Abstract
It is demonstrated that the fully parallel turbo decoding algorithm can achieve an approximate error correction decoding performance when 36 iterations are used and when the log-map algorithm with 6 iterations is used. By comparison, it is shown that it can achieve much higher decoding rates than the log-map algorithm for various frame lengths of LTE standard turbo codes at the cost of higher hardware resource requirements. According to the fully parallel turbo decoding algorithm, this paper proposes a scheme for implementing a fully parallel turbo decoder on FPGA, detailing the overall structure and processing of the decoder hardware implementation, the design of the algorithm block processing unit, and the interleaving module. The performance of the decoder is tested by fixed-point simulation for different frame lengths of turbo coding in LTE standard, and it is proved that the fully parallel turbo decoder can be applied to turbo coding of various frame lengths. Both simulation and experimental results show that the distributed cancellation method and the joint estimation cancellation method have good results for both time-domain impulse noise and large-amplitude single frequency noise cancellation, while the joint estimation cancellation method of large-amplitude single frequency noise cancellation first has better performance.
Highlights
Hydroacoustic communication is a rapidly developing field of scientific research; its engineering applications used to be limited to military aspects to solve the problem of mine remote control, submarine to submarine, mother ship and submarine, or other underwater unmanned combat platform transmissions to obtain battlefield information, and limited bandwidth, multipath, transmission delay, and channel structure of the rapid time change are currently difficult problems [1].After years of development, OFDM has fully demonstrated its advantages, but some problems based on the hydroacoustic OFDM communication system are still not well solved
Many communication methods are controversial, there is no unified standard, and different experiments are usually used in different system parameters, such as coding modulation, communication bandwidth, and carrier frequency. e problems in hydroacoustic OFDM communication need to be studied in more depth, such as how to eliminate external noise interference; how to eliminate and compensate the impact of UAC on the OFDM system to ensure high system reliability; how to better use the sparsity characteristics of UAC to improve system performance; how to adapt to the hydroacoustic communication channel by using coding techniques to improve system performance; and how to improve the utilization of frequency band to achieve high-speed hydroacoustic communication
E hydroacoustic channel is very complex, with strong multipath and complex noise interference, and the channel parameters are time varying, so it is very difficult to get the state information of the hydroacoustic channel at the transmitter side. e transmitter side achieves adaptive transmission based on the obtained CSI, but the hydroacoustic channel is time varying and there is a certain delay Journal of Robotics in the process of feeding CSI back to the transmitter side. erefore, this paper investigates the prediction of hydroacoustic channels based on the OFDM system and proposes a channel prediction technique based on the sparsity of hydroacoustic channels to compensate for the time delay of underwater transmission, so that the obtained channel state information can better reflect the current channel condition
Summary
Hydroacoustic communication is a rapidly developing field of scientific research; its engineering applications used to be limited to military aspects to solve the problem of mine remote control, submarine to submarine, mother ship and submarine, or other underwater unmanned combat platform transmissions to obtain battlefield information, and limited bandwidth, multipath, transmission delay, and channel structure of the rapid time change are currently difficult problems [1]. E problems in hydroacoustic OFDM communication need to be studied in more depth, such as how to eliminate external noise interference; how to eliminate and compensate the impact of UAC on the OFDM system to ensure high system reliability; how to better use the sparsity characteristics of UAC to improve system performance; how to adapt to the hydroacoustic communication channel by using coding techniques to improve system performance; and how to improve the utilization of frequency band to achieve high-speed hydroacoustic communication. E hydroacoustic channel is very complex, with strong multipath and complex noise interference, and the channel parameters are time varying, so it is very difficult to get the state information of the hydroacoustic channel at the transmitter side. E transmitter side achieves adaptive transmission based on the obtained CSI, but the hydroacoustic channel is time varying and there is a certain delay. Due to the above complex characteristics of the shallow sea hydroacoustic channel, various OFDM-based communication technologies must be improved to apply to the hydroacoustic channel, and a lot of experimental validation is needed after the improvement to be put into use
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