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Support of Ultra-reliable and Low-Latency Communications (URLLC) in NR

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Support of Ultra-reliable and Low-Latency Communications (URLLC) in NR

Introduction

With the advent of 5G wireless technology, Ultra-Reliable and Low-Latency Communication (URLLC) has become a crucial requirement for many mission-critical applications. URLLC refers to a set of communication services that require extremely low latency and high reliability, such as industrial automation, remote surgery, and autonomous vehicles. In this context, 3GPP, the organization responsible for standardizing cellular communication systems, has introduced new features in the 5G New Radio (NR) standard to meet the requirements of URLLC. This article provides an overview of the technical aspects of URLLC in NR and discusses the key features that support it.

Requirements of URLLC

URLLC is characterized by the following requirements:

  1. High reliability: URLLC services require high levels of reliability to ensure that critical data is delivered correctly and in a timely manner. The reliability requirement for URLLC is typically higher than that for other communication services.
  2. Low latency: URLLC services require low latency to enable real-time communication between devices. The latency requirement for URLLC is typically much lower than that for other communication services.
  3. High availability: URLLC services require high availability to ensure that critical communication is not disrupted, even in the presence of interference or congestion.
  4. High data rates: URLLC services require high data rates to enable the transmission of large amounts of data quickly and efficiently.

Key Features of URLLC in NR

The following features of NR are designed to support URLLC:

Numerology and Frame Structure

The NR numerology and frame structure are designed to support low latency and high reliability. The basic NR numerology is based on a subcarrier spacing of 15 kHz, which enables a transmission time interval (TTI) of 1 ms. The frame structure is based on a flexible slot-based design, where a slot can be 14 symbols, 12 symbols, or 1 symbol long. This enables the use of short transmission time intervals (TTIs) of 1 ms, 0.5 ms, and 0.125 ms, respectively, to support low latency communication.

Time-Sensitive Networking (TSN)

Time-sensitive networking (TSN) is a set of standards that enable deterministic Ethernet communication over a network. TSN can be used to support URLLC by providing guaranteed latency and bandwidth for critical traffic. NR supports TSN by providing a TSN-enabled Ethernet interface that can be used to connect to TSN networks.

Control and User Plane Separation (CUPS)

Control and User Plane Separation (CUPS) is a feature that separates the control plane and user plane of the communication system. This enables more efficient use of network resources and provides better support for URLLC by allowing the control plane to have higher priority than the user plane. NR supports CUPS by allowing the control plane to use a dedicated bearer with higher priority than the user plane.

Ultra-Reliable Low-Latency Communication (URLLC) Bearer

The URLLC bearer is a dedicated bearer that is designed to support high reliability and low latency communication. The URLLC bearer is characterized by the following features:

  • Guaranteed bit rate: The URLLC bearer provides a guaranteed bit rate, which ensures that the communication system can deliver critical data within a specific time frame.
  • Short transmission time interval (TTI): The URLLC bearer supports short TTIs of 1 ms or less to support low latency communication.
  • High reliability: The URLLC bearer is designed to provide high reliability by using advanced error correction techniques and redundant transmissions.
  • Low latency: The URLLC bearer is designed to support low latency by using advanced scheduling techniques and minimizing the processing time

Quality of Service (QoS)

Quality of Service (QoS) is a mechanism that enables the communication system to prioritize different types of traffic based on their requirements. NR supports QoS by providing different QoS classes that can be used to prioritize traffic based on the requirements of the application. The QoS classes include:

  • Conversational: This QoS class is designed for real-time communication, such as voice and video.
  • Streaming: This QoS class is designed for high-bandwidth applications, such as video streaming.
  • Interactive: This QoS class is designed for interactive applications, such as online gaming.
  • Background: This QoS class is designed for low-priority applications, such as software updates.

Multi-Connectivity

Multi-connectivity is a feature that enables a device to connect to multiple base stations simultaneously. This provides better coverage and higher reliability by reducing the risk of a single point of failure. NR supports multi-connectivity by allowing a device to connect to both 5G and 4G base stations simultaneously.

Beamforming

Beamforming is a technique that enables the communication system to focus the transmission signal towards a specific receiver. This improves the signal strength and reduces interference, which improves the reliability and latency of the communication. NR supports beamforming by using advanced antenna arrays and beamforming algorithms.

Network Slicing

Network slicing is a feature that enables the communication system to partition the network into multiple virtual networks, each with its own set of resources and QoS requirements. This enables the communication system to provide customized services to different types of applications and users. NR supports network slicing by providing a flexible architecture that allows the network to be partitioned into multiple slices.

Conclusion

In conclusion, Ultra-Reliable and Low-Latency Communication (URLLC) is a crucial requirement for many mission-critical applications. The 5G New Radio (NR) standard has introduced several new features to support URLLC, including a flexible numerology and frame structure, Time-Sensitive Networking (TSN), Control and User Plane Separation (CUPS), an Ultra-Reliable Low-Latency Communication (URLLC) bearer, Quality of Service (QoS), multi-connectivity, beamforming, and network slicing. These features are designed to provide high reliability, low latency, and high availability, which are critical for URLLC applications. With these features, the NR standard is well-positioned to support the growing demand for URLLC services in the 5G era.