AN EFFICIENT FREQUENCY DIVISION MULTIPLEXING ALGORITHM
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2002-Feb-27
Frequency division multiplexing (FDM) is the backbone for many spectrally efficient digital com- munications systems. Implementing the frequency division multiplexing in a practical system, oRen using digital signal processors, is a difftcult task since each signal (on the transmitter side, for example) to be frequency division multiplexed has to be interpo- lated, filtered, modulated (all of these being performed in the digital domain), and then summed together, If not computed in an efficient manner, these tasks take an enormous amount of processing power and therefore (for complicated modulation schemes) make the digital communications system unrealizable with one digital signal processor. One commonly used solution is the filterbank/polyphase filter implementation ofthe FDM concept. It exploits redundancies in the computation and multiplications by zeroes, allowing the computational savings. There is still a great deal of computation in the filterbank since each signal to be multiplexed together is filtered separately. A more efficient algorithm is the overlap- add algorithm. While being more computationally efficient, it does not allow arbitrary frequency spac- ing. The new invention alleviates some ofthe draw- backs of the overlap-add algorithm by allowing arbi- trary frequency spacing.