Multi-carrier modulation or MCM is an approach to data transmission that involves segregating the data into several more or less equal components. The individual components are then routed across different carrier signals. At the point of termination, the individual components are reassembled and delivered.
The actual history of multi-carrier modulation goes back to the middle of the 20th century. At the time, this method of transmitting data was employed by the military arms of the United States and several other countries. The actual process relied on each of the carriers used to route the components to have an narrow bandwidth. This made it possible for the composite broad bandwidth transmission to be broken down into segments or components that could be securely routed and converted back into a single transmission that could be decrypted and understood at the receiving end. Using multi-carrier modulation in this method allowed the military to make effective but secure use of the analog technology of the day.
However, the use of multi-carrier modulation is not limited to making use of analog audio transmissions. Today, concept of this process is also gaining attention as a tool to make use of bandwidth in digital communications protocols. This is especially the case in such modern communication of voice and visuals as digital television. At the same time, the idea of multi-carrier modulation is also being utilized in modern day audio communications such as with wireless local area networks. When it comes to Internet connectivity, multi-carrier modulation can also be employed with such high speed methods as asymmetric digital subscriber lines (ADSL).
One of the more attractive advantages of data transmission using multi-carrier modulation is the fact that the process tends to minimize the incidence of signal fading, and also appears to encounter fewer instances of noise than most single-carrier methods. While there are some problems noted with the use of multi-carrier modulation, such as issues in synchronizing the carriers, these are becoming less of an issue as technology continues to evolve.