Due to the large growth in video over mobile networks, video optimization systems such as those from Bytemobile, Flash Networks, Ortiva, Vantrix, etc., have become popular for their ability to help control the growth of video-related bandwidth (examples include transcoding, buffer control, caching and so on).  Often, these systems are initially installed standalone to perform a static function for all traffic for all users on the network.  However, joining optimization systems with policy control adds a number of additional benefits:

• Selectively differentiate optimization based on subscriber tier—as tiers become more common, these tiers require the coordination of QoS, charging & quota treatment across multiple network elements including GGSN, DPI and other systems
• Selectively differentiate optimization based on roaming status—for example, a user (or his enterprise IT manager who may be paying the bill) may want very limited or no video at all when roaming
• Intelligently utilize adjunct functions commonly found in optimization boxes such as content filtering, http header insertion or redirection to notify the user of some service change, or use of  a self-care portal to let subscribers manage their own service choices

• Only utilize optimization resources when needed, minimizing the required investment in optimization capacity.  In particular, if the PCRF is provided with near-real time RAN Aware status data, optimization can be applied only when network is at risk of congestion or actually congested, minimizing resource requirements as well as any negative impact on a subscriber. This is particularly relevant in the case of RAN congestion.

• Re-use existing integration work to get subscriber, device, network and roaming status from the PCRF rather than requiring another integration project to re-deliver that data to the optimization system.

The most commonly used interface between the PCRF and an optimization system is based on 3GPP Gx, the interface originally designed between the PCRF and GGSN.  Since optimization systems have a number of functions not anticipated by 3GPP, this interface can use what are referred to as “pre-defined rules” in the Charging-Rule-Install portion of the 3GPP Gx specification to pass what are effectively proprietary commands.  Also, the systems need to make some adjustment to required and optional fields since the optimization box may or may not know mobile specific entities such as IMSI, MSISDN, IMEI, etc.

3GPP recently acknowledged the common use of Gx in this way with optimization systems, DPI and other non-GGSN devices, by defining a “Traffic Detection Function” or TDF in Release 11.  The TDF to PCRF reference point, listed as Sd, will have strong similarities to Gx while adapting to some of the unique natures of a non-GGSN device.  In other words, the spreading out of the mobile packet core is officially underway.