In my previous blog, I discussed Quasi-Earth fixed beams vs. Earth-moving beams, including their differences, impacts, and functionality for network architectures.
In this blog post, I would like to explore Beam Hopping, including its requirements, applications, and challenges.
Beam Hopping is a technique used in satellite communications to dynamically allocate a limited number of satellite beams across different geographic areas over time. Instead of illuminating all coverage areas simultaneously, beams are “hopped” or shifted in scheduled time slots to serve high-demand regions more efficiently. High-level use cases include providing broadband connectivity to cruise ships moving across ocean regions and delivering on-demand capacity to rural or underserved communities during peak usage periods. This approach maximizes satellite resource utilization, enabling cost-effective and scalable coverage across wide and diverse areas.
Beam Hopping requires a limited number of satellite spot beams, given the power constraints, to sweep over the entire area of ground covered by a satellite over a period of time. This process typically occurs over several slots. This enables a satellite to cover a much larger area by using beam-forming and hopping this set of beams across the entire coverage area. By illuminating only a limited number of simultaneous spot beams, the system can share the available satellite power, radio, and antennas. An efficient beam-hopper ensures that not only all of the geographical area on the ground is covered, but also meets the defined QoS requirements for services to users across different geographical cells.
Beam Hopping Scheduler
Satellite coverage can reach a span of the order of hundreds and thousands of kilometers, covering a large number of geographical cells on the ground. Satellite payload systems are power-constrained and therefore cannot serve all cells in all slots simultaneously. Different geographical cells, covered by a satellite at any time, can have different user and traffic densities. For example, a satellite may have some geographical cells falling on uninhabited areas, like the sea or oceans, while some of the geographical cells could be covering ocean liners with high user and traffic density. Given these power constraints and the dynamic nature of user and service distribution, Beam Hopping becomes a critical capability to efficiently allocate limited satellite resources while still ensuring full coverage and service quality.
As part of the Beam Hopping process, a limited set of beams can serve a subset of the entire coverage area (i.e., geographical cells) at any time. Meanwhile, the same limited set of beams, appropriately beam-formed, would cover a different set of geographical cells. Over a period of time, the entire area under the satellite coverage is served using only a limited set of satellite beams. The Beam Hopping schedule must also account for service continuity and mobility, ensuring that handovers between beams meet 3GPP requirements for mobility management, especially in scenarios involving fast beam transitions or moving platforms like ships or aircraft. Beam Hopping scheduling is done in the granularity of well-defined slots, where one or several slots, per the estimated Beam Hopping schedule, are assigned to a geographical cell. In this scenario, Beam Hopping scheduling occurs in every beam scheduling slot. The Beam Hopping scheduling slot, typically, comprises several 5G NR scheduling slots or TTIs (transmission time intervals).
For example, for 30 KHz Subcarrier Spacing (SCS), NR scheduling slot is 0.5ms whereas the Beam Hopping slot could be 2ms implying that for every Beam Hopping period, a beam (or set) would serve a geographical cell(s) for 2ms scheduling it’s users for 4 consecutive NR scheduling slots before the next set of geographical cells is selected and served in the next Beam Hopping slot. The Beam Hopping scheduler provides a slot-wise schedule of the cells in a satellite’s coverage span to be served by the available beams.
While downlink Beam Hopping can be centrally managed by the satellite payload, uplink scheduling presents additional challenges due to the need for accurate timing advance and UE-side power control. Ensuring uplink synchronization across hopping beams is essential for maintaining 3GPP-compliant performance.
In the diagram above, I have included an example of Beam Hopping scheduling. The figure on the left shows 4 (M=4) simultaneous satellite beams, serving a set of geographical cells on the ground in kth and k+1th slots. The figure on the right shows an example of a Beam Hopping schedule, where 128 satellite beams can be powered simultaneously to serve 2500 geographical cells over multiple slots, with 128 geographical cells illuminated every Beam Hopping slot. In the example figure, each Beam Hopping slot is 1 ms, and each beam is assigned to a set of cells and serves those cells across multiple slots using beam forming to illuminate a specific geo-cell. Cells 1, 4, 9, 22, and 50 are assigned to Beam 1, and similarly, other cells are assigned to different beams. A cell, per its current user and traffic density, can be assigned to a beam for multiple slots. For example, Cell 1 is assigned 3 slots, Cell 4 is assigned 4 slots, Cell 9 a single slot, and so on.
Key Considerations
Some of the key considerations to keep in mind for Beam Hopping applications include:
- Ensure the QoS requirements of different services for all the User Equipment (UEs) across all the cells covered by a satellite are met:
- All cells under the coverage span of a satellite need to be served based on the aggregate outstanding load, the number of active Users, and their respective bearer QoS requirements, as well as the end-to-end deployment KPIs. These inputs need to be made available dynamically by the MAC Scheduler.
- Traffic requirements in any direction are usually paired with corresponding acknowledgements in the reverse direction. Beam Hopping needs to take UL-DL coordination into account to reduce redundant cell scheduling.
- Interference mitigation: Satellite beams can overlap with adjacent cells, creating interference. To avoid interference, adjacent cells operating on the same frequency should be separated in time scheduling.
- Maintaining cell availability by ensuring SSB/RMSI (SIB-1) periodic broadcast requirements for each covered cell are met to keep the cell available. While Beam Hopping focuses primarily on aspects of traffic handling, it also needs to ensure that each cell is provided with a transmission opportunity for periodic broadcast, access, control, and signaling scheduling. Traffic scheduling opportunities for cells should leverage transmission opportunities for signaling traffic transmissions.
- Additional considerations:
- Downlink Control scheduling associated with traffic needs to be delinked from actual traffic-based scheduling.
- Coverage enhancement features that require repetitive transmissions would impact the opportunities provided to covered cells and must be factored into the Beam Hopping plan.
- A Beam Hopping schedule needs to be created in advance for a duration comprising multiple slots. The system needs to balance the rate of generation of a new schedule with system agility in responding to dynamic changes in load conditions across cells.
Key Components Involved in Beam Hopping
Some of the key components necessary for successful Beam Hopping operations include:
- Satellite Network Operation Center: Responsible for ARFCN (Absolute Radio Frequency Channel Number) planning for cells based on frequency reuse
- Payload Mission Management: Beam forming vectors for satellite spot-beams based on geographical cells on the ground to be illuminated.
- Beam Hopping Scheduler: Creation of a slot-wise schedule for cells for all of the spot beams that could be powered simultaneously, to be served based on all considerations as captured earlier. This is done based on cell-wise KPIs provided by the MAC scheduler.
- MAC Scheduler: Provides the following inputs to the Beam Hopping scheduler
- Aggregate cell load KPI
- Active UEs per cell and their respective 5QI Data Radio Bearer (DRB) requirements
- Works on demand rather than every TTI
- Needs to support mechanisms to decouple downlink control scheduling from traffic-based scheduling
RAN Software Design to Address Beam Hopping Challenges
Beam Hopping in satellite-based 5G networks represents a vital evolution in how operators can extend coverage, manage scarce payload resources, and ensure service quality across vast, dynamic geographies. However, the business challenge for mobile and satellite operators lies in balancing performance with complexity. Implementing an efficient Beam Hopping framework requires careful orchestration of QoS enforcement, UL-DL coordination, timing synchronization, broadcast signaling, and interference mitigation—all while staying compliant with 3GPP specifications.
Operators must also account for real-world variables such as fluctuating traffic demands, varying user densities across rural and maritime regions, and the need for seamless mobility. Ensuring periodic SSB/RMSI broadcasts and avoiding scheduling collisions in overlapping beams further add to operational complexity. The need for interoperability with terrestrial and non-3GPP networks adds another layer of system-level consideration.
Yet, the benefits are substantial. Beam Hopping enables targeted and energy-efficient coverage delivery, improving spectral efficiency while reducing payload power consumption. It allows for intelligent resource allocation, making it possible to dynamically prioritize mission-critical use cases such as emergency communications, maritime connectivity, aviation, and remote enterprise backhaul. By optimizing coverage patterns and beam usage in real time, operators can also lower OPEX while meeting diverse 5QI-based service requirements.
What makes this practically achievable today is the availability of flexible, software-defined RAN components designed with non-terrestrial networks in mind. With the right technology partner, operators can simplify implementation and focus on delivering differentiated services at scale.
Radisys’ 3GPP Release 18-compliant 5G Multi-RAN software suite sets a new industry benchmark for enabling ubiquitous, intelligent connectivity. This next-generation RAN solution is designed to seamlessly integrate terrestrial, non-terrestrial (NTN), and non-3GPP access networks—empowering operators to deliver high-performance services across every geography and use case.
Contact Radisys today to learn how we can help you deploy a beam-hopping-enabled 5G NTN solution that’s future-ready, standards-aligned, and built to unlock new business opportunities.
For my next blog, I plan to discuss TN-NTN integration.
Explore More from the Satellite & NTN Blog Series
Continue your deep dive into the evolving world of Non-Terrestrial Networks (NTN) with our dedicated Satellite & NTN series, sponsored by Radisys:
- The Evolution of Non-Terrestrial Networks: From Experimental Beginnings to Global Connectivity – From early pilots to large-scale commercial rollouts bridging the digital divide worldwide.
- 5G NR Transparent NTN: Deployment Aspects and Challenges – Explore integration considerations and technical hurdles for transparent payloads and hybrid architectures.
- Regenerative Non-Terrestrial Network (NTN) Deployment Architecture – Understand how regenerative payloads enable in-orbit processing, lower latency, and smarter spectrum use.
- Quasi-Earth Fixed Beams vs. Earth-Moving Beams – Dive into beam architecture trade-offs for capacity optimization, roaming, and consistent user experience.
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