5G, IoT

The Emergence of NR Light in 3GPP Release 17: Redefining Mid-Tier NR Device Operations

12 Jun

Abstract

The advent of ‘NR Light’ or ‘Reduced Capability’ (RedCap) in 3GPP Release 17 marks a significant stride in 5G technology. This article explores NR Light’s role in enhancing mid-tier New Radio (NR) device operations, focusing on efficiency, cost-effectiveness, and power conservation. We delve into the technical enhancements of RedCap, its impact on the Radio Resource Control (RRC) and Packet Data Convergence Protocol (PDCP) layers, and its implications for IoT and MTC use cases. A comparison of RedCap and Release 15 NR devices further elucidates the cost and complexity reductions achieved by this novel concept.

The Concept of NR Light

RedCap is designed with a clear objective – to simplify device operations, thus contributing to cost-effectiveness. This novel concept, also known as ‘Reduced Capability’ or RedCap, is set to redefine the operation of mid-tier New Radio (NR) devices, promising a higher degree of efficiency, cost-effectiveness, and power conservation.

NR Light is not just a technological advancement; it’s a strategic move towards enriching the 5G ecosystem. It is designed to cater to a wide range of Internet of Things (IoT) and Machine Type Communication (MTC) use cases, providing a more streamlined and cost-effective solution for device operation.

RedCap devices can exhibit a range of capabilities that fall between the simplest and the most advanced configurations. For instance, a RedCap device might support two downlink MIMO layers while not supporting 256 quadrature amplitude modulation (QAM) in the downlink. However, certain limitations apply to RedCap devices. They cannot support transmit/receive bandwidths exceeding 20 MHz for low/mid frequency bands or beyond 100 MHz for high frequency bands. Furthermore, they are not equipped to support features and capabilities associated with carrier aggregation, dual connectivity, more than two receive antenna branches, over two downlink MIMO layers, more than one transmit antenna branch, or more than one uplink MIMO layer.

 

In the specific context of NB-IoT, RedCap brings about significant advantages, particularly concerning enhancements to the Radio Resource Control (RRC) and Packet Data Convergence Protocol (PDCP) layers. These benefits stem from the core design philosophy of RedCap, which aims to reduce device complexity while leveraging the capabilities of 5G NR.

Use Cases for RedCap Devices in NB-IoT

The advent of RedCap devices in 3GPP Release 17 brings forth a multitude of potential use cases, particularly within the scope of Narrowband Internet of Things (NB-IoT). Here are a few examples:

  1. Smart Metering: RedCap devices can be instrumental in smart metering applications, such as utility meters for gas, water, or electricity. Their reduced complexity and power consumption make them ideal for these types of applications, where devices often need to operate for long periods on battery power and communicate over long distances.
  2. Asset Tracking: In logistics and supply chain management, RedCap devices could be used for asset tracking. The cost-effectiveness and power efficiency of RedCap devices make them a suitable choice for tracking assets over extended periods and across large geographical areas.
  3. Smart Cities: RedCap devices could play a significant role in smart city applications, such as smart parking, waste management, and environmental monitoring. The power efficiency and cost-effectiveness of these devices make them suitable for large-scale deployments in urban environments.
  4. Agriculture: In the agriculture sector, RedCap devices could be used for various NB-IoT applications such as soil moisture monitoring and livestock tracking. The reduced complexity and power consumption of RedCap devices make them ideal for these types of applications, where devices often need to operate in remote locations and under harsh conditions.
  5. Industrial IoT: In the industrial sector, RedCap devices could be used for applications such as machine health monitoring, predictive maintenance, and automated control systems. The cost-effectiveness and power efficiency of these devices make them a suitable choice for large-scale industrial deployments.

These examples illustrate the potential of RedCap devices to enhance the capabilities of NB-IoT and open up new possibilities for IoT applications across various sectors.

Enhancements Brought by RedCap

RedCap introduces several enhancements that significantly improve the operation of 5G NR devices, particularly in the context of Narrowband IoT (NB-IoT). Two of the most notable enhancements relate to the Radio Resource Control (RRC) and Packet Data Convergence Protocol (PDCP) layers.

The RRC layer plays a critical role in managing the radio resources between the device and the network. In a 5G NR device, the RRC states define the connection status between the device and the network. These states have a considerable impact on the device’s power consumption, as transitioning between these states incurs power costs. RedCap NR devices are expected to support fewer RRC states compared to their full-featured counterparts. This reduction simplifies the state management within the device, leading to fewer state transitions, and as a result, contributes to lower power consumption.

The other key enhancement associated with RedCap relates to the optimization of the PDCP layer. The PDCP layer in a 5G NR device plays a crucial role in data transfer, handling functions such as header compression, ciphering, and reordering of data packets. RedCap introduces optimizations to the PDCP layer that streamline these processes, further enhancing the efficiency of data transfer and contributing to the overall performance of the device. These enhancements are a testament to RedCap’s core design philosophy, which aims to reduce device complexity while leveraging the capabilities of 5G NR.

Cost-Effectiveness of RedCap Devices

Understanding the cost reduction mechanisms inherent in RedCap devices requires a comparison with their predecessors, the Release 15 NR devices. This comparison reveals three primary mechanisms that contribute to the reduction of baseband complexity, thereby facilitating cost-efficiency.

  1. Bandwidth Reduction: RedCap devices operate with a narrower bandwidth compared to Release 15 NR devices. This decrease in bandwidth reduces the required baseband processing power, leading to less complex and more cost-effective designs.
  2. Reduction in Maximum Number of MIMO Layers: Multiple Input, Multiple Output (MIMO) technology is a critical component of modern wireless communication systems. However, by decreasing the maximum number of MIMO layers, RedCap devices can simplify signal processing, further reducing baseband complexity.
  3. Relaxation of Maximum Downlink Modulation Order: The downlink modulation order refers to the complexity of the modulation scheme used for transmitting data from the base station to the user device. By allowing for a lower maximum downlink modulation order, RedCap devices can achieve less complex and less costly baseband processing.

These mechanisms, combined with the enhancements brought about by RedCap to the RRC and PDCP layers, contribute to a significant reduction in device complexity and cost, making RedCap devices a more cost-effective solution for a wide range of IoT and MTC use cases.

Comparing Baseline and RedCap Devices Across FR1 and FR2

To further elucidate the cost and complexity reductions achieved by RedCap, it’s instrumental to compare the capabilities of RedCap devices with those of baseline NR devices across Frequency Range 1 (FR1) and Frequency Range 2 (FR2). The table below provides a detailed comparison:

  FR1 – Baseline Device FR1 – RedCap Device FR2 – Baseline Device FR2 – RedCap Device
Maximum Device Bandwidth 100 MHz 20 MHz 200 MHz 100 MHz
Minimum Number of Device Receive Branches 2 or 4 (depends on frequency band) 1 for bands where baseline NR device is required to have 2. For bands where a baseline NR device is required to have 4, it’s still under discussion (TBD). 2 1
Maximum Number of Downlink MIMO Layers 2 or 4 (depends on frequency band) 1 for RedCap device with 1 Rx branch; 2 for RedCap device with 2 Rx branches 2 1
Maximum Downlink Modulation Order 256QAM 64QAM 64QAM 64QAM
Duplex Operation Full Duplex (FD-FDD), Time Division Duplex (TDD) The device may implement Half-Duplex (HD-FDD), Full Duplex (FD-FDD), Time Division Duplex (TDD) Time Division Duplex (TDD) Time Division Duplex (TDD)

Table 1: Comparing Baseline and RedCap Devices Across FR1 and FR2

 

This comparison highlights the key differences between baseline and RedCap devices, providing a clear picture of the cost and complexity reductions achieved by RedCap.

Furthermore, specific measures target a reduction in the bill of material (BOM) costs related to antennas and RF components:

  • Reduction in Minimum Required Receive Branches: The number of receive branches in a device can significantly impact the complexity and cost of the RF front-end.
  • Allowance for Half-Duplex Operations in All Bands: Traditionally, full-duplex operations necessitate separate antennas or complex isolation techniques for simultaneous transmission and reception.

Conclusion

With the introduction of NR Light in 3GPP Release 17, we are poised to witness a significant transformation in the landscape of mid-tier NR devices. By supporting devices with reduced capabilities and prioritizing power savings, NR Light holds immense potential for the future of IoT and MTC applications. As the details of NR Light continue to evolve, it is evident that this technology holds the key to unlocking a new era of efficiency and cost-effectiveness in the 5G ecosystem.

References

  • 3GPP RP-193264 “Rel-17 enhancements for NB-IoT and LTE-MTC”
  • 3GPP RP-191047 : NR-Lite for Industrial Sensors and Wearables (Ericsson)
  • What is reduced capability (RedCap) NR and what will it achieve? – Ericsson (2021)