The Importance of Low Latency in 5G Networks: A Deep Dive into URLLC

Rip and replace technology changes are painful, expensive and time-consuming for enterprises. There needs to be a compelling set of advantages to motivate an enterprise to make the change.

For enterprise wireless networking, Wi-Fi is the entrenched player in part due to the backward compatibility built into the standard which plays into organizations’ disdain for forklift technology changes.

The new enterprise wireless option is private 5G and one of the reasons that makes adoption compelling is low latency.

Understanding Latency and Its Role in 5G Networks

Latency—the time it takes for data to travel between a source and a destination—is one of the most critical factors that define private 5G’s impact on industrial and real-time applications.

In previous generations of mobile networks, such as 3G and 4G, latency was often a limiting factor for real-time applications. 4G LTE networks typically offer a latency of around 50 milliseconds, which is insufficient for applications requiring near-instantaneous data exchange. 5G, in contrast, is designed to provide latency as low as 1 millisecond, enabling a new era of hyper-responsive connectivity.

Low latency is crucial for a variety of applications. As we have written in a previous post, the key applications that need low latency include manufacturing 4.0, autonomous vehicles, augmented and virtual reality (AR/VR) and IoT are applications that benefit from URLLC latency levels. To this list, I would also add enterprise AI applications.

At the heart of achieving this low latency is Ultra-Reliable Low-Latency Communications (URLLC), a key component of 5G standards designed to support mission-critical applications.

URLLC: The Backbone of Ultra-Low Latency in 5G

URLLC is one of the three primary service categories defined by the 3rd Generation Partnership Project (3GPP) for 5G networks, alongside Enhanced Mobile Broadband (eMBB) for mobility and Massive Machine-Type Communications (mMTC) for IoT.

URLLC is specifically designed for applications that demand high packet delivery reliability (99.999% or higher) and extremely low latency (under 1 millisecond). It enables new use cases that were previously unattainable due to network limitations.

URLLC achieves its objectives through several key technologies. These include:

• Shorter transmission time intervals (TTIs): Shorter TTIs directly reduce the latency experienced by data packets by minimizing the time it takes to transmit and acknowledge data, URLLC applications can achieve the stringent latency requirements necessary for time-critical operations. This reduction in TTI allows for faster feedback loops, which are essential for applications requiring immediate responses, such as industrial automation and remote surgery.

• Optimized scheduling techniques: Efficient scheduling algorithms prioritize URLLC traffic, ensuring that critical data is transmitted with minimal delay. These techniques involve dynamic resource allocation and preemptive scheduling to guarantee low-latency delivery. By intelligently managing network resources, optimized scheduling can prevent congestion and minimize queuing delays, both of which are detrimental to URLLC performance.

• Advanced error correction methods: URLLC demands extremely high reliability, and advanced error correction codes, such as Forward Error Correction (FEC), play a crucial role in achieving this. These methods allow for the detection and correction of errors without requiring retransmission, minimizing latency. FEC techniques such as polar codes and Low Density Parity Check (LDPC) codes are used to keep the error rate extremely low, even in noisy environments.

• Time-sensitive networking (TSN): TSN provides deterministic and time-synchronized communication over Ethernet networks, which is essential for URLLC applications in industrial environments. It ensures that critical data packets are delivered within strict time constraints. TSN uses time synchronization and traffic shaping to eliminate jitter and guarantee predictable latency. TSN enables the integration of URLLC with existing industrial infrastructure, facilitating the deployment of advanced automation systems.

• Grant-free uplink transmission: Grant-free uplink transmission reduces latency by eliminating the need for a scheduling request and grant process. This allows devices to transmit data immediately when needed, which is critical for time-sensitive applications. This technique is especially useful for applications that generate sporadic but time-critical data, where the overhead of a scheduling request would introduce unacceptable delays. By allowing devices to transmit without first requesting permission the overall communication delay is shortened, and the system can react faster to events.

Major 5G Standards Enabling URLLC

The implementation of URLLC is guided by several standards developed by the 3GPP, which define the technical specifications of 5G networks. Some of the most important standards influencing URLLC include:

1. 3GPP Release 15– This initial release of 5G specifications laid the foundation for URLLC by introducing the concept of low-latency and high-reliability communication. While Release 15 primarily focused on eMBB, it provided the groundwork for subsequent enhancements in URLLC.

   
   

2. 3GPP Release 16– This release brought significant improvements to URLLC by introducing features such as enhanced physical layer optimizations, improved link adaptation, and more efficient resource allocation techniques. These advancements enabled sub-millisecond latency and higher reliability levels, making URLLC more viable for real-world applications.

   
   

3. 3GPP Release 17 and beyond– Further refinements in URLLC continue with ongoing 3GPP releases, focusing on network slicing, improved coexistence with other 5G services, and better integration with industrial and IoT applications. Future releases are expected to enhance the adaptability of URLLC for even more diverse use cases.

Conclusion

Low latency is a defining feature of private 5G networks, enabling a new generation of applications that demand real-time responsiveness and unwavering reliability. URLLC plays a pivotal role in achieving this goal, providing the technological foundation for mission-critical use cases across industries.

As private 5G networks continue to evolve with new standard and optimization, URLLC will remain at the forefront of innovation, shaping the future of telecommunications and unlocking new possibilities in connectivity. The journey towards a fully integrated, low-latency 5G ecosystem is still underway, but its potential impact on society is undeniable.