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FDMA
- FDMA transmits over a dedicated frequency in each direction. It can be looked at in terms of a non-technical example of a classroom. If a classroom were to be dedicated to one class and no other class could be taught in that room.

TDMA
- In TDMA, conversations and data are broken into packets that are then sequentially sent over a single selected frequency. In the same example, the classroom would be used for a specific period of time for one class, and then when that one class finishes another can begin.

CDMA
- In CDMA, conversations and data are broken into individual packets each marked with an identification code and then sent out over a spread of spectrum frequencies. In the classroom analogy, it would be as if multiple classes were being taught in the same room at the same time but you can only hear the information from the class you are in and you have the ability to filter out all the noise from the other classes.

The wireless industry
In the wireless industry the two most widely adopted technologies are CDMA and TDMA. TDMA technology works by identifying natural breaks in speech and utilizing one radio wave to send out multiple transmissions.In CDMA technology, each individual packet receives a unique code that is broken up over a wide-frequency spectrum and is then reassembled on the other end. CDMA allows multiple people to speak at the same time over the same frequency, allowing more conversations to be transmitted over the same amount of spectrum; this is one reason why CDMA eventually became the most widely adopted channel access method in the wireless industry.

The origins of CDMA can be traced back to the 1940's where it was patented by the United States government and used throughout World War II to transmit messages. However, following the war the patent expired and the use of CDMA diminished and was widely replaced by TDMA. That was until Dr. Irwin M. Jacobs an MIT engineer, and fellow employees from the company Linkabit founded the telecommunications company Qualcomm. At the time Qualcomm was founded, Dr. Irwin Jacobs had already been working on addressing telecommunications problems for the military and attempting to find ways to increase the capacity of spectrum. At Qualcomm they further worked to address the growing issues with capacity and attempted to introduce digital technology and voice encoding and compression in an effort to increase the usability of available spectrum.

Qualcomm knew that CDMA would greatly increase the efficiency and widespread availability of wireless, but the wireless industry having already invested millions of dollars into TDMA was skeptical. Jacobs and Qualcomm spent several years improving infrastructure and performing tests and demonstrations to prove the success of CDMA. It was then in 1993, that CDMA became accepted as the wireless industry standard. By 1995, CDMA was being used commercially in the wireless industry to be the foundation of 2G and eventually 3G and even today with 4G and 5G.

Duplexing Methods
A duplexing communication system can be either half-duplex or full duplex. In a half-duplex system, communication only works in one direction at a time. A walkie-talkie is an example of a half-duplex system because both users can communicate with one another, but not at the same time, someone has to finish transmitting before the next person can begin. In a full-duplex system, both users can communicate at the same time. A telephone is the most common example of a full-duplex system because both users can speak and be heard at the same time on each end. Some types of full-duplexing methods are: