A Sandvine Technology Showcase Contents Executive Summary... 1 Introduction to VoLTE... 2 Sandvine s Service Delivery Engine... 3 VoLTE Features... 3 Deployment Architecture... 4 Scalability... 4 Reducing Signaling Requirements... 4 NFV and Elastic Scaling... 5 Service Configuration On-Demand... 5 A Universal PCRF for Converged Networks... 6 Example Use Cases... 7 Guaranteed QoS for VoLTE... 7 Guaranteed QoS for OTT Applications... 7 VoLTE QoE Measurements... 8 OneNumber... 9 Conclusions... 10 Related Resources... 10 Invitation to Provide Feedback... 10 Executive Summary The Policy and Charging Rules Function (PCRF) is the key element that enables the transition to and reliable operation of Voice over LTE (VoLTE) services. But with critical voice services now sharing the pipe with other data services like web browsing, video and social media, the ability to manage the speed, quality, volume and diameter signaling associated with VoLTE is critical to providing a differentiated experience. Additionally, although the LTE network provides a framework for signaling application QoS, CSPs need to verify the actual quality experienced by subscribers who have purchased VoLTE services. The upgrade cycle to support VoLTE can be leveraged by CSPs as an opportunity to consolidate their control plane architecture by introducing a universal PCRF. Such a device goes beyond enabling VoLTE, to: leverage the LTE QoS architecture to enable use cases including quality-protection for non-ims voice services, video applications, and gaming services simplify policy control across all access technologies (e.g., 2G, 3G, CDMA, LTE, Cable, DSL, WiFi, etc.), by deploying a single system that can make decisions and enforce policies across multiple standards In short, a capable PCRF offers CSPs the opportunity to save costs and deploy additional revenue-generating services that capitalize on the new QoS capabilities of the LTE network. The Sandvine Service Delivery Engine (SDE) is this universal PCRF, and this paper explains how it can change the way you think about network policy control.
Introduction to VoLTE Voice over LTE (VoLTE) is a game-changer for communications service providers (CSPs) because of the challenges and opportunities it represents. With voice services now sharing the pipe with other data services like web browsing, video and social media, the ability to manage the speed, quality, volume and diameter signaling associated with VoLTE is critical to providing a differentiated experience. These issues are discussed in detail in the Sandvine whitepaper VoLTE: Challenges and Opportunities. In addition, although the LTE network provides a framework for signaling application QoS, CSPs need to verify the actual quality experienced by subscribers who have purchased VoLTE services. There is a significant difference between signaling priority and verifying subscriber quality of experience (QoE). The majority of legacy systems (particularly PCRFs) either don t support the necessary interfaces to enable VoLTE or cannot cope with VoLTE s unique performance and scalability challenges. As a result, CSPs are investigating large-scale network upgrades to enable VoLTE. However, this upgrade cycle brings opportunities beyond just enabling basic VoLTE services: CSPs can use the necessity of upgrading to VoLTE-capable PCRFs as an opportunity to truly revolutionize their policy control solutions. For instance, by investing in a universal policy controller with close integration to an intelligent PCEF, CSPs can: leverage the LTE QoS architecture to enable use cases including quality-protection for non-ims voice services, video, and gaming services simplify policy control across all access technologies (e.g., 2G, 3G, CDMA, LTE, Cable, DSL, WiFi, etc.), by deploying a single system that can make decisions and enforce policies across multiple standards Sandvine s access-agnostic PCRF, the Service Delivery Engine (SDE) 1, operates not only as a universal policy controller for your traditional data networks (2G, 3G, CDMA, Cable, DSL, etc.), but is also optimized for LTE and VoLTE environments. This paper describes how the SDE delivers and manages VoLTE services and enables a wide range of additional use cases that only become possible with an intelligent, universal PCRF. 1 Information about the SDE is available online at: https://www.sandvine.com/platform/service-delivery-engine.html Page 2
Sandvine s Service Delivery Engine The SDE is a standards-based, universal policy control solution specifically designed to support the complex requirements of HD-quality VoLTE services while still providing a single point of policy control for any and all access types. The SDE provides much more than the basics of guaranteed quality of service (QoS), presenting CSPs with opportunities to leverage the QoS Class Identifier (QCI) framework to generate additional revenue and valuable insight. VoLTE Features The Service Delivery Engine supports the standard features outlined in Table 1. Table 1 - Features of Sandvine's VoLTE-capable PCRF Function Voice Services Emergency Services and Location Information VoLTE Roaming Scalability and Reliability Explanation of Features Premium call quality with dedicated-bearer set up and teardown with dynamic quality of service (QoS) that offers a competitive quality advantage over OTT voice services HD Voice Allow IMS emergency call priority and data plan override; high QoS by default when invoked Ensure access to reliable emergency call support; 3GPP standards for networkprovided subscriber location information (NPLI) Global roaming coverage for VoLTE services with guaranteed QoS Local breakout support: supplying policy rules and charging parameters to outbound / inbound roamers with guaranteed VoLTE QoS Identify subscriber location and apply appropriate QoS / charging parameters Support for the always-on nature of the VoLTE dedicated bearer and increased number of concurrent voice sessions Handle the ten-fold increase in diameter signaling generated by VoLTE call flows Manage increased performance requirements as more VoLTE services and devices are on-boarded Reduce signaling with policy decision point capability in the data plane Circuit-switched fall back (CSFB) in case the LTE network is not available Rich Communication Services (RCS) When required, support of QCI for RCS features is available Setup differentiated dedicated bearers for Video Conferencing and See what I see services QCI adjustments allow VoLTE calls to be upgraded/downgrade to/from Video Conferencing Regulatory, Standards, and Device Requirements Support Rx call flows in real time to ensure highest available media codec on a perdevice basis 3GPP standards-based solution; includes comprehensive 3GPP R7 through R12 support Modify and customize VoLTE policy rules per device: reject improper calls, adjust QoS parameters when needed Dual stack IPv4 and IPv6 support with intelligent NAT integration: deploy a futureproof solution with support for multiple IP address allocation and a broad range of VoLTE devices Fraud prevention: CSPs need to guarantee the proper utilization of dedicated bearers and minimize exposure to revenue leakage and fraud Lawful intercept: support regulatory requirements for identification and filtering of targeted voice traffic Page 3
Deployment Architecture The SDE is easily deployed in any LTE network, is interoperable with third-party PCEF, OCS and B/OSS elements, and is deployable in completely virtualized networks. For CSPs who want to introduce a separate LTE PCRF, the SDE fulfills this role and coexists with legacy PCRF elements while handling the over 10-fold increase in signaling demand from VoLTE services. Figure 1 shows a typical Sandvine deployment in an LTE network. The PTS (Policy Traffic Switch) is Sandvine s PCEF/TDF. 2 Figure 1 - Sandvine VoLTE deployment architecture, assuming a single PCRF Scalability A key challenge specific to VoLTE is the over 10-fold increase of signaling load on the control plane and PCRF element, which must specify QoS for every single voice call passing through the LTE network. When one considers the addition of non-voice application services such as streaming video and online gaming, the signaling load increases further. A detailed report from Oracle shows that global LTE Diameter signaling traffic will grow at a 78 percent compound annual growth rate (CAGR) from 2013 to 2018, expanding from 12 million messages per second (MPS) to nearly 216 million MPS. In the same report, Oracle predicts LTE Diameter signaling traffic will increase at a 140 percent compound annual growth rate (CAGR), from 1.2 million messages per second (MPS) in 2012 to nearly 99 million MPS by 2017. Reducing Signaling Requirements One way to significantly reduce signaling at the front end is with data plane decision-making: the PCRF signals an overall service plan identifier to a data plane PCEF, which hosts Traffic Flow Templates 2 More information about the PTS is available online: https://www.sandvine.com/platform/policy-traffic-switch.html Page 4
(TFTs) that manage the actual QoS required for thousands or even millions of VoLTE- and QCI-related flows per second. 3 In this model, which is fully supported by Sandvine, the PCEF makes decisions in real-time, per-flow, and communicates updates to other elements as required. The result is a reduction in signaling by, potentially, orders of magnitude. Figure 2 - Policy Decision Point (PDP) capability on the data plane reduces signaling NFV and Elastic Scaling Sandvine s end-to-end network policy control solution does not require as much orchestration in the control plan because the PTS (PCEF/TDF) has a data plane decision capability that reduces overall signaling load. Sandvine s Service Delivery Engine scales to support the signaling requirements of standards-based VoLTE, and both platforms support network function virtualization (NFV) that allows them it to scale elastically. Service Configuration On-Demand As operators continue to learn the different nuances around the technical requirements behind the scenes, a platform that provides infinite scalability without the need for code customization is absolutely necessary. Enabling services like VoLTE and RCS require interoperability with a variety of different network elements and the ability to adjust specific configurations (being in the form an AVP value or a specific alternate call-flow) is not desired, but mandatory. A real PCRF should allow for the support of different adjacent system implementations by accommodating these nuances without the need to request such systems to be changed. PCRFs cannot be rigidly designed through a pre-defined set of hardcoded options. Sandvine s SandScript allows for what would have been a customization in other platforms to be implemented through configuration, on the spot. 3 TFTs are explained in the Sandvine whitepaper VoLTE: Challenges and Opportunities Page 5
A Universal PCRF for Converged Networks Converged network operators (i.e., those with multiple access technologies) face a number of challenges relating to implementing network-wide policy control. It is not uncommon for these operators to have a different policy control solution in each access type: mobile networks have a PCRF; cable networks have supported signaled QoS since 2007 4; and traffic prioritization in DSL networks is now an increasingly established practice. In addition to an onerous training and maintenance overhead that comes with a fractured approach to policy control, in which different systems are used on different networks, it impacts the CSP s ability to introduce network-wide subscriber services. For instance, to enable quotas across multiple access types, or to zero-rate sponsored data, then functionally identical policies must be defined in many different locations a process that is both operationally intensive and prone to error. So, given the complications and limitations of fractured policy control, why is that the route many CSPs take? The simple answer is that until now, there has never been a single system that can speak the language of every access technology. To simplify network policy control deployments and to enable consistent subscriber services across access technologies, the Service Delivery Engine acts as a universal policy controller: the SDE allows CSPs to signal QoS and policy enforcement to any and every network types from a single, universal PCRF (as shown by Figure 3). Different implementations of the VOIP application can lead to specific needs including the ability to seamlessly handoff a call from/to LTE to Cable/Wifi, making the Sandvine Universal PCRF a great resource for coordinating QoS. In other cases, when only hard handoffs are possible, the PCRF can still guarantee the orchestration of the necessary QoS parameters according to user s profile and location. Figure 3 Universal policy control: a single PCRF coordinates policy for every access technology 4 PacketCable version 1.0 first defined QoS in cable networks in 2007. Page 6
Example Use Cases The subsections below outline some example use cases supported by Sandvine s VoLTE-capable Service Delivery Engine. 5 Guaranteed QoS for VoLTE Guaranteed QoS is a fundamental feature of VoLTE, and no PCRF should claim to have VoLTE support without this feature. To provide guaranteed QoS, the SDE receives application signaling via Rx, then sends the flow information to the PGW. Figure 4 - Application signaling using LTE QCI Guaranteed QoS for OTT Applications As a prerequisite of VoLTE services, the SDE supports Quality Class Identifier (QCI) signaling (the signal matrix is shown in Figure 5). Figure 5 - LTE QCI values 6 Not all network services can use IMS, and some devices are not VoLTE-capable under normal circumstances, this means that a large amount of traffic would not be able to receive QoS guarantees. 5 6 This list is by no means exhaustive See a full breakdown here. Page 7
However, a Sandvine deployment makes it possible to use QCI to assign QoS for arbitrary applications, which opens the door to many subscriber service possibilities (e.g., QoS-protected gaming, OTT voice, video streaming, video conferencing and business applications, etc.). To enable such services, the PTS performs traffic classification via deep packet inspection (DPI) technology, then informs the SDE of the identity (e.g., application, protocol, website, provider, etc.) of each flow. Via QCI, the SDE then signals QoS to all the enforcement devices in the network. Figure 6 Signaling to ensure QoS for OTT applications and services VoLTE QoE Measurements Although the LTE network provides a framework for signaling application QoS, such signalling isn t a true guarantee of call quality. To ensure a strong customer experience, CSPs need to verify the actual quality experienced by subscribers who have purchased VoLTE services, so that they can take immediate action if quality is not as high as intended or expected. In short, there is a significant difference between signaling priority and verifying subscriber quality of experience With Sandvine, CSPs have access to QoE metrics that let them assess whether or not the subscriber experience actually matches that of the intended QoS. Figure 7 Example VoLTE QoE Score Report Page 8
The Sandvine Policy Traffic Switch identifies VoLTE traffic in real-time and applies measurements to determine QoE. VoLTE operators can establish custom QoE thresholds to isolate segments of poor call quality and to be quickly alerted to where problem areas of the LTE network exist and where improvements can be made. Plus, the detailed traffic classification provided by the PTS lets the network operators dig deeply into the QoE data, to understand if the QoE issues are widespread, or isolated to a particular type of mobile device (e.g., by operating system, by manufacturer, by model, etc.). Additionally, consider the scenario in which a user is engaged in a mobile VoIP phone call and then enters his or her house. Upon entering the home, the VoIP call will likely switch to the home s WiFi network. If the user has the same CSP for both the mobile data and home Internet, then the Sandvine solution allows the CSPs to monitor a variety of QoE factors for this call, including the call in its entirety, and the individual components (i.e., mobile network and WiFi network). As a bonus, deploying the PTS also gives CSPs access to a range of QoE measurements beyond VoIP, including Web Browsing QoE 7, Video QoE 8, routing efficiency, and round-trip time measurements. OneNumber For consumers, managing several personal contact numbers across multiple communications platforms (e.g., personal mobile, PC softphone, business mobile, WebRTC, office desk phone, etc.) is cumbersome. With a universal policy controller, CSPs can offer their customers a single number that s linked to a broad range of devices. Several implementations of OneNumber use Web technologies not existing in the IMS world such as WebRTC where a full communications client is supported from an HTML5 browser interface. With Sandvine s universal policy controller that s enabled for VoLTE environments, LTE operators can offer their VoLTE subscribers innovative services such as OneNumber with guaranteed QoS across multiple access technologies. And if the subscriber happens to be using a 3rd party network not managed by the operator on a WebRTC call for example, Sandvine can still report on the achieved QoE levels. Figure 8 - Would your subscribers like this service? 7 8 You can learn about Web Browsing QoE here. You can learn about Video QoE here. Page 9
Conclusions With voice services now sharing the pipe with other data services like web browsing, video and social media, the ability to manage the speed, quality, volume and diameter signaling associated with VoLTE is critical to providing a differentiated experience. Additionally, although the LTE network provides a framework for signaling application QoS, CSPs need to verify the actual quality experienced by subscribers who have purchased VoLTE services. There is a significant difference between signaling priority and verifying subscriber quality of experience (QoE). The upgrade cycle to support VoLTE can be leveraged by CSPs as an opportunity to consolidate their control plane architecture by introducing a universal PCRF. A universal policy controller can go beyond enabling VoLTE, extending into a range of additional use cases and benefits: leverage the LTE QoS architecture to enable use cases including quality-protection for non-ims voice services, video applications, and gaming services simplify policy control across all access technologies (e.g., 2G, 3G, CDMA, LTE, Cable, DSL, WiFi, etc.), by deploying a single system that can make decisions and enforce policies across multiple standards In short, a capable PCRF offers CSPs the opportunity to save costs and deploy additional revenuegenerating services that capitalize on the new QoS control capabilities of the LTE network. The Sandvine Service Delivery Engine (SDE) is this universal PCRF, operating not only as a VoLTE PCRF, but also as a PCRF and policy controller for all the access technologies in the network. Related Resources To learn more about what the SDE can do for your network, beyond the specific context of VoLTE, please consider reading Universal Policy Control and the Service Delivery Engine. Invitation to Provide Feedback Thank you for taking the time to read this technology showcase. We hope that you found it useful, and that it helped you understand the value that our Service Delivery Engine can bring either as a PCRF for your VoLTE implementation or as a universal PCRF for your network as a whole. If you have any feedback or have questions that have gone unanswered, then please send a note to whitepapers@sandvine.com. Page 10
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