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Next-generation broadband policy control systems: Where are they heading?

2015.05.01 By Wang Minghu

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Existing broadband policy control systems are already unable to meet the requirements currently placed on them by LTE and its future development. The next generation of policy control systems will need critical features such as 200,000 TPS performance, 99.9999% reliability, rapid policy TTM, open access, fixed and mobile policy convergence, and NFV support.

With the rapid deployment and popularization of LTE networks, the amount of data traffic handled by these networks has seen breakneck growth of over 400% year-on-year, due to the high-bandwidth, "zero" wait and always-on nature of the technology. Carriers have implemented refined traffic solutions in order to boost their revenue from data services. Such developments have placed much higher requirements on broadband policy control systems. Existing policy control systems are already unable to meet the requirements currently placed on them by LTE, and will be unable to meet the requirements that future developments bring.

What the next generation of policy control systems need

High performance

Rapid increases in the number of concurrent subscribers: The fast growth of LTE subscribers has caused the overall number of broadband subscribers to rise rapidly. According to a report by Informa, the number of broadband subscribers is expanding by nearly 18% year on year. Added to this, the growth in the average Internet usage time per subscriber will mean a year-on-year increase in the number of concurrent subscribers by 25%.

More refined policy controls: When it comes to broadband deployment, operators' current main focus is data traffic, with fair use policies (FUP) and packages for specific applications (such as unlimited Facebook plans) being common. In the future, operators will implement more policies that support more refined mobile broadband services. These will include policies based on factors such as time, location, subscriber level, network congestion status, and subscriber terminal type. In 2013, operators adopted on average 12 policy use cases. According to a report by Heavy Reading, this figure will rise to 35 in 2015 and continue to increase rapidly as time goes on.

Broader policy control scope: At present, policy control systems typically only control data gateways and DPI equipment for the management of user traffic and QoS. In the future, they will control more user traffic processing devices to strengthen user experience management. Such equipment will include video optimization servers to compress video during times of network congestion; URL filtering servers to prevent children from accessing inappropriate content; and in the future SDN gateway equipment for the management of user traffic QoS on SDN networks.

There needs to be a substantial enhancement in the performance of the next-generation of policy control systems to meet the requirements of more refined traffic operations in the future. According to estimates from Huawei's Core Network MI department, performance needs will increase 20-fold on 2013 levels by 2020, from 10,000 to 200,000 Transactions per Second (TPS).

High reliability

Using policy controls to guarantee user experience is a key measure for boosting subscriber loyalty and reducing churn rates.

The user experience of LTE data services will suffer greatly if policy control systems are unavailable. Take the example of subscribers participating in an important teleconference or watching the live feed of an important football match. If user experience could not be guaranteed due to the policy control system being unavailable, subscribers would be unable to take part in the conference or watch the match; this would significantly impact subscriber satisfaction.

If policy control systems are unavailable, VoLTE services will be unusable. VoLTE services will continue to be an essential service of LTE networks. Policy control systems need to coordinate with wireless systems to notify the latter what traffic is that of VoLTE services so that VoLTE quality can be guaranteed and to implement voice handover between base stations. If policy control systems are unavailable, VoLTE calls cannot be established at the outset.

Policy control systems play a crucial role in LTE data and voice operations. For this reason, the requirements for reliability placed on them should be higher than that of IT and general telecommunications equipment. The aim should be for 99.9999% reliability.

Rapid policy time-to-market (TTM)

With the rapid spread of LTE, mobile Internet has become an essential part of our everyday lives. We watch video, listen to music, shop and socialize on mobile devices. In order to increase revenue, operators need to respond to the rapidly changing, diverse needs of users by releasing targeted packages or policies in time frames as short as one month or less, encompassing all steps from design to release-to-market. According to Heavy Reading's 2012 report, 65% of operators had to adjust policies every month. The telecom industry's typical six months' time-to-market can no longer meet the operational requirements of LTE.

Take the case of one particular West African carrier. In 2014, this carrier began to plan the release of a YouTube video data package one month before the FIFA World Cup to encourage subscribers to watch the competition on their mobile network. The carrier completed a ROI analysis, designed and deployed the YouTube package/policy within a month. Thanks to the data package it successfully created an additional source of income during the World Cup.

Open

For Internet OTT applications, user experience is a crucial factor for their success. For example, every increase in latency of 100 milliseconds leads to an 8% drop in page views for Google. This is why many OTT content providers are willing to pay operators to enhance the user experience of their content. In terms of LTE networks, when end-to-end QoS policy controls were implemented, policy control systems began to have a true impact on the user experience of various OTT applications.

If operators want to work with OTT providers, they need to start opening up their policy control capabilities. Take the example of a user watching a YouTube video. When the subscriber starts to watch the video, if the operator has provided an open interface to its policy control capabilities, YouTube will be able to send a request to the operator via the interface to guarantee the service experience for this particular instance.

Fixed and mobile policy convergence

The vast majority of operators have already deployed policy control systems across their mobile networks. As fixed networks, like mobile networks, also have limited bandwidth, an increasing number of operators will start to implement policy control systems across their fixed networks in the future to prevent heavy subscribers from excessive use.

The policy control systems of fixed and mobile networks will ultimately converge. This will not only reduce set-up and maintenance costs, but will also allow operators to offer combined packages across fixed and mobile networks, for example unified data management (e.g., data caps, URL filtering) and QoS management.

NFV support

Network functions virtualization (NFV) has been gaining momentum throughout the telecom industry, and is hailed as the latest innovation in network architecture since All IP. The technology offers hardware and software decoupling, standardized hardware platforms, resource sharing, and dynamic resource scheduling – benefits that can reduce operators' procurement and maintenance costs and decrease time-to-market, offering maximum investment protection. In Europe, the majority of tier-1 operators have already tested NFV on the network control plane (core networks such as IMS and EPC) and began commercially deploying the technology in 2015. As important components of IMS and EPC, policy control systems therefore also need to support NFV.

A comparison of two policy control decision-making center solutions

As defined by the 3GPP, Policy and Charging Rules Function (PCRF) is the decision center of the entire policy control system. It controls the bandwidth policy of every individual user based on their individual usage. It instructs the policy and charging enforcement function (PCEF) to execute policy control, and the online charging system (OCS) to complete the charging function.

The two main PCRF solutions currently in use in the industry are standalone PCRF and OCS-embedded PCRF. The former is a standalone product, while the latter is integrated into the OCS product – a PCRF software module added to the OCS.

Standalone PCRF will be better able to meet the requirements of policy control systems in the future. As a standalone product, it will offer greater flexibility for technological upgrades, which will give it a significant advantage.

In contrast, it will be difficult for OCS-embedded PCRF to meet future requirements because it will be limited by developments in OCS architecture and the OCS product itself. This will make it difficult for technologies that are best suited to PCRF to be adopted. For this reason, OCS-embedded PCRF can only act as a temporary solution.

Standalone PCRF to dominate in future

Developments in LTE are placing new demands on the next generation of policy control systems. The PCRF solution – the decision-making center of the policy control system – must meet these demands. The standalone PCRF solution has a significant advantage due to its greater flexibility for technology upgrades. Standalone PCRF has already been deployed on the majority of 3G networks, with 90% of operators using the solution, according to figures from the MI department of Huawei Core Networks. In the future, standalone PCRF will continue to occupy a dominant market position. 

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