Impulse Radio Ultra-wideband Research Articles

Scheme design of the optimal background clutter suppression for impulse radio ultrawide band radar in complex fire environment: a simulation and experimental study

Impulse radio ultrawide band (IR-UWB) radar possesses several advantages, such as heat flow insensitivity, high resolution, great penetration, good mobility, and lightweight, making it a promising technology for detecting and rescuing individuals trapped in fire scenarios. However, reliable detection and extraction of vital signs of trapped people in the presence of complex fire environment, such as water droplets, smoke, wall occlusions, and reflections, require an optimal background clutter suppression scheme designed specifically for fire scenarios. This study comprehensively evaluates 20 background noise suppression schemes using an exhaustive approach that involves constructing radar echo simulation signals and designing an evaluation method for algorithms. The practical applicability of the improved design solutions was evaluated by conducting small-scale fire experiments in an acrylic chamber. The results indicate that the designed scheme is effective in overcoming the background interference from the combustion environment and is capable of supporting subsequent trajectory identification and vital sign extraction in the fire scene environment.

A wideband monopolar patch antenna with a high system fidelity factor for IR‐UWB application

AbstractA compact, broadband microstrip patch antenna with stable monopole‐like radiation patterns is proposed for impulse‐radio ultrawideband (IR‐UWB) positioning systems. Such the antenna consists of a circular patch with eight conductive vias placed concentrically, resulting in the and modes. Moreover, a tapered feeding probe at its center is presented to enhance the matching and excite an antiresonance mode. The compact size of is obtained by using a square ground. The measured results show that the antenna has an impedance bandwidth of 44.1% from 6 to 9.4 GHz and stable monopole‐like radiation patterns in the frequency domain. Finally, a system fidelity factor larger than 96% and a relatively stable group delay are simulated and measured in the time domain. Therefore, this antenna can be potentially useful for UWB pulse transmission with attractive features in engineering applications.

Convolutional Neural Networks for the Real-Time Monitoring of Vital Signs Based on Impulse Radio Ultrawide-Band Radar during Sleep.

Vital signs provide important biometric information for managing health and disease, and it is important to monitor them for a long time in a daily home environment. To this end, we developed and evaluated a deep learning framework that estimates the respiration rate (RR) and heart rate (HR) in real time from long-term data measured during sleep using a contactless impulse radio ultrawide-band (IR-UWB) radar. The clutter is removed from the measured radar signal, and the position of the subject is detected using the standard deviation of each radar signal channel. The 1D signal of the selected UWB channel index and the 2D signal applied with the continuous wavelet transform are entered as inputs into the convolutional neural-network-based model that then estimates RR and HR. From 30 recordings measured during night-time sleep, 10 were used for training, 5 for validation, and 15 for testing. The average mean absolute errors for RR and HR were 2.67 and 4.78, respectively. The performance of the proposed model was confirmed for long-term data, including static and dynamic conditions, and it is expected to be used for health management through vital-sign monitoring in the home environment.

High-Precision and Resilient-to-Interference Ultrawideband Two-Way-Ranging Based on Clock-Less Active Reflector in 65-nm CMOS

An impulse-radio ultrawideband (IR-UWB) two-way ranging (TWR) system for indoor and harsh environments is described. In the proposed system, a synchronization (sync) word with a specific sequence of UWB impulses and with a particular pulse-position modulation (PPM) is transmitted from the anchor and then detected by the tag using a continuous-time sync detection mechanism. Then, the tag instantaneously reflects a similar sync-word back to the anchor. Finally, the anchor detects the sync-word using the same continuous-time sync detection mechanism as the tag. The time of flight (ToF) between the transmitted sync and the received sync on the anchor is then calculated to measure the distance between the transmitter and the receiver. Unlike common TWR systems, here in the tag, a clock-less active reflector is used, which reduces sync detection and reply time and, hence, increases the ranging accuracy due to the mitigation of clock drift. To reduce narrowband interference (NBI) and multiuser interference (MUI), the sync-word uses a combination of ON–OFF keying (OOK) and PPM. The proposed sync-word detector continuously verifies the presence of UWB impulses having the correct time intervals. As a proof of concept, a 4-bit sync-word is utilized although the technique can be directly expanded to longer sync-words. The proposed system is fabricated using a 65-nm CMOS integrated circuit technology. Experimental results show the accuracy and resilience-to-interference (NBI and MUI) of the proposed TWR. The technique shows a 1.2-cm standard deviation for the accuracy of a single-measurement TWR in a semiclosed metal box using omnidirectional antennas.

Utilization of Carrier-Frequency Offset Measurements in UWB TDoA Positioning with Receiving Tag.

High-capacity impulse-radio ultra-wideband (IR-UWB) indoor localization systems are typically based on the time difference of arrival (TDoA) principle. When the fixed and synchronized localization infrastructure, the anchors, transmit precisely timestamped messages, a virtually unlimited number of user receivers (tags) are able to estimate their position based on differences in the time of arrival of those messages. However, the drift of the tag clock causes systematic errors at a sufficiently high magnitude to effectively deny the positioning, if left uncorrected. Previously, the extended Kalman filter (EKF) has been used to track and compensate for the clock drift. In this article, the utilization of a carrier frequency offset (CFO) measurement for suppressing the clock-drift related error in anchor-to-tag positioning is presented and compared to the filtered solution. The CFO is readily available in the coherent UWB transceivers, such as Decawave DW1000. It is inherently related to the clock drift, since both carrier and timestamping frequencies are derived from the identical reference oscillator. The experimental evaluation shows that the CFO-aided solution performs worse than the EKF-based solution in terms of accuracy. Nonetheless, with CFO-aiding it is possible to obtain a solution based on measurements from a single epoch, which is favorable especially for power-constrained applications.

Spectral Unmixing Successive Variational Mode Decomposition for Robust Vital Signs Detection Using UWB Radar

The evaluation of clinical status and vital signs is a crucial component of remote medical care. Radar provides a non-contact monitoring measurement without consideration of lighting or privacy. However, the multipath effect generated by multiple people gathered in a small indoor space seriously affects the detection of vital sign information. This study presents a non-contact measurement of the vital signs based on stepped-frequency continuous wave ultra-wideband(SFCW-UWB) and impulse radio ultra-wideband(IR-UWB) radars. Additionally, this study suggests the Spectral Unmixing Successive Variational Mode Decomposition (SUSVMD) algorithm since the respiratory components have a probability of mixing with the heartbeat signal’s frequency. The suggested approach extracts band-limited modes through back projection and spectral unmixing optimization. The alternate direction method of multiplication is used to address the optimization problem. The experiments are conducted under two radar measurements and three subjects. The results show that the suggested method is superior and effective.

Passive IR-UWB Localization System for UAV-Based Electric Facility Inspection During GPS Outage

A practical localization system is proposed for a substation inspection unmanned aerial vehicle (UAV) performing its mission under global positioning system (GPS) signal blockage. The sensor hardware consists of a single transmitter and a cruciform receiver array, which produces the range difference (RD) information used for UAV positioning. The use of impulse-radio ultra wide-band (IR-UWB) devices secures the robustness against RF interference often caused by an exogenous electromagnetic field. With this hardware configuration, the UAV localization can be formulated as the state estimation problem for an uncertain linear state space model and be solved by using the computationally efficient robust weighted least squares (RWLS) estimator. Since the standard RWLS estimator could be sensitive to the imperfectness of prior knowledge on the noise statistic, a geometric constraint expressed in terms of a UAV position is exploited to secure the reliable localization performance in practice. Through experimental results, it is verified that the proposed solution provides reliable UAV positioning performance despite using the imperfect measurement noise statistics for the localization system.

A Study on 3D Human Pose Estimation Using Through-Wall IR-UWB Radar and Transformer

In this paper, we propose a human pose estimation algorithm for an impulse radio ultra-wideband (IR-UWB) radar based on the transformer-based deep learning model. We have built an IR-UWB radar system with an 8-by-8 multiple-input multiple-output (MIMO) antenna array. The IR-UWB radar system in our paper is advantageous for the through-wall detection application since it operates on a very low frequency range (i.e., 0.45 to 3.55 GHz) compared to other existing works on RF-based human pose estimation. Moreover, the human pose estimation by an IR-UWB radar has not been studied very well in other existing works since all existing works have used a frequency-modulated continuous wave (FMCW) radar or a WiFi device. We propose a 3D-TransPOSE algorithm for the 3D human pose estimation from the IR-UWB radar signals. The proposed algorithm is designed based on the transformer architecture. While the transformer has actively been studied in the natural language processing (NLP) or vision domains, no prior work has applied the transformer model to the RF-based human pose estimation problem. The attention mechanism of the proposed algorithm is able to focus on the relevant time segments of the IR-UWB radar signals for detecting the human pose, eliminating the needs of converting radar signals to a voxelized 3D image. We have gathered a large dataset of IR-UWB radar signals labeled with 3D human skeletons, and shown that the proposed algorithm is able to detect human skeletons with a high accuracy.

Contactless multiscale measurement of cardiac motion using biomedical radar sensor.

A contactless multiscale cardiac motion measurement method is proposed using impulse radio ultra-wideband (IR-UWB) radar at a center frequency of 7.29 GHz. Electrocardiograph (ECG), heart sound, and ultrasound are traditional state-of-the-art heartbeat signal measurement methods. These methods suffer from defects in contact and the existence of a blind information segment during the cardiogram measurement. Experiments and analyses were conducted using coarse-to-fine scale. Anteroposterior and along-the-arc measurements were taken from five healthy male subjects (aged 25-43) when lying down or prone. In every measurement, 10 seconds of breath-holding data were recorded with a radar 55 cm away from the body surface, while the ECG was monitored simultaneously as a reference. Cardiac motion detection from the front was superior to that from the back in amplitude. In terms of radar detection angles, the best cardiac motion information was observed at a detection angle of 120°. Finally, in terms of cardiac motion cycles, all the ECG information, as well as short segments of cardiac motion details named blind ECGs segments, were detected. A contactless and multiscale cardiac motion detection method is proposed with no blind detection of segments during the entire cardiac cycle. This paves the way for a potentially significant method of fast and accurate cardiac disease assessment and diagnosis that exhibits promising application prospects in contactless online cardiac monitoring and in-home healthcare.

Accurate sensing of multiple humans buried under rubble using IR-UWB SISO radar during search and rescue

Upon the collapse of man-made structures like buildings, bridges, etc., the search and rescue personnel must locate and rescue the buried people. Considering the radar’s beam width, victims may be buried under rubble at the same longitudinal range from the radar and fall into blind spots due to missed detections. Here, we will address this problem efficiently. Experimental work has been undertaken by placing subjects under randomized rubble with an impulse-radio ultra-wideband (IR-UWB) radar placed above the debris. Pre-processing the raw data removes stationary and non-stationary clutter, while the novel variance threshold method proposed herein identified the potential targets. The inter-target dynamic range (ITDR) concept is presented to extract the exact number of targets per range bin by considering the difference in the power level of consecutive dominant target breathing frequencies. Consequently, variable mode decomposition (VMD) is used to extract the breathing signal. An average correlation coefficient of 87.9 % was achieved between the target vital signs from the radar and the respiration belt. Finally, a range compensation algorithm is developed to increase detection efficiency to an average of 7.23 % range error. Thus, multiple targets are successfully extracted with reasonably accurate range and vital signs under varying target postures.

A 21.3%-Efficiency Clipped-Sinusoid UWB Impulse Radio Transmitter with Simultaneous Inductive Powering and Data Receiving.

An ultra-wide-band impulse-radio (UWB-IR) transmitter (TX) for low-energy biomedical microsystems is presented. High power efficiency is achieved by modulating an LC tank that always resonates in the steady state during transmission. A new clipped-sinusoid scheme is proposed for on-off keying (OOK)-modulation, which is implemented by a voltage clipper circuit with on-chip biasing generation. The TX is designed to provide a high data-rate wireless link within the 3-5 GHz band. The chip was fabricated in 130nm CMOS technology and fully characterized. State-of-the-art power efficiency of 21.3% was achieved at a data-rate of 230Mbps and energy consumption of 21pJ/b. A bit-error-rate (BER) of less than 10 -6 was measured at a distance of 1m without pulse averaging. In addition, simultaneous wireless powering and VCO-based data transmission are supported. A potential extension to a VCO-free all-wireless mode to further reduce the power consumption is also discussed.

Design of Optical-Wireless IR-UWBoF Systems with Spectral Line Suppression Capabilities

Impulse-Radio Ultra-Wide Band (IR-UWB) over Fiber (IR-UWBoF) has been proposed to interconnect IR-UWB-based deployments separated by hundreds of meters or even kilometers. IR-UWB transmissions must comply with spectral masks provided by radio spectrum regulatory agencies. The maximum transmit power of an IR-UWB signal is adversely affected by the presence of spectral lines in its Power Spectral Density (PSD). Thus, it is desirable that the PSD of signals generated by IR-UWBoF systems does not show spectral lines. Previous works have shown the feasibility of deploying of optical-wireless IR-UWBoF systems. However, most of these proposals report PSDs showing spectral lines. To the best of our knowledge, spectral line suppression has not been previously studied for optical-wireless IR-UWBoF systems. This work shows the design and implementation of optical-wireless IR-UWBoF systems generating signals with Spectral Line-Free (SLF) PSDs. The proposal considers the use the use of a specifically designed convolutional code combined with Binary Phase Shift Keying (BPSK) or Quaternary Biorthogonal Pulse Position Modulation (Q-BOPPM) to provide a SLF PSD in IR-UWBoF systems. A testbed consisting of 30 km of single-mode optical fiber (SMF) concatenated to a 20 cm wireless link was physically implemented. The results show that a SLF PSD is achieved for both the optical and the wireless transmissions, even when the binary data source feeding the system is not perfectly random.

Early screening tool for developmental delay in infancy: Quantified assessment of movement asymmetry using IR-UWB radar.

In the untact COVID-19 era, the feasibility of a noncontact, impulse-radio ultrawideband (IR-UWB) radar sensor has important medical implications. Premature birth is a major risk factor for brain injury and developmental delay; therefore, early intervention is crucial for potentially achieving better developmental outcomes. Early detection and screening tests in infancy are limited to the quantification of differences between normal and spastic movements. This study investigated the quantified asymmetry in the general movements of an infant with hydrocephalus and proposes IR-UWB radar as a novel, early screening tool for developmental delay. To support this state-of-the-art technology, data from actigraphy and video camcorder recordings were adopted simultaneously to compare relevant time series as the infant grew. The data from the three different methods were highly concordant; specifically, the ρz values comparing radar and actigraphy, which served as the reference for measuring movements, showed excellent agreement, with values of 0.66 on the left and 0.56 on the right. The total amount of movement measured by radar over time increased overall; movements were almost dominant on the left at first (75.2% of total movements), but following shunt surgery, the frequency of movement on both sides was similar (54.8% of total movements). As the hydrocephalus improved, the lateralization of movement on radar began to coincide with the clinical features. These results support the important complementary role of this radar system in predicting motor disorders very early in life.

Noncontact assessment for fatigue based on heart rate variability using IR-UWB radar

Physical fatigue can be assessed using heart rate variability (HRV). We measured HRV at rest and in a fatigued state using impulse-radio ultra wideband (IR-UWB) radar in a noncontact fashion and compared the measurements with those obtained using electrocardiography (ECG) to assess the reliability and validity of the radar measurements. HRV was measured in 15 subjects using radar and ECG simultaneously before (rest for 10 min before exercise) and after a 20-min exercise session (fatigue level 1 for 0–9 min; fatigue level 2 for 10–19 min; recovery for ≥ 20 min after exercise). HRV was analysed in the frequency domain, including the low-frequency component (LF), high-frequency component (HF) and LF/HF ratio. The LF/HF ratio measured using radar highly agreed with that measured using ECG during rest (ICC = 0.807), fatigue-1 (ICC = 0.712), fatigue-2 (ICC = 0.741) and recovery (ICC = 0.764) in analyses using intraclass correlation coefficients (ICCs). The change pattern in the LH/HF ratios during the experiment was similar between radar and ECG. The subject’s body fat percentage was linearly associated with the time to recovery from physical fatigue (R2 = 0.96, p < 0.001). Our results demonstrated that fatigue and rest states can be distinguished accurately based on HRV measurements using IR-UWB radar in a noncontact fashion.

A Non-Contact Detection Method for Multi-Person Vital Signs Based on IR-UWB Radar.

With the vigorous development of ubiquitous sensing technology, an increasing number of scholars pay attention to non-contact vital signs (e.g., Respiration Rate (RR) and Heart Rate (HR)) detection for physical health. Since Impulse Radio Ultra-Wide Band (IR-UWB) technology has good characteristics, such as non-invasive, high penetration, accurate ranging, low power, and low cost, it makes the technology more suitable for non-contact vital signs detection. Therefore, a non-contact multi-human vital signs detection method based on IR-UWB radar is proposed in this paper. By using this technique, the realm of multi-target detection is opened up to even more targets for subjects than the more conventional single target. We used an optimized algorithm CIR-SS based on the channel impulse response (CIR) smoothing spline method to solve the problem that existing algorithms cannot effectively separate and extract respiratory and heartbeat signals. Also in our study, the effectiveness of the algorithm was analyzed using the Bland–Altman consistency analysis statistical method with the algorithm’s respiratory and heart rate estimation errors of 5.14% and 4.87%, respectively, indicating a high accuracy and precision. The experimental results showed that our proposed method provides a highly accurate, easy-to-implement, and highly robust solution in the field of non-contact multi-person vital signs detection.

A Three-Stage Low-Complexity Human Fall Detection Method Using IR-UWB Radar

This paper proposes a novel three-stage low-complexity human fall detection method using an impulse radio ultra-wideband (IR-UWB) radar. The core idea lies in the three cascaded stages, namely large-motion detection, rough fall detection and enhanced fall detection. For the large-motion detection, we assume the fall is a very sparse event in daily life and achieve this by a checking of the high Doppler frequency energy. For the rough fall detection, we do not intuitively determine the fall events, but propose six time-frequency features and two position features, and use the support vector data description (SVDD) detector to divide the large-motions into non-fall and fall-like events. For the enhanced fall detection, we add a new feature and use a Mahalanobis distance classifier to finally determine whether a fall happened. The reasons that two classifiers cascaded instead of one classifier are that (1) we can reduce the difficulty of identifying falls directly from daily events by using a large number of non-fall samples to train the SVDD model for anomaly detection, and allowing a certain false alarm rate; and (2) we can achieve a higher fall detection accuracy in a much smaller searching space by identifying falls only from the fall-like events. Additionally, a real-time edge fall detection system with a commonly used micro control unit is developed. Experiment results show that the proposed method exhibits a low computational complexity, and a relative robustness and high fall detection accuracy under a low false alarm rate.

An IR-UWB CMOS Transceiver With Extended Pulse Position Modulation

An impulse radio ultra-wideband (IR-UWB) transceiver is implemented with low power, high data rate communication techniques, such as extended multipulse position modulation (E-MPPM), cross-coupled (CC) envelope detection, and digital frequency hopping (DFH). The use of the E-MPPM helps increase the modulation efficiency. The capacitive-CC technique helps improve the sensitivity by increasing the conversion gain of an envelope detector. DFH increases the pulse energy of a transmitted impulse without sacrificing the power spectral density (PSD) requirement. The proposed CMOS transceiver achieves a data rate of 1.125 Gbps and a radio range of 2 m with a power consumption of 28 mW and energy efficiency of 24.9 pJ/b.

A Deionized Water-Infilled Dual-Layer Insulator-Applied Brain-Implanted UWB Antenna for Wireless Biotelemetry Applications

We propose a novel double-layered insulator configuration for a human-brain-implanted impulse radio ultra-wideband (IR-UWB) antenna. The dimension of the antenna is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10.0\times 11.0\times0.954$ </tex-math></inline-formula> mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , including the dual-layer insulator. The insulator provides a dielectric loading effect of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varepsilon _{r}~\approx ~50$ </tex-math></inline-formula> (lossless) for obtaining an improved radiating power and the broadband-impedance-matching characteristic in brain tissues. The outer layer is made of biocompatible 3-D printing material, and the inner insulator is filled with deionized water with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varepsilon _{r}~\approx ~80$ </tex-math></inline-formula> and loss tangent (tan <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\delta$ </tex-math></inline-formula> ) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\approx ~0.25$ </tex-math></inline-formula> at 4 GHz. A slotted UWB antenna with the proposed insulator is located between the emulated dura and CSF tissues inside the skull for brain signal detection. The design uses a multilayer phantom, mimicking the seven tissue layers of the brain. The impedance and radiation performance of the proposed antenna configuration are also discussed using the commercial high-precision human phantom model. The designed IR-UWB antenna shows a boresight radiation characteristic toward the top of the head with a proper high gain in the target frequency of 3–5 GHz. The computed expectations are verified experimentally. Furthermore, it is demonstrated that the UWB spectrum generated from a UWB radio-frequency (RF) transmitter can be transmitted stably using the proposed antenna as a transmitting antenna. In addition, the link budget of the system setup is analyzed. The improved gain characteristic of the antenna from the proposed dual-layer insulator can be utilized to retain the link margins while satisfying the UWB communication regulation and average specific absorption rate (SAR) limitation.

An Integrated Primary Impulse Radio Ultra-Wideband Radar for Short-Range Real-Time Localization

This paper presents a primary impulse-radio ultra-wideband (IR-UWB) radar system for real-time short-range localization, e.g., for smart traffic and automotive applications. The radar system consisting of an integrated radar transceiver (TRx) using 45-nm SOI CMOS technology and an FPGA-based signal processing. The efficient transmitter (Tx), which complies with the regulations for both indoor and outdoor applications, modulates and emits a seventh derivative Gaussian pulse. In the receiver (Rx), echo signals will be amplified and sampled in real-time. The echo pulses are recovered by signal processing hardware on the FPGA, which is also used to perform simple classification tasks like user warning. The radar system is compact, portable, and power efficient. The Tx has a high-energy efficiency of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {11~ \text {p} \text {J} /pulse}$ </tex-math></inline-formula> . The proposed radar system achieves very high signal-to-noise ratio (SNR) and range precision. It has a maximum detection range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {15~m }$ </tex-math></inline-formula> and a range resolution down to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {3~ \text {cm}}$ </tex-math></inline-formula> . Moreover, a target of interest can be warned with a latency as fast as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {16~\mu s }$ </tex-math></inline-formula> by using 1-bit real-time sampling.

A Portable Traffic Counting, Speed Estimation, and Classification Terminal Using IR-UWB Radar

Because of the stable performance under any light and weather conditions, radar becomes one of the most important sensors for traffic flow surveillance in intelligent transportation system (ITS). This paper proposes a novel portable traffic counting, speed estimation, and classification terminal using impulse radio ultra-wideband (IR-UWB) radar. The proposed terminal is lightweight, installed at the roadside, and potable. Moreover, it can only operate on a micro control unit of ARM Cortex-M7 with low-complexity signal processing approaches. Specifically, a vehicle detection and counting approach based on target location combined with trajectory tracking, a non-coherent speed estimation approach by exploiting the trajectory and prior geometric information, and a vehicle type classification approach based on four different attribute features are developed. Finally, experiment results show the improved performance of the proposed approaches.