Microsemi sees OTN role in 5G fronthaul

While there's been a lot of talk about time-sensitive Ethernet and the upcoming enhanced Common Public Radio Interface (CPRI) protocol for mobile 5G fronthaul, Microsemi Corp. (NASDAQ: MSCC) believes that Optical Transport Network (OTN) technology should not be overlooked. The company expects to make 100-Gbps OTN silicon built on the DIGI-G4 family of OTN processors it acquired with PMC-Sierra generally available this summer for such applications.

While there's been a lot of talk about time-sensitive Ethernet and the upcoming enhanced Common Public Radio Interface (CPRI) protocol for mobile 5G fronthaul, Microsemi Corp. (NASDAQ: MSCC) believes that Optical Transport Network (OTN) technology should not be overlooked. The company expects to make 100-Gbps OTN silicon built on the DIGI-G4 family of OTN processors it acquired with PMC-Sierra generally available this summer for such applications.

Scott Wakelin, senior product line manager with in the Communications Business Unit of Microsemi, said he foresees 4G/5G fronthaul aggregation requirements following a 10 Gbps to 100 Gbps upgrade cycle similar to what metro networks are now experiencing. This will prove likely for 5G fronthaul, where operators will want to aggregate CPRI and 10 and 25 Gigabit Ethernet (GbE) traffic from small cell sites as part of a centralized radio access network (C-RAN) architecture. OTN at 100 Gbps has already proven its value in such applications with similar bandwidth requirements and therefore should prove a natural choice for C-RAN fronthaul, Wakelin explained. An OTN-based approach also will enable the use of grey optical modules based on 100GBASE-LR4 rather than more expensive WDM optics, he said.

Toward this end, the DIGI-G4 will support CPRI option 5, 6, and 7 as well as 10GbE, 25GbE, 40GbE and 100GbE. The device will accommodate synchronization via integrated 1588v2 features. It also will support of the necessary low-latency transmission parameters, with latency as low as 8 µs with forward error correction. The device also will support CPRI latency measurement and reporting as well as automatic uplink and downlink latency equalization within nanoseconds. An embedded optical security engine will meet security needs for fronthaul as well.

"Microsemi has been a long-time key enabler for China Mobile to deploy 100G OTN switching in the metro and long haul network," said Dr. Li Han, deputy director of the Network Department of China Mobile Research Institute, via a Microsemi press release. "We are pleased to see Microsemi extending its OTN leadership to 4G OTN fronthaul and actively prepare for 5G OTN fronthaul by enabling cost-effective, low-latency, high capacity, and future-proof 100G OTN mobile fronthaul in its DIGI family."

Wakelin added that Microsemi has secured design wins for the 4G/5G-friendly version of the DIGI-G4.

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