Dynamic Spectrum Sharing: It’s Not Just for 4G and 5G

Ed Gubbins – Principal Analyst

Summary Bullets:

• Dynamic spectrum sharing (DSS) can improve the coverage and capacity of 4G/5G networks by allowing both technologies to efficiently share the same finite, licensed spectrum.

• Spectrum-sharing goes beyond 4G/5G, including 2G and 3G and potentially Internet of Things technologies, increasing its value and diversity.

As the 5G era dawns, a technology known as DSS has become a hot topic. DSS allows operators to use the same spectrum bands simultaneously for different radio access technologies. Specifically, the industry’s 3GPP standards enable using 4G and 5G in the same spectrum. It’s “dynamic” in that the network is continually re-evaluating user activity and reallocating spectrum to 4G and 5G traffic as needed – sometimes as often as every millisecond.

Efficiently consolidating 4G and 5G traffic in the same spectrum can be particularly relevant to the first wave of 5G network deployments that use “non-standalone” 5G, which involves 5G radio technology but a legacy 4G core, since these networks manage 4G and 5G traffic using much of the same infrastructure. What’s more – DSS can help with a common challenge in 5G deployment: Because 5G is often deployed on higher frequency bands than 4G (bands with shorter range), it’s harder for operators to establish the same coverage in 5G that they had with 4G (at least initially). With DSS, they can achieve greater coverage. For example, using DSS, Vodafone Germany launched 5G in 700 MHz spectrum with a reach of around 20 square kilometers – five times the coverage area that 5G would have in a mid-band frequency like 3.5 GHz. But even without deploying 5G in low-band spectrum, DSS’s more efficient use of spectrum can increase the throughput of 4G and 5G services.

That said, spectrum sharing can be applied beyond just 4G and 5G. Some equipment vendors have been offering spectrum sharing for earlier generation technologies, including 2G and 3G, for years, and the benefits are slightly different than they are for 4G/5G. Using legacy technologies in the same spectrum can allow operators to preserve some voice services, for example, giving them more flexibility in the migration to voice-over-LTE or voice-over-5G. It can also preserve some Internet of Things (IoT) networks, some of which are delivered over 2G networks. One reason this move makes sense is the fact that applications on legacy networks, such as voice or IoT, often don’t consume much bandwidth, making them good candidates for sharing bandwidth with other services.

Those benefits notwithstanding, DSS is still evolving. In the near future, some vendors hope to enable the capability to share spectrum simultaneously among three technologies instead of just two (e.g., 3G, 4G, and 5G). In fact, in the spring of 2020, China Unicom Henan tested 3G/4G/5G spectrum sharing in order to extend 5G coverage while preserving 3G voice service. In addition, some vendors hope to add a fourth technology: Narrowband IoT. The idea of DSS as a strictly 4G/5G solution – much-promoted in recent months – may soon evolve as operators appreciate the full breadth of its capabilities.

 

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