Virtualized RAN: Bridging the Network Architectures of Today and Tomorrow

By Wolfgang Weber, VP of Business Development, Dali Wireless. Published with the permission of Dali Wireless.

Large cellular radio access networks (RAN) today have upwards of tens of thousands of base stations which naturally means operational complexity. To complicate matters further, these base stations operate on multiple radio access technologies and different parts of the spectrum. All this results in high costs (OPEX and CAPEX), and network planning or operations headaches. To address these challenges and set the heterogeneous network (HetNet) up for long-term growth and scalability, operators also have to consider how to expand coverage and capacity to handle the increase in traffic volumes while lowering the Total Cost of Ownership (TCO). As a means to manage traffic growth, network densification through small cells is usually the first consideration for operators looking to provide service to traffic hotspots. However, operators are also turning to alternatives, such as offloading to carrier-grade Wi-Fi, or a virtualization approach to deliver effective responses to the capacity challenge.

While Cloud RAN emerges, virtualizing the RAN is a promising alternative

Wireless architectures also have to consider cost efficiency, operational simplicity, flexibility, and scalability. At the current stage of technological evolution, a cloud RAN (C-RAN) architecture is meant to address these considerations by providing benefits in operational costs and improving network manageability. The concept of C-RAN is the separation of the radio and antenna from the digital baseband and pools baseband units for multiple cells in a central location. This pool of baseband resources can be linked e.g. by fiber to radio heads at the antenna location. Advantages of C-RAN architectures include better utilization and allows capacity expansion of deployed baseband resources easily.

Even with these expected benefits, operators remain cautious about the relatively nascent technology. Operators are particularly concerned about the ROI on such a major shift in platform because at this time, C-RAN is still a concept. Operators naturally wonder if the predicted cost reduction and revenue growth advantages will pay off. Initial C-RAN implementations are expected to be deployed in commercial networks, at the earliest, 2016. However, operators need to address the expected growth in mobile traffic volume – today.  RAN virtualization is a comprehensive method and should be a strong consideration for operators looking for efficient solutions for the capacity crunch. The scalability and flexibility of a virtualized RAN delivers substantial capacity and efficiency gains already today and will be even more effective when combined with a future C-RAN deployment.

Operators are right to mull over the long-term implications and costs of such an overhaul to their networks, even though C-RAN has some potential. RAN virtualization empowers operators to remotely reconfigure and redistribute the radio coverage and capacity from the core to the antenna. It’s a solution with more immediate benefits than those of C-RAN without requiring a complete adaptation of the radio network infrastructure.

RF Routing virtualizes the entire RAN

Legacy RAN infrastructures provide coverage and capacity with a fixed allocation of baseband and radio resources and with a price – high TCO and the amount of spectrum resources required. Static allocation of resources means that systematic over-provisioning is needed in order to meet peak demands at any time. C-RAN has its limitations in virtualizing only the baseband whereas RF Routing virtualizes entire cells, allowing for efficient use of the most precious resource: spectrum. Even with more budget, operators cannot add spectrum because it’s a finite resource. By making radio signals route-able, RF Routing makes better use of the limited spectrum resources which is a priceless commodity. C-RAN alone cannot do this, therefore, the impact of a fully virtualized RAN can be tremendous for operators.

RF Routing will allow operators to dynamically allocate network resources of multiple virtualized cells. By routing coverage and capacity to where it’s needed, when it’s needed in a service area, operators are in a position to meet demand with optimum efficiency of spectrum usage by allocating both baseband and radio resources in response to dynamic traffic conditions. RF Routing helps operators avoid over-provisioning, ultimately reducing TCO while keeping the QoE up.

Virtualizing the RAN through RF Routing is an appealing opportunity for operators to handle the forecasted deluge of mobile data traffic while at the same time, increasing ROI of the deployed radio infrastructure. The C-RAN architecture may well be part of operators’ future, but RAN virtualization covering both the baseband and the radio part of the cells can offer all of the benefits of C-RAN and more in a more comprehensive and flexible approach – today.

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