SDN and virtualization: more intelligence in 5G networks

New uses for 5G imply a new way of managing telecommunications networks. To open the way for new actors, we will have to divide and virtualize network slices, and find a dynamic way of allocating them to new services. This organization is made possible thanks to SDN: a technique which redesigns network architecture to make it as flexible as possible. Researchers at EURECOM are using SDN to make networks more intelligent.

The sole objective of 4G is to serve one purpose: broadband Internet. Not only will 5G need to pursue this effort, it will also have to satisfy the needs of the Internet of Things and provide considerably more reliable means of communication for the transmission of sensitive data. Combining these three usages in one type of network is far from simple. Especially as each of them will create many services, and therefore many new operators who will have to get along with each other. Depending on demand, certain services will have to be favored over others. This requires managing resources in a dynamic way.

A new way of organizing the network will need to be found. One solution is network slicing. The infrastructure remains unchanged, under the control of the current operators, but is shared virtually with the new operators. “Each service shares the network with others, but has its own independent slice which is specific to them” explains Adlen Ksentini, mobile networks researcher at Eurecom. The slice left to the virtual operator is a slice from end to end. This means that it leaves space for a new entrant both in sharing the radio bandwidth and on the management platform for this radio resource.

For researchers, the main challenge is the lifespan of the slices. The slicing system needs to be able to create and close them on demand. A data collection system for connected object will not run all day long, for example. “If an electricity distributer records data from smart counters between midnight and 4am, a slice needs to be created for this precise timeframe to allocate resources to other services the rest of the time” Adlen Ksentini illustrates.

Greater network intelligence

Establishing these slices is made possible through a new type of network architecture, whose behavior is programmed by software. Until present, the paths followed by data in the network were dictated by routers. The physical boxes, spread throughout the network, handled the way in which packages of information were sent. With the new architecture, known as SDN,  or software-defined network, a central entity controls the equipment and makes the routing decisions.

The greatest advantage of SDN is its flexibility in network management. “In a traditional architecture, without SDN, the routing rules are set in advance and are difficult to change” explains Christian Bonnet, another networks and telecommunications researcher at Eurecom. “SDN allows us to make the network intelligent, to change the rules if we need to” he continues. This greater freedom is what makes it possible to cut the network up, creating rules which isolate data pathways for specific use by each service.

Eurecom researchers are exploring the possibilities offered by these new architectures on the technological platform OpenAirInterface (OAI). “We are experimenting both with how to transform the 4G network to introduce intelligence, and how to shift towards a 5G architecture” Christian Bonnet explains. This open source work helps us to understand how SDN impacts the state of radio resources, its potential for creating new services, and the associated constraints or opportunities for improvement in managing mobility (see insert at the end of the article).

“Technically speaking, there are several possibilities for installing an SDN and slicing up the network. As each operator has slightly different requirements, there are many different angles to explore”, the researcher explains. Each operator could have their own way of virtualizing the network to allow for new services. 3GPP, the standardization body for mobile communication technologies, could however play a role of consolidation in the near future, should more operators decide to go in a common direction.

This article is part of our dossier 5G: the new generation of mobile is already a reality

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SDN for better management of mobility

SDN architecture may be used to ensure continual data emission to a mobile terminal. This technique makes it possible to better handle changes of interface in switching from a 4G network to a WiFi network without interrupting the flow of information. Compared with traditional mobility techniques, SDN is faster, and reduces the amount of flow reduction operations required. For the end user, this results in a higher quality service.

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