Bandwidth efficiency improvement for multi-carrier systems

A novel multi-carrier transmission system named high compaction multi-carrier modulation (HC-MCM) is proposed to improve the spectral efficiency of OFDM. The HC-MCM can arbitrarily overlap the spectra of its subcarriers with an operation for the transmitting signal, whereby a fast transmission rate can easily be achieved. A DFT-based transmitter and receiver, spectral efficiency, the minimum Euclidean distance, and bit-error rate (BER) characteristics are elaborated. As a result, it is shown that a remarkable improvement in spectral efficiency can be obtained by the HC-MCM as the number of subcarriers increases. It is also shown that subcarrier spectra overlapping is sensitive to the minimum Euclidean distance, but large enough in comparison with OFDM under the condition that the transmission rate and the frequency spacing of subcarriers are identical to those in OFDM.