Experimental Demonstration of Visible Light Communication based Downhole Telemetry System

In this paper, we demonstrate an experimental study on the use of visible light communications (VLC) for downhole gas pipeline telemetry/monitoring systems. To emulate real field conditions, an experimental setup is created, which consists of a carbon steel coated gas pipeline, a receiving detector, and a transmitting light source such that the medium possesses properties of nitrogen gas. The performance of a VLC system employing an asymmetrically clipped optical orthogonal frequency division multiplexing modulation technique is practically tested by taking channel estimation and synchronization into account. The implementation is tested for a quadrature phase-shift keying modulation technique with a sampling rate of 2 Mbps. The channel impulse response is presented along with a proposed path-loss model. As a performance metric, the system’s signal-to-noise ratio (SNR) against bit-error-rate (BER) behavior is investigated for nitrogen gas at atmospheric pressure. The results of the free-space air medium are also included as a benchmark.