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Who moved my Cheese? - Mobile Data Charging

Worldwide predictions on Mobile Data usage are hinting towards more and more demand. The demand for mobile device data is many folds higher compared than PC or laptop demand which clearly proves mobile broadband traffic is increasing. Mobile network operators (MNOs) have to find new ways and means to lower the operating costs of their networks in order to deliver innovative, faster & high revenue-generating services to their subscribers. This article is focused on this subject along with other issues on voice revenue being depleted from MNOs financial statements.

Possible solutions to these challenges are described in the main story part below. Integrate the applications needed to optimize and monetize a mobile network into the mobile gateway or provision each application on separate standalone servers. Mobile Data, Bundled packages, Mobile Money, Mobile Banking, Mobile Payments, OTT services like Facebook, Whatsapp and internet packages are the core business for many players with all other possible overlay services.

Introduction โ€“ There are millions of solutions and solution providers around the globe for refining the issues of mobile data attributes like speed, cost, capping issues, what should be charged, what should be free rated and what should be blended with data bunddles. Solutions to handle problems of revenue going down on almost all MNO service offerings through OTT players eating into voice revenue etc. Time started for MNO to take charge and start innovating in order to survive. They also realise that they themselves are responsible for cannibalising their own voice revenue by encouraging revenue share based VAS services from VAS service providers rather than affiliating with OTT players.

Learnings and new streams to be open for their future and retirement plans rather then just choking and getting extinct like dinosaurs. These days, everyone is talking about Greece and Puerto Rico who plainly pose danger to themselves. Their stories diverge in the danger they pose to others. This story can be easily put to the MNOs face where the MNO can be called the Greece of today and their whole problem can be compared to the current economic situation of Greece. The risk of contagion remains at the heart of the MNO crisis. 

Main Story  - Wireless access to Internet data services is getting increasingly popular, thanks to the deployment of 3G/4G cellular networks. Mobile Network Operators are facing two challenges: how to optimize and monetize their networks as voice revenue continues on a south bound journey. As per the Google research, mobile broadband traffic is projected to increase by up to 35 times from its 2011 size by 2015, the response to these two issues could mean the difference between significantly growing your business over the next five years or falling behind the competition. As mentioned before many of the MNOs have, in search of revenue actually cannibalised their own voice revenue by encouraging revenue share based VAS services from VAS service providers as usage on the network remain the same at 1 to 10 USD on average.

As per expectation, in the shortest possible time, mobile broadband networks will take up 40 exabytes (1 billion gigabytes) annually, up from a total of 1.08 exabytes in all of 2009. Policy based Charging Control i.e. PCRF system, Deep Packet Inspection (DPI) and a simplified architecture are the baseline elements needed to monetized a mobile broadband network and reduce overall capital expenditures and operational expenses, yet increase performance. Bring VAS services in house or engage third party vendors on the condition of delta ARPU which can be increased by VAS partners and not eat into your voice revenue and converting it to VAS. The PCRF interfaces with the main packet gateway and takes charging enforcement decisions on its behalf.

When it comes to optimizing performance and making Revenue Assurance (REVA) team happy, the most important uses of DPI today are around internally facing network optimization and control as a practice MNO has data bundles & social media bundles, which are very useful and high on demand at sales. Solutions designed for security detection, mitigation and QoS prioritization needs to be on mind at all times but not at cost of revenue or by making REVA team unhappy for example Whatsapp bundles which are normally unlimited might cost 2 USD per month but now if DPI is not implemented to stop the revenue loss, subscribers will share audio, video and pictures on the same bundle cost which will result in a huge loss to the MNO. While MNOs may not readily be transparent to the subscriber base at all times, this enables operators to maximize on revenue.

DPI in combination with applications that further optimize the network and monetization โ€“ such as content filtering, firewall, payload compression, application detection, content charging, and others โ€“ form a foundation for PCRF and other services that will address the business needs of mobile network operators now and into the future. In a PCRF environment, the centralized device can act as a policy decision point (PDP) for the wireless operator and gets as granular as individual subscribers.  Policy and Charging Control has a key role and importance in this game and the purpose of the PCC rule is to detect a packet belonging to a service data flow. The service data flow filters within the PCC rule are used for selection of downlink IP. CAN bearers and Service data flow filters within the PCC rule are used for the enforcement that uplink IP flows are transported in the correct IP CAN bearer

  • Identify the service data flow contributes to
  • Provide applicable charging parameters for a service data flow
  • Provide policy control for a service data flow

How DPI and PCRF helps to ensure security & revenue leakage: attackers are usually looking for ways to obtain free mobile data services. Without a doubt these worms do exist and always find loopholes in the charging policy. Operators allow free data service for certain data flow, but usually forget or do-not enforce that the transmitted packets indeed belong to the designated free flow. Even worse, no effective mechanism is implemented to limit the traffic volume going through this free ride. Consequently, these loopholes can be exploited to enable any form of mobile data services for free. The 3G standards offer the operators flexibility to define their own charging policies. Unfortunately, their policies and implementations may contain serious flaws.

In normal audit we can easily find loopholes to implement this free-DNS policy in reality. First, there is almost no enforcement mechanism to ensure that the packets going through free DNS-reserved port are indeed DNS messages or call it as free fake DNS loophole. Second, there is no effective mechanism to limit the traffic volume going through free rated port or no volume-check loophole.

Gx (An offline charging interface) reference point is located between the Policy Control and Charging Rules Function (PCRF) and the Policy and Charging Enforcement Function (PCEF). The Gx reference point is used for provisioning and removal of Policy and Charging Control (PCC) rules from the PCRF to the PCEF and the transmission of traffic plane events from the PCEF to the PCRF. The Gx reference point can be used for charging control, policy control or both by applying AVPs relevant to the application. The PCEF (Policy and Charging Enforcement Function) select a PCC rule for each received packet by evaluating received packets against service data flow filters of PCC rules in the order of the precedence of the PCC rules. When a packet matches a service data flow filter, the packet matching process for that packet is completed, and PCC rule for that filter shall be applied.

Policy Control and Charging Rules Function (PCRF) - Dedicated policy equipment standardize in 3GPP that enables the policy function for bandwidth and charging on multimedia networks. PCRF is a fairly new term, introduced in late 2007 (As per Internet findings from various web sites but I don't take any responsibility in case its not true) so take it as perception when standards for the 3GPP Policy Charging Control (PCC) architecture were published. The PCRF function is part of the larger PCC architecture, which also includes the Proxy Call Session Control Function (P-CSCF) and the Policy and Charging Enforcement Function (PCEF). Combined, the elements of the PCC provide access, resource, and quality-of-service (QoS) control. 

Functional element that comprises flow based charging control and policy control decision functionalities. The PCRF stipulates network control regarding the service data flow detection, gating, QoS and flow based charging (except credit management) towards the PCEF. PCRF receives session and media related information from the Application Function and informs Application Function for data traffic. The PCEF (Policy and Charging Enforcement Function) is the functional element that encompasses policy enforcement and follow based charging functionalities.

Conclusion:  To step up as one single team, exploit technology and leverage on existing MNO infrastructure to acquire customers, enrich use cases, lower costs and increase revenue especially in markets where regulators play a dominant role. Customers are funny enough and real quick to blame the service provider for over charging (Though there is non and will never complain about under charging or free usage) for an instance if you move your network from 2G to 3G or from 3G to 4G and tell your customer to use the faster connection and enjoy speedy data next day customer will complain that you (Service provider) stolen his money and would never realise that his/her data now would not last for 30 days due to speed it may vanish in 15 days as package bought was on the total data amount not unlimited data under time bound package. When customer use 1GB data on 2G network it may take 30 days (Just for argument sake) and on 3G it might vanish in 22 days and on 4G it might take just 10 days to be consumed and customer says whaaaatttt ..... where is my data ..... crying....crying... and will say you stole my data / money.

DPI, PCRF supporting Mobile data in a big way as the Internet is going wireless and mobile. Two driving forces for this trend have been the explosive growth of smartphones and the rapid deployment of 3G/4G infrastructure. Unlike the wired Internet, cellular networks have implemented usage-based charging, rather than the simpler flat charging. The 3G/4G standards stipulate the accounting architecture, yet provide freedom for the MNO to define their own charging policy. In this work, if we conduct experiments on operational 3G networks to study the security implication of such an architecture and practice. We will find and surely discover loopholes and simple attacks, which can be validated by experiments over operational networks.


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