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The design of optimal covert underwater acoustic communication systems is required from an analysis of the impact on communication performance by applying the low probability of interception (LPI) techniques for reducing the probability of intercept information transmitted. In this paper, we propose a transceiver model using a spread spectrum based on turbo equalization in order to improve performance...
The use of orthogonal waveform can offer many advantages in covert underwater acoustic communication, including improved symbol detection ability. In this paper, we derive a new orthogonal code design. The proposed code has a good autocorrelation property compared to other codes. We present some results of a lake trial to evaluate the performance of the proposed method.
This paper proposed a new decoder architecture which employs HSS algorithm and simple check node update algorithm. Memory architecture is a major point of in terms of high speed and area of implementation, therefore the efficient memory design to accelerate decoding throughput is studied. In conventional decoder architectures, p- parallelism, dc-serialism, and q-serialism are required. This paper...
Underwater acoustic communications have multipath errors because of reflection by sea-level and sea-bottom. The multipath of underwater channel causes signal distortion and error floor. In order to improve the performance, it is necessary to employ an iterative coding scheme. Among the iterative coding schemes, turbo codes and LDPC codes are dominant channel coding schemes in recent. This paper concluded...
Soft based linear block codes combined with linear modulation cannot obtain the coding gains by increasing iterations. In this paper, we propose rate-compatible turbo product codes with extended BCH codes by zero padding and shortening the row and/or column to adapt next generation (NG) DVB-RCS system. And also, in order to make various coding rates required on standard, we used different coding rates...
This paper proposes three kinds of simplified complexity-reduced algorithms for a low density parity check (LDPC) decoder. First, sequential decoding using a partial group is proposed. Second, an early detection method for reducing the computational complexity is proposed. Finally, in order to support the high-speed systems, we implemented LDPC decoder using three algorithms by N=648, R=1/2. And the...
Implementation of concatenate code has various problems such as frame synchronization and clock utilization for design on the FPGA chip. This paper proposed an efficient design methodology for serial concatenation coding of cable systems and fabrication on the FPGA chip Vertex II pro xc2vp30-5, Xilinx.
Underwater acoustic communication has multipath error because of reflection by sea-level and sea-bottom. The multipath of UWA channel causes signal distortion and error floor. In this paper, we proposed the compensation method of multipath effect using the impulse response of the UWA channel. As shown in simulation results, the performance of proposed compensation method is better than the performance...
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