Multi-User ACO-OFDM Based Optical Wireless Communications

In this paper, a new asymmetrically clipped optical orthogonal frequency-division multiplexing (ACO-OFDM) based optical wireless communication system which uses code-division multiple-access (CDMA) technique to satisfy the requirement of the multi-user transmission is proposed. In the proposed system, each user is assigned one of modified maximum length sequence (modified m-sequence) which is mainly constructed by performing both cyclic-shifted copy and zero-padding operations on the traditional m-sequence, as the spreading sequence for supporting the (synchronous) downlink transmission of the system.