CmWave: an essential enabler of 6G

With relatively large bandwidth and wide coverage capabilities, the cmWave range is expected to play a pivotal role in enabling the explosive technological possibilities of 6G – from smart and sustainable cities to high-definition, holographic and sensory digital immersion.

It will also be key to addressing a critical shortfall of wide-area spectral capacity, enabling the continued growth of mobile data traffic beyond 2030.

• Combines good coverage with reasonably large bandwidths.
• Supports wide-area coverage through the use of massive MIMO technologies.
• Unleashes fairly large amounts of spectrum for cellular usage.
• Deployments in the lower cmWave range, immediately adjacent to today’s “classical” mid-band, allow for a larger reuse of the existing grid and reduction in the number of new sites, costs, and power consumption.
• Enables higher capacity due to massive spatial reuse.
• Enables continued evolution and growth of mobile broadband and AR/VR applications, such as holographic communication.

Additional spectrum within the cmWave range will be essential to realize the capacity-demanding use cases in future 6G networks and enable their outdoor and indoor mobility. While it is expected that Wi-Fi and other solutions will continue to play an important role in partially offloading indoor traffic, mobile networks will remain key to enabling wide-area mobility and ensuring low delays even outside confined environments.

Holographic communication

As the next expected paradigm shift after the smartphone, holographic communication will be a key driver of additional spectrum requirements in the CM-wave range for two main reasons:

• High data rate requirements. Holographic communications will need to encode a multitude of high-resolution images from different angles and with low delays to facilitate realistic viewing experiences and reduce motion sickness. To support this, estimated uplink and downlink data rates of 100 Mbit/s and 1 Gbit/s respectively will be needed.
• High data capacity requirements. While the amount of spectrum required depends on the assumptions made, an additional 2.4 GHz of spectrum suitable for wide-area coverage will be needed to enable and support holographic-based use cases in the 6G era.

Internet of senses

Over time, holographic communication will be complemented with multisensory extensions such as touch, taste, and smell to increase the level of immersion beyond audio-visual and realize the internet of senses vision. These developments will further and greatly drive network traffic and spectrum need.

Massive digital twinning

Several digital twin applications are expected to significantly drive the need for wide area spectrum, including, but by no means limited to:

• Smart cities. Building high precision 4D digital maps of a city requires data and information on every object and process. And while the data rate from each sensor will be modest, the sheer number of sensors will significantly challenge aggregated data rates.
• Less dense suburban areas. While lower spectral efficiency is expected in this environment, a reasonable amount of wide-area spectrum will still be required. For example, the UL-heavy traffic connected to this use case will require approximately 300 MHz of wide-area spectrum for communication purposes alone.
• Radio-based sensing. In addition to sensors, radar-like operations can also provide input to the digital twin. For example, a base station at a street intersection can be used to assist traffic safety applications by estimating the position or speed of vehicles. In this scenario, a 0.5 m range resolution will require at least 300 MHz of bandwidth.

Learn more about 6G spectral requirements in our 6G spectrum white paper.

Many bands within the cmWave range are already allocated to mobile, fixed and other services on a co-primary basis. This poses a unique set of spectrum-sharing and coexistence challenges, both of which will require careful consideration and further studies.  

It is also anticipated that the cmWave will initially be deployed close to- or on the same grid as "classical" mid-band, maximizing the re-use of the existing network grid. Nonetheless, this will require at least four times as many antenna elements to compensate for the omni-directional pathloss increase that occurs between 3.5 and 7 GHz. For this, many different architectural choices exist to implement the larger antenna array, each of which will need to strike a balance between challenges of complexity, flexibility and energy efficiency.

Learn more about example deployment scenarios in our cmWave blog post.