Autumn 2017 Optical Connections Magazine


With standards for 5G wireless networks yet to be finalised, there are many options for fibre’s future role, finds Andy Extance. Optical technologies in it for the fronthaul – and the crosshaul?


S atisfying customers’ Research. And as providers build networks to feed that appetite and consider fifth- generation (5G) wireless technologies, dierent approaches aect their need for fibre-optic devices. 5G seeks to support driverless cars, Internet-of-Things, ultrafast downloads, and many other new uses that Lively likens to a many-headed serpent. The demands will challenge fronthaul fibre links that have emerged since 2012 to partner backhaul links that connect mobile networks to core wired and optical networks. Fronthaul networks connect remote radio heads (RRHs) typically found up cell towers to baseband units (BBUs) using the Common Public Radio Interface (CPRI) standard. As a digitised version of radio frequency (RF) transmission destined for the RRH and antennae, CPRI is bandwidth intensive. Where network providers adopt huge hunger for wireless bandwidth has spawned a monster, according to John Lively, Principal Analyst at LightCounting Market

scarcer, vendors like Infinera oer WDM systems. That loads signals serving all sectors, and the antennae they contain, for a cell site onto one fibre pair. Baldry refers to Infinera’s work with Hutchison, which provides wholesale 4G mobile services in Hong Kong. ‘The configuration on a lot of cell sites in the network is 18 channels on day one,’ Baldry says. ‘Without WDM, that would need 18 fibre pairs per cell site. You very quickly use a lot of fibre.’ Antonella Sanguineti, Head of Optical and Fronthaul at Stockholm, Sweden, headquartered Ericsson Business Area Networks, asserts that WDM will be important in 5G infrastructure. She emphasises its low cost per bit, low latency, high capacity and flexibility. ‘Ideally, the combination of WDM and other technologies like Ethernet and IP provide the best results,’ she says. In May 2017, Ericsson used its Fronthaul 6080 passive solution to provide WDM for a 5G-connected ‘smart home’ that it demonstrated together with Verizon Communications at the Indianapolis 500 race.

fronthaul for existing 3G and 4G networks, links need low latency to maintain CPRI transmission integrity. This restricts these networks to around 20 kilometres. Cell towers have several antennae, each needing a separate CPRI feed, notes Jon Baldry, Director of Metro Marketing at Sunnyvale, California, based Infinera. Fronthaul networks without wavelength division multiplexing (WDM) can therefore quickly consume many fibre pairs. This happened in early fronthaul deployments, for example in China. Where fibre is

Satisfying customers’ huge hunger for wireless bandwidth has spawned a monster.


| ISSUE 10 | Q3 2017

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