he large-scale construction of 5G new infrastructure also places higher demands on the bearer network. The 5G bearer network mainly includes 5G fronthaul networks and 5G backhaul networks. 

Wavelength division multiplexing(WDM) technology is the preferred solution for 5G fronthaul networks. According to the different wavelengths used, it can be divided into DWDM (Dense Wavelength Division Multiplexing), CWDM (Coarse Wavelength Division Multiplexing),the newly proposed MWDM, and LWDM.

Coarse Wavelength Division Multiplexing (CWDM) and Dense Wavelength Division Multiplexing (DWDM) are both mature WDM technologies. 

What is MWDM?

To understand what MWDM is, you first need to know why MWDM was proposed.

5G fronthaul network requires high reliability, high performance, low cost and easy deployment solutions. Need a low-cost technical solution that can quickly respond to market needs. Chinese telecom operators innovatively put forward the concept of 12-wave multiplexing WDM. MWDM is proposed based on mature CWDM technology.
CWDM has 18 wavelengths (1271~1611nm), but due to the relatively large attenuation of the 1270~1470nm band and cost considerations, usually only 6 wavelengths (1271nm, 1291nm, 1311nm, 1351nm, 1371nm) are used. MWDM is based on the 6 wavelengths of CWDM, shifted by 3.5nm left and right to expand to 12 waves (1267.5, 1274.5, 1287.5, 1294.5, 1307.5, 1314.5, 1327.5, 1334.5, 1347.5, 1354.5, 1367.5, 1374.5nm).

What are the advantages of this? 

MWDM emphasizes the first 6 wavelengths of CWDM, compresses the 20nm wavelength interval of CWDM to 7nm, and uses Thermal Electronic Cooler (TEC) temperature control technology to expand 1 wave into 2 waves. In this way, an increase in capacity can be achieved while further saving optical fibers.

MWDM can reuses the production process and industrial chain of CWDM to meet the urgent needs of 5G commercial.