July 18, 2024
As we continue our exploration of 5G synchronization in this second installment of our series, we shift our attention to the importance of synchronization in the radio access. The global rollout of 5G NR, predominantly employing TDD technology, underscores the necessity for all radios within a network to transmit in sync. This synchronization is crucial not only for network efficiency but also for minimizing RF interference, which is vital for maintaining high-quality service. In this article, we explore some of the stringent synchronization requirements of the radio layer and the innovative solutions needed to ensure these standards are met.
Why Synchronization is Important
While 5G is yet to reach its full potential, deployments are picking up pace and it’s set to be the dominant form of cellular connectivity within the next few years. In search of true optimization, synchronization becomes increasingly necessary, particularly under the rigorous standards set by 3GPP for 5G networks. These standards stipulate that time errors must be less than 3µ seconds (±1.5µ seconds) to ensure optimal functioning of the network. Such precision is crucial because even minor deviations can lead to significant disruptions in service quality and network reliability, affecting everything from data throughput to RF interference. In low-latency applications such as remote surgery or autonomous driving, even microseconds of time misalignment can lead to errors with serious consequences, so maintaining rigorous synchronization standards is crucial for enabling these time-sensitive applications to function reliably.
In addition to network efficiency, precise synchronization in 5G is integral for facilitating the seamless coexistence of various radio channel frequencies and service providers at the same location. In addition, as networks evolve to support a larger array of services, from high-definition video streaming to critical machine-to-machine communications, synchronization ensures that these diverse data streams do not interfere with one another. Effective synchronization minimizes the risk of data collision and timing discrepancies which are crucial to maintaining the integrity and reliability of real-time data transmission across the 5G network.
The need for accurate synchronization in 5G is especially pronounced given its use of Time Division Duplex (TDD) technology, where both uplink and downlink operations share the same frequency but are separated in time. Without precise synchronization, there’s a high risk of RF interference, which can lead to a range of Quality-of-Service issues for end-users including decreased data rates and increased latency. This is why mobile operators are now keenly focused on implementing robust synchronization strategies as they roll out new 5G networks across the globe.
Timing is Everything
In the context of 5G radio access, the distinction between absolute and relative measurements plays a pivotal role in assessing timing and synchronization accuracy. Absolute measurements involve evaluating time errors across different channels simultaneously, providing a comprehensive overview of synchronization performance across networks. Conversely, relative measurements focus on comparing time errors between neighboring antenna sectors within the same network using physical cell identity (PCI) values to define each antenna’s location. Understanding both types of measurements is crucial for ensuring optimal synchronization and minimizing RF interference which can disrupt signal transmission and degrade service quality.
Challenges and Strategies in Deployment
Mobile operators deploying 5G face critical decisions on how to effectively synchronize their networks with common strategies involving the use of existing transport networks to distribute Precision Time Protocol (PTP) or the installation of GNSS receivers in the cell site. Each method ensures that synchronization signals are accurately relayed to and from 5G cell sites within the tight tolerances required. However, these methods are not without challenges as they must account for complex environments and varied geographical features that can disrupt synchronization signals.
The challenges are particularly pronounced in border areas where networks from neighboring countries may overlap – a common occurrence – leading to potential RF interference due to synchronization discrepancies. Operators must rigorously test and verify synchronization to ensure there are no time errors that exceed the designed error margins. This requires effective testing equipment and methodologies that can accurately assess synchronization across a network’s transport and radio interfaces, ensuring seamless service delivery and adherence to international standards.
Operators must also consider the logistics of deploying and managing synchronization technologies over large and often geographically challenging environments. In urban areas for example, high-rise buildings and underground infrastructure can obstruct GNSS signals making it difficult to rely solely on satellite-based synchronization. This leads to a hybrid approach where both PTP delivered via the transport network and direct GNSS solutions are used together to ensure effective coverage.
What’s more, the dynamic nature of new 5G services in the future, which range from ultra-reliable low-latency communications to massive machine-type communications, will place additional demands on synchronization accuracy. Each service type may require different synchronization parameters, adding layers of complexity to network design and management. Operators must deploy adaptable synchronization solutions that can meet these varied requirements effectively, ensuring seamless service delivery across all user scenarios.
Solutions for Testing Radio Precision
To address the critical synchronization needs of 5G networks, VIAVI offers advanced tools like the OneAdvisor-800, equipped with the Timing Expansion Module (TEM2). These devices are engineered to perform comprehensive timing and synchronization over-the-air (OTA) tests essential for 5G deployment. Their radio capabilities expand beyond the radio access and into assessing GNSS signals, evaluating PTP/SyncE performance, and conducting detailed frequency and time error validation across various network scenarios, ensuring that all synchronization specifications are met within the stringent limits set by industry standards. The TEM2 is particularly useful for indoor testing where there may not be GPS coverage.
These standards are designed to cater to the high demands of next-generation network technologies, enforcing limits that ensure ultra-precise coordination across devices and services. Set by bodies such as the ITU-T and 3GPP, these standards specify maximum allowable errors in timing and frequency to prevent disruptions in communication flows. For instance, the ITU-T’s G.8271 standard outlines the network limits for time and frequency synchronization ensuring that deviations do not exceed thresholds that could affect critical network functionalities and service delivery.
These tools not only facilitate precise synchronization. They also empower operators to troubleshoot and resolve synchronization issues swiftly in the field including those in the radio access. This over-the-air (OTA) testing capability is crucial for maintaining network performance and avoiding the QoS degradation that can result from synchronization errors. With the ability to address and measure a wide range of network conditions, these solutions from VIAVI help ensure that 5G networks operate seamlessly, delivering the high-speed, low-latency communication promised by this next generation of wireless technology.
The upcoming third installment of our series will explore the resilience layer of 5G synchronization, highlighting strategies to enhance network robustness and reliability across diverse operational environments.
In order to ensure service quality when Vietnam operators officially deploy 5G networks, technical experts from COMIT Corporation and VIAVI Solutions have introduced solutions to test radio network quality and transmission network quality, synchronous quality according to PTP 1588v2, SyncE standards... applying the world's leading telecommunications technology in seminars and consulting sessions. We hope to accompany Vietnam's leading operators such as Viettel, VNPT, Mobifone,... to bring the best experience to users.
Read more the last article of our series at: https://comitcorp.com/news/communications-5g-synchronization-mastering-transport-layer-dynamics/83/
Source: https://blog.viavisolutions.com/2024/05/28/5g-synchronization-ensuring-radio-precision/