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3GPP compliance and dynamic spectrum sharing – Verizon’s next steps

The deployment of millimeter wave 5G networks by Verizon, AT&T and T-Mobile has been a significant boost to Samsung’s networks business, since the Korean firm has strong expertise in this area. It has leveraged extensive R&D efforts in its homeland and the experiences from the WiMAX market, where it was a leader, to inform its 5G offerings for 28 GHz and 39 GHz bands.

This has led it into very close cooperation with the operators, especially Verizon, which takes an almost Korean-like approach to procuring its networks, working closely with key vendors and insisting on a large measure of customization to meet its requirements optimally. That was seen in the telco’s development of its own pre-standard 5G network, to enable it to gain a headstart on its rivals in deployment, but the close partnerships will persist as it migrates to fully standard networks.

That process has begun, with the conversion of its Chicago fixed wireless access (FWA) service from pre-standard to 3GPP-compliant networks, which will support more and cheaper devices, as well as self-installable fixed CPE. Verizon has also said it will be the first customer for Samsung’s new 3GPP-compliant integrated radio access unit (AU) for mmWave bands, which it showed off at Mobile World Congress Los Angeles (MWC LA) last week, claiming it was the first of its kind.

This offers many of the capabilities of the emerging class of equipment called mini-macro – which have the compactness and deployability of small cells, but are close to macro base stations in performance. Since Verizon is by far the biggest owner of 28 GHz spectrum in the USA – and in other parts of the world, 26 GHz is a more common choice – it is clear that this product was developed with the US operator in mind. Combined in the AU are the radio, antenna and digital units in one box that is designed to be easily installable on street furniture.

Samsung’s Derek Johnston said the all-in-one architecture eliminates the need for a fronthaul link between the radio unit and the baseband, reducing the use of fiber and therefore the cost, while delivering 10Gbps throughput. The product is 25% smaller and more power-efficient than its predecessor, which had a split architecture, and has upgraded from 2×2 to 4×4 MIMO antennas.

Samsung is also developing units that support additional mmWave bands including 24 GHz, 26 GHz and 39 GHz. The device incorporates the first 5G New Radio system-on-a-chip modem from Samsung’s electronics division.

As well as moving to new form factors and 3GPP-based systems, Verizon was also describing its plans to introduce dynamic spectrum sharing (DSS) technology into its network next year. This is an important way to improve interworking between LTE and 5G, optimize spectrum utilization and prepare the path for standalone 5G networks based on a 5G core (a transition Verizon plans to start next year).

The technology will be supported by all three of its vendors – Ericsson, Samsung and Nokia, though only Ericsson has so far publicly announced its DSS products. That may force Verizon to make the upgrade first only in markets where Ericsson provides the equipment, according to VP of technology Heidi Hemmer.

“If it is something we think we can launch with one infrastructure vendor that might create an issue in the other areas [of the network] then we wouldn’t do it,” she said,

Samsung’s  Johnston said a DSS product is still in testing and development stages, but is now “on the horizon” for launch in the second half of 2020.

Even Ericsson’s solution is not fully market-ready. The firm’s head of 5G commercialization, Thomas Noren, said at MWC LA that “the software needs to be hardened and proven in the field”. He indicated that DSS had proved far harder to do than vendors had expected. “Eighteen months ago, one other vendor said, ‘we already have it’,” he told the conference. “Then they realized they didn’t have it. Then they said it was impossible. Then we did it. Every operator in the world is interested in this.”

Hemmer said DSS would initially be deployed to improve capacity in areas of high traffic such as stadiums, which have been a major focus of Verizon’s first-phase 5G launches. In these environments, an operator can harness all the spectrum at its disposal to boost speeds.  She commented: “DSS will be very important where we have large capacity needs, which would be venues, so while it will help improve all of our network it will be particularly important in places where you have lots and lots of people that are gathering.”

She added: “When we get to a 5G core, we get to dynamic spectrum sharing ubiquitously, we’ll be able to do network slicing”

Last month, Ericsson announced its DSS solution, which it co-developed with Qualcomm to support spectrum sharing between 4G and 5G, without the need to refarm spectrum. The vendor said this would enable 5G to be rolled out more quickly and cheaply, using bands which the operator already has, and to boost overall capacity and network flexibility. It stated: “Traditionally, new generation radio access technologies are deployed on separate spectrum blocks – as was the case with 2G, 3G and 4G. This would require operators to buy new spectrum or refarm the existing spectrum to allocate the new generation. This is a very slow and costly process.”

Refarming could take a decade whereas spectrum sharing can be activated, in ERS software, overnight, and the resources can then be dynamically allocated between 4G and 5G in the same band based on demand from the users or applications.

With DSS, spectrum can be reallocated to different radios every millisecond. It allows an MNO to move spectrum between different radio technologies as required, and was designed mainly to give greater flexibility and efficiency in spectrum usage, in high bandwidth situations.

It can also help with interoperability, as an MNO could buy 5G equipment, with DSS support, from a new vendor and initially run the system in 4G mode, using some existing 4G spectrum. This overlay would support interoperability between the incumbent 4G and the new 5G systems, with roaming between the two 4G radios happening at packet core level as usual.

The DSS solution is rooted in 3GPP standards but uses Ericsson’s own intelligent scheduler algorithms to decide on optimal use of both LTE and 5G in a single block of spectrum.

Other vendors are also pushing DSS as a future way to encourage MNOs to accelerate 5G deployments – as well as a way to ease the path to introducing alternative suppliers to their networks. In the the Non-Standalone environment, 5G and 4G base stations both connect to the LTE core using Dual Connectivity. However, most of the options for deploying this work more efficiently if both base stations come from the same supplier, which causes issues for MNOs which want to migrate to a new vendor for their first-stage 5G RANs. This predicament has been highlighted by the risk that operators in some countries may be barred from buying RAN gear from Huawei – Huawei users such as VHA in Australia now have to make a difficult migration to a different vendor to comply with government restrictions.

The use of DSS can help with this, argue both Ericsson and Nokia (see Wireless Watch April 10 2019). Nokia has described a solution based on DSS which allows the existing LTE to communicate with the new base stations without using the X2 interface (which has been implemented in incompatible ways by different vendors).

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