O-RAN Alliance: opening up the 5G networks

5G networks require new radio access network (RAN) architecture. As part of this major change, the global O-RAN Alliance (Open RAN) is laying the groundwork for more innovative RANs that are more open to multiple providers. What does the success of this concept depend on?

Ultimately, a new community of mobile network providers will find opportunities with operators the world over

The O-RAN (open radio access network) Alliance is bringing together many of the world’s players in telecoms to develop openness in access networks. Five operators, AT&T, China Mobile, Deutsche Telekom, NTT DoCoMo and Orange, announced their founding of this global alliance in February 2019. Their shared objectives were to encourage innovation and new providers to enter this market, thereby making access networks as innovative and flexible as possible.

Fostering the emergence of new players

Three providers (Ericsson, Huawei and Nokia) dominate the mobile networks market. This state of affairs has a bearing on the cost of equipment and the scope for innovation. By producing interface specifications that are truly open, the O-RAN Alliance’s aim is to allow any provider to offer hardware and software solutions that will work with its standard 5G architecture. Thanks to these interfaces, O-RAN enables the access network to be spliced virtually into smaller pieces. The entry threshold in terms of R&D is thereby lowered, which in turn enables new players to enter the market.

The Orange Group is playing a leading role in this field. While the operator is a contributor to all eight O-RAN working groups, it is leading the group that defines the open interfaces that enable the base station “as such” to operate, and to manage the “lower layers” of the mobile network. “Over time”, explains Olivier Simon, Head of Innovation for Radio Networks at Orange, “the access network has become a very complex system that is constantly seeing new functions added. For new players in the market, developing all of these functions is therefore difficult. With O-RAN, we are creating open architecture and open interfaces, and allowing new players to develop some parts of the access network rather than having to develop the access network in its entirety. “Ultimately, a new community of providers will be able to find opportunities with operators the world over, even when they only offer sub-systems of the access network”. In this way, the O-RAN specifications allow for greater flexibility. For example, “where we want to use 4G and 5G networks from two different providers, the O-RAN specifications can simplify the integration of both networks. Another option that becomes possible is the use of active 5G antennas connected to the networks of two different providers,” explains Olivier Simon.

Virtualisation of network functions

The RAN architecture of the future uses virtualised network functions rolled out across data centres that use servers that are as generic as possible. Olivier Simon confirms that O-RAN has a prominent place in this field: “O-RAN provides a guide to carrying out this long and complex transformation in a uniform way whilst achieving economies of scale”.

Here again, Orange has an important role in the process as leader of the O-RAN working group responsible for defining the network function virtualisation infrastructure (NFVI). Thanks to the specifications produced by O-RAN on the virtualisation of network functions, operators use infrastructure elements that have been approved by everyone. According to Olivier Simon, “the purpose of the alliance is to ensure that, for example, all operators that use the O-RAN specifications work from the same definition of what a data centre is. The providers of network functions can then rely on this definition, which makes both the integration phase and life cycle management easier”.

Sharing the integration effort

Nevertheless, Oliver Simon warns that “the virtualisation and openness promised by O-RAN come at price” and that “this can be seen in the complexity of the testing and integration phases”. If several manufacturers are involved in an access network, it is effectively more difficult to guarantee that the system works properly. The reasons behind any given problem may lie with a single participant or several at a time.

Presently, it is the equipment suppliers themselves that carry out the testing and propose their own integration solutions. In the future, an integrator role will be needed to carry out this same task.

In order to minimise integration costs, O-RAN operators are working on establishing joint integration and certification laboratories that will allow the bulk of this effort to be pooled.

Open source code: innovation and flexibility

In April 2019, O-RAN partnered with the Linux Foundation to set up the “O-RAN Software Community”. Its purpose is to provide the open source code for a number of modules along the access network. In this way, these software modules, just like some parts of the 5G network, will no longer be exclusive to any one given provider. In addition to the field being opened up to new players, everyone can pool their own “white box” software development (in full view of everyone else) with the software development of other stakeholders, thereby saving time and money. The first open source code will be released in November 2019.

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