Intel targets 5G fronthaul with a 100G CWDM4 module

• Intel announced at ECOC that it is sampling a 10km extended temperature range 100-gigabit CWDM4 optical module for 5G fronthaul. 

• Another announced pluggable module pursued by Intel is the 400 Gigabit Ethernet (GbE) parallel fibre DR4 standard.

• Intel, a backer of the CWDM8 MSA, says the 8-wavelength 400-gigabit module will not be in production before 2020.

Intel has expanded its portfolio of silicon photonics-based optical modules to address 5G mobile fronthaul and 400GbE.

Robert BlumAt the European Conference on Optical Communication (ECOC) being held in Rome this week, Intel announced it is sampling a 100-gigabit CWDM4 module in a QSFP form factor for wireless fronthaul applications.

The CWDM4 module has an extended temperature range, -20°C to +85°C, and a 10km reach.

“The final samples are available now and [the product] will go into production in the first quarter of 2019,” says Robert Blum, director of strategic marketing and business development at Intel’s silicon photonics product division.

Intel also announced it will support the 400GBASE-DR4, the IEEE’s 400 GbE standard that uses four parallel fibres for transmit and four for the receive path, each carrying a 100-gigabit 4-level pulse amplitude modulation (PAM-4) signal. 

5G wireless

5G wireless will be used for a variety of applications. Already this year the first 5G fixed and mobile wireless services are expected to be launched. 5G will also support massive Internet of Things (IoT) deployments as well as ultra-low latency applications. 

The next-generation wireless standard uses new spectrum that includes millimetre wave spectrum in the 24GHz to 40GHz region. Such higher frequency bands will drive small-cell deployments. 

5G’s use of new spectrum, small cells and advanced air interface techniques such as multiple input, multiple output (MIMO) antenna technology is what will enable its greater data speeds and vastly expanded capacity compared to the current LTE cellular standard. 

Source: Intel.

The 5G wireless standard will also drive greater fibre deployment at the network edge. And it is here where mobile fronthaul plays a role, linking the remote radio heads at the antennas with the centralised baseband controllers at the central office (see diagram). Such fronthaul links will use 25-gigabit and 100-gigabit links. “We have multiple customers that are excited about the 100-gigabit CWDM4 for these applications,” says Blum 

Intel expects demand for 25-gigabit and 100-gigabit transceivers for mobile fronthaul to begin in 2019. 

Intel is now producing over one million PSM4 and CWDM4 modules a year

Client-side modules 

Intel entered the optical module market with its silicon photonics technology in 2016 with a 100-gigabit PSM4 module, quickly followed by a 100-gigabit CWDM4 module. Intel is now producing over one million PSM4 and CWDM4 modules a year. 

Intel will provide customers with 400-gigabit DR4 samples in the final quarter of 2018 with production starting in the second half of 2019. This is when Intel says large-scale data centre operators will require 400 gigabits.

“The initial demand in hyperscale data centres for 400 gigabits will not be for duplex [fibre] but parallel fibre,” says Blum. “So we expect the DR4 to go to volume first and that is why we are announcing the product at ECOC.”       

Intel says the advantages of its silicon photonics approach have already been demonstrated with its 100-gigabit PSM4 module. One is the optical performance resulting from the company’s heterogeneous integration technique combining indium-phosphide lasers with silicon photonics modulators on the one chip. Another advantage is scale using Intel’s 300mm wafer-scale manufacturing. 

Intel says demand for the 500m-reach DR4 module to go hand-in-hand with that for the 100-gigabit single- wavelength DR1, given how the DR4 will also be used in breakout mode to interface with four DR1 modules. 

“We don’t see the DR1 standard competing or replacing 100-gigabit CWDM4,” says Blum. “The 100-gigabit CWDM4 is now mature and at a very attractive price point.”

Intel is a leading proponent of the CWDM8 MSA, an optical module design based on eight wavelengths, each a 50 gigabit-per-second (Gbps) non-return-to-zero (NRZ) signal. The CWDM8 MSA was created to fast-track 400 gigabit interfaces by avoiding the wait for 100-gigabit PAM-4 silicon. 

When the CWDM8 MSA was launched in 2017, the initial schedule was to deploy the module by the end of this year. Intel also demonstrated the module working at the OFC show held in March. 

Now, Intel expects production of the CWDM8 in 2020 and, by then, other four-wavelength solutions using 100-gigabit PAM-4 silicon such as the 400G-FR4 MSA will be available. 

“We just have to see what the use case will be and what the timing will be for the CWDM8’s deployment,” says Blum.