Optical Networking
Understanding Metro Wave Division Multiplexing (MWDM): A Beginner Guide
Jul
Wavelength division multiplexing (WDM) technology has evolved to meet the growing demand for higher bandwidth and capacity in optical communication networks. In addition to CWDM and DWDM, which we have discussed in previous articles, some technologies have emerged in recent years, such as metro wavelength division multiplexing (MWDM) and LAN-WDM.
In this guide article, we will take a closer look at MWDM technology and explain the background of its emergence, application scenarios, and how it differs from other WDM technologies.
If you are a beginner in optical communications, we believe this guide will give you a good understanding of MWDM technology.
Without further ado, let’s get started.
Table of Contents
- What is Metro Wave Division Multiplexing (MWDM)?
- Why is MWDM proposed?
- CWDM vs. MWDM vs. DWDM, What is the difference?
- What is the advantage of Metro Wave Division Multiplexing (MWDM)
- FAQs about Metro Wave Division Multiplexing (MWDM)
- Final Words
What is Metro Wave Division Multiplexing (MWDM)?
MWDM is the abbreviation of Metro Wave Division Multiplexing, a medium wavelength division multiplexing technology conceptualized and strongly advocated by China Mobile in recent years.
This technology doubles the number of wavelength channels under the same conditions by reducing the wavelength spacing of CWDM from 20nm to 10nm. However, the smaller wavelength spacing also requires a more stable laser, i.e., the wavelength shift of the laser cannot be larger than 3.5nm to avoid “collision” of adjacent wavelengths.
Ultimately, Metro Wave Division Multiplexing (MWDM) is proposed to meet the urgent needs of 5G commercialization. It makes parameter adjustments based on the mature CWDM technology. Therefore, the industry can reuse the CWDM modules production process, and the industry chain can quickly meet market demand.
| No. | Wavelength (nm) | Wavelength Band |
| 1 | 1267.5nm | O-Band |
| 2 | 1274.5nm | O-Band |
| 3 | 1287.5nm | O-Band |
| 4 | 1294.5nm | O-Band |
| 5 | 1307.5nm | O-Band |
| 6 | 1314.5nm | O-Band |
| 7 | 1327.5nm | O-Band |
| 8 | 1334.5nm | O-Band |
| 9 | 1347.5nm | O-Band |
| 10 | 1354.5nm | O-Band |
| 11 | 1367.5nm | S-Band |
| 12 | 1374.5nm | S-Band |
Why is Metro Wave Division Multiplexing (MWDM) proposed?
5G has a higher demand for high reliability, high performance, low cost, and easy deployment of the fronthaul network, which requires a technology solution that can quickly respond to market demand and lower prices.
5G fronthaul technology CWDM is an early and mature solution, and the primary need of operators for 5G fronthaul is to meet the 12-wavelength WDM, so based on CWDM, China Moblie proposes MWDM. MWDM is mainly suitable for China’s 5G fronthaul network environment.
CWDM can support up to 18 wavelengths (1271~1611nm). Still, due to the relatively significant attenuation of the 1271~1471nm band and cost-based considerations, only 6 of these wavelengths (1271nm, 1291nm, 1311nm, 1351nm, 1371nm) are used more in 5G transmission. MWDM is based on the 6 commonly used wavelengths of CWDM, and the left and right offset of the center wavelength is reduced to 3.5nm, thus expanding to 12 wavelengths.
MWDM is to reuse the first 6 wavelengths of CWDM, compress the 20nm wavelength interval of CWDM to 10nm, and use TEC (Thermal Electronic Cooler) temperature control technology to reduce the wavelength offset and double the number of CWDM wavelengths channels. MWDM increases the bandwidth capacity while further saving fiber resources.
CWDM vs. MWDM vs. DWDM, What is the difference?
The below table shows the difference comparison between CWDM vs. MWDM vs. DWDM. From the table, we know the key difference is wavelength spacing, channel capacity, and cost. MWDM is a better choice between CWDM and DWDM, which can better balance the number of wavelength channels and the cost and price.
| Compare | CWDM | MWDM | DWDM |
| Wavelength spacing | 20nm | 10nm | 0.8nm, 0.4nm, 0.2nm, 0.1nm |
| Typical Channels | 18 Channels | 12 Channels | 80 or 160 Channels |
| Pricing | Low | Medium | Highest |
| Suitable Transceiver | 1G Transceiver 2.5G Transceiver 4G Transceiver 8G Transceiver 10G Transceiver 25G Transceiver 40G Transceiver 100G Transceiver | 25G Transceiver | 1G Transceiver 2.5G Transceiver 4G Transceiver 8G Transceiver 10G Transceiver 25G Transceiver 40G Transceiver 100G Transceiver |
| Built-in TEC | Without TEC | With TEC | With TEC |
| Manufacturing complexity | Low | Medium | Highest |
What is the advantage of Metro Wave Division Multiplexing (MWDM)?
The critical advantage includes:
- Save fiber resources: MWDM is based on CWDM. It can double the number of wavelength channels under the same conditions by reducing the wavelength spacing of CWDM from 20nm to 10nm.
- MWDM can transmit 8~16 channels through a pair of single-mode fibers (SMF), significantly saving the cost of building dark fibers or leasing optical fibers.
- Reduce expenses: MWDM technology uses CWDM Mux/Demux devices, OADMs, and other devices with relatively mature technology and low prices in the market.
- Simplify network architecture and improve management efficiency: MWDM technology can multiplex different services on a single wavelength channel, which significantly reduces the use of devices, cables, and patch panels and improves the flexibility of adding or dropping services.
- Good scalability and expandability: The MWDM system can be expanded flexibly according to the actual needs of the network. MWDM Mux/Demux devices allow multiplexing or adding new wavelength channels without changing other equipment in the system.
FAQs about Metro Wave Division Multiplexing (MWDM)
Q: What is Center Wavelength Offset?
A: In MWDM systems, the center wavelength is a light source’s nominal or average wavelength. The offset is the difference in wavelength between the peak power wavelength and the center wavelength.
Q: What is Wavelength Channel Spacing?
A: Channel spacing is the distance in wavelength between two channels.
Q: What is Thermal Wavelength Stability?
A: Thermal wavelength stability measures how well a light source can maintain its center wavelength as temperature changes.
Q: What is Gaussian Pass Band?
A: Gaussian Pass Band refers to a type of DWDM MUX/DEMUX device whose spectral profiles within the passband are essentially Gaussian.
Final Words
It is all about Metro Wave Division Multiplexing, and we hope this guide helps you to understand MWDM better. We are now seeing more and more 25G MWDM transceiver modules in the market. It’s an excellent choice for high-density and bandwidth 5G front-haul and mid-haul applications. If you are looking for MWDM 25G transceivers, please visit Optcore.net for further information.
Read more:
- CWDM Wavelength ITU Channels List: A Complete Guide (2022)
- OPTCORE Best 10G CWDM SFP+ Transceiver Solution
- DWDM Wavelength ITU Channels Chart: A Complete Guide (2022)
