Hardware Implementation of A Non-RLL Soft-decoding Beacon-based Visible Light Communication Receiver

Visible light communication (VLC)-based beacon systems, which usually transmit identification (ID) information in small-size data frames are applied widely in indoor localization systems. There is one fact that flicker of LED light should be avoided in any VLC systems. Current flicker mitigation solutions based on run-length limited (RLL) codes suffer from reduced code rates or are limited to hard-decoding forward error correction (FEC) decoders. Recently, soft-decoding techniques of RLL- codes are proposed to support soft-decoding FEC algorithms, but they include high-complexity and time-consuming computations. Fortunately, non-RLL direct-current (DC)-balance solutions can overcome the drawbacks of RLL-based algorithms. In this paper, we introduce a non-RLL flicker mitigation method for the VLC- based beacon systems that combines a simple pre-scrambler with a Polar encoder to keep the DC-balance of VLC system even in short data frames. Also, we have proposed a hardware architecture for the proposed non-RLL VLC receiver for the first time. Moreover, to enable the soft-decoding of the Polar decoder, we introduce a 3-bit soft-decision filter which helps improve the bit-error-rate performance of the system.