{"id":31268,"date":"2023-03-01T04:14:18","date_gmt":"2023-03-01T09:14:18","guid":{"rendered":"https:\/\/www.iridian.ca\/?p=31268"},"modified":"2023-03-01T04:14:18","modified_gmt":"2023-03-01T09:14:18","slug":"multiplexing-in-a-data-center-how-does-it-work","status":"publish","type":"post","link":"https:\/\/www.iridian.ca\/zh-hans\/learning_center\/light-notes\/multiplexing-in-a-data-center-how-does-it-work\/","title":{"rendered":"Multiplexing in a Data Center: How Does it Work?"},"content":{"rendered":"

Data centers are increasingly pivotal in the digital world, and there is an ever-growing need for faster and more efficient data transmission. Fiber optics remain the primary method of guiding optical signals from one point to another in a data center. However, single-channel transmission using a standard pair of fibers is unsuitable for the demands of modern communications. Multiplexing is an innovative method of dramatically increasing the transmission capacity of fiber optic links by enabling multiple signals to share a single channel. There are challenges, such as the risk of interference and signal degradation, but different forms of multiplexing offer different solutions to these issues. This blog post will explore the role of multiplexing in data centers with a focus on two of the most commonly used techniques: TDM and WDM.<\/span><\/p>\n

The Importance of Data Centers<\/span><\/h2>\n

Data centers are like the nervous system of digitally-connected communities\u2013be those businesses or metropolitan areas. They receive and transmit staggering volumes of data signals to control and coordinate various processes. According to a report by Cisco, global internet traffic was expected to reach 7.7 exabytes (EB) per day in 2021. A single exabyte represents a billion gigabytes, and the EB has been adopted as the most common measurement of global data traffic, given the exorbitant scale of growth. Multiplexing has become a critical method of meeting the incredible demands of modern data transmission, making it a crucial component of our digital infrastructure. Now let\u2019s explore those two common techniques mentioned above.<\/span><\/p>\n

TDM<\/span><\/h3>\n

Time-division multiplexing (TDM) divides a single communication channel into time slots. Each time slot is assigned to a different signal, and the signals are transmitted in a cyclic order. This is achieved using an interleaved pulse train where multiple data streams are combined into a single stream by separating each into a series of short, periodic pulses alternated in sequence. As with other forms of temporal multiplexing, critical requirements of TDM include extremely short pulse durations, often in the picosecond range.<\/span><\/p>\n

WDM<\/span><\/h3>\n

Wavelength-division multiplexing (WDM), on the other hand, divides a single communication channel into multiple wavelength bands, with each band assigned to a different signal. These bands are known as WDM channels. Signals are multiplexed into different WDM channels by optical filters at the sender and demultiplexed by receivers, allowing multiple signals to be transmitted simultaneously. One advantage of the WDM approach is that it can be applied to existing fiber links with limited capacities, increasing bandwidth by replacing senders and receivers rather than cabling.<\/span><\/p>\n

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The Role of Optical Filters<\/span><\/h2>\n

Optical filters are used to filter specific wavelength channels. Ensuring that each signal is correctly transmitted without interference requires filters with high transmission efficiency, low insertion loss, and high out-of-band rejection is essential. Currently, two main optical filter types are used in multiplexing: Fiber Bragg gratings and thin-film filters.<\/span><\/p>\n