  A visible light communication (VLC) system can adopt multi-color light
emitting diode (LED) arrays to support multiple users. In this paper, a
multi-layer coding and constrained partial group decoding (CPGD) method is
proposed to tackle strong color interference and increase the system
throughput. After channel model formulation, user information rates are
allocated and decoding order for all the received data layers is obtained by
solving a max-min fairness problem using a greedy algorithm. An achievable rate
is derived under the truncated Gaussian input distribution. To reduce the
decoding complexity, a map on the decoding order and rate allocation is
constructed for all positions of interest on the receiver plane and its size is
reduced by a classification-based algorithm. Meanwhile, the symmetrical
geometry of LED arrays is exploited. Finally, the transmitter-user association
problem is formulated and solved by a genetic algorithm. It is observed that
the system throughput increases as the receivers are slightly misaligned with
corresponding LED arrays due to the reduced interference level, but decreases
afterwards due to the weakened link gain.
