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Fiber: the path to 5G

Previously published on RCRWireless

Although 5G deployments are still some ways off, networks are already slowly transforming to meet the requirements for ultra-high speed, ultra-low latency and ultra-high capacity that are expected to be a hallmark of 5G systems.

However, LTE still has a long life left in it. LTE Advanced Pro deployments are just getting started and are expected to be able to achieve gigabit speeds – so operators are likely to be able to address some 5G use cases with their LTE networks. But that can only happen if network architectures can support the increased speeds and capacity needs of LTE Release 13 and beyond.

The pivot toward LTE Advanced Pro and 5G is happening to both physical and logical network architectures. Centralized Radio Access Network approaches are emerging that simplify antenna sites because no baseband unit cabinet is required; use less energy; and enable lower operating costs because pools of BBUs are located in a single location for service and maintenance. C-RAN also lays the framework for real-time radio resource coordination and very low latency in 5G.

Meanwhile, network virtualization is ramping up as operators seek to build more flexible and cost-effective use of their resources. Ultimately, virtualization will underpin 5G concepts such as network slicing, where networks intelligently support a variety of end user profiles, each with different specified performance parameters such as latency and data rate. A 5G RAN will be a centralized, virtualized RAN.

Fiber is the key to enabling these new architectures, both for LTE Advanced Pro and eventually for 5G. The 5G-PPP has identified the availability of reliable optical distribution services as crucial to large-scale 5G deployment. Common Public Radio Interface signals must be carried between the BBU hotels and the distributed cell sites – so fiber-to-the-antenna implementations will continue to proliferate. The demands on even short fiber installations will increase, due to performance pressures on fronthaul and the CPRI bit rate in order to support multi-gigabit speeds. Fronthaul was originally designed for relatively short distances where it was fairly easy to meet parameters – but fronthaul can mean links of 15 to 25 km (10 to 16 miles) where performance metrics get harder to meet and dispersion becomes a factor.

So it may not seem critical to performance-test short FTTA installations now, but they are likely to eventually be part of a longer C-RAN path or need to carry faster bit-rates where their performance makes or breaks a deployment. Consistent, high-quality installation that assures clean connections, the integrity of the fiber and the end-to-end bit error rate as well as proper configuration needs to happen the first time around. In fronthaul scenarios, testing should include testing and validation from the antenna to the BBU: assessing optical power budget (power loss), latency and optical loss between the cell site and the BBU; BBU functionality and verification; measuring power loss on the optical distribution network; and optical transmission problems such as radio interference.

Testing the optical distribution network and the CPRI transport protocol in today’s roll-outs will ensure better network performance and return on both current and future network investments. EXFO’s comprehensive fronthaul test portfolio can support all your testing needs for installing, maintaining and troubleshooting mobile fronthaul networks, including C-RAN. Learn more here.