NR enhanced Reduced Capability

Description

NR eRedCap (enhanced Reduced Capability) is a RAT (Radio Access Technology) type identifier defined by 3GPP for use in the core network. It is a sub-type of the NR RAT type and is specifically used to identify when a User Equipment (UE) is indicating NR enhanced Reduced Capability. This identifier is introduced in Release 19 and is specified in TS 23.501 (System architecture for the 5G System) and TS 29.061 (Interworking between the Public Land Mobile Network and Packet Data Networks). The NR eRedCap identifier allows the core network to recognize devices that have reduced capabilities compared to standard NR devices, but with enhancements over the original RedCap (Reduced Capability) devices defined in Release 17.

In the 5G architecture, the RAT type is a parameter used by core network functions such as the Access and Mobility Management Function (AMF), Session Management Function (SMF), and User Plane Function (UPF) to determine the characteristics of the radio access being used. The RAT type is typically included in signaling messages during registration and PDU session establishment. For NR eRedCap, the core network receives this identifier when a UE indicates its enhanced reduced capability status. This allows the network to apply appropriate policies, such as different QoS parameters, charging rules, or access restrictions, tailored to the capabilities of these devices.

The need for NR eRedCap arises from the growing market for IoT devices that require higher data rates and lower latency than those supported by NB-IoT and LTE-M, but do not need the full capabilities of standard NR devices. The original RedCap (NR Reduced Capability) devices, introduced in Release 17, target use cases like wearables, industrial sensors, and video surveillance with data rates up to 100 Mbps. NR eRedCap further optimizes these devices by reducing complexity and power consumption even more, while still providing enhanced performance compared to LTE-M and NB-IoT. The core network identifier ensures that these devices are properly managed and that operators can offer differentiated services.

From an implementation perspective, the NR eRedCap identifier is used in the N1/N2 interfaces between the UE and AMF, and in the N4 interface between SMF and UPF. When a UE registers with the network, it includes its capability information, which may indicate NR eRedCap. The AMF then includes the RAT type in the UE context and forwards it to other core network functions as needed. The SMF uses this information to select appropriate UPF and QoS policies. The charging system also uses this identifier to apply specific charging models for eRedCap devices, which may have different data usage patterns.

The introduction of NR eRedCap in Release 19 aligns with the ongoing evolution of 5G to support massive IoT. It provides a standardized way for the core network to handle these devices efficiently, ensuring interoperability across different vendors and networks. As the number of connected devices continues to grow, identifiers like NR eRedCap become essential for network management, resource allocation, and service differentiation.

Purpose & Motivation

The NR eRedCap identifier was created to address the specific needs of a new class of IoT devices that require more capabilities than NB-IoT and LTE-M but less than full 5G NR. While the original RedCap (Rel-17) provided a mid-tier option, further enhancements were needed to reduce device complexity and power consumption even more, enabling lower-cost devices with longer battery life. The core network identifier allows operators to distinguish these devices and apply tailored policies, ensuring that they receive appropriate treatment without impacting regular NR users.

Before NR eRedCap, the core network could not easily differentiate between standard NR devices and those with reduced capabilities, leading to inefficient resource allocation and suboptimal service for IoT devices. The introduction of this RAT type identifier solves this by providing a clear signal to the core network about the device's capabilities. This enables operators to offer new service tiers, optimize network slicing for IoT, and implement specific charging models. It also facilitates roaming and interworking, as the identifier is standardized across 3GPP networks.

The motivation for NR eRedCap stems from the market demand for affordable, energy-efficient devices for applications such as smart wearables, industrial automation, and smart cities. By defining a core network identifier, 3GPP ensures that these devices can be seamlessly integrated into 5G networks, benefiting from the advanced features of the 5G core while maintaining low cost and power consumption. This is a key step towards realizing the full potential of massive IoT in the 5G era.