That means 1) knowing what traffic granularity they need to transport and then 2) scaling the capacity in their transport network so that it aligns with the traffic granularity they need to move.

In addition, operators are looking for a common solution that can maximize network capacity over the widest network coverage. This can provide the ability to scale to higher capacity in a cost-effective way.

400GbE is Today’s Unit of Currency
Networks are evolving from 100GbE to 400GbE dominant traffic. As Telia Carrier stated, “400G: it’s here and huge!.” Network operators now need to figure out a way to build their networks to best support 400GbE traffic. True multi-haul solutions have emerged to meet this need because they were designed to be a flexible solution for DCI, metro, long-haul and subsea applications. However, a multi-haul solution is only effective if it can carry the different types of traffic it needs to transport while maximizing the value of existing infrastructure and reducing operational costs.

Multi-haul solutions maximize fiber utilization and simplify deployment.

Modulation Order Drives Design Decisions
Class 2 implementations utilizing 4 bits/symbol (~16QAM) and 60-64Gbaud have been standardized in the industry because they address a wide range of DCI and service provider metro applications as networks transition to 400GbE. Multi-haul implementations allow even greater reaches using approximately 4 bits/symbol with shaping and higher gain forward error correction algorithms. Class 2 multi-haul products transport 400GbE clients over the majority of network applications using 4 bits/symbol, with the ability to dial down the modulation format to 2 bits/symbol for the most challenging ultra-long-haul links.

Looking to Class 3 multi-haul products, efficient transmission of 400GbE traffic can best be achieved by doubling the baud rate to 120-128Gbaud. This enables 4 bits/symbol transmission supporting 800G line rates and 2 bits/symbol supporting 400G line rates. In high-capacity edge applications, these Class 3 products can support up to 1.2T line rates. By aligning client traffic granularity with the modulation orders that can best support network applications, identifying the preferred baud rate for Class 3 implementations becomes straightforward.

The industry has standardized on Class 2 implementations utilizing 4 bits/symbol (~16QAM) and 60-64Gbaud for various 400G implementations that address a range of DCI and service provider network applications.

Maximizing Network Application Coverage
A recently introduced Class 3 multi-haul solution, Acacia’s Coherent Interconnect Module 8 (CIM 8), can address transmission of multiple 400GbE client interfaces over virtually any network application, delivering 1.2T per carrier capacity for high-capacity DCI interfaces, 800G per carrier capacity over most optical links using 4 bits/symbol (~16QAM) modulation, and 400G per carrier over long-haul and subsea links.

Leveraging actual data from representative networks, the below simulation shows that the CIM 8 can effectively address subsea applications with 400G links, long-haul and metro with regional 800G (2x400G) and DCI and metro networks with 1.2T.  This means that the CIM 8 can provide efficient transport of 400GbE client traffic across the entire network, including 90 percent coverage using 800G (2x400GbE client traffic).

Utilizing data from actual service provider networks, Acacia’s CIM 8 can provide ~90% 800G network coverage compared to <20% for ~96Gbaud systems.

Scaling Efficiently and Cost-Effectively Today and Tomorrow
Network operators are being challenged more than ever before to scale their networks efficiently and cost effectively. Key to achieving this is knowing what kinds of traffic they are transporting and then building the right system that can most effectively transport that traffic.

As we approach Shannon’s Limit, further improvement will come from going to higher baud rates, but in a cost-effective way. As this article has discussed, having one solution that can be leveraged across all the various applications can enable an efficient and cost-effective solution for network operators looking to scale their networks today and in the future.

Acacia is gearing up for a great show at ECOC 2019 – and Dublin is a great place to host Europe’s largest optical communications event. We look forward to having another opportunity to discuss the latest trends and innovations with our customers and partners including multi-haul applications, 400GbE, 400ZR and open optical standards.

Network operators are looking to support today’s 100GbE clients, as well as emerging 400GbE clients, across key network segments such as DCI edge, metro, long-haul and submarine in an efficient, scalable, and cost-effective manner. Multi-haul coherent solutions, software configurable transponders that provide various transmission capacities and reaches by varying the modulation order and baud rate settings, can provide flexible options for network operators.

Introducing the AC1200-SC² Coherent 1.2T Single-Chip, Single-Channel Module

One such solution is the AC1200-SC² (‘SC squared’). Powered by Acacia’s 1.2T Pico DSP chip, the AC1200-SC² coherent 1.2T single-chip, single-channel module was designed to enable network operators to support today’s 100GbE clients, as well as emerging 400GbE clients.

Figure 1: Acacia’s AC1200-SC² Coherent 1.2T Single-Chip, Single-Channel Module

We are excited to demonstrate our newest AC1200 family member just announced last week. The AC1200-SC²’s high-performance and flexibility make it ideally suited for multi-haul applications ranging from high-capacity 1.2T DCI edge to the most challenging terrestrial and submarine networks that require 400G transport over QPSK modulation. The module also features Acacia’s 3D shaping technology designed to optimize fiber capacity and reach by filling gaps in margin and spectrum. Check out this video to learn how 3D shaping allows for the fine-tune adjustment of the modulation order and baud rate to provide network operators with the ability to adapt the transmission characteristics to meet the requirements of both greenfield and brownfield deployments.

Standardized Coherent Interconnects

Standardization activities have defined a variety of interoperability modes supporting operation ranging from 100G to 400G. Recently there have been many opinions on the idea of ZR+. What if a mode was created to combine the benefits of elements from 400ZR and OpenROADM, two existing standards, to define and deliver an interoperable ZR+ mode called OpenZR+?

The result is an open, flexible and interoperable coherent solution in a small form factor pluggable module. By simply defining a data path that includes the appropriate functionality, an interoperable OpenZR+ mode can be established. These enhanced modes will allow an OpenZR+ module in a QSFP-DD or OSFP form factor to support reaches well beyond 400ZR. The OpenZR+ modes are supported by merchant DSP vendors who have exchanged test vectors to ensure the interoperability of these OpenZR+ implementations. The availability of merchant DSP solutions supporting OpenZR+ will further expand the ecosystem of module vendors supporting OpenZR+. We’re sure to hear more about OpenZR+ at ECOC. For a more detailed explanation of OpenZR+ and its growing momentum please refer to the Optical Connections Magazine contributed article titled “OpenZR+ Offers Performance and Interoperability.”

Acacia Thought Leaders Speaking at ECOC

We are proud to have our Acacia experts sharing their views about some of the topics mentioned above.

• Tom Williams, Acacia’s Vice President of Marketing, is speaking on a Market Focus Panel titled “Next Generation Coherent – Beyond Transport Networks.” Tom’s panel is scheduled for Tuesday, September 24^th at 13:15.
• Hongbin Zhang, Acacia’s Principal DSP Designer, is speaking on a panel titled “Real-Time Transmission of Single-Carrier 400 Gb/S And 600 Gb/S 64QAM Over 200km-Span Link, scheduled for Tuesday, September 24^th at 14:45.

If We are “Lucky,” We’ll See you there!

If you are attending ECOC 2019, we’d love to see you. To set up a meeting at the show, contact us.