IC enables 100Gbps transmission over SMF optical links

Due to the proliferation of smart devices, expansion of cloud-computing and delivery of cloud-based services, network bandwidth demand continues to rise. Migration to 100G optical links between data centres has started and will grow very rapidly over the next few years. Distribution of 4G and 5G services through the network is also placing a burden on optical network capacity.

The need for low-cost, efficient transport at the physical layer is key to supporting growth in both these markets, in addition to the requirement to maximise fiber capacity by driving 100Gbps over a single wavelength. One way to do this is to use multi-level signaling to increase the symbol rate and run a higher bit rate for the same Baud rate.

Using this technique (2 bits/symbol) to get from 25Gbps per wavelength, a standard binary signaling rate, to 50Gbps is a good step forward. But to get to 100Gbps, the next step is to double the Baud-rate to 56GBaud. This is challenging to achieve with low-performance optical components, particularly for distances greater than a couple of kilometers.

Another alternative is DMT, a multi-carrier modulation format that inherently runs at a very low Baud rate. DMT is a robust and proven technology, forming the basis for high-speed broadband delivery over millions of copper links since it was introduced over 15 years ago. With advances in mixed-signal technology over the last few years, particularly high-speed, low-power ADCs and DACs, Socionext is uniquely positioned to deliver DMT transmission at 100Gbps, several orders of magnitude faster than broadband delivery in the access network.

“OFDM-based communications technologies like DMT, using individually modulated, orthogonal carriers, have been successful in overcoming limitations of legacy modulation formats where low-cost, higher data capacity is the goal. DVB-T, xDSL and LTE were all enabled using OFDM” said Manfred Mettendorff, Senior Director Marketing & Business Management, Socionext. “Proven, leading-edge mixed signal IPs, designed by Socionext’s Network SoC BU in Europe and Japan, now take this approach a major step forward for fiber optic networks”.

For transport over fiber medium, at distances of a few tens of kilometers, the limiting factor is not fiber but the components at the each end of the link. Owing to the fundamental capability of DMT to adapt to channel characteristics and interferences, it is suited to the challenge of using low-performance optical components to transport data over such links very efficiently. This, in turn, allows DMT to support the growing requirements for 100G optical links in datacenter interconnect and wireless back hauling and front hauling.