PROJECT TITLE :

Multiuser MIMO-OFDM for Visible Light Communications

ABSTRACT:

Visible lightweight communication (VLC) is rising as a promising technique to provide ubiquitous wireless association. During this paper, a multiuser VLC system utilizing multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) is investigated. Since the distances of the multiple transmitter–receiver links are different, their temporal delays also are totally different, ensuing in complicated channel gain and phase variations when transformed to the frequency domain. For each subcarrier in OFDM, the corresponding precoding matrix is calculated within the frequency domain to eliminate multiuser interference. Section information in the frequency domain is 1st considered, where complex, rather than real, channel matrices are used for precoding, that reduces the channel correlation and achieves better performance. Moreover, minimum dc bias, unified dc bias, and asymmetrically clipped optical OFDM-based schemes are proposed to generate real-valued nonnegative signals for intensity modulation, and their performances are validated via simulations with zero forcing and minimum mean-squared error (MMSE) precoding techniques.