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One of the most challenging problems in autonomous driving is trajectory planning for lane changes. Conventional trajectory planning is generally realized by optimizing a specific cost function. However, the model performance required for different scenarios makes it repetitive and time-consuming to tune the cost function. Furthermore, to ensure driving safety, comfort as well as traffic efficiency, it is essential to interact with other vehicles by predicting their driving intentions. Therefore, this paper proposes a segmented-updated lane-change trajectory planning method for autonomous vehicles on closed highways. The maximum entropy inverse reinforcement learning (IRL) algorithm for human demonstration learning and the long short-term memory and Bayesian network (LSTM-BN)-based model for target vehicles' driving intentions are applied. Three contributions are made in this work: 1) The LSTM-BN is used to judge the intentions of surrounding vehicles based on its historical information to inform lane-change trajectory planning. 2) Different feature-based cost functions of the IRL algorithm are designed according to different lane-change scenarios, which enhances its adaptability to different scenarios. 3) Segmented-updated trajectory planning is used to dynamically optimize trajectories via an online optimization process, which reduces the model's limitations and improves overall lane-change performance. Finally, simulation experiments demonstrate that the proposed method has strong generalization ability, reliable accuracy, and can adjust lane-change trajectories reasonably according to the driving intentions of surrounding vehicles. [ABSTRACT FROM AUTHOR]

This paper presents a self-sustained soil electrical conductivity (soil-EC) sensing IC. The sensing system harvests energy and measures the conductivity of the soil simultaneously using the proposed wide-range DC–DC converter. The power management circuits must accommodate the wide variations of the soil conductivity at varying power levels. The time-domain current sensing mechanism, which is embedded in the DC–DC converter, is employed to measure conductivity. Also, the digital codes are recorded and control the converter for achieving maximal power extraction and maintaining high conversion efficiency. The self-sustained soil-EC monitoring IC was fabricated using 0.18- $\mu \text{m}$ CMOS technology. The range of the input voltage from a soil cell is from 0.8 to 1 V when carbon and zinc electrodes are used. The design achieves a tracking efficiency of 98% over an input range of 416– $5000~\mu \text{W}$ , a throughput power range from $150~\mu \text{W}$ to 4.32 mW, and a peak system conversion efficiency of 88%, while the regulated voltage is about 1.7–1.8 V. The design can also measure the soil EC from 0.114 to 0.744 mS/cm in a resolution of 0.00568 mS/cm per bit. [ABSTRACT FROM AUTHOR]

Aiming to increase the transmission data rate, the spatial modulation (SM) scheme maps each block of information bits to a digitally modulated symbol and additionally a transmit antenna index in a multiple transmit antenna system. In this brief, we focus on the maximum likelihood detection (MLD) scheme that detects SM signals with low computational complexity. By reformulating the MLD problem, we obtain a new mathematical expression as the MLD solution. To avoid the numerically unstable division operation, we apply the Givens rotation to realize this new expression and obtain a low-complexity MLD algorithm. We also propose a coordinate rotation digital computer-based hardware architecture to detect SM signals with 64-quaternary amplitude modulated (QAM) symbols over the correlated channel with eight transmit antennas and four receive antennas. The VLSI implementation results under the TSMC 90-nm CMOS technology reveal that our division-free architecture requires 70.5K gates and provides detection throughput 432.68 Mb/s, while operating at frequency 384.6 MHz. Our design is the first hardware architecture to achieve the exact MLD performance and is easily modified to detect SM signals with arbitrary ${M}$ -ary QAM symbols and arbitrary numbers of transmit and receive antennas. [ABSTRACT FROM AUTHOR]

This paper presents a systematic method for decreasing the amount of transconductors used by an operational transconductance amplifier–capacitor (OTA–C) filter to decrease the power consumption and the active area. An OTA with a local-feedback linearized technique and a transconductance booster is proposed based on the presented method. The proposed OTA combines current division with source degeneration to enhance linearity and implement low transconductance. This topology enables the proposed OTA to drive multiple integration capacitors without an additional output stage. The OTA-based circuit realizes low power consumption by operating under a weak inversion at a supply voltage of 1 V. Thus, a fifth-order ladder-type low-pass Butterworth OTA–C filter is implemented for the acquisition of electrocardiograph signals. The proposed method is validated using a prototype fabricated through a 1P6M 0.18-μm CMOS process. Results show that in ECG signal acquisition, the proposed filter has a signal bandwidth located within 250 Hz, a dynamic range of 61.2 dB, and a power consumption of 41 nW to achieve a figure-of-merit of 5.4 × 10−13. The active area of the filter is 0.24 mm2. [ABSTRACT FROM AUTHOR]

Compared with the single tree detector, the layered orthogonal lattice detector (LORD), developed by Siti et al., is a well-known soft-output multiple input multiple output detector to exploit M parallel tree traversals to deliver data with M times of detection throughput rate. The preprocessing QR-decomposition (QRD) of the M -by- M channel matrix for the single tree detector is of complexity proportional to M^3 . However, the preprocessing QRD for the LORD needs to compute the M permuted channel matrices that are constructed from the original M -by- M channel matrix through the root conditioning criterion. The original LORD algorithm for this root conditioning QRD (RC-QRD) relies on the Gram-Schmidt orthogonalization and is of complexity proportional to M^4 for large M . In this brief, we apply the Givens rotation and take advantage of the relationships among the M permuted matrices to develop an RC-QRD algorithm with complexity proportional to M^3 . Furthermore, when M is large, our proposed RC-QRD algorithm requires the number of real Givens rotations about 1.8 times necessary for computing a conventional matrix QRD. Also, for M=4 , our proposed RC-QRD hardware architecture requires gate count 2.1 times that required by the conventional triangular systolic array to compute a matrix QRD. Accordingly, with only about two times of complexity for the preprocessing RC-QRD, the LORD is able to perform M tree traversals to deliver data with M times of throughput rate. [ABSTRACT FROM AUTHOR]

The compressed beamforming weights (CBWs) feedback is used in the IEEE 802.11n/ac WLAN, an example of the practical beamforming multiple input multiple output-orthogonal frequency division multiplexing system, to reduce the amount of feedback information so that the beamformee can respond rapidly to the beamformer. The CBW associated with each sub-carrier includes the quantized angles obtained from QR-decomposition (QRD) of the right singular vectors of each corresponding channel matrix. Efficient matrix QRD and singular value decomposition (SVD) together are therefore desirable for computing the CBWs associated with all sub-carriers. Considering the exemplary antenna configuration of 4 beamformer and 2 beamformee antennas, we propose to apply the same matrix triangulation to compute the SVD of a 2-by-4 matrix and to compute the QRD of a 4-by-2 matrix. We can achieve gate count reduction by exploiting only one matrix triangulation module in our architecture. The VLSI implementation results under the TSMC 90-ns CMOS technology reveal that our architecture requires 194.25K gates while operating at frequency 200.75 MHz. Additionally, with better normalized matrix throughput and gate efficiency, our architecture outperforms one earlier architectural design to compute the CBWs. [ABSTRACT FROM PUBLISHER]