In this paper, we introduce a couple of hardware implementations of compact VLC transmitter and receiver for the first time. Compared with related works, our VLC transmitter is non-RLL one, that means flicker mitigation can be guaranteed even without RLL codes. In particular, we have utilized a centralized bit probability distribution of a prescrambler and a Polar encoder to create a non-RLL flicker mitigation solution. Moreover, at the receiver, a 3-bit soft-decision filter is proposed to analyze signals received from real VLC channel to extract log-likelihood ratio (LLR) values and feed them to the FEC decoder. Therefore, soft-decoding of Polar decoder can be implemented to improve the bit-error-rate (BER) performance of the VLC system. Finally, we introduce a novel very large scale integration (VLSI) architecture for the compact VLC transmitter and receiver; and synthesis our design under FPGA ASIC synthesis tools. Due to the non-RLL basic, our system has an evidently good code-rate and a reduced-complexity compared with other RLL-based receiver works. Also, we present FPGA and ASIC synthesis results of the proposed architecture with evaluations of power consumption, area, energy-per-bits and so on.
Table summarizes proposals related to FEC and flicker mitigation for VLC. The conventional solution is defined in the IEEE 802.15.7 standard, which employs Reed-Solomon (RS) codes, Convolutional Codes (CC) and RLL codes with hard-decoding of RLL codes (hard-RLL) @cite_8 . However, hard-RLL methods of inner RLL codes limit to hard-decoding of outer FEC codes @cite_8 @cite_10 @cite_5 ; consequently, the error-correction performance of the entire VLC system is restricted. Recently, soft-decoding RLL (soft-RLL) solutions have been proposed in @cite_7 @cite_3 @cite_2 @cite_1 . These techniques permit soft-decoding FEC algorithms to be applied to improve the bit-error-rate (BER) performance of the VLC system, but they also require heavy computational efforts, with many additions and multiplications.
@cite_7 @cite_8 @cite_1 @cite_3 @cite_2 @cite_5 @cite_10
2206502523 2100816365 2054470560 2005598127
In this letter, we propose a new decoding algorithm based on a soft-input soft-output run-length limited (RLL) decoder in visible light communication (VLC) with on–off keying (OOK) modulation and Reed–Solomon (RS) codes. Conventional RLL codes are used for dimming adjustments in VLC; however, in our receiver model, the posterior probability matrix is produced by the new RLL decoder, and it can be matched as the input of the soft RS decoder to enhance the throughput in the VLC system. A significant advantage of our proposed method is that it leads to the enhancement of bit error rate (BER) and frame error rate (FER) performances without any change in the transmitter in VLC systems. The simulation results show that the majority of the BER and FER performances of our proposed method are better than those of hard-input hard-output RLL decoding and soft-input hard-output RLL decoding methods. In this letter, we propose a novel forward error correction (FEC) coding method using a modified Reed-Muller (RM) code for providing accurate dimming control in on-off keying (OOK) based visible light communication (VLC) systems. The proposed FEC scheme has a property that produces exactly same occurrence probability of 1's and 0's. Therefore, it can contain minimal compensation symbols in supporting multiple dimming target values. Moreover, VLC with our proposed scheme provides more coding gain than VLC scheme with the conventional FEC codes [the first-order RM and Reed-Solomon (RS) codes]. Simulation results for various dimming target values show that the proposed scheme leads to at least 2 dB or more signal-to-noise ratio (SNR) gain in 1 bit error rate (BER) than two FEC codes. In this letter, we propose a new decoding algorithm based on a soft run-length limited (RLL) decoding in visible light communication (VLC) with on-off keying modulation and Reed-Solomon codes. Conventional RLL codes are used for dimming adjustments in VLC; however, in our receiver model, the proposed RLL decoder produces one or multiple candidates with greater probabilities to enhance the throughput in the VLC system. We also propose a selection method based on a cyclic redundancy check among multiple candidates. A significant advantage of our proposed method is that it leads to performance enhancement without any change in the transmitter in VLC systems. Simulation results show that the bit error rate of our proposed method is better than that of RLL hard decoding. In this letter, we propose a new forward error correction (FEC) coding method using a coset constructed from a bent function and a Reed-Muller (RM) code for providing accurate dimming control in on-off keying-based visible light communication (VLC) systems. By partitioning the coset made from bent function and the first-order RM codes, the new FEC scheme can be made to be suitable for dimming close to 0 or 100 . Therefore, it can contain minimal compensation symbols in supporting multiple dimming target values, which causes improved coding gain when the total amount of frame data is fixed. Simulation results for various dimming target values show that the proposed scheme leads to about 1-dB signal-to-noise ratio gain in 10-2 bit error rate compared with other three FEC codes.