Raptor Codes for Real-time Mud Pulse Telemetry in M/lwd System

The Measurement/Logging While Drilling (M/LWD) system is a kind of sensors system which is used to help oil/gas drilling field technicians to steer well drilling. In M/LWD, several kinds of sensors are installed into drill string to measure the underground logging data during well drilling operations, and a sink within the drill string collects the logging data from the sensors and then transmits the collected data to the surface site by mud pulse telemetry. Since the drilling mud channel is an erasure channel with very limited feedback, the surface site has to protect against erasure by means of a suitable form of error control in real time. To improve the transmission efficiency of M/LWD system, this paper proposes a Raptor Codes based Transmission (RCT) scheme for reliable real-time logging data transmission in M/LWD systems, where the original logging data can be recovered at the surface site without traditional mechanisms, including erasure correction code (ECC) and Automatic Repeat Request (ARQ), which thus greatly improves the bandwidth efficiency. To further enhance the transmission performance, we introduce the Differential Pulse Code Modulation (DPCM) and short-length Raptor codes to the proposed RCT scheme. Extensive experiments performed with real logging data show that RCT scheme achieves good erasure decoding performance to provide precise enough results for drilling field technicians and also achieves good real-time performance.