously low before a call and even during the call. Naturally this
leads to greater customer satisfaction.
<br><i>Technical Terms</i>
For any further discussions we would need to use some technical terms. They are discussed in this section.
<ul><li>Interrogating PLMN (IPLMN): The PLMN that interrogates the Home PLMN (HPLMN) for information to handle mobile terminating call.
</li><li>CAMEL Service Environment (CSE): A CSE is a logical entity which processes activities related to Operator Specific Services (OSS).
</li><li>CAMEL Subscription Information (CSI): Identifies that CAMEL support is required for the subscriber and the identities of the CSEs to be used for that support.
</li><li>Service Control Function (SCF): SCF contains the actual independent service logic to apply to the call.
</li><li>Basic Call State Model (BCSM): BSCM represents an
abstract view of call processing, seen from the perspective of service
feature control performed by the SCF. The BCSM consists of two sets of
call processing logic, Originating BCSM (O-BCSM) and Terminating BCSM
(T-BCSM). </li><li>Points in Call (PIC): PIC are defined by standards to
represent those points in which action might be taken. They provide a
view of a state or event in which call processing logic may initiate an
action, such as suspension of call processing while a database is
queried.
</li><li>Detection Points (DP): DP represent transitional events that occur between some PICs.
</li><li>Triggers: A trigger is the term used to define specific
call-processing logic associated with a given point in call. Triggers
are nothing more than software logic that is loaded in a network
element to carry out instructions to initiate an intelligent network
process based on analysis of conditions at a detection point.
</li><li>Events: Unlike a trigger, which depends on some form
of input criteria, an event is simply a call occurrence such as no
answer, busy signal or call termination.
</li><li>Arming of detection points: Detection points have two
classifications: Trigger Detection Points (TDP) and Event Detection
Point (EDP). A detection point is armed if control logic is established
to initiate service control based on a trigger or event. </li><li>GSM Service Control Function (gsmSCF): functional
entity that contains the CAMEL service logic to implement OSS. It
interfaces with the gsmSSF, the gsmSRF, the GMLC and the HLR.
</li><li>GSM Service Switching Function (gsmSSF): functional
entity that interfaces the MSC or GMSC to the gsmSCF. The concept of
the gsmSSF is derived from the IN SSF, but uses different triggering
mechanisms because of the nature of the mobile network.
</li><li>GSM Specialised Resource Function (gsmSRF): functional entity which provides various specialized resources. It interfaces with the gsmSCF and with the MSC.
</li></ul>
Customised Applications for Mobile network
Enhanced Logic also known as CAMEL was developed as a standard for
mobile intelligence across different vendor equipments for GSM network.
What this means is that the end user should be able to roam between
different networks (maybe in different countries) and be reachable at
the same number and should receive only one bill from the original
service provider (Home Operator).
Before CAMEL, the GSM networks used INAP
(Intelligent Network Application Part) for injecting intelligence in
GSM networks. The limitations of INAP was that it did not support
mobility management. CAMEL solved the mobility management problem and
provided with much more functionality. With the evolution of 3G
standards, CAMEL has evolved to provide new functionalities that will
be discussed later.
CAMEL has been divided into Phases. The last
section in this primer lists the functionality of each phases. The
latest Phase is Phase 4. If an IPLMN (Interrogating PLMN) or VPLMN
(Visiting PLMN) supports CAMEL Phase 4, it shall also provide the
functionality of all previous CAMEL phases. The first commercial implementation of CAMEL
(phase 1) was in August 2000 by France Telecom Mobiles (France),
Mobistar (Belgium) and Dutchtone (The Netherlands). <i>NOTE: CAMEL feature is a network feature and not a supplementary service. It is a tool to help the network operator </i>
<br><i>Applicability of CAMEL procedures</i>
<ul><li>The CAMEL feature is applicable to Mobile Originated and Mobile
Terminated Call Related Activities. CAMEL procedures are applicable to
all circuit switched basic services without distinction (except
Emergency calls).
</li><li>The CAMEL feature is applicable to Supplementary Services Invocation
</li><li>CAMEL procedures are applicable to GPRS sessions and PDP contexts
</li><li>CAMEL procedures are applicable to Mobile
Originating/Terminating short message service through both circuit
switched and packet switched serving network entities
</li><li>CAMEL procedures are applicable to IP multimedia services (except Emergency calls) to support legacy services
</li><li>CAMEL shall support IPMM sessions which are based on the same
charging paradigm as CS/PS calls. This applies most probably to VoIP
and Video over IP.
</li><li>CAMEL procedures are applicable to IP multimedia sessions addressed by either E.164 numbers or SIP URLs.
</li></ul>
<br><i>Example of CAMEL procedure</i>
Before we proceed further and use more technical
terms, it would be wise to understand CAMEL procedure with the help of
some examples.
<center>
<img src="http://www.3g4g.co.uk/Tutorial/ZG/Camel/Logic.jpg">
</center>
Take a simple scenario of a voice call being made.
When a subscriber starts to make a call, this request is received by
the network's Mobile Switching Centre (MSC). The MSC then sends a
message that 'queries' the SCP's database. Note that the essential
element of any CAMEL solution is a Service Control Point (SCP). This
unit effectively hosts a database which holds the instructions needed
for an intelligent application. The SCP processes that query, comes up with an
appropriate response and then sends a message back to the MSC telling
what action it should take with the subscriber’s request for a specific
service. The call is then connected in the most appropriate manner, a
process which is transparent to the customer. A very good example of
this process in action is short code dialling over a VPN (Virtual
Private Network) where the user calls a colleague’s internal extension
telephone number but is, in fact, routed to that person’s mobile phone
which is roaming abroad.
The main addition in CAMEL phase 2 which phase
1 omitted is support for a Specialised Resource Function (SRF) a
component most often found in Voice Response Units (VRUs). For example,
when an account balance reaches zero for a pre-paid customer under
phase 1, the customer will simply be cut off. With phase 2 thanks to
support for SRF, the customer will hear automatically generated
messages from the Voice Response Unit warning that the balance is
dangerously low before a call and even during the call. Naturally this
leads to greater customer satisfaction.
<br><i>Technical Terms</i>
For any further discussions we would need to use some technical terms. They are discussed in this section.
<ul><li>Interrogating PLMN (IPLMN): The PLMN that interrogates the Home PLMN (HPLMN) for information to handle mobile terminating call.
</li><li>CAMEL Service Environment (CSE): A CSE is a logical entity which processes activities related to Operator Specific Services (OSS).
</li><li>CAMEL Subscription Information (CSI): Identifies that CAMEL support is required for the subscriber and the identities of the CSEs to be used for that support.
</li><li>Service Control Function (SCF): SCF contains the actual independent service logic to apply to the call.
</li><li>Basic Call State Model (BCSM): BSCM represents an
abstract view of call processing, seen from the perspective of service
feature control performed by the SCF. The BCSM consists of two sets of
call processing logic, Originating BCSM (O-BCSM) and Terminating BCSM
(T-BCSM). </li><li>Points in Call (PIC): PIC are defined by standards to
represent those points in which action might be taken. They provide a
view of a state or event in which call processing logic may initiate an
action, such as suspension of call processing while a database is
queried.
</li><li>Detection Points (DP): DP represent transitional events that occur between some PICs.
</li><li>Triggers: A trigger is the term used to define specific
call-processing logic associated with a given point in call. Triggers
are nothing more than software logic that is loaded in a network
element to carry out instructions to initiate an intelligent network
process based on analysis of conditions at a detection point.
</li><li>Events: Unlike a trigger, which depends on some form
of input criteria, an event is simply a call occurrence such as no
answer, busy signal or call termination.
</li><li>Arming of detection points: Detection points have two
classifications: Trigger Detection Points (TDP) and Event Detection
Point (EDP). A detection point is armed if control logic is established
to initiate service control based on a trigger or event. </li><li>GSM Service Control Function (gsmSCF): functional
entity that contains the CAMEL service logic to implement OSS. It
interfaces with the gsmSSF, the gsmSRF, the GMLC and the HLR.
</li><li>GSM Service Switching Function (gsmSSF): functional
entity that interfaces the MSC or GMSC to the gsmSCF. The concept of
the gsmSSF is derived from the IN SSF, but uses different triggering
mechanisms because of the nature of the mobile network.
</li><li>GSM Specialised Resource Function (gsmSRF): functional entity which provides various specialized resources. It interfaces with the gsmSCF and with the MSC.
</li></ul>