Blind frame synchronization of Reed-salomon codes

International audienceWe consider in this paper the problem of blind frame synchronization of systems using reed-Solomon (RS) codes and other related families. We present first of all three techniques of blind frame synchronization based on the non-binary parity check matrix of RS codes. While the first two techniques involve the calculation of hard and soft values of the syndrome elements respectively, the third one perform an adaptation step of the parity check matrix before applying the soft criterion. Although RS codes are constructed from non-binary symbols, we show in this paper that it is also possible to synchronize them using the binary image expansion of their parity check matrix. Simulation results show that the synchronization algorithm based on the adaptation of the binary parity check matrix of RS codes has the best synchronization performance among all other techniques. Furthermore, the Frame Error Rate (FER) curves obtained after synchronization and decoding are very close to the perfect synchronization curves

Communication Systems Design for Downhole Acoustic Telemetry

The goal of this dissertation is to design a reliable and efficient communication system for downhole acoustic communication. This system is expected to operate in two different modes. A broadband high data rate mode in case of transmission of an image or a video file and a narrowband low data rate mode in case of transmission of sensor readings. This communication system functions by acoustic vibration of the pipes and uses them as the channel instead of installing long cables in areas that are hard to reach. However, this channel has unique characteristics where it exhibits several passbands and stopbands across the frequency spectrum. The communication system is expected to get around those challenges in both modes of operation. In the broadband case, the system uses Orthogonal Frequency Division Multiplexing to transmit data across multiple orthogonal frequencies spanning multiple passbands combined with an error-correction code to recover some of the losses caused by the channel. In the narrowband case, a short packet is transmitted at a low data rate where the signal spectrum can fit inside one passband. However, transmitting short packets induces a new synchronization problem. This dissertation investigates and explores in detail the problem of synchronization on short packets where each synchronization stage is examined. A simple algorithm that exploits the presence of error-correction codes is proposed for the frame synchronization stage and demonstrated to approach the optimal solution. Then, all synchronization stages are combined in order to study the effect of propagated errors caused by imperfect synchronization from one stage to the next and what can be done in the design of the packet and the receiver structure to mitigate those losses. The resulting synchronization procedure is applied to the pipe strings and demonstrated to achieve desirable levels of performance with the assistance of equalization at the receiver

Communication Systems Design for Downhole Acoustic Telemetry

The goal of this dissertation is to design a reliable and efficient communication system for downhole acoustic communication. This system is expected to operate in two different modes. A broadband high data rate mode in case of transmission of an image or a video file and a narrowband low data rate mode in case of transmission of sensor readings. This communication system functions by acoustic vibration of the pipes and uses them as the channel instead of installing long cables in areas that are hard to reach. However, this channel has unique characteristics where it exhibits several passbands and stopbands across the frequency spectrum. The communication system is expected to get around those challenges in both modes of operation. In the broadband case, the system uses Orthogonal Frequency Division Multiplexing to transmit data across multiple orthogonal frequencies spanning multiple passbands combined with an error-correction code to recover some of the losses caused by the channel. In the narrowband case, a short packet is transmitted at a low data rate where the signal spectrum can fit inside one passband. However, transmitting short packets induces a new synchronization problem. This dissertation investigates and explores in detail the problem of synchronization on short packets where each synchronization stage is examined. A simple algorithm that exploits the presence of error-correction codes is proposed for the frame synchronization stage and demonstrated to approach the optimal solution. Then, all synchronization stages are combined in order to study the effect of propagated errors caused by imperfect synchronization from one stage to the next and what can be done in the design of the packet and the receiver structure to mitigate those losses. The resulting synchronization procedure is applied to the pipe strings and demonstrated to achieve desirable levels of performance with the assistance of equalization at the receiver