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29 June 2020

Nokia throws down its O-RAN gauntlet with reboot of AirScale

Nokia has introduced its latest 5G portfolio, updating its Cloud-RAN architecture with support for the O-RAN Alliance’s open interfaces. This launch represents high stakes for the Finnish company, coming at a time when it is in a precarious position in terms of market confidence in its platforms, and reported to be vulnerable to hostile takeover.

A new CEO, and a new 5G RAN platform, will be tasked with boosting Nokia’s flagging market valuation, strengthening its defences against unwelcome predators, and kickstarting new 5G sales – no mean feat in the current climate, where the whole industry is beset by uncertainties over the impact of the pandemic and the USA/China cold war.

Nokia’s incoming CEO, Pekka Lundmark, will take up his new position on August 1, a month earlier than planned – seen as a move to boost investor confidence by introducing a new broom as quickly as possible, amid rumbling speculation about a hostile takeover bid, or even a US government-financed acquisition plan.

The later months of last year saw Nokia suffering setbacks in some of its early 5G deployments and a humiliating U-turn on its critical 5G RAN chip platform (see separate item). That hit profitability and the confidence of investors and customers, just at a time when the vendor should have been taking advantage of the even greater trials of its arch-rival Huawei. Despite a generally strong track record, CEO Rajeev Suri had to be sacrificed, and Lundmark will take the reins, moving from Finnish utility Fortum.

A strong reception for the new 5G Cloud-RAN offering would give him a welcome boost of positivity for his first weeks in a tough job. The new products will be burdened with three big responsibilities:

  • To restore faith in Nokia’s foundational capabilities as a RAN provider. If that confidence is undermined, all its recent successes in new areas, such as enterprise and private networks, or webscale routers, will be seriously overshadowed
  • To remind the market that Nokia has been more advanced than its competitors in Cloud-RAN. It adopted elements of a virtualized RAN architecture almost a decade ago in its Liquid Net portfolio, and opened itself up to the idea of running its software on third party hardware, when that was still a radical idea in telecoms networks. Arguably it moved too early, adopting Cloud-RAN architectures before current thinking – about containers, for instance, or distributed units – was formed. But it has stored up considerable software expertise, and just as important for the large MNOs, experience of integrating large-scale virtual networks.
  • To play Nokia’s high-stakes O-RAN gamble (see introductory analysis).

Nokia has made it clear that it intends to take the lead in supporting open interfaces, despite all the risks that presents for its traditional economics and its hold over customers.

In O-RAN, it appears to be hoping that, if O-RAN (or another open architecture) prove to be unstoppable, it will have seized competitive advantage from its main rivals, while also offering an end-to-end, fully telco-grade solution.

In the best case for Nokia, operators will opt for single-vendor O-RAN implementations, comforted by the ‘get-out clause’ of the open interfaces and swappable hardware and software elements.

In a less ideal scenario, they will want fully multivendor networks but will need a trusted, large-scale partner to do the integration and roll-out, which would see Nokia working with challenger suppliers, but keeping hold of the pivotal role in the value chain.

Some operators will be like Rakuten and shoulder the burden of integration themselves, and of course Nokia will not want to be excluded from such deals because it could not tick the O-RAN checkbox, but the Rakuten example – in which Nokia provided 4G radios but was replaced by NEC for 5G – shows how vulnerable individual suppliers are in a truly open platform. It will be an important element of Nokia’s strategy, surely, to play on the nervousness of most large MNOs, and encourage them to cling to the security blanket of a well-established prime contractor.

Just scaring the operators about the risks of introducing brand new architectures to their most important networks will not be enough of course. The products will have to perform to at least the same standard as a conventional RAN, if not better, while providing the cost-effectiveness, flexibility and openness that operators are demanding from their next generation 5G (particularly Standalone) systems. They may currently be deploying 5G in a conventional way, and saving experimental O-RAN for secondary networks, but they will soon be issuing their RFIs and RFPs for a next wave of roll-out, and testing the waters to see how realistic their open RAN dreams may be.

Nokia’s initial offering for those MNO conversations is based on key elements it already offers, such as the second generation 5G AirScale Cloud-RAN platform, and on some of the work it did for Rakuten to open up its interfaces for third party virtual network functions (VNFs) or hardware elements. That work was initially done specifically for the Japanese operator, but the experience will help in allowing it to support O-RAN interfaces as a standard feature.

Sandro Tavares, head of mobile networks marketing at Nokia, says it already has customers for the new generation of AirScale, although he would not comment on whether those had been motivated by the ability to support O-RAN.

The “fully cloudified and disaggregated 5G base station” will be commercially available to selected customers this year, with wider availability in early 2021. And while O-RAN support has grabbed the headlines, the really important improvement on the first 5G AirScale release is to introduce the virtualized distributed unit (vDU).

This is where Nokia can be argued to have moved too early in vRAN, adopting a very centralized architecture – which was the early thinking about the platform. However, that is challenged by any RAN services that require low latency, real time response, or which involve very high levels of signal processing. These are better supported in distributed units, closer to the radio units on the cell site (and sometimes collocated with it), and based on cloud hardware with specialized accelerators to handle the very intensive processing. Those DUs are then linked by an open midhaul interface to the centralized unit (CU), which can run on generic cloud infrastructure.

However, Nokia had to support the real time functions, where required with a conventional, physical DU, adding to cost and reducing flexibility. The simpler CU/RU  architecture has been implemented in some Nokia projects, such as AT&T’s and Verizon’s millimeter wave 5G networks, but the fully virtualized DU option will be important for wider appeal, especially when operators starting thinking about low latency applications with their upgrades to the more industrial and IoT-focused 3GPP Releases  16 and 17.

With the new vDU, both non-real time and real time RAN functions are virtualized and run on a cloud stack in x86-based Nokia AirFrame Open Edge Servers and Rackmount Servers.

And Nokia points out another of the key advantages of the three-tiered architecture – which also lies at the heart of O-RAN. This is the ability to use the same distributed cloud infrastructure to run other applications as well as the RAN functions, such as low latency IoT services and analytics for enterprise users, or slice management.

The challenge remains of developing hardware for the DUs which is off-the-shelf – to achieve low costs and allow VNFs from multiple vendors on the same units – but sufficiently powerful to handle the challenging demands of a macro RAN engaged in low latency and highly synchronized functions such as dynamic spectrum sharing.

Most current architectures either stick with proprietary, optimized hardware, or use FPGAs (field programmable gate arrays) to offload the most intensive tasks from a standardized x86 or ARM processor, but this solution can be expensive (as Nokia knows from its use of FPGAs in its initial 5G platform). Both Ericsson and Nokia are interested in the potential of using graphical processing units (GPUs) as a more commoditized alternative for acceleration, and Ericsson has a joint development ongoing with Nvidia to explore the potential.

Nokia said last week that it is also working on GPUs for hardware acceleration in DUs and those should be ready in 2022. Tavares told FierceWireless that these GPU-based accelerator cards would be used to process some of the functionality in the lower Layer 1 of the distributed unit.  However, like Ericsson, Nokia does not think GPUs are ready yet for this use case, and are currently unable to match the performance of a single-purpose or FPGA solution. In the interview, Tavares said that FPGAs were ready now, whereas GPUs “still need some significant development work to adapt them to this specific L1 use case”.

The evolution of the AirScale architecture and hardware – the current iteration and the promise of future updates – is critical, because here are the areas where Nokia can potentially secure a real advantage with its scale and experience (however tainted at the moment). In standalone network elements or VNFs, it has to play on a more level field with specialist providers.

Of course, this is why O-RAN is important. It neutralizes one of the advantages of the new vendors, while Nokia seizes the chance to provide an end-to-end solution – consistently its claim to 5G differentiation – but with open interfaces. So not only does it offer every element of an open RAN (though with the comfort factor that operators can swap in elements from a third party if they prefer), but it also promises advanced backhaul, routing and cloud-native core, together with software to manage and orchestrate the virtualized and the physical networks.

Nonetheless, Tavares was playing the open card, saying the new AirScale is an “initial step toward a scenario where seamlessly mixing different vendors in the RAN will be a reality” – once work is complete to “fully define and test the open interfaces”.

So the new AirScale architecture supports the O-RAN taxonomy – radio unit (RU), DU, radio access point (RAP – an option which combines DU and RU),  CU and RAN Intelligent Controller, all connected by the various O-RAN interfaces. The vDU and vCU can be colocated at a central or regional edge cloud, or the vDU can be decentralized to an edge or far edge cloud, or the vDU can be located at the cell site. Nokia said: “Such flexibility is of paramount importance due to varying topologies and transport network needs even within the same network.”

The O-RAN interfaces, and the RIC, are in different stages of maturity, but Nokia has been careful to stamp its mark on several of them, most notably the RIC.

This was originally based on Nokia seed code, and is the most original feature of the O-RAN platform to date. It is potentially a powerful point of control for the whole network, since it comes in real time as well as non-real time versions, with the former able to support strategic and complex 5G operations such as slicing. Non-RAN vendors such as Cisco and Amdocs are eyeing the RIC as a possible entry point to the 5G access network, and an important way to gain a strategic position with operators – so Nokia needs to move quickly to cement its current advantage.

The RIC only operates within O-RAN networks so will not always be present in AirScale deployments. Tavares said: “Not every cloud-RAN implementation is an Open RAN case. Also, not all Open RAN cases will be implemented using Cloud RAN/vRAN, even though it is fair to assume that most will.”

Nokia also released details of its network slicing software, Digital Operations Center, which will be available by the end of this year to automate the process of designing and operating slices across multiple networks and equipment suppliers. It integrates with Nokia’s orchestration and assurance software stacks and is currently being trialled by four operators, with SingTel the only one named.