GSM Vs CDMA - A Comparative Study

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History of Code Division Multiple Access (CDMA)

CDMA became commercially available only in the mid-1990s. However, the origin of CDMA can be traced back to 1940. In that year, Hollywood actress turned inventor, Hedy Lamarr, and co-inventor George Antheil, co-patented a way to control torpedoes by sending signals over multiple radio frequencies using random patterns. They tried their best to get this technology from the experimentation phase to the implementation phase. But the U.S. Navy considered the technology to be unfeasible. The technology (initially known as frequency-hopping and later as frequency-hopping spread-spectrum technology23) remained dormant until 1957, when engineers at the Sylvania Electronic Systems Division, in Buffalo, New York, took up the idea. After the Lamarr-Antheil patent expired, they used it to secure communications for the U.S. during the 1962 Cuban Missile Crisis.24 It remained an integral part of government security technology till the mid -1980s, after which it was declassified. The technology then came to be known as CDMA technology.

CDMA works by converting multiple conversations into digital signals, attaching a code to the sender and receiver, dividing the signals into bits, and then reassembling them at the receiver's end. The military loved CDMA technology because coded signals with millions of possible combinations resulted in extremely secure transmissions. Qualcomm, which patented CDMA, and other telecommunications companies were attracted to the technology because it enabled many simultaneous conversations on the same frequency, unlike analog technology and the earlier digital option-GSM technology. CDMA was not tested for commercial use until 1991, and was launched commercially in Hong Kong in 1995.

Commercial Development

Qualcomm realized that CDMA technology could be used for commercial cellular communications more efficiently than other technologies as it could make use of the available radio spectrum better than the older analog and digital technologies. They therefore applied CDMA technology to cellular phones, demonstrated a working prototype, and began to license the technology to telecom equipment manufacturers.

The first CDMA networks were commercially launched in 1995. They provided roughly about 10 times more capacity than analog networks and much more than GSM. Since its launch, CDMA has become the fastest-growing technology of all wireless technologies, with over 100 million subscribers worldwide. In addition to supporting more traffic, CDMA brings many other benefits to carriers and consumers, including better voice quality, broader coverage and better security.

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23] Uses a technique by which a signal transmitted hops among several frequencies at a specified rate and sequence as a way of avoiding interference.
24] In October 1962, President John F Kennedy informed the world that the erstwhile Soviet Union was building secret missile bases in Cuba. Kennedy demanded that the Russian premier remove all the missile bases and their deadly contents. He also ordered a blockade of Cuba, to prevent the Russians from bringing any more missiles to the island. After a week, the Russian premier acceded to President Kennedy's demand

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