The 5G era is quickly approaching. This next generation of mobile networks will provide high-bandwidth mobile broadband and underpin many converging technologies and use cases: smart cities, smart factories, autonomous vehicles, augmented and virtual reality, video communications, the Internet of Things (IoT), and more. 5G promises to be the data backbone of the future economy.
In order for the benefits of 5G to be fully realized, 5G networks must be deployed as efficiently as possible. Unfortunately, this presents a difficult challenge. With its utilization of higher frequencies, 5G requires denser networks than previous generations of mobile networks like 4G. Yet even 4G, nearly ten years after its introduction, still has not achieved complete coverage in most countries. If the same roll-out techniques are used for the next generation, 5G networks will not be deployed effectively. Instead, new network architectures and solutions must be enacted.
Dynamic spectrum access
One challenge in deploying mobile networks is that populations are generally divided into two categories: urban, in which large populaces are highly concentrated, and rural, in which smaller communities are spread further apart. Consequently, network coverage is both easier and more profitable in urban areas. This often means that rural areas are slow to receive sufficient coverage. However, a solution to this problem may lie in how 5G spectrum is regulated.
Many countries around the world have begun allocating 5G pioneer spectrum in the mid-band vicinity of 3.5 GHz. Europe has allocated 3.4 – 3.8 GHz, the United States will allocate 3.1 – 3.55 GHz, China is examining 3.3 – 3.6 GHz, and Japan is examining 3.6 – 4.2 GHz. The coverage of rural areas can be facilitated by applying an opportunistic Dynamic Spectrum Access (DSA) layer to these pioneer bands.
The Dynamic Spectrum Alliance (DSA) is a global organisation advocating for laws and regulations that will lead to more efficient and effective spectrum utilisation around the world. “The DSA is supporting dynamic spectrum access across a variety of complementary spectrum bands and promoting the use of geolocation databases and other interference protection mechanisms” Said Pasquale Cataldi, Head of Wireless at Nominet and member of the board of the Dynamic Spectrum Alliance. The DSA works in liaison with organizations that pursue similar objectives in particular the CBRS alliance and important founding members include Microsoft, Google or Broadcom.
Coming back to the DSA (A as in Access, the same acronym refers to the alliance or the technology) is a method in which spectrum is allocated in real-time in accordance with a central geolocation database. DSA allows different Mobile Network Operators (MNOs) to use the same spectrum in different geographic locations. The availability of commercial, off-the-shelf Software Defined Radios (SDRs) enables such dynamic spectrum switching to be both feasible and cost-effective.
The adoption of DSA with the 5G pioneer bands has the potential to dramatically improve the efficiency of 5G networks. Firstly, it would allow the entire range of pioneer spectrum to be available at every location, increasing data capacity and speeds. Secondly, it would allow new network operators to use 5G pioneer spectrum in regions not covered by existing MNOs. Finally, incumbent spectrum users could retain their use of the spectrum in a specific location while making it available for others elsewhere.
DSA is a technology that’s been used in the management of TV White Spaces (TVWS). TVWS refers to the spectrum between channels in TV transmission systems around the globe. This spectrum is allocated dynamically through the use of a regulator-approved database. “Nominet has already certified TVWS databases in the UK and US, and it is supporting other regulators in the world by providing TVWS databases that follow the best-practices recommended by the Dynamic Spectrum Alliance. Beside TVWS, the concept of DSA advocated by the Alliance has been applied to other bands too, such as 3.5 GHz pioneer bands in the US and potentially to 6 GHz (see FCC’s Notice of Proposed Rulemaking)” said Pasquali.
Market expansion
The proposal to use DSA with 5G pioneer bands is a method of market expansion. In this solution, 5G networks can be more efficiently deployed by encouraging a higher number of network providers. To most effectively promote market expansion, a small portion of the available pioneer spectrum could be set aside as “anchor spectrum,” a lightly licensed band for new market entrants. For example, a regulator could allocate five 20 MHz blocks of pioneer spectrum as opportunistic DSA, in which licensed operators have priority over the spectrum, and allocate a single 20 MHz block as open DSA, the anchor spectrum to be shared among all operators.
Anchor spectrum could be utilized in rural areas that are slow to receive coverage from MNOs. Even if all MNOs were to roll-out their 5G spectrum on all their current 4G masts, many rural areas would still find themselves in a no-coverage zone. New operators in these communities could deploy 5G networks using the anchor spectrum, so that even if the area were to be covered in the future by existing MNOs, the local network could still function.
The market expansion model could also provide benefits in urban environments that are already sufficiently covered by existing MNOs. For example, organizations such as schools, hospitals, and office buildings could establish private small cells using anchor spectrum, thereby avoiding interference with existing networks.
Realizing the benefits of 5G
New technologies provide now the ability to manage how and where spectrum is used in any given location at any given time through geolocation databases and spectrum sensing. This combination of centralized database and local sensors enable secondary and tertiary access by new users and applications while protecting the incumbent users. This technology also enables regulators to solve interference problems where they arise. To capitalize on 5G promises, it’s important to deploy spectrum efficiently and effectively with dynamic spectrum allocation and sharing.
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