Difference Between TDMA and CDMA

TDMA vs CDMA

Ever since the invention and commercialization of cellular systems, industry leaders and engineers had already foreseen the inevitable overcrowding of simultaneous callers because the number of accessible channels is very limited.

RF engineers of the industry are now using methods to remedy these problems. Two examples of such methods are TDMA and CDMA. In essence, both are different methods but accomplish same objectives. Their primary goal is to significantly increase the quantity of concurrent users within a definite section of radio spectrum ‘“ something that the traditional systems cannot achieve.

TDMA and CDMA are used for high capacity cellular systems and these two standards of digital technology are in competition and also incompatible with each other. Basically, they have differing specifications on how the bandwidth of the spectrum is distributed during users’ cellular calls. Therefore, the main difference of the two technologies is in the way which the users share the same physical channel.

TDMA

TDMA is an abbreviation of “Time-Division Multiple Access”. TDMA chops or divides the channel into sequential time portions. Users of the channel will have their respective round-robin turns in receiving and transmitting data. Breaking it down, only a single user is actually utilizing the channel at any given instance. Each user only uses the channel in short bursts at a time and that grant to use resources is given up for a while to also allow others to use the channel.

Actually, TDMA has been included into GSM for a very long time as it is already considered an old technology and it is beginning to become obsolete.

CDMA

CDMA is short for “Code-Division Multiple Access” and it is also a kind of multiplexing that allows several signals to use a single transmission channel.

CDMA, unlike TDMA, virtually allows numerous users to use the channel at the same time. Thus, transmitting and receiving are all done by various users simultaneously. This is only made possible by a process called Spread Spectrum, a type of modulation that captures every user’s flow of digital bits and spreads them all around the channel in a pseudo-random manner. The receiving end just interprets the scattered bits or in other words, un-randomize the bits to make them coherent

Of the two technologies, CDMA is the later one. Essentially, it emerged to resolve the inadequacies and the setbacks associated with TDMA.

Summary:

1. Their abbreviation meanings actually give light to the manner they optimize channels. TDMA is short for Time-Division Multiple Access while CDMA is for Code-Division Multiple Access.

2. TDMA emerged and was utilized first. CDMA is the more recent technology gradually replacing TDMA.

3. TDMA chops or divides the channel into sequential time portions as each user has its respective right turn for channel use.

4. CDMA uses a process called Spread Spectrum ‘“ scattering of digital bits in pseudo-random manner and collecting them for interpretation.

5. CDMA allows numerous users to use the channel at the same time while TDMA does not.

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