Convolutional multiplexing for multicarrier systems

A new multiplexing scheme with high diversity gain for multicarrier systems, which is called Multicarrier Convolutional Multiplexing (MCCM), is proposed. In this scheme the data symbols are spread onto several subcarriers by a convolutional spreader. Compared to the conventional OFDM (Orthogonal Frequency Division Multiplexing) system, the MCCM system using well designed spreading codes can achieve diversity with order equal to the length of the codes in frequency selective fading channels. A simple free distance searching algorithm is utilized to search the codes with the optimized performance. The best codes of length four are presented and their performance is evaluated by numerical simulations.