A Serial Concatenation-Based Coding Scheme for Dimmable Visible Light Communication Systems

Dimming control is desirable for visible light communication (VLC) systems to provide different levels of brightness. In this letter, we propose a new coding scheme for dimmable VLC systems based on serial concatenation of column-scaled (CS) low-density parity-check (LDPC) codes and constant weight codes (CWCs). In the proposed scheme, the cardinality of the finite field on which the CS LDPC code is defined varies adaptively according to the CWC. Hence, transformation between symbol metrics and bit metrics is avoided. Other advantages of the proposed scheme are described as follows: 1) its coding rates are not constrained by the dimming range as error control and dimming control are decoupled; 2) it can be easily configured to support a wide range of dimming targets; and 3) it requires essentially the same hardware architecture to implement the encoder/decoder pair. Hence, the proposed coding scheme provides an attractive candidate for VLC systems with both error and dimming control.