Meeting increased data center demand by expanding bandwidth with wavelength-division multiplexing

Written by 

James Merchant

Product Manager Optical Transport

The demand for data center capacity continues to rise, driven by the burgeoning of smart devices and improved connectivity. Chief amongst this growth is the surging consumption of over-the-top (OTT) media services that is expected to further fuel demand for increased bandwidth within data centers. According to research from Fortune Business Insights, the global OTT services market is projected to grow from $44.54 billion in 2021 to $139.00 billion in 2028 at a CAGR of 17.7%. This means data center operators need to capitalise on their assets.

The ever-growing requirement for more bandwidth is a constant challenge. To meet this expansion, data centers must improve performance and ensure higher path redundancy while further enhancing the stability of the physical layer. By implementing bandwidth expansion solutions, data centers will also benefit by boosting capacity and transmission reach that increases data flow without the need to add more fiber.

Within a data center it is normally no problem to add more fibers to existing ones via structured cabling to support the additional bandwidth requirements between equipment. When it comes to deploying fiber outside the data center, things become much more challenging. Not only can this be extremely expensive and take a long time but, in some cases, it is not possible at all. Expanding the capacity of the existing fiber is a better solution. 

Bandwidth expansion with wavelength-division multiplexing 
Bandwidth expansion is an ever-present topic in data center infrastructure. While there is no universal solution, there are crucial considerations regarding media conversion, power class support, distance and link redundancy that can help solidify your overall approach. 

The best and most cost-effective technology to expand the fiber capacity is wavelength-division multiplexing (WDM). This works on the principal that optical signals with different wavelengths do not interfere with each other, making it possible to combine and separate these different signals. In the visible light spectrum this principle can be seen when a white light passes through a prism and is separated into the individual spectral colours. The spectrum for optical transport and multiplexing on single mode cables is in the non-visible infrared area within a wavelength range of approximately 1260nm to 1625nm.

Using different WDM topologies 
Bandwidth expansion based on WDM is an ideal alternative to deploying new fiber. Not only is it more cost-effective but the time to deploy is a mere fraction compared to laying additional fiber. The flexibility of working with different topologies makes WDM a versatile solution. It becomes even more advantageous when adding active modules such as optical amplification, transponders, or optical protections switches.

The most common and most basic topology is to connect two points. The same WDM multiplexer/demultiplexer (MUX) is used on both ends to virtually increase the given number of fibers by using several channels in parallel. This increases the bandwidth between both points. 

Of course, WDM is not limited to the interconnection of only two sites. When many sites are connected then two fundamentally different multiplexing functions come into play: the MUX, which launches or terminates all traffic. The other option is optical add-drop multiplexers (OADM) and daisy-chain multiplexers which both only add or drop some of the channels and transparently pass through all remaining channels or traffic. The different multiplexing functions can be used to create a logical network topology independently that differs from the physical cable connection.

WDM is an ideal solution for bandwidth expansion. Combined with a selection of active products, WDM is even more versatile and covers even more applications. The CUBO system is the HUBER+SUHNER active transport solution. This flexible modular system is based on a 19” chassis and line cards. These can be mixed and matched in any combination and managed via an intuitive web-based user interface.