[3][4]. Within the scope of the new era the importance of localisation [5][20] as a primary concept for service customisation, network reconfigurability and operator.
GENERIC FRAMEWORK FOR THE PROVISION OF EFFICIENT LOCATION-BASED CHARGING OVER FUTURE MOBILE COMMUNICATION NETWORKS Spyridon Panagiotakis, Maria Koutsopoulou, Athanassia Alonistioti, Alexandros Kaloxylos National and Kapodistrian University of Athens, Department of Informatics and Telecommunications, Communication Networks Laboratory, 157 84 Athens, Greece Tel: +30 1 72 75 334, emails: {spanag, mkoutsop, nancy, agk}@di.uoa.gr Abstract - The provision of location-based services is expected to have essential impact in the competition among 3rd Generation network operators. To support the realization of this functionality the standard UMTS infrastructure will probably need to be supplemented with additional intelligent components. Furthermore, flexible Location-based charging mechanisms have to be designed and deployed to allow subscribers to be charged with different rates, depending on their location and profiles. In this paper a proposed platform for location-aware service provision is introduced and the interactions among its constituent components for applying an efficient locationbased charging scheme are discussed in detail. Keywords - Location, Charging, Service Provisioning, Reconfiguration, Framework. I. INTRODUCTION With the evolution of broadband and 3rd generation mobile communications, the software reconfigurable radio system and network concept has been heralded as potentially offering a pragmatic solution for the provision of a wide range of sophisticated services to mobile users [3][4]. Within the scope of the new era the importance of localisation [5][20] as a primary concept for service customisation, network reconfigurability and operator differentiation has boosted the activities of many Telecommunication companies and institutions to develop or integrate positioning systems into their networks. Location-based charging as described in 3GPP [1] is a flexible model that takes into account location information provided by the Location Service (LCS) Server [2] of the network operator to provide subscribers with a personalised and customised charging scheme. More specifically, according to the approach adopted in our prototypical implementation, with location-based charging subscribers are provided with the ability to define their own Home Zones comprising some favorite places (e.g. home or work environment, etc). The current location information of users is constantly compared against predefined service zones established for them and they are billed accordingly. Furthermore, different rates may be applied in different zones based on the time of day or week. Location based charging may also be applicable on a group basis, which may be desirable for example, for business groups.
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Location Based Charging may be invoked upon initial registration with a service, while subscribers shall be able to activate/deactivate this feature by using specific feature’s codes on their services subscription profiles [6] kept in HSS. Moreover, Location based Charging has to be authorised by the subscriber every time this is apt to be applicable. In this paper at first a generic framework for intelligent service provision is introduced and then the interactions required among its constituent components to accomplish effective location-based charging are discussed. II. A FLEXIBLE FRAMEWORK FOR RECONFIGURABLE SERVICE PROVISIONING AND MANAGEMENT To support the demand of future communications for efficient and personalised service provision the standard UMTS infrastructure should be supplemented with intelligent components. Figure 1, depicts the general architecture and an example physical placement of the Reconfiguration Control and Service Provision Platform (RCSPP) to meet requirements for the beyond 3G era. It is assumed that the independent Value Added Service Providers (VASPs) will offer their Value Added Services (VAS) using the transport service provided by the underlying UMTS network. The RCSPP constitutes an integrated distributed software framework for reconfigurable deployment and management of VAS offered to mobile users as well as charging for their usage [4][8]. The framework introduces several components involved in service provisioning namely, the Reconfiguration Control and Service Provision Manager (RCSPM), the Charging Accounting and Billing (CAB) System and the Metering Devices (MDs). IP connectivity is considered to be available between all the aforementioned components. Although business roles may be integrated to one entity (e.g. the RCSPP provider and the network access provider business roles may be undertaken by the mobile operator), we see that the business domains can also be physically separated. In more detail: The RCSP Manager (RCSPM) may reside in a Third Party domain. It co-ordinates the required procedures for dynamic application deployment and personalized, consistent and reconfigurable discovery, provision and execution of VAS to mobile users. For that reason, it
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Fig. 1. General architecture and example physical placement of the RCSPP framework. maintains a database with information about the services offered by the platform (the Service DB), as well as user profile data. The RCSPM hosts the Reconfiguration and the Location Manager modules. The former is responsible for interacting with other components of the proposed architecture (e.g. MDs) in order to configure them properly as well as to perform reconfiguration actions on them. Reconfiguration actions are based on policies (e.g. QoS or metering policies) tailored to user location, terminal capabilities, user preferences and usage data. On the other hand, the Location Manager interacts with the location information’s sources of the underlying network infrastructure (e.g. the LCS Server or the Presence Server [9]) to track the location and mobility of the subscribers. Hence, it enhances the service provisioning approach adopted by the RCSPP with location aware features (e.g. the location based charging), enabling better customisation and personalisation of the whole service offering. Since the RCSPP administratively may be situated on and managed by entities independent to the operator network, interactions among the modules of the platform and Basic Network Elements, such as the HSS, the LCS server [2], the Policy Decision Point (PDP) [10], etc., should take place through open network interfaces. Various industry initiatives, such as OSA [6] [11], PARLAY [12], and JAIN [13], address the introduction of open network interfaces to third party providers. Common to all these architectures is the provision of a Basic Network Management Layer by the mobile operator, which act as gateway (mediator) between Third Parties and provided basic network services [14]. Hence, in order for the
RCSPP to access the network services offered by the underlying network infrastructure, interaction with the Basic Network Management Layer provided by the mobile operator is required. By accessing the standard open network interface provided by the Basic Network Management Layer, the RCSPP is then able to build its services based on network features and functionality offered by the network operator. The MDs [15] are dynamically configured by the RCSPM through policies [16] to process and monitor the traffic over the IP layer as well as to meter data about resource consumption in the network (e.g. transmitted volume). Alternative approaches of such MDs are the Layer 4 SmartSwitch-Router [15] and the IPmeter [21]. In the proposed architecture the MDs are located at the edge of the Network Access Provider so that they process all traffic between VASPs and the end users. The collected metering data are formatted into appropriate records, the VAS Data Records (VASDRs) and sent to the CAB for further processing. The VASDRs, apart from calculating of charges, are also used by the CAB for the retrieval of specific information, such as the VAS that are currently executed by a specific user. The functionality of MDs is under the supervision of the MD Reconfiguration Manager, which is responsible for the policy-based configuration and reconfiguration of the MDs. Since it is proposed that the MDs are to be included into the standard network infrastructure, access to the reconfiguration of MDs should be offered to the RCSPM and other authorised entities through a standard open API provided by the MD Reconfiguration Manager [3]. The MD Reconfiguration Manager mediates between
authorised entities and MDs to securely grant the MD services to the respective parties (e.g. VASPs). Since reconfiguration of MDs is policy based, communication with the MDs is built upon the common protocols for policy provisioning such as the COPS [16] or COPS-PR [17]. The MD Reconfiguration Manager maps all incoming calls on the aforementioned open interface to the appropriate COPS messages for interacting with MDs. The CAB system [3] is responsible for the overall control of the charging process, providing advanced charging, accounting and billing services to VASPs and end users. To elaborate, the CAB collects charging information from both network infrastructure (in the form of Charging Data Records (CDRs) from the CGF and CCF) and MDs (in the form of VASDRs), applies the appropriate pricing model, calculates the portions that are due to each business entity and produces a single itemised bill to each subscriber [3]. Additionally, the CAB provides advanced charging services through open APIs in order to enable the RCSPM and independent VASPs to apply pricing policies dynamically, to retrieve statistical information concerning the VAS usage (e.g. the users that currently execute a specific VAS, or the VAS that are currently executed by a specific user), to add content based charges and to be informed about current status of their VAS revenues. III. LOCATION AND MOBILITY BASED CHARGING/BILLING Location and Mobility based charging [1] is a flexible, location and mobility aware, charging model that takes location information by the network to provide subscribers with a personalised and customised charging/billing scheme. More specifically, with mobility and location based charging the RCSPP provider enables subscribers to define their own Home Zones comprising some favorite places of them (e.g. home or work environment). Home Zones are included into the user profile of each subscriber. Location information, is then compared against Home Zones established for the users, so that subscribers are charged, for example, the same low “Home Zone” flat rate when they use their mobiles within Home areas. Outside Home Zones they will be billed at a higher rate, while different tariffs may be applied in different zones based on the time of day or week. Therefore, the descriptive document describing each VAS (probably in XML format) provided by VASPs to the RCSPM upon VAS registration should include information relevant to the location based charging offering. This information comprises a statement whether this VAS is offered through the location based charging service, along with the applicable pricing policies that are associated with VAS usage from within Home Zones or out of them. In addition, location based charging service shall also be applicable on a group basis, which may be desirable for example, for business groups. As subscribers move or cross predefined charging zones, or the applicable rate changes, it is required individuals and group subscribers to be notified of their location-based charging service offering indicating either "in" or "out" of
zone, while a session is in progress or prior to its initiation. The user preference related to the location based charging activation/deactivation is included into the general user preferences part of the user profile, indicating consequently the user general preferred policy relevant to this special service offering. So, in case that the location based charging feature has been enabled by a subscriber into his user profile, the RCSPM shall apply this advanced charging scheme onto all activated sessions by the user that concern the usage of VAS. In such a case only VAS explicitly associated with a different pricing policy (as it is included into the XML document describing the VAS) are excluded from the location-based charging offering. However, despite the users’ acceptance to this feature, as it is implicitly expressed into their user profiles, prior to the location based charging activation, an appropriate notification is sent to the involved subscriber asking his confirmation for enabling location based charging and tracking his location. Furthermore, location based charging may be invoked upon initial registration with a VAS, while subscribers will be able to activate/deactivate this feature by using specific feature’s codes of their services subscription profiles kept in their user profile [7]. Location and mobility based charging service is offered to VAS and other authorised entities through the open API provided by the Location Manager of the RCSPM. Hence, by invoking the ActivateLocationBasedChargingReq method, authorised entities are given the ability to request the Location Manager of the RCSPM to activate this advanced charging feature onto a specified user, or session (that is per specific user and application). In case that the location based charging activation is requested on a per user basis, it results in the activation of this functionality for all the sessions the user is involved in, relevant to the usage of VAS. In such a case only VAS explicitly associated with a different pricing policy (as it is included into the XML document describing the VAS) are excluded from the location-based charging offering. Location based charging offering can be disabled at any time by invoking the CancelLocationBasedCharging method that is offered to authorised entities by the Location Manager of the RCSPM. Each cancellation requests should be sent by the same authorised entity that requested the activation of the location based charging service and should explicitly specify the corresponding ActivateLocationBasedCharging request that it cancels. To apply effective Location/mobility based charging, taking into account that a user may cross back and forth between zones multiple times during a session, and that a session may terminate in the zone it was originated from, or in a different zone, multiple interactions of the Location Manager of the RCSPM with the Location server [2] of the underlying network infrastructure may be required during a single session. More specifically, interactions required to take place, in case that Location based charging activation has been requested to the Location Manager of the RCSPM, include: 1. Upon invocation by an authorised entity (e.g. an internal module of the RCSPM, or a VAS) of the
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ActivateLocationBasedChargingReq method for a user or a specific session the Location Manager of the RCSPM at first examines its caches to find out whether location based charging service has already been activated for the specified user. In case that this is not the fact, an appropriate notification is sent to the specified user (by accessing the Push or messaging server of the underlying network through the open interface provided by the Basic Network Management Layer) asking his confirmation for enabling location based charging and tracking his location. On positive response the Location Manager of the RCSPM retrieves the current location of the user, by accessing the LCS Server of the mobile network (through the open interface provided by the Basic Network Management Layer), in order to identify the originating Home Zone of the user. Then, the Location Manager invokes to the LCS server of the network (through the associated open network interface) a Mobile Terminated Deferred Location Request [2] specifying as response event the crossing of the applicable Home Zones by the targeting User Equipment (UE). This request includes all the parameters defined on [18] [19] [11] with respect to the user privacy settings. This information will enable the RCSPM to track the charging zones that the user visits while location based charging offering is enabled. Following the notification by the LCS Server (through the Basic Network Management Layer) that the requested UE has entered into a new Home Zone or moves out of it, the RCSPM instructs the MD (calling the directCollectMeteringDataReq method through the open interface provided by the MDs Reconfiguration Manager) to close and send to the CAB the VASDRs that are associated with the specified session or user and concern the usage of VAS within the previous charging zone. The RCSPM incorporates into the aforementioned request the geographical area (Home Zone or not) that the requesting user currently exited, along with the cause that triggered this method call (e.g. “In Home Zone Billing” or “Out Home Zone Billing”) so that MD includes this location sensitive information into the VASDRs that it generates. The MD Reconfiguration Manager maps this incoming method call to the appropriate COPS-PR messages to interact with MDs and stimulate them to close and send to the CAB the requested VASDRs. The CAB, in turn, uses these records to charge the subscriber for the service usage in the associated Home Zone, based on the applicable rates for this zone. In case that per user activation of the location based charging has been requested, the RCSPM at first requests the CAB to find out the VAS that the specified user currently executes (by invoking the directCollectMeteringDataReq method offered by the CAB) and then instructs the MDs (through the MD Reconfiguration Manager) to close and send to the CAB the associated VASDRs. By receiving the CAB response, the RCSPM at first interacts with the Service DB to retrieve the
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applicable pricing policies of the active VAS on the current Home Zone of the user and then notifies the subscriber about the new applicable pricing rates (by accessing the Push or messaging server of the underlying network). Steps 4, 5 are repeated until the authorised entity that activated the Location based charging feature on step 1 invokes the CancelLocationBasedChargingReq method provided by the Location Manager of the RCSPM (specifying the ActivateLocationBasedCharging request that it cancels). Upon receipt of such a cancellation request the Location Manager interacts with the LCS server of the network (through the associated open API) to cancel the Mobile Terminated Deferred and Periodic Location Request invoked on step 3.
Fig. 2. Interactions regarding Location and mobility based charging/billing. The Message Sequence Chart (MSC) in Figure 2 (derived from the simulations that have been performed following the SDL specification of the RCSPP functionality) depicts the required interactions among components of the proposed architecture to accomplish location/mobility based charging activation on a per user basis. In order for this procedure to work properly, it is required the
mechanism specified in [2], concerning the Mobile Terminated Deferred Location Requests, to be enhanced to accomplish the new type of event (event = UE crosses Home Zone) described on step 3 above. Additionally, for privacy reasons, a notification message indicating the type of location request (e.g., current location) and the identity of the requesting LCS client (e.g., the RCSPM) should be sent to the targeting UE by the LCS server on a per location retrieval request basis.
[7] [8]
[9] [10] [11]
IV. CONCLUSIONS Location-based charging is quite likely to constitute key application enabler in the forthcoming communication era since it provides subscribers with the opportunity to select the most beneficial service provision and charging for them, while it offers to the operators the possibility to customize and differentiate their services attracting new subscribers. In this paper a generic framework for intelligent service provision was introduced and the interactions required to accomplish effective locationbased charging were discussed.
[12] [13] [14]
[15] REFERENCES [1] [2] [3]
[4]
[5]
[6]
3GPP TS 22.071: “Location Services (LCS); Service description, Stage 1”. 3GPP TS 23.271: “Functional stage 2 description of LCS”. M. Koutsopoulou, N. Alonistioti, E. Gazis, A. Kaloxylos, “Adaptive Charging Accounting and Billing system for the support of advanced business models for VAS provision in 3G systems”, Invited paper at the PIMRC 2001, San Diego, USA. S. Panagiotakis, N. Houssos, N. Alonistioti, "Integrated Generic Architecture for Flexible Service Provision to Mobile Users", Invited paper at the PIMRC 2001, San Diego, USA. At. Alonistioti, S. Panagiotakis, N. Houssos, A. Kaloxylos, "Issues for the provision of Locationdependent services over 3G networks", Invited paper at the 3GIS 2001, Athens, Greece. 3GPP TS 23.127: “Service aspects; The Virtual Home Environment.
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3GPP 23.240: “3GPP Generic User ProfileArchitecture, stage 2”. Alonistioti, N. Houssos, S. Panagiotakis , "A framework for reconfigurable provisioning of services in mobile networks", Invited paper at the ISCTA 2001, Ambleside, Cumbria, UK, July 2001 3GPP TS 22.141: "Presence Service, stage 1”. Parlay APIs 3.0, “Policy Management Specification - version 1.0”. 3GPP TS 29.198: “Open Service Access (OSA); Application Programming Interface (API); Part 112”. Parlay Group, “Parlay API Spec. 3.0”, December 2001, available from http://www.parlay.org/specs/index.asp. J. Keijzer, D. Tait, R.Goedman, “JAIN: A new approach to services in communication networks”, IEEE Communications Magazine, January 2000. M. Grech, R. McKinney, S.Sharma, J. Stanaway, D. Varney, K. Vemuri, “Delivering seamless services in open networks using intelligent service mediation”, Bell Labs technical journal, JulySeptember 2000. Layer 4 Switching: An Overview, http://www.enterasys.com/technologies/smartswitc h-router RFC 2748, “Common Open Policy Service protocol (COPS)”, D. Durham, J. Boyle, R. Cohen, S. Herzog, R. Rajan, A. Sastry, http://www.ietf.org/rfc/rfc2748.txt RFC 3084, “COPS Usage for Policy Provisioning (COPS-PR)”, K. Chan, J. Seligson, D. Durham, S. Gai, K. McCloghrie, S. Herzog, F. Reichmeyer, R. Yavatkar, A. Smith, http://www.ietf.org/rfc/rfc3084.txt 3GPP TR 23.871: “Enhanced support for user privacy in location services”. Location Interoperability Forum (LIF), http://www.locationforum.org/ K. Molnár, Z. Nagy, S. Panagiotakis, V. Gazis, N. Houssos, M. Koutsopoulou, "Location features in the MOBIVAS project", Invited poster at the Mobile Location Workshop MLW2001, Espoo, Finland, June 2001. Ipmeter White Paper, 2000, http://www.ipmeter.com/doc/whitepaper/t1.htm
