Shi Jin, He Jing
Opt Lett. 2024 Apr 1;49(7):1836-1839. doi: 10.1364/OL.520900.
To enable a higher transmission rate in optical camera communication (OCC) systems, severe inter-symbol interference (ISI) occurs owing to the reduction of the number of pixel-row-per-bit (PPB). Therefore, those pixels representing data bit 0 or 1 may have same gray scale values, significantly deteriorating the bit decision when using the conventional thresholding scheme. In this Letter, a simple yet efficient scheme, referred to as nearest neighbor bit assisted decision (NNBAD) scheme, is proposed and experimentally demonstrated for signal decision in OCC systems. NNBAD leverages the nearest neighbor bit to jointly assist bit decision for pixels with severe ISI. Experimental results show that, for OCC systems with on-off keying (OOK) modulation, those pixels with severe ISI cannot be distinguished by the conventional thresholding scheme. Yet, the NNBAD scheme exhibits strong robustness against ISI, remarkably improving the bit error rate (BER) performance. The proposed scheme can achieve a throughput of 8.2 kbps with OOK modulation under an illuminance of 600 lx.
为了在光学相机通信（OCC）系统中实现更高的传输速率，由于每比特像素行数（PPB）的减少，会出现严重的码间干扰（ISI）。因此，那些表示数据比特0或1的像素可能具有相同的灰度值，这在使用传统阈值方案时会显著恶化比特判决。在本信函中，提出了一种简单而有效的方案，称为最近邻比特辅助判决（NNBAD）方案，并在OCC系统中进行了信号判决的实验验证。NNBAD利用最近邻比特共同辅助对具有严重ISI的像素进行比特判决。实验结果表明，对于采用开关键控（OOK）调制的OCC系统，传统阈值方案无法区分具有严重ISI的像素。然而，NNBAD方案对ISI表现出很强的鲁棒性，显著提高了误码率（BER）性能。所提出的方案在600 lx的照度下采用OOK调制时可实现8.2 kbps的吞吐量。
