Ericsson Spectrum Sharing – running on Cloud RAN
Ericsson Spectrum Sharing (ESS) is an innovative, award-winning, and market-disruptive solution that has set a new standard in the wireless industry. ESS enables service providers to utilize its scarce spectrum assets in the most efficient way possible by instantly – on a millisecond level - sharing spectrum between 4G and 5G.
ESS introduces a new way of rolling out 5G Frequency Division Duplex (FDD) spectrum that re-uses hardware, spectrum, sites and increases coverage of the mid/high band so that operators can shift Capex investments from new sites to new 5G use-cases. Ericsson Spectrum Sharing brings 5G to everyone, everywhere, much faster.
So, the question is, will this powerful solution work on Cloud RAN, leveraging the benefits it brings while keeping the value of ESS? The very short answer to this question is – yes!
In this blogpost we will explore the details on how ESS will work seamlessly across our Cloud RAN and our purpose-built Ericsson Radio System, and how we can take advantage of decisions made already when designing the original solution, as well as our deep radio knowledge and experience to move this innovation into the cloud paradigm.
How Ericsson Spectrum Sharing works
To understand how we extend ESS from purpose-built infrastructure to Cloud RAN, we must go back to the design of the original solution. In short, the power of ESS is to realize a combined 4G/5G carrier, that both 4G and 5G devices can use. This entailed a number of challenges:
Secure the right 3GPP toolbox required - There was and is no feature called 4G/5G sharing in 3GPP. Therefore, we worked with the 3GPP standardization to secure the needed functionality. This resulted in a list of tools as a baseline for the initial ESS support, mainly on the device side.
Get day 1 support from the device ecosystem for a swift rollout - Early discussions with the major device chipset suppliers was critical so that time plans, interoperability tests, and early field testing were aligned according to needs.
Additional Ericsson innovations beyond 3GPP were needed - Additional innovation beyond 3GPP was needed to be designed. Some examples include avoidance of colliding signals on the air-interface, initial access additions for the period until the device is configured and aware of dynamic spectrum sharing and scheduler coordination between 4G and 5G with 1ms periodicity.
Ensure total performance of both 4G and 5G - On the journey to ESS some very tricky performance challenges had to be solved which resulted in 1ms scheduling periodicity between scheduler decisions and Resource Block Group level allocation in the air-interface. Last, but not least, 4G feature parity had to be secured in order to not jeopardize 4G performance as delivered from legacy deployments.
Efficient update of Ericsson Radio System - ESS was designed to be deployed as a remote software installation, without site visits and can be deployed using existing basebands and radios in the field when adding 5G to an existing site. To achieve this, we used our unique advantage of 5G ready Ericsson Radio System radios and RAN Compute basebands. This means high usability of the solution and also reduced operator Capex and Opex.
Optimizing and future proofing the architecture - As described above, ESS means combining 4G and 5G data streams to one carrier on the air-interface. The physical placement of this combination function was an important decision. There are three principal options – on the Ericsson Radio System mixed mode basebands, on an external unit between Ericsson Radio System basebands and radios, or inside the Ericsson Radio System radios.
We decided to implement it in the mixed mode baseband to avoid duplication of CPRI lines out of the basebands. This would have resulted in higher costs and site visits, but the architecture and realization are still prepared for all three options to leave room for future innovation. For the same reason, the architecture is also prepared to be implemented on several deployments, not only on a single mixed mode baseband, but also on multiple, single mode basebands. Without explicit requirement, the architecture is prepared even for the execution of 4G or 5G on Cloud RAN.
See figure 1 for the final implementation for ESS on a purpose-built platform.
Ericsson Spectrum Sharing implementation extended to Cloud RAN – How do we do that?
Ericsson now brings ESS also to our Cloud RAN. This means that service providers leveraging both Ericsson Radio System as well as Cloud RAN by Ericsson can enjoy the full benefits of ESS.
With Cloud RAN we realize RAN functions (such as ESS) on a generic compute hardware platform, Commercial off-the-shelf (COTS), instead of a purpose-built hardware platform. Cloud RAN also means managing virtualized RAN applications based on cloud-native principles, e.g. running several, loosely coupled, microservices in containers, handling resilience and scaling by replication and independent life cycle management following DevOps principles.
Cloud RAN offers a very attractive alternative for deploying 5G RAN networks and at the same time get the benefits of a generic compute platform (The four components of Cloud RAN). Our Cloud RAN solution complements and extends our existing and well proven purpose-built offering.
We are now realizing an extension of ESS also into Cloud RAN and the solution is a direct continuation of the concepts and implementation on the ERS side. As mentioned above, when we decided on the ESS architecture for the purpose-built platform, we considered a future where it could be deployed on multiple architectures.
Also, there is no need for any 3GPP additions. Cloud RAN will re-use the necessary specifications and the Cloud RAN with ESS implementation will be completely transparent to the device ecosystem. This means that there is no need for repeated interoperability with associated field testing, resulting in short time to market.
ESS on Cloud RAN will use the same innovation toolbox for initial access, scheduler coordination and Quality of Service adaptation and there is no performance penalty due to Cloud RAN – the crucial 1ms scheduling period is preserved and as well as the granularity of spectrum allocation (Physical resource block allocation). However, there were some clever engineering tricks involved to make it happen.
Key innovations for running Ericsson Spectrum Sharing on Cloud RAN
A key innovative solution to bring ESS to Cloud RAN is Ericsson Elastic RAN and specifically the ability to enable instant 1ms sharing between different platforms. With our Elastic RAN as an enabler, ESS on Cloud RAN is realized with 5G executing on Cloud RAN whilst 4G (or both 4G and 5G) is executed on the Ericsson Radio System RAN Compute baseband with an inter-system interface in between. This configuration can be seen in Figure 2.
The 1ms sharing between different platforms enabled by Ericsson Elastic RAN is critical for a successful deployment of ESS since the 5G Cloud RAN scheduler needs to interwork with the 4G scheduler on that timeframe.
In the RAN Compute platform, the communication between the 4G and 5G parts is done through the Ericsson unique E5 interface that is very stable and continuously proven in the field, since more than 80 service providers already has the ESS software.
As we introduce ESS with 5G on Cloud RAN, the same reliability of communication between 4G and 5G is necessary. Since the original architecture was designed with this in mind, it makes perfect sense to use the Elastic RAN technology to re-use and extend the field proven internal E5 interface to go beyond the borders of the purpose-built baseband and to also allow connections with the Cloud RAN platform. We see this as a powerful proof-point of our technology leadership, expertise and our commitment to work with our customers to seamlessly move from one technology paradigm to the next.
Ericsson Elastic RAN and NR Advanced RAN Coordination as enabler for further network evolution
But it does not stop here. By using our Elastic RAN technology, the Cloud RAN can not only interwork with a single RAN Compute baseband, but with several, which can be single mode basebands or mixed mode basebands (ref Fig 1.) or a mixture of both. Our award-winning Elastic RAN technology has also been further enhanced for NR Carrier Aggregation features and renamed to NR Advanced RAN Coordination. Thus, NR Advanced RAN Coordination will enable the next step of our network evolution such as Carrier Aggregation between Ericsson Radio System and Cloud RAN.
The value of choosing Ericsson Cloud RAN
Ericsson Spectrum Sharing is a breakthrough in mobile communication and changes the way spectrum can be utilized. We believe that this will be the new normal when new technologies are introduced. Now, we the take a next step by bringing ESS to our Cloud RAN.
With the extension of an installed base of Ericsson Radio System to a Cloud RAN based architecture, service providers can expect to leverage the full capability of Ericsson Spectrum Sharing - providing 4G and 5G spectrum sharing on an instant - 1ms - basis.
In addition, our solution for extending Ericsson Spectrum Sharing onto Cloud RAN also enables service providers to fully utilize already made investments and keep flexibility when rolling out 5G.
ESS will work seamlessly, no matter if it runs on purpose-built hardware or on a combination of purpose-built and cloud infrastructure.
Our underlying design philosophy and technology will secure a seamless network evolution for service providers’ beyond ESS. As the next step, we will bring our innovative Carrier Aggregation across both purpose-built and cloud infrastructure.
This is only the start of our journey, with more to come that will unlock the full potential of networks beyond today.
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