CDMA stands for Code Division Multiple Access and DWDM stands for Dense Wavelength Division Multiplexing. The word ‘division’ is common to both four-letter acronyms as is their respective approaches to increased bandwidth and speed in telecommunications networks, which has enabled the rise of the smartphone and the emergence of the ‘cloud’ in 2015.
Electromagnetic radiation propagating through the air, the medium for wireless communications, or traveling down an optical waveguide, the medium for optical transport networks, can deliver infinite bandwidth at the speed of light.
With CDMA and its low power design and high frequency operation, as introduced by Qualcomm during the 1990s, it allowed for the use of a smaller antenna and hence smaller cells, leading to more cost-effective and, as it turns out, superior wireless communication performance. Dividing big cells into smaller cells is a good thing for wireless operators.
CDMA offered other attendant advantages, such as its ability to handle multipath interference, a phenomenon where transmitted signals bounce off buildings and trees and arrive at different times at the receiver handset. Qualcomm implemented a new concept, the rake receiver, co-invented by fiber optic innovator Paul Green, to combine the three strongest sent signals received, into one. Existing TDMA systems at the time, saw multipath signals arriving at different times as interference in other assigned timeslots. CDMA, however, doesn’t break up the signal into timeslots, so incoming multipath signals actually strengthen the signal at the receiver, thus making the CDMA system more robust, critical for clear voice calls and quality data transfer.
DWDM is a technological innovation used on optical fiber. It continues to allow for more and more bandwidth to transit the nation’s communications infrastructure. Whereas optical transport systems of the 1980s used a single wavelength of light for each fiber sheathed in a cable, the 1990s brought greater than 32 wavelengths of light traversing a single fiber. Coupled with this increase in wavelength efficiency, optical bit rates increased four-fold from 2.5 billion bits per second to 10 Gb/s. Today, another ten-fold increase in bit rates routinely delivers 100 Gb/s optical transport systems, which can also concurrently support hundreds of wavelengths of light. ‘Dividing’ the fiber up to support more and more wavelengths is a good thing for service provider operators.
Claude Shannon (1916–2001) , the father of Information Theory, if he were alive today, would recognize the importance of DWDM for high-capacity transport. DWDM utilizes a number of separate bit streams at much lower power than a single bit stream would require. The physics tells us that sending many low-powered bit streams down an optical fiber  will outperform a single high-powered bit stream any day of the week.
Pundits during the 1990s saw that wireless would ultimately deliver voice and data services as cheap and clear as wireline offerings. Not only that, but the mobility of wireless would also offer greater access and more convenience, as the customer would no longer be tethered to a desk phone. Industry watchers foresaw that CDMA technology would make wireless systems usable for data and Internet access, which would soon become the dominant market for wireless – remember PDAs? The promise of CDMA was enticing.
The technology pundits were right. CDMA has since enabled smartphones, which combine voice and data efficiently, and DWDM has delivered greater capacity (massive bandwidth transfer) and faster speed (low latency) to support mobile Internet access of voice, data, and now video streaming.
You’ve got to love those four-letter words!
 Shannon invented the field of Information Theory as a new science, something not done since the time of the Renaissance. Shannon’s landmark paper, "A Mathematical Theory of Communication", published in 1948 had ramifications across the world as early as the 1950s. It spawned the entire world of wired and wireless communications, including the integrated circuit, computer mainframes, satellite communications, personal computers, fiber optic transmission systems, high definition television, mobile phones, DNA sequencing, and more. Shannon’s digital revolution is so complete that terms like bits and bytes are as common to the average person as watts and calories.
 The following slide was presented by Infinera, in 2014, at a webinar they sponsored. The Cerent era, from 1998 through 2006, witnessed DWDM evolve to include support for EDFAs, dispersion management, FEC, addition of the L-band to complement the C-band for capacity increases, and the inclusion of Raman amplification techniques. Many of these long-haul innovations migrated to regional and metropolitan networks that Cerent effectively served.