Data rate optimization in inter-cell interference environment of visible light communication

This paper investigates the higher-order modulation using Hadamard matrix to improve the data rate performance, particularly in the interference regions of a multi-cell environment in visible light communication. It presents a novel scheme which utilizes Hadamard matrix to produce orthogonal pulses (OPs) that mitigate the inter-cell interference, and covers the interference areas of the room for mobile receivers. The minimum power requirements is examined to achieve optimum data rate in whole area of the room. Moreover, the signal-to-noise ratio is derived to provide the similar capacity distribution between cells. Theoretical analysis and simulation experiments of bit error rate (BER) and capacity performances are conducted and three arrangements of signals in cells are compared, which are defined as all cells use different sets of OPs (DSOPs), all cells use the same set of OPs (SSOPs) and reuse OPs in diagonal (ROPD) cells of the room. The results show that the BER performance of DSOPs is 10 - 2.7 at the high interference area, which is the best performance compared to ROPD and SSOPs. Moreover, DSOPs requires less power to achieve 2, 3 and 4 bits/symbol compared to ROPD and SSOPs.