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- ItemA Novel Tree Model-based DNN to Achieve a~High-Resolution DOA Estimation via Massive MIMO Receive Array(Radioengineering society, 2024-12) Li, Y.; Shu, F.; Song, Y.; Wang, J.To satisfy the high-resolution requirements of direction-of-arrival (DOA) estimation, conventional deep neural network (DNN)-based methods using grid idea need to significantly increase the number of output classifications and also produce a huge high model complexity. To address this problem, a multi-level tree-based DNN model (TDNN) is proposed as an alternative , where each level takes small-scale multi-layer neural networks (MLNNs) as nodes to divide the target angular interval into multiple sub-intervals, and each output class is associated to a MLNN at the next level. Then the number of MLNNs is gradually increasing from the first level to the last level, and so increasing the depth of tree will dramatically raise the number of output classes to improve the estimation accuracy. More importantly, this network is extended to make a multi-emitter DOA estimation. Simulation results show that the proposed TDNN performs much better than conventional DNN and root multiple signal classification algorithm (root-MUSIC) at extremely low signal-to-noise ratio (SNR) with massive multiple input multiple output (MIMO) receive array, and can achieve Cramer-Rao lower bound (CRLB). Additionally, in the multi-emitter scenario, the proposed Q-TDNN has also made a substantial performance enhancement over DNN and Root-MUSIC, and this gain grows as the number of emitters increases.
- ItemGridless Sparse Recovery-based Wind Speed Estimation for Wind-shear Detection Using Airborne Phased Array Radar(Radioengineering society, 2024-12) Zheng, Z.; Lai, J.; Zhang, Q.; Guo, J.The accuracy of wind speed estimation is an important factor affecting wind-shear detection in airborne weather radar. Aiming at the problem that dictionary mismatch in the sparse recovery-based wind speed estimation leads to the performance degradation, this paper proposes a wind speed estimation method based on atomic norm minimization for airborne array weather radar. The method first constructs joint sparse recovery measurements by compensating multiple array element data with wind-shear orientation information, and then the wind speed is estimated on continuous parameter domain using atomic norm minimization with multiple compensated measurements. Simulation experiments demonstrate that the proposed method can effectively improve the accuracy of wind speed estimation under dictionary mismatch, and the performance is better than that of the existing sparse recovery-based method of wind speed estimation with the pre-set discretized dictionary.
- ItemInnovative TCAM Solutions for IPv6 Lookup: Don't Care Reduction and Data Relocation Techniques(Radioengineering society, 2024-12) Pham, A.; Bui, D.; Nguyen, P. T. P.; Tran, L.Ternary Content-Addressable Memory (TCAM) enables high-speed searches by comparing search data with all stored data in a single clock cycle, using ternary logic ("0", "1", "X" for "don't care") for flexible matching. This makes TCAM ideal for applications like network routers and lookup tables. However, TCAM's speed increases silicon area and limits memory capacity. This paper introduces a low-area, enhanced-capacity TCAM for IPv6 lookup tables using Don't Care Reduction (DCR) and Data Relocation (DR) techniques. The DCR technique requires only (N + log_2(N))-bit memory for an N-bit IP address, reducing the need for 2N-bit memory. The DR technique improves TCAM storage capabilities by classifying the IPv6 into 4 different prefix length types and relocating the data in the prefix bit into the "X" cells. The design features a 256x128-bit TCAM (eight 32x128-bit memory banks) on a 65 nm process with a 1.2 V operation voltage. Results show a 71.47% increase in area efficiency per stored IP value compared to conventional TCAM and a 20.97% increase compared to data-relocation TCAM.
- ItemInfrared Small Target Detection, High-Precision Localization and Segmentation: Using TDU Kernel(Radioengineering society, 2024-12) Ding, C.; Chen, S.; Liu, H.; Luo, Z.; Zhang, J.Aiming at the challenge of infrared small target detection with different shape and size under the different scene, a novel algorithm architecture is proposed using the kernel of Target Detection Unit (TDU). The TDU incorporates the fractal geometry design and dual-scale structure, which can execute three main sub-tasks: preliminary target detection, target localization with high precision and target segmentation by pixel-level. First, the principle establishes a dual-scale target detection structure, selects the central point, decomposes the scale information and constructs the Integrated Local Contrast Saliency (ILCS) map, the target preliminary result is obtained by the visual attention mechanism of “top to bottom”. Second, the principle adopts the scale-recursion algorithm by the mechanism of “bottom to up” to locate the target precisely from the preliminary result along with Area Optimal Recommend Mechanism (AORM) strategy. At last, the separated local histogram is used to segment the target by per-pixel with suitable threshold. From the experimental results, conducted across five different types of infrared-scenes including infrared sky scene, infrared maritime scene, backlight illuminance scene, infrared scene with interference and infrared scene with small and dim target, we observe the performance of high accuracy rate and remarkable robustness.
- ItemCovert Communication System Based on Walsh Modulation and Noise Carriers(Radioengineering society, 2024-12) Xu, Z.-J.; Zhang, S.; Liu, Z.-W.; Lin, J.-L.; Huang, X.-S.; Hua, J.-Y.This study proposes a covert communication system, in which a non-zero-mean normally distributed random process is used as a carrier, and its mean is modulated by a Walsh code carrying M covert bits. The number of combinations is so huge that it is difficult for malicious parties to decode the covert information, even if they are aware of the existence of the transmitting signal. The received signal is multiplied at the receiving end with each Walsh code, and the mean value is computed. The Walsh code corresponding to the largest mean value is the transmitter's modulation code, thus recovering the transmitted covert bits. The system's theoretical symbol error rate and bit error rate are derived under additive white Gaussian noise and quasi-static fading channels, respectively. Simulation results are very consistent with the theoretical derivation. Compared with other existing schemes, the proposed scheme has good security, flexibility, and BER performance, and is very suitable for IoT devices with limited resources and low transmission rate but high concealability requirements.