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To realize the autonomous operation of a terraced rice sowing robot, a set of sowing robot operation path planning algorithms with universal significance for small, irregular terraced plots is proposed. According to the characteristics of terraces and the agronomic requirements of sowing seeding, the operation path mainly includes parallel operation and boundaries surrounding the operation path. The boundary pre-collision detection method is expounded, and the cyclic detection method judges the U-turn area. The Bézier curve fitting algorithm was used to smooth the boundary wrapping path. To verify the feasibility of the algorithm, four typical irregular small fields located in 666.7-hectare terraces of Sama in Hong He Prefecture, Yunnan Province, were randomly selected, and a field map was obtained through Google Earth. An existing seeding robot was used as a model, and the simulation and comparison tests were carried out with the mainstream EHNS algorithm and boundary polyline algorithm under the ROS-kinetic platform in the Cen Village Scientific Research Base of South China Agricultural University. The actual boundaries of the four fields with the same simulation test were used as the map to verify the field experiment. The simulation test results show that the area coverage of the sowing operation is greater than 93.53% and the replay rate is less than 3.46%, and the field test results show that the area coverage of the sowing operation is greater than 94.33% and the replay rate is less than 3.03%. The simulation test is in good agreement with the field test results, indicating that the algorithm has good adaptability, which meets the requirements of a sowing robot for sowing operation path planning and can provide a certain reference for the path planning of irregular field operation robots in hilly and mountainous areas.

Expectation Propagation (EP)-based Multiple-Input Multiple-Output (MIMO) detector is regarded as a state-of-the-art MIMO detector because of its exceptional performance. However, we find that the EP MIMO detector cannot guarantee to achieve the optimal performance due to the empirical parameter selection, including initial variance and damping factors. According to the influence of the moment matching and parameter selection for the performance of the EP MIMO detector, we propose a modified EP MIMO detector (MEPD). In order to obtain the optimal initial variance and damping factors, we adopt a deep learning scheme, in which we unfold the iterative processing of MEPD to establish MEPNet for parameters training. The simulation results show that MEPD with off-line trained parameters outperforms the original one in various MIMO scenarios. Besides, the proposed MEPD with deep learning parameters selection is more robust than EPD in practical scenarios., Comment: 11 pages, 13 figures

For the time-frequency overlapped signals, a low-complexity single-channel blind source separation (SBSS) algorithm is proposed in this paper. The algorithm does not only introduce the Gibbs sampling theory to separate the mixed signals, but also adopts the orthogonal triangle decomposition-M (QRD-M) to reduce the computational complexity. According to analysis and simulation results, we demonstrate that the separation performance of the proposed algorithm is similar to that of the per-survivor processing (PSP) algorithm, while its computational complexity is sharply reduced.

For the interference hidden in the expected multi-carrier signal, this paper proposes a novel detection and recognition algorithm. The algorithm cannot only detect the single-carrier interference (SCI) by the high-order cumulant, but also finds the multi-carrier signal based on spectrum character. Besides, the algorithm can distinguish the modulation types of the SCI. The algorithm does not depend on any prior knowledge and data-aided, which is propitious to practical applications. The analysis and simulation results demonstrate that the proposed algorithm is effective.

Markov Random Field (MRF) based design methodology presents a new approach to establish high noise-immune structure for ultra-low power circuit designs. The MRF design technique is able to significantly improve the reliability and interference tolerance of the logic circuits. The main idea of this methodology is that the circuit has the highest likelihood for correct logic states from the viewpoint of joint probability distribution. At present, the researches of MRF-based circuit designs focus on the circuit structure and noise tolerant performance analysis for ultra-low supply voltage applications. But there is no investigation on the timing performance of MRF-based circuits. In this paper, we simulated different well-known structures of the fundamental MRF-based elements with HSPICE, and measured the corresponding propagation delay and transition time to evaluate the timing performance of circuit. From the measurements, we find that the propagation delay of MRF-based circuits is one order bigger than that of the traditional (complementary metal oxide semiconductor) CMOS circuits, but MRF-based circuits can achieve similar transition time with traditional CMOS circuits.

In Residue Number System-based systems, how to select moduli set and evaluate its performance is an important issue. The objective of this study is to propose a systemic performance evaluation method for RNS based on the properties of moduli set. By abstracting the inherent properties of moduli sets, such as the complexity of arithmetic units, utilization ratio of dynamic range, parallelism and balance between residue channels, this method can provide advices on moduli set selection and carry out performance estimation before circuits implementation. Furthermore, we also propose a new multi-channel moduli set by introducing a new radix component in this paper. Performance analysis and comparison results show that the proposed multi-channel moduli set has better performance of dynamic range utilization ratio, parallelism and balance than that of the commonly used moduli set with the same number of channels.

In the paper, a new time-delay estimation algorithm, which is based on the cyclic auto-correlation function, is proposed for single-channel two mixed OFDM signals without data-aided. In the method, the linear equations on time delay parameters are constructed from different cyclic autocorrelation functions, and the closed-form solutions are obtained by solving the equations without any prior information of fading parameter and shaping filter. Besides, it also analyzes the Cramer-Rao bound of time-delay estimation of mixed OFDM signal, and verifies the effectiveness of the proposed method through computer simulation. The analysis and simulation results show that the proposed algorithms can achieve good blind estimation for the time delay of mixed OFDM signal in a single channel.

The design of high efficient modulo adders is important for the implementation of DSP algorithms based on Residue Number System (RNS). Moduli sets with this form 2n-2k-1 offer many advantages, such as larger dynamic range and excellent balance among the RNS channels. In this paper, a general algorithm and its VLSI implementation structure are proposed for modulo 2n-2k-1 adder. The proposed algorithm is based on the techniques of prefix operation and carries correction, which eliminates the re-computation of carries. And any existing prefix operation structure can be adopted in the proposed structure. Compared with the same modulo adders with different structures, the proposed modulo 2n-2k-1 adder offers better area*delay.

One of the main limitations for OFDM-based transmission systems is the high Peak-to-Average Power Ratio (PAPR) of the transmitted signals. In this paper, the residue number system (RNS) based OFDM transmission scheme is proposed to reduce the PAPR, which uses the features of RNS to control the dynamic range of the transmitted signals and avoid the nonlinear distortion for the PAPR reduction. Experimental results show that at least 5dB of PAPR performance is improved with the proposed method, compared with the original OFDM.

To fulfill future airport capacity requirements, the proposed data link has to be a high capacity, high rate data link. Air-ground Data Link System can be used in orthogonal frequency division multiplexing (OFDM) systems to improve communication quality and capacity. A channel estimation design method for OFDM system by using correlation of pilot sequences has been proposed in this paper. The main point of this algorithm is the autocorrelation of the sequences. This paper presents a method for optimum training sequences design and the channel estimation implementation that follows. By using these training sequences, in frequency domain, we can get the channel frequency response easily; in time domain, we can get the data fading which are between the adjacent pilot training symbols by some means of interpolation. Simulation and implementation results indicates that this method can obtain good system performance and with low complexity.

In this paper, we propose a new design method of interleavers for interleave-division multiple access (IDMA) system, 2-dimension interleavers. Through a same interleaving rule Gamma, we scramble the row indices and column indices of a traditional block interleaving matrix, and obtain an interleaver. We mark this interleaver as master interleaver. Different interleavers are generated by circular shifting master interleaver. Besides, we prove that the minimum distance between two adjacent bits resulted from 2-dimension interleavers is much larger than random interleavers. The simulation results show that 2-dimension interleavers achieve much better performance with much less resource consumption compared to random interleavers in IDMA systems.

The interleave division multiple access (IDMA) relies on the interleavers as the only means to separate users. In this paper, we analyze the multiple access interference (MAI) performance of interleavers and propose a new design method for interleavers with lower complexity and less memory consumption: shifting interleavers. A series of interleavers can be generated by circular shifting a specific pseudo noise (PN) interleaver, which is generated by a PN sequence generator. Thus, the architecture of the proposed interleaver is much simpler than that of other interleaver schemes for IDMA systems. The simulation results show that shifting interleavers can achieve the same performance with much less resource consumption compared to random interleavers in the IDMA systems.