Is NTN D2C Just Business as Usual?

No, it is not. Although the satellites function like a cellular repeater or a base station in the sky, several adaptations are necessary to effectively support NTN D2C services.

Let’s explore some of the most critical adaptations and consideration required to support NTN D2C.

Adaptations for Fast-Moving Satellites

Rather than creating constantly moving beams that necessitate frequent handovers, NTN systems use Earth-fixed or slowly moving beams focused on the same geographic area for extended periods (several minutes). This reduces the need for handovers and spectrum switching within those beams. However, LEO satellites introduce new complexities since they are constantly moving at high speeds – handover procedures must be maintained even when a user remains stationary for long periods.

Satellites broadcast ephemeris data – precise information about their position and velocity – that user equipment (UE) uses, along with Global Navigation Satellite System (GNSS) location data, to calculate timing advance and Doppler shift compensation before accessing the network. This ensures frequency alignment despite satellite movement. The network proactively manages handovers between satellite beams and from satellite to terrestrial cells using advanced signaling techniques. Conditional handovers enable UEs to prepare in advance based on time and location triggers, minimizing service interruptions.

Adaptations to Mobile Core Signaling

The core network must adapt its signaling and mobility management to meet NTN-specific challenges. This includes implementing latency-tolerant signaling protocols, enhanced security measures, satellite-aware handover procedures, and a flexible, cloud-native, service-based architecture. Integration with the NTN control function is crucial for coordinating satellite beam mapping to terrestrial cells, timing advance correction, and location-based routing – ensuring optimal user experience with session continuity and optimal network performance.

Traffic Management Becomes More Critical

Incorporating NTN connectivity elevates the importance of traffic management, given the higher costs and resource limitations of satellite links compared to terrestrial networks. Even if mass-market wideband and broadband services like video conferencing and video streaming is not expected to be supported for direct communication to mobile phones (NTN D2C) anytime soon, as discussed, there are other NTN use cases using VSAT technology with antennas capable of delivering broadband services integrated with the mobile core. We may even see larger antennas installed in car roofs in the not-too-distant future.

Reducing traffic loads – especially from video, which currently accounts for approximately 75% of all mobile data – is crucial. Effective traffic classification, in coordination with PCRF/PCF, can prioritize critical data while assigning lower priority to non-essential traffic over satellite links.

AI and machine learning techniques will help predict traffic patterns, enabling proactive optimization of handovers, bandwidth allocation, and resource provisioning between terrestrial and satellite domains. These methods help reduce interference and maximize throughput. Additional techniques such as TCP acceleration, RAN congestion management, and load balancing further improve traffic efficiency.

Advanced and Flexible Policy Management

The 4G Policy and Charging Rules Function (PCRF) and 5G Policy Control Function (PCF) are critical for managing traffic and resources in NTN D2C networks. They act as centralized decision-makers for enforcing policies related to user access, QoS, data prioritization, and usage limits, tailoring resource allocation based on subscription profiles, network conditions, and service requirements.

Due to the higher costs and limited capacity of satellite links, PCRF/PCF policies often include bandwidth caps for non-critical applications, prioritization of emergency or premium services, and stricter usage limits. These policies are dynamically linked to charging rules – higher prices or special packages may be applied when users access the network via satellite to incentivize efficient usage.

Utilizing real-time network data, PCRF/PCF can adjust policies based on factors such as satellite link quality, congestion levels, user location, and device type – all to optimize resource utilization and user experience.

In some cases, users may need notifications when switching between terrestrial and satellite networks. Additionally, in 5G, PCF helps manage network slicing, which can be used within NTN D2C to segregate traffic requiring different SLAs, security policies, or latency requirements.