LTE is taking the global market by storm with 83 commercial networks having been launched as of the end of May, of which 10 were commercialized in the month of May alone. The objective of LTE is to place mobile operators on a trajectory to economically deliver mobile broadband services with all-IP networks that finally dispense with legacy circuit switched infrastructure. This brings the advantages of a converged IP ecosystem and sees the replacement of legacy SS7 with SIP and Diameter signaling protocols.
The SIP protocol provides session management functionality for telephony, messaging and multimedia communication. Diameter is an extensible protocol that is used to exchange subscriber profile information for a variety of policy, charging, quality-of-service and mobility management functions. In combination, the SIP and Diameter signaling protocols enable advanced personalized mobile service capabilities.
To date most mobile operators have priced and packaged their LTE offers with an emphasis toward bandwidth usage, as opposed to the overall service experience delivered. This dumb-pipe mentality has enabled over-the-top (OTT) players to gain greater control over value creation and compromise the market position of mobile operators. We believe that as LTE ecosystems mature, mobile operators will seek to distinguish themselves relative to OTT players through their ability to personalize and manage the quality of data services delivered over their networks. As this occurs, the Diameter signaling infrastructure and associated policy, charging and subscriber data management functionality will become increasingly strategic for mobile service delivery.
Mobile operators generally recognize their need to focus on customer experience and service personalization, but at the same time typically have conservative implementation strategies. In practice, solutions are complex to implement at scale and must address a variety of demands, which include:
• Scalability: Service personalization and customer experience management will drive a massive increase in core network signaling (aka signaling storms). In particular, future Diameter signaling traffic could easily exceed 100,000 messages per second per million users with personalized service offers. Scalability demands are exacerbated further as the number and variety of interconnected policy, charging and subscriber data nodes increase, with each node driving significantly signaling traffic of their own.
• Resilience: Without reliable signaling, networks are prone to wide-scale outages. Such outages have been observed with LTE networks in the past. This illustrates the importance for Diameter signaling networks to be capable of coping with the signaling storms that can occur with usage spikes and in cases where rogue network elements generate excessive traffic.
• Security: The shift to all-IP introduces a variety of security considerations for signaling networks, particularly with external network interfaces. This includes a variety of threats such as denial of service attacks and fraud.
• Extensibility: The mobile industry has adopted the Diameter signaling standard for LTE because of its extensibility as market demands evolve. While it is generally anticipated that service personalization and customer experience will be two major axes for mobile operator differentiation, it is still unclear exactly how policy, charging and subscriber data management functionality will be implemented in future service offers. The architectures that are being implemented today must have adequate flexibility and extensibility to account for these uncertainties.
The requirements for reliable and scalable LTE core networks parallel those of traditional telecom infrastructure and are subject to similar design principles. This moderates the rate at which mobile operators can realistically innovate, which pales in comparison to the cadence of innovation in the mobile industry as a whole. We believe that this will ultimately drive operators toward delivering differentiated customer experiences, in terms of service distribution and personalization, and transaction management.
Phil Marshall is Tolaga Research's chief research officer