One of the key performance demands of 5G is stricter timing accuracy. Timing and synchronization across devices were already needed for mobile networks to operate, but with the rollout of 5G, timing accuracy is even more critical to support new use cases. 5G deployments thus require high-performance, cost-effective timing distribution solutions at a massive scale in order to handle the large number of anticipated sites.
Timing and Synchronization Before 5G
Wireless technology (e.g. 3G/LTE) historically relied on global navigation satellite systems (GNSS) as the primary source to maintain network synchronization. By utilizing the coordinated universal time (UTC) derived from GNSS, operators can optimize radio spectrum more efficiently to prevent coverage overlaps from causing interference or service degradation.
GNSS can be impacted by physical interference, solar fade, or criminal elements looking to disrupt or take down critical communications infrastructure. A Grandmaster or Master timing appliance mitigates these challenges. The timing appliance offers distributed, highly accurate timing using Precision Time Protocol (PTP) and synchronized via onboard physical interfaces.
This highly accurate atomic clock maintains time, phase and frequency synchronization to the distribution ports. Timing distribution fanout can be limited to onboard ports on the Grandmaster/Master appliance and these ports are often expensive. For 5G, service providers must deploy reliable and high-performance timing distribution networks that are cost-effective and massively scalable. Additionally, they must support multiple use cases and densification of the 5G network with small cells.
5G Timing and Synchronization Requirements
In 5G networks, timing distribution and synchronization are much more complex and critical to ensure efficient and continuous network operations. New timing requirements also demand multiple timing sources to ensure secure, high-availability operations. Support for mixed-vendor environments is also a strict requirement, so it is important that operators use an open standards-based platform with proven interoperability across a diverse and complex RAN ecosystem.
Timing distribution platforms, whether part of the transport network or operating as standalone appliances, must address critical 5G requirements:
- Low latency: The average 4G latency is approximately 50 ms. With 5G, latency decreases to 1 ms. 5G’s Ultra Reliable Low Latency Communications (URLLC) enables more advanced applications.
- Faster speeds: 5G is estimated to be nearly 100 times faster than 4G.
- Higher frequency ranges: 5G high-band spectrum is 24 GHz or higher while mid and low 5G bands are below 6 GHz. 4G is deployed over frequencies at or below 2.6 GHz. Higher frequencies transmit more data, and timing is necessary to maintain high performance.
- Shorter wavelengths: 4G base stations transmit long wavelengths in all directions, often wasting energy and power. 5G uses shorter wavelengths via smaller antennas to provide precise directional control.
- More devices: 5G can support 1,000+ more devices per meter than 4G. With 5G radios closer to users combined with a higher number of radios and devices supported, operators must manage the increased potential for interference within 5G networks.
- Phase alignment is required: The duration of any given timing cycle must be exact and the beginning and end must align across the network.
- Multiple inputs for redundancy: Operators require the ability to work across many input timing sources and to distribute across a broad array of endpoints through packet networks to various technologies and vendors.
Affordable High-Performance 5G Timing and Synchronization
The flexiHaul M6424 platform is a packet-based transport and timing distribution solution based on Time Sensitive Networking (TSN). The M6424 platform is a cost-effective, scalable, high-capacity TSN switch with the ability to provide xHaul service delivery, plus timing and synchronization services. It supports 5G eCPRI, 4G CPRI using Radio over Ethernet (RoE) encapsulation (IEEE 1914.3) and Ethernet up to 25 Gbps. The M6424 platform also supports TSN (IEEE 802.1cm) for fronthaul, including Class “C” and Class “D” master clock distribution using PTP. With a Grandmaster/Master clock appliance feeding the platform, timing distribution is accomplished from multiple redundant sources to large numbers of distributed sites.
The M6424 platform delivers high performance and superior economics for timing distribution on the same embedded platform and management used in xHaul applications for RAN transport. This is valuable for a mobile network operator supporting mixed generations of technologies and vendors, as well as for neutral hosts responsible for distributing timing sources for multiple service providers. As timing distribution scales dramatically with 5G use cases, it is critical to have integrated management such as the flexiHaul EMS to ensure robust and simplified network operation.
M6424 deployed as timing distribution appliance and as fronthaul with timing distribution
For more information on Timing and Synchronization:
Download our Application Note titled “Economical Timing Distribution Using the flexiHaul M6424 TSN Switch”