| 1. |
- Ahmed, Soban, et al.
(författare)
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Development and Optimization of Deep Learning Models for Weapon Detection in Surveillance Videos
- 2022
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Ingår i: Applied Sciences. - : MDPI. - 2076-3417. ; 12:12
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Tidskriftsartikel (refereegranskat)abstract
- Featured Application This work has applied computer vision and deep learning technology to develop a real-time weapon detector system and tested it on different computing devices for large-scale deployment. Weapon detection in CCTV camera surveillance videos is a challenging task and its importance is increasing because of the availability and easy access of weapons in the market. This becomes a big problem when weapons go into the wrong hands and are often misused. Advances in computer vision and object detection are enabling us to detect weapons in live videos without human intervention and, in turn, intelligent decisions can be made to protect people from dangerous situations. In this article, we have developed and presented an improved real-time weapon detection system that shows a higher mean average precision (mAP) score and better inference time performance compared to the previously proposed approaches in the literature. Using a custom weapons dataset, we implemented a state-of-the-art Scaled-YOLOv4 model that resulted in a 92.1 mAP score and frames per second (FPS) of 85.7 on a high-performance GPU (RTX 2080TI). Furthermore, to achieve the benefits of lower latency, higher throughput, and improved privacy, we optimized our model for implementation on a popular edge-computing device (Jetson Nano GPU) with the TensorRT network optimizer. We have also performed a comparative analysis of the previous weapon detector with our presented model using different CPU and GPU machines that fulfill the purpose of this work, making the selection of model and computing device easier for the users for deployment in a real-time scenario. The analysis shows that our presented models result in improved mAP scores on high-performance GPUs (such as RTX 2080TI), as well as on low-cost edge computing GPUs (such as Jetson Nano) for weapon detection in live CCTV camera surveillance videos.
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| 2. |
- Dost, Shahi, et al.
(författare)
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Reduced reference image and video quality assessments : review of methods
- 2022
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Ingår i: EURASIP Journal on Image and Video Processing. - : Springer. - 1687-5176 .- 1687-5281. ; 2022:1
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Forskningsöversikt (refereegranskat)abstract
- With the growing demand for image and video-based applications, the requirements of consistent quality assessment metrics of image and video have increased. Different approaches have been proposed in the literature to estimate the perceptual quality of images and videos. These approaches can be divided into three main categories; full reference (FR), reduced reference (RR) and no-reference (NR). In RR methods, instead of providing the original image or video as a reference, we need to provide certain features (i.e., texture, edges, etc.) of the original image or video for quality assessment. During the last decade, RR-based quality assessment has been a popular research area for a variety of applications such as social media, online games, and video streaming. In this paper, we present review and classification of the latest research work on RR-based image and video quality assessment. We have also summarized different databases used in the field of 2D and 3D image and video quality assessment. This paper would be helpful for specialists and researchers to stay well-informed about recent progress of RR-based image and video quality assessment. The review and classification presented in this paper will also be useful to gain understanding of multimedia quality assessment and state-of-the-art approaches used for the analysis. In addition, it will help the reader select appropriate quality assessment methods and parameters for their respective applications.
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| 3. |
- Khan, Muhammad Gufran, et al.
(författare)
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A Doublet-Shift Transmitted Reference Scheme for Ultra-Wideband Communication Systems
- 2007
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Konferensbidrag (refereegranskat)abstract
- The transmitted reference (TR) scheme has gained attention for ultra-wideband (UWB) communications as it bypasses the complex task of channel estimation and provides a simple receiver structure. However, the low-complexity detection in this scheme is achieved at the expense of a loss in performance. To this end, this paper proposes a doublet-shift TR (DsTR) signaling and detection scheme to improve the performance of conventional TR impulse radio UWB system. The performance of the proposed scheme is compared with conventional TR signaling scheme in terms of uncoded bit error rate (BER). The simulation results validate that the doublet-shift TR scheme achieves about 1.5-2 dB better performance than the conventional TR scheme. The DsTR scheme does not require extra energy and still has the low-complexity.
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| 4. |
- Khan, Muhammad Gufran, et al.
(författare)
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An energy-efficient signaling and detection scheme for transmitted reference UWB systems
- 2008
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Konferensbidrag (refereegranskat)abstract
- The transmitted reference (TR) schemes do not require the complex task of channel estimation and provide a simple receiver structure. However, the low-complexity detection in conventional TR scheme is achieved at the expense of 50% energy/rate loss. In this paper, an energy-efficient TR signaling and detection scheme is presented with the aim to improve the performance of conventional TR impulse radio UWB system. The proposed scheme is a combination of the conventional TR scheme and the differential TR scheme. The simulation results validate that the proposed TR scheme utilizes 1.76 dB less energy per bit and recovers 25% rate loss of conventional TR scheme, while maintaining the same BER performance. Further, the proposed ATR scheme improves the BER performance by about 2 dB using simple averaging of the reference pulses. ©2008 IEEE.
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| 5. |
- Khan, Muhammad Gufran, et al.
(författare)
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Detection of Impulse Radio Ultra-Wideband Signals using Recursive Transmitted Reference Receivers
- 2007
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Konferensbidrag (refereegranskat)abstract
- For the detection of impulse radio (IR) UWB signals, complex RAKE receiver or low-complexity transmitted reference (TR) autocorrelation receivers can be used. However, there is a performance loss associated with the low-complexity TR scheme. This paper proposes recursive structures of the conventional TR and averaged TR schemes to improve the detection performance of IR-UWB signals. The performance of proposed schemes is evaluated over the standard IEEE 802.15.4a multipath channels. The performance is compared with conventional TR receivers in terms of uncoded bit-error-rate (BER), assuming that the channel is quasi-static. For averaged and recursive averaged TR schemes, the TR sequence is also slightly modified. The simulation results validate that the proposed schemes has better performance by about 2 dB than the conventional TR and averaged TR receivers.
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| 6. |
- Khan, Muhammad Gufran, et al.
(författare)
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Energy efficient binary PPM/code-multiplexed transmitted-reference multi-user UWB system
- 2011
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Konferensbidrag (refereegranskat)abstract
- This paper presents a combined binary pulse position modulation (BPPM)/code-multiplexed transmitted-reference (CM-TR) ultra wideband (UWB) system. The low complexity CM-TR UWB is not energy efficient as one half of the energy is used to transmit reference pulses and, even at low-to-medium data rates, it suffers from strong multi-user interference (MUI) and inter-frame interference (IFI). Keeping the information rate constant, the combined BPPM/CM-TR UWB system utilizes 3 dB less energy per bit as compared to the CM-TR system and achieves relatively longer silent periods between the pulses, which not only mitigate the IFI but also decrease the MUI due to less collisions with other asynchronous users. In the high SNR region, where the effect of IFI and MUI severely degrades the bit-error-rate (BER) performance of the multiuser CM-TR system, simulation results verify that the multiuser BPPM/CM-TR outperforms the multiuser CM-TR system.
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| 7. |
- Khan, Muhammad Gufran, et al.
(författare)
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Measurements and Analysis of UWB Channels in Industrial Environments
- 2005
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Konferensbidrag (refereegranskat)abstract
- Communication in industrial environments is an important scenario for ultra wideband (UWB) systems. The characteristics of this environment differ considerably from office environments, where most of the channel measurements reported in the literature are performed. In this paper, we present the results and analysis of UWB channel measurements in an industrial environment. We investigate both peer-to-peer non-line-of-sight (P-P NLOS) and base station NLOS (BS NLOS) scenarios. The measurements are performed in the frequency range 3.1 to 8 GHz, at distances 2-16 m, using a vector network analyzer in conjunction with virtual antenna arrays. From these measurements, we extract channel model parameters such as power delay profiles, pathloss exponents, rms delay spread and the percentage of energy captured by RAKE receivers with a finite number of fingers. In addition, Saleh- Valenzuela parameters such as ray and cluster power decay constants and distribution of cluster interarrival times are extracted.
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| 8. |
- Khan, Muhammad Gufran, et al.
(författare)
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Non-coherent detection of impulse radio UWB signals based on fourth order statistics
- 2009
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Konferensbidrag (refereegranskat)abstract
- Non-coherent receivers are an attractive solution for impulse radio (IR) ultra wideband (UWB) systems due to their low-complexity implementation and low power consumption. However, low-complexity detection is achieved at the expense of some loss in performance. In this paper, a non-coherent detection scheme based on fourth order statistics, i.e., kurtosis, is proposed for low data rate IR-UWB systems. The performance of a conventional energy detector (ED) and the proposed kurtosis detector (KD) is compared in terms of bit-error-rate (BER). The simulation results validate that the KD receiver outperforms a conventional ED receiver on both additive white Gaussian noise (AWGN) and IEEE 802.15.4a multipath channels.
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| 9. |
- Khan, Muhammad Gufran, et al.
(författare)
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Non-coherent detection of impulse radio UWB signals based on fourth order statistics
- 2011
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Ingår i: Wireless Personal Communications. - : Springer Science and Business Media LLC. - 1572-834X .- 0929-6212.
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Tidskriftsartikel (refereegranskat)abstract
- Low-complex and low power non-coherent energy detector (ED) is interesting for low data rate impulse radio (IR) ultra wideband (UWB) systems but, compared to coherent receivers, it suffers from a loss in performance due to low signal-to-noise ratio (SNR) at the detector. In addition, the performance of an ED strongly depends on the integration interval (window size) of the integrator and the window position. A non-coherent kurtosis detector (KD) and a fourth-order detector (FD), which can discriminate between Gaussian noise signals and non-Gaussian IR-UWB signals by directly estimating the fourth-order moment of the received signal, are presented. The performance of the detectors is evaluated using real channels measured in a corridor, an office and a laboratory environment. The results show that bit-error-rate (BER) performance of the proposed KD receiver is better than the ED receiver only under certain conditions, while the FD receiver is slightly better than the ED in low SNR region and its performance improves as the SNR increases. In addition, the performance of the FD receiver is less sensitive to overestimation of the integration interval making it relatively robust to variations of the channel delay spread. Finally, a criteria for the selection of integration time of the proposed detector is suggested.
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| 10. |
- Khan, Muhammad Gufran, et al.
(författare)
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Non-Coherent Fourth-Order Detector for Impulse Radio Ultra Wideband Systems : Empirical Evaluation Using Channel Measurements
- 2013
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Ingår i: Wireless personal communications. - : Springer. - 0929-6212 .- 1572-834X. ; 68:1, s. 27-46
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Tidskriftsartikel (refereegranskat)abstract
- Low-complex and low-power non-coherent energy detectors (EDs) are interesting for low data rate impulse radio (IR) ultra wideband (UWB) systems, but suffer from a loss in performance compared to coherent receivers. The performance of an ED also strongly depends on the integration interval (window size) of the integrator and the window position. This paper presents a non-coherent fourth-order detector (FD) which can discriminate between Gaussian noise signals and non-Gaussian IR-UWB signals by directly estimating the fourth-order moment of the received signal. The performance of the detectors is evaluated using realistic channels measured in a corridor, an office and a laboratory environment. The results show that bit-error-rate (BER) performance of the proposed FD receiver is slightly better than the ED in low signal-to-noise ratio (SNR) region and its performance improves as the SNR increases. In addition, BER of the FD receiver is less sensitive to overestimation of the integration interval making it relatively robust to variations of the channel delay spread. Finally, a criteria for the selection of integration time of the proposed detector is suggested.
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| 11. |
- Khan, Muhammad Gufran
(författare)
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On Coherent and Non-coherent Receiver Structures for Impulse Radio UWB Systems
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The demand and growth of short-range wireless communications has been tremendous in the past few years for a diverse range of applications. There is significant interest in ultra wideband (UWB) as a physical layer technology for both high-data-rate (HDR), and low power, low-data-rate (LDR) short-range communications. The unique qualities of UWB such as large bandwidth, very low power spectral density (PSD) and fine time-resolution provide higher channel capacity, reduced fading effects and position location capability in a UWB system. The extremely wide bandwidth of UWB systems also poses many system design challenges to achieve low cost and low-complexity UWB devices. The UWB systems have difficulties in using digital signal processing (DSP) technology, require high sampling frequencies and also face frequency dependent signal distortion. The propagation characteristics of UWB signals also require consideration as it differs significantly from traditional narrowband systems. In this thesis, the issue of design and performance evaluation of coherent and non-coherent receivers for detection of impulse radio (IR) UWB signals is addressed. The coherent RAKE and non-coherent transmitted reference (TR) receiver structures are investigated for low power and low-data-rate wireless sensor network applications. First, the performance of coherent RAKE receivers for a single-user system operating in non-line-of-sight (NLOS) scenarios in an industrial environment is evaluated. The results and performance comparison is presented for partial RAKE (PRake) and selective RAKE (SRake) using maximal ratio combining (MRC) and equal gain combining (EGC). Secondly, the recursive structures of conventional TR and averaged TR schemes are presented to decrease the performance loss associated with the low-complexity TR scheme for IR-UWB systems. Further, a doublet-shift TR (DSTR) signaling and detection scheme is presented for IR-UWB systems. The simulation results validate that the doublet-shift TR signaling scheme improves the performance over conventional TR signaling scheme. Finally, dual-doublet TR (DDTR) signaling and detection schemes are proposed. The proposed dual-doublet TR schemes recover 25 to 50% energy/rate loss of conventional TR scheme. The performance of receiver structures is evaluated in terms of uncoded bit-error-rate (BER) over the channels measured in a medium-sized industrial environment and standard IEEE 802.15.4a multipath channels.
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| 12. |
- Khan, Muhammad Gufran
(författare)
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On Modulation and Detection Schemes for Low-Complexity Impulse Radio UWB Communications
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Due to wealth of advantages offered by short range ultra wideband (UWB) technology, such as capacity improvement, fading reduction and localization, it has gathered a considerable attention. Distinct UWB qualities also pose many system design challenges like difficulties in using digital processing, complex channel estimation and different propagation characteristics. The main objective of the thesis is to develop and evaluate efficient modulation and detection schemes for impulse radio (IR) UWB with a focus on wireless sensor networks characterized by low cost and low power consumption. The content of the thesis comprises of five parts. In Part I, a coherent RAKE and non-coherent energy detector (ED) and transmitted reference (TR) receivers are examined and their bit-error-rate (BER) performance is evaluated using channels measured in an industrial environment. In specific, selective RAKE (SRake) and partial RAKE (PRake) for both maximal ratio combining (MRC) and equal gain combining (EGC) are compared. Based on the analysis and simulation results, it is concluded the SRake with EGC is to be preferred, whereas the best complexity/performance trade-off is provided by the ED based receivers. Part II presents several signaling and detection schemes; the proposed schemes are recursive TR (R-TR), dual-doublet TR (DDTR), doublet-shift TR (DSTR) and binary pulse position modulation (BPPM)/DSTR. Analysis and simulations verify that the proposed schemes may be preferred over the conventional TR in terms of BER, energy efficiency and/or implementation complexity. Part III presents a non-coherent kurtosis detector (KD) and a fourth-order detector (FD), which can discriminate between Gaussian noise and non-Gaussian IR-UWB signals by directly estimating the fourth-order moment of the received signal. Empirical evaluations and simulations using channel measurements conducted in a corridor, an office and a laboratory environment verify that performance of the proposed FD receiver is slightly better than the ED in the low SNR region and its performance improves as the SNR increases. Part IV presents a robust weighted ED (WED) in which the weighting coefficients are estimated adaptively based on the received stochastic data. Simulation results confirm that performance of the proposed weight estimation method is close to that of a data-aided (DA) scheme. Finally, Part V focuses on a multi-user scenario and develops a weighted code-multiplexed TR (WCM-TR) receiver employing the robust adaptive weight estimation scheme. Secondly, a BPPM/CM-TR UWB system is presented to mitigate inter-frame interference (IFI) and multi-user interference (MUI) from other asynchronous users. The BPPM/CM-TR system is 3 dB energy-efficient and improves the BER performance by mitigating MUI/IFI in the high SNR region, while for the low SNR case and single-user scenario, a dual-mode BPPM/CM-TR system is suggested
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| 13. |
- Khan, Muhammad Gufran, et al.
(författare)
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Performance Evaluation of RAKE Receiver for Low Data Rate UWB Systems using Multipath Channels for Industrial Environments
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Since US FCC passed a resolution in 2002 allowing ultra wideband (UWB) transmissions within a specified unlicensed spectral mask, the interest in UWB technology has grown tremendously. The large bandwidth, low power spectral density (PSD), high multiple access capability and high resolution are some qualities of UWB technology. For UWB communication systems, the industrial environments are an important scenario. However, due to large number of metallic scatterers in the environment, the multipath offered by UWB channels is dense and many multipath components have significant energy. In this report, the performance evaluation of RAKE receivers for a single user system operating in non-line-of-sight (NLOS) scenarios in industrial environments is presented. The channels used for the evaluation are measured in a medium-sized industrial environment. In addition, the standard IEEE 802.15.4a channel model for NLOS industrial environment is used for comparison with the results of the measured channels. The performance is compared for partial RAKE (PRake) and selective RAKE (SRake) in terms of uncoded bit-error-rate (BER) with the assumption that the channel is known. The effect of different number of fingers on BER of PRake and Srake is studied. Moreover, the performance of maximal ratio combining (MRC) and equal gain combining (EGC) is compared for PRake and Srake receiver. The results also provide a performance comparison between different Tx-Rx separations. Finally, based on the simulation results, conclusions are presented considering the performance and complexity issues.
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| 14. |
- Khan, Muhammad Gufran, et al.
(författare)
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Performance Evaluation of RAKE Receiver for UWB Systems using Measured Channels in Industrial Environments
- 2006
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Konferensbidrag (refereegranskat)abstract
- The industrial environments are an important scenario for ultra wideband (UWB) communication systems. However, due to large number of metallic scatterers in the surroundings, the multipath offered by UWB channels is dense with significant energy. In this paper, the performance of RAKE receivers operating in a non line-of-sight (NLOS) scenario in these environments is evaluated. The channels used for the evaluation are measured in a medium-sized industrial environment. In addition, a standard IEEE 802.15.4a channel model is used for comparison with the results of the measured data. The performance of partial RAKE (PRake) and selective RAKE (SRake)is evaluated in terms of uncoded bit-error-rate (BER) using different number of fingers. The performance of maximal ratio combining (MRC) and equal gain combining (EGC) is compared for the RAKE receiver assuming perfect knowledge of the channel state. Finally, based on the simulation results, conclusions are drawn considering the performance and complexity issues for system design in these environments.
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| 15. |
- Khan, Muhammad Gufran, et al.
(författare)
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Recursive Transmitted Reference Receivers for Impulse Radio UWB Systems
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- For the detection of impulse radio (IR) UWB signals, RAKE receivers or transmitted reference (TR) autocorrelation receivers can be used. The complexity of RAKE receiver increases significantly when the number of received multipath components is large. The TR scheme is a low-complexity alternative as it does not require channel estimation. However, there is a performance loss associated with the low-complexity TR scheme. The recursive structures of the conventional TR and averaged TR schemes are presented to improve the detection performance of IR-UWB signals. The performance of proposed schemes is evaluated over the standard IEEE 802.15.4a multipath channels. The performance is compared with conventional TR receivers in terms of uncoded bit-error-rate (BER), assuming that the channel is quasi-static. For averaged and recursive averaged TR schemes, the TR sequence is also slightly modified. The simulation results validate that the proposed schemes have better performance by about 2 dB than the conventional TR and averaged TR receivers.
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| 16. |
- Khan, Muhammad Gufran, et al.
(författare)
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Robust Weighted Non-Coherent Receiver for Impulse Radio UWB PPM Signals
- 2011
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Ingår i: IEEE Communications Letters. - : IEEE Communications Society. - 1089-7798 .- 1558-2558. ; 15:06, s. 614-616
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Tidskriftsartikel (refereegranskat)abstract
- This letter proposes an energy detection based robust weight estimation scheme for pulse-position modulated (PPM) impulse radio ultra-wideband (IR-UWB) signals using weighted non-coherent receiver (WNCR). Conventional data-aided WNCR (DA-WNCR) scheme estimates the weighting coefficients, or channel state information (CSI), using a large number of training symbols over time-varying channels. In contrast, the proposed Robust WNCR (R-WNCR) scheme is non-data-aided (NDA), adaptive and robust to channel variations. The proposed R-WNCR estimates the weighting coefficients adaptively based on the received stochastic data, and the weight estimation process is refined using a decision directed approach.
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