CWDM and DWDM are two acronyms that mobile operators are hearing a lot as they densify their networks with small cells. CWDM is coarse wave division multiplexing and DWDM is dense wave division multiplexing. Wave division multiplexing is a way to increase the bandwidth of fiber by combining optical signals of different wavelengths on one strand of fiber. This technology is appropriate for small cell deployments because small cells are typically connected to base stations by fiber fronthaul.
Operators implement WDM by adding modules to their base station equipment. Coarse wavelength division multiplexers (CWDM) are modules that increase the amount of bandwidth a fiber optic system can carry by transmitting multiple signals at various wavelengths along the fiber optic cables. Dense wavelength division multiplexers (DWDM) are modules that put data from different sources together on a fiber optic cable. DWDM modules further increase system bandwidth and capacity by using closely spaced wavelengths to carry multiple signals on the same cable.
According to Wes Oxlee, director of business development at CommScope Connectivity Solutions, CWDM can typically support up to 16 channels, while DWDM can support up to 40 channels on one strand of fiber. CWDM is less expensive, explained Oxlee. That’s because DWDM requires operators to use temperature controlled lasers.
“Operators have to choose – they have to offest the cost of the more expensive lasers against getting more capacity,” Oxlee said. He said roughly 60% of the operators that work with CommScope are choosing CWDM and 40% are choosing DWDM. Oxlee added that choosing CDWM does not rule out the possibility of upgrading to DWDM.
“If the operators make the decision on day one to only go [with] coarse wave division multiplexing, and perhaps only put in 16 channels on day one, and they find that they’ve run out of capacity and they need more channel spacing sometime in the future, you can overlay a dense wave division multiplexing system on top of the coarse,” he said. “So the operators aren’t tying their hands by making one choice or the other. They have the flexibility to be able to make changes into the future.”
Watch the full interview with CommScope’s Wes Oxlee here:
