How To Choose Between WDM vs OTN?

The Internet has revolutionized our lives, offering immense convenience without which life would be challenging. However, its rapid growth has strained network transmission capabilities, leading to a rising demand for ultra-large bandwidth in data centers. Optical networking is a mature and widely adopted technology that addresses this need. Yet, as the demand for high bandwidth escalates, the transmission capacity of optical networks needs to meet the burgeoning requirements of Internet information and data services. So, how do we tackle bandwidth challenges? This article about WDM and OTN can answer your questions.

 

Comparing WDM and OTN Technologies: A Comprehensive Analysis

 

WDM

 

Wavelength Division Multiplexing (WDM) revolutionizes fiber-optic transmission by leveraging multiple light wavelengths, or colors, to transmit data through a single medium. This technique allows for the simultaneous transmission of two or more colors of light on a single fiber, facilitating the transmission of multiple signals through an optical waveguide at varying wavelengths or frequencies across the optical spectrum.

Typical WDM Model

 

Currently, there are two main types of Wavelength Division Multiplexing (WDM) in use:

 

Coarse WDM (CWDM): CWDM systems are characterized by having fewer than eighteen active wavelengths per fiber. CWDM is primarily utilized for short-range communications, employing wide-range frequencies with wavelengths spaced far apart. This design includes standardized channel spacing to accommodate wavelength drift caused by temperature fluctuations during operation. CWDM is favored for its compactness and cost-effectiveness, making it an ideal choice when spectral efficiency is not a critical requirement.

 

Dense WDM (DWDM): DWDM systems are defined based on frequencies. Unlike CWDM, DWDM utilizes tighter wavelength spacing to accommodate more channels on a single fiber, albeit at a higher implementation and operational cost. Designed for systems with more than eight active wavelengths per fiber, DWDM finely segments the spectrum, enabling the fitting of over 40 channels into the C-band frequency range.

 

In Dense Wavelength Division Multiplexing (DWDM), vendors have developed various techniques to pack 40, 80, or 96 wavelengths, each with fixed spacing, into the C-band spectrum of a fiber. Traditional DWDM line systems utilize Wavelength Selective Switches (WSS) with fixed 50GHz or 100GHz filters. These fixed-grid line systems can accommodate channels from earlier generations of coherent transponders, whose wavelengths require less than 50GHz or 100GHz of spectrum, depending on the filter employed.

 

Today, as networks with high-bandwidth applications and continuous bandwidth growth approach capacity limits, they are turning to C+L-band solutions. These solutions leverage not only the C-band but also the L-band spectrum of a fiber, potentially doubling the fiber's capacity to meet the escalating demands of data transmission.

 

OTN

 

The Optical Transport Network (OTN) is a standard telecommunications protocol outlined in ITU Recommendations like G.709 and G.798. It is an efficient method to transport, switch, and multiplex various services over high-capacity wavelengths within optical networks. Today, network providers heavily rely on OTN-enabled technology within their optical infrastructure, reaping benefits such as heightened resilience, streamlined operations, improved Service-Level Agreements (SLA), extended reach via Forward Error Correction (FEC), and the capacity to maximize wavelength usage while ensuring guaranteed end-to-end service delivery efficiently.

 

Often referred to as a 'digital wrapper,' OTN transparently encapsulates each client/service into a container for seamless transport across optical networks, maintaining the integrity of the client's native structure, timing information, and management data. Its advanced multiplexing capabilities allow diverse traffic types, including IP, Ethernet, storage, digital video, and SONET/SDH, to efficiently carry over an OTN framing structure, a pivotal factor driving its widespread adoption.

 

Since its establishment in 2001, OTN has evolved significantly beyond its initial SONET/SDH wrapper role. It has been finely tuned to accommodate Ethernet, the prevailing client service of today, ranging from 1GE to 400GE. OTN-enabled technology frequently forms the foundation of next-generation optical networks by supporting versatile packet technologies such as new Ethernet interfaces, Multi-Protocol Label Switching (MPLS), Segment Routing, and Time Sensitive Networking (TSN).

 

Over time, OTN technology has seen extensive deployment across global networks, expanding its reach across a broad spectrum of applications. Hundreds of thousands of OTN ports are now operational, carrying vital traffic from the network edge to the metro and core and in submarine applications, highlighting its indispensable role in modern telecommunications infrastructure.

 

The Difference Between WDM vs. OTN Transmission Technology

 

1. WDM technology operates solely within the optical layer, while OTN encompasses optical and electrical layers.

 

2. In a traditional WDM network, each wavelength can only transmit a single service, whereas in an OTN network, a single wavelength can carry multiple services concurrently.

 

3. Traditional WDM sites typically feature only OTU boards for wavelength conversion, while OTN incorporates separate tributary and line boards and additional electrical cross-connect boards. OTU boards can also be directly integrated into OTN products.

 

4. OTN offers robust overhead and monitoring capabilities that enhance network self-healing and reliability. It supports optical and electrical layer protection, while WDM technology only provides optical layer protection.

 

5. OTN supports a broader array of services and boasts higher board integration.

 

6. Through electrical-layer cross-connection grooming, OTN can dynamically allocate channel resources, thus enhancing bandwidth utilization.

 

7. Unlike WDM, OTN features a complete frame structure.

 

8. Due to the extensive use of electrical-layer boards in OTN sites, network construction costs are higher than in WDM sites, which do not require as many electrical-layer boards.

 

9. Traditional WDM is primarily deployed in the access layer as OTM sites, while OTN networks are utilized for large-granularity services, serving as OADM sites in aggregation and core layers.

 

Compare The QSFPTEK WDM and OTN Devices

 

The QSFPTEK Wavelength Division Multiplexing (WDM) system significantly enhances network capacity, optimizing the utilization of optical fiber resources. With transmission rates ranging from 1.25Gbit/s to 100Gbit/s per single wavelength, it accommodates up to 64 channels and supports various networking configurations. Comprised of wavelength conversion modules, MUX, DEMUX, fiber amplifiers, dispersion compensators, network management units, and other key components, the QSFPTEK WDM system ensures seamless transmission, shaping, and reception of network signals, establishing a reliable WDM transmission infrastructure. Its notable features include flexible networking options, robust scalability, and secure management methods. QSFPTEK WDM system products find applications in metro, regional, and CWDM or DWDM network environments.

 

 

The QSFPTEK Optical Transport Network (OTN) series, including the QT850, QT860, and QT900 models, represents a new generation of wavelength division products tailored for the optical transmission market. These systems offer smooth upgrade paths, supporting multi-frame cascading and seamless expansion capabilities. They facilitate business upgrades from 10Gbit/s to 100/200/400Gbit/s services, supporting 40 to 80 waves or 48 to 96 waves smooth upgrade capabilities. Achieving a maximum transmission capacity of 9.6T@QT860/25.6T@QT850&QT900 over a single optical fiber, these systems offer versatile networking options. The QSFPTEK OTN System can be flexibly configured as an Optical Multiplexing Terminal (OTM), Optical Line Amplification (OLA), Optical Line Protection (OLP) Electrical Relay (REG), Optical Add-Drop Multiplexer (OADM), and other equipment types, supporting various networking methods, including point-to-point, chain, ring, and mesh configurations.

 

 

 

Conclusion: Why I Am More Recommend OTN to Your Network?

As information technology and business bandwidth expand, Optical Transport Network (OTN) emerges as a DWDM derivative. This technology combines the strengths of both SDH and WDM while enhancing networking functions to suit evolving business transmission needs. Notably, improvements in network application, dispatching, business access, and management monitoring greatly enhance the ability to meet new service quality standards. The OTN system boasts transparent business transmission, robust error correction capabilities, and flexible scheduling at both optical and photonic layers. With the network construction in the 5G era, the market application of OTN technology has surged, which is an inevitable trend in future network development.