Packet transport networks for radio-mobile systems

Today's mobile uses are undergoing a profound transformation, driven by the deployment of new high-speed radio technology standards (HSPA and HSPA+) and the growing availability of 3G USB sticks or terminals such as smartphones, enabling easy, fast, mass access to rich multimedia content (e.g. video, Internet, email, instant messaging, RSS feeds, music, mobile TV, social networks or augmented reality) in addition to traditional telephony and messaging services such as SMS or MMS.

These new uses and their intensity are driving a significant, almost exponential increase in the volume of traffic carried by mobile radio networks. This represents a major challenge for mobile operators, who must upgrade their networks to absorb this traffic and continue to offer quality services to their subscribers. Indeed, this increase in traffic does not translate into a proportional increase in revenues. In fact, average revenues per subscriber tend to remain constant; even if new services and capacities are offered, they are most often with "flat-fee" type offers (unlimited consumption of data services as part of normal use), similar to what we see today in residential broadband access on DSL, cable or fiber access. As a result, if investments are made on the basis of the technologies that have been used to date for infrastructures that mainly support voice services, there is a risk of a sharp divergence between the additional investments that the operator has to make to meet users' needs and the revenues it obtains.

To meet this challenge, new technologies that reduce the cost per byte transported over the radio interface are currently being deployed, such as HSPA+, or will soon be, such as LTE. The emergence of these new technologies, and the need to maintain revenues per subscriber, therefore generate additional pressure on the transport network that carries mobile traffic between the various nodes of a mobile radio network and external networks (such as the Internet, Intranet, voice networks, etc.). As a result, it is becoming necessary to change the way transport networks are designed in order to increase their capacity while keeping costs under control. Circuit- and ATM-based transport networks are not very economical when scaled up. Packet-based technologies (IP/MPLS, Carrier Ethernet, MPLS-TP*) are beginning to be deployed to address this problem. These technologies are economically more advantageous, more scalable, and better suited to carrying and optimizing traffic flows that are massively made up of data services (with very high throughput variation characteristics during a session).

This article outlines the technical challenges that need to be addressed when migrating from a conventional mobile transport network to an all-packet transport network....