Real-Time Smartphone Based Mobile Optical Wireless Reception with Reliable Anchor Recognition and XOR Recovery

We propose and experimentally demonstrate a real-time mobile 4-composite amplitude shift keying optical camera communication (4CASK-OCC) system using a smartphone receiver. The Android receiver directly processes the Y component of the YUV camera stream and performs real-time demodulation without image storage, offline transfer, or computer-based post-processing. Under mobile reception, receiver movement, LED intensity fluctuation, camera noise, and reduced symbol spacing may cause sampling position offsets and missed, false, or shifted grayscale peaks in the rolling-shutter sequence. To improve sampling stability, a reliable anchor recognition based sampling point supplementation method is proposed. Pre-reliable peaks are identified according to their spacing relationships with the symbol period and used as dynamic anchors, thereby reducing error propagation caused by unreliable peaks. To address data loss caused by camera inter-frame gaps, a Repetition-XOR recovery scheme with bright region distance based reliability selection is further introduced to reconstruct missing data and resolve inconsistent repeated or XOR-related symbol decisions. Experimental results show that the proposed system achieves a packet-level payload throughput of approximately 6.01 kbit/s and a final effective data rate of approximately 2.06 kbit/s after synchronization, repetition, and XOR overheads. The BER remains below the 7% overhead HD-FEC threshold of 3.8 × 10^-3 at distances up to 275 cm under static transmission, at an axial distance of 225 cm during movement over a 50 cm lateral range, and over the 225-275 cm range under longitudinal movement. A real-time text communication demonstration on the Android smartphone further verifies the practical feasibility of the proposed system.