| 41. |
- Abu-Shaban, Z., et al.
(författare)
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Enhanced List-based Group-wise overloaded receiver with application to satellite reception
- 2014
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Ingår i: 2014 IEEE International Conference on Communications (ICC). - : IEEE conference proceedings. ; , s. 5616-5621
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Konferensbidrag (refereegranskat)abstract
- The market trends towards the use of smaller dish antennas for TV satellite receivers, as well as the growing density of broadcasting satellites in orbit require the application of robust adjacent satellite interference (ASI) cancellation algorithms at the receivers. The wider beamwidth of a small size dish and the growing number of satellites in orbit impose an overloaded scenario, i.e., a scenario where the number of transmitting satellites exceeds the number of receiving antennas. For such a scenario, we present a two stage receiver to enhance signal detection from the satellite of interest, i.e., the satellite that the dish is pointing to, while reducing interference from neighboring satellites. Towards this objective, we propose an enhanced List-based Group-wise Search Detection (LGSD) receiver architecture that takes into account the spatially correlated additive noise and uses the signal-to-interference-plus-noise ratio (SINR) maximization criterion to improve detection performance. Simulations show that the proposed receiver structure enhances the performance of satellite systems in the presence of ASI when compared to existing methods.
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| 42. |
- Abu-Shaban, Z., et al.
(författare)
-
Overloaded satellite receiver using SIC with hybrid beamforming and ML detection
- 2013
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Ingår i: 2013 IEEE 14th Workshop on Signal Processing Advances in Wireless Communications (SPAWC). - New York : IEEE. - 9781467355773 ; , s. 450-454
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Konferensbidrag (refereegranskat)abstract
- In this paper, a new receiver structure that is intended to detect the signals from multiple adjacent satellites in the presence of other interfering satellites is proposed. We tackle the worst case interference conditions, i.e., it is assumed that uncoded signals that fully overlap in frequency arrive at a multiple-element small-size parabolic antenna in a spatially correlated noise environment. The proposed successive interference cancellation (SIC) receiver, denoted by SIC Hy/ML, employs hybrid beamforming and disjoint maximum likelihood (ML) detection. Depending on the individual signals spatial position, the proposed SIC Hy/ML scheme takes advantage of two types of beamformers: a maximum ratio combining (MRC) beamformer and a compromised array response (CAR) beamformer. The performance of the proposed receiver is compared to an SIC receiver that uses only MRC beamforming scheme with ML detection for all signals, a joint ML detector, and a minimum mean square error detector. It is found that SIC Hy/ML outperforms the other schemes by a large margin.
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| 43. |
- Abu-Shaban, Zohair, et al.
(författare)
-
Reduced complexity satellite broadcast receiver with interference mitigation in correlated noise
- 2018
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Ingår i: International Journal of Satellite Communications And Networking. - : Edward Elgar Publishing. - 1542-0973 .- 1542-0981. ; 36:5, s. 402-415
-
Tidskriftsartikel (refereegranskat)abstract
- The recent commercial trends towards using smaller dish antennas for satellite receivers and the growing density of broadcasting satellites necessitate the application of robust adjacent satellite interference cancellation schemes. This orbital density growth along with the wider beamwidth of a smaller dish have imposed an overloaded scenario at the satellite receiver, where the number of transmitting satellites exceeds the number of receiving elements at the dish antenna. To ensure successful operation in this practical scenario, we propose a satellite receiver that enhances signal detection from the desired satellite by mitigating the interference from neighboring satellites. Towards this objective, we propose an enhanced list-based group-wise search detection (E-LGSD) receiver under the assumption of spatially correlated additive noise. To further enhance detection performance, the proposed satellite receiver utilizes a newly designed whitening filter to remove the spatial correlation among the noise parameters, while also applying a preprocessor that maximizes the signal-to-interference-plus-noise ratio. We exploit the structure of this filter and propose a reduced complexity LGSD (RC-LGSD) receiver. Extensive simulations under practical scenarios show that the proposed receiver enhances the performance of satellite broadcast systems in the presence of adjacent satellite interference compared with existing methods. Also, under pointing error, RC-LGSD exhibits similar behavior to that of the optimum receiver
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| 44. |
- Afzal, Hassan, et al.
(författare)
-
Full 3D Reconstruction of Non-Rigidly Deforming Objects
- 2018
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Ingår i: ACM Transactions on Multimedia Computing, Communications, and Applications (TOMCCAP). - : Association for Computing Machinery (ACM). - 1551-6857 .- 1551-6865. ; 14:1s
-
Tidskriftsartikel (refereegranskat)abstract
- In this article, we discuss enhanced full 360 degrees 3D reconstruction of dynamic scenes containing non-rigidly deforming objects using data acquired from commodity depth or 3D cameras. Several approaches for enhanced and full 3D reconstruction of non-rigid objects have been proposed in the literature. These approaches suffer from several limitations due to requirement of a template, inability to tackle large local deformations and topology changes, inability to tackle highly noisy and low-resolution data, and inability to produce online results. We target online and template-free enhancement of the quality of noisy and low-resolution full 3D reconstructions of dynamic non-rigid objects. For this purpose, we propose a view-independent recursive and dynamic multi-frame 3D super-resolution scheme for noise removal and resolution enhancement of 3D measurements. The proposed scheme tracks the position and motion of each 3D point at every timestep by making use of the current acquisition and the result of the previous iteration. The effects of system blur due to per-point tracking are subsequently tackled by introducing a novel and efficient multi-level 3D bilateral total variation regularization. These characteristics enable the proposed scheme to handle large deformations and topology changes accurately. A thorough evaluation of the proposed scheme on both real and simulated data is carried out. The results show that the proposed scheme improves upon the performance of the state-of-the-art methods and is able to accurately enhance the quality of low-resolution and highly noisy 3D reconstructions while being robust to large local deformations.
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| 45. |
- Afzal, H., et al.
(författare)
-
RGB-D multi-view system calibration for full 3D scene reconstruction
- 2014
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Ingår i: 2014 22nd International Conference on Pattern Recognition. - : IEEE conference proceedings. ; , s. 2459-2464
-
Konferensbidrag (refereegranskat)abstract
- One of the most crucial requirements for building a multi-view system is the estimation of relative poses of all cameras. An approach tailored for a RGB-D cameras based multi-view system is missing. We propose BAICP+ which combines Bundle Adjustment (BA) and Iterative Closest Point (ICP) algorithms to take into account both 2D visual and 3D shape information in one minimization formulation to estimate relative pose parameters of each camera. BAICP+ is generic enough to take different types of visual features into account and can be easily adapted to varying quality of 2D and 3D data. We perform experiments on real and simulated data. Results show that with the right weighting factor BAICP+ has an optimal performance when compared to BA and ICP used independently or sequentially.
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| 46. |
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| 47. |
- Al-Hraishawi, Hayder, et al.
(författare)
-
Energy Harvesting from Jamming Attacks in Multi-User Massive MIMO Networks
- 2023
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Ingår i: IEEE Transactions on Green Communications and Networking. - : Institute of Electrical and Electronics Engineers (IEEE). - 2473-2400. ; 7:3, s. 1181-1191
-
Tidskriftsartikel (refereegranskat)abstract
- Fifth-generation (5G) and beyond communication systems offer new functionalities and significant performance improvements but that comes at the cost of tougher energy requirements on user devices. Addressing this issue while reducing the environmental impact of the substantial increase in energy consumption can be achieved through energy-neutral systems that operate using energy harvested from radio frequency (RF) transmissions. In this direction, this work examines the concept of utilizing an unconventional source for RF energy harvesting. Specifically, the performance of an RF energy harvesting scheme for multi-user massive multiple-input multiple-output (MIMO) is investigated in the presence of multiple active jammers. The key idea is to exploit the jamming transmissions as an energy source to be harvested by the legitimate users. To this end, the feasibility of this concept is studied via system performance analysis for a training-based massive MIMO encompasses imperfectly estimated channel state information (CSI) at the base-station and employing the time-switching protocol. In particular, the achievable uplink sum rate expressions are derived in closed-form for two different antenna configurations at the base-station. Two optimal time-switching schemes are also proposed based on maximum sum rate and user-fairness criteria. The essential trade-off between the harvested energy and achievable sum rate in time-switching protocol are quantified in closed-form as well. Our analysis reveals that the proposed energy harvesting scheme from jamming signals is viable and can boost massive MIMO uplink performance by exploiting the surrounding RF signals of the jamming attacks for increasing the amount of harvested energy at the served users. Finally, numerical results validate the theoretical analyses and the effectiveness of the derived closed-form expressions through simulations.
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| 48. |
- Al Ismaeil, Kassem, et al.
(författare)
-
Bilateral Filter Evaluation Based on Exponential Kernels
- 2012
-
Konferensbidrag (refereegranskat)abstract
- The well-known bilateral filter is used to smooth noisy images while keeping their edges. This filter is commonly used with Gaussian kernel functions without real justification. The choice of the kernel functions has a major effect on the filter behavior. We propose to use exponential kernels with L1 distances instead of Gaussian ones. We derive Stein's Unbiased Risk Estimate to find the optimal parameters of the new filter and compare its performance with the conventional one. We show that this new choice of the kernels has a comparable smoothing effect but with sharper edges due to the faster, smoothly decaying kernels.
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| 49. |
- Al Ismaeil, K., et al.
(författare)
-
Depth super-resolution by enhanced shift and add
- 2013
-
Ingår i: Computer Analysis of Images and Patterns. - Berlin, Heidelberg : Springer. - 9783642402456 ; , s. 100-107
-
Konferensbidrag (refereegranskat)abstract
- We use multi-frame super-resolution, specifically, Shift & Add, to increase the resolution of depth data. In order to be able to deploy such a framework in practice, without requiring a very high number of observed low resolution frames, we improve the initial estimation of the high resolution frame. To that end, we propose a new data model that leads to a median estimation from densely upsampled low resolution frames. We show that this new formulation solves the problem of undefined pixels and further allows to improve the performance of pyramidal motion estimation in the context of super-resolution without additional computational cost. As a consequence, it increases the motion diversity within a small number of observed frames, making the enhancement of depth data more practical. Quantitative experiments run on the Middlebury dataset show that our method outperforms state-of-the-art techniques in terms of accuracy and robustness to the number of frames and to the noise level.
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| 50. |
- Al Ismaeil, K., et al.
(författare)
-
Dynamic super resolution of depth sequences with non-rigid motions
- 2013
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Ingår i: 2013 IEEE International Conference on Image Processing, ICIP 2013 - Proceedings. - : IEEE Signal Processing Society. - 9781479923410 ; , s. 660-664
-
Konferensbidrag (refereegranskat)abstract
- We enhance the resolution of depth videos acquired with low resolution time-of-flight cameras. To that end, we propose a new dedicated dynamic super-resolution that is capable to accurately super-resolve a depth sequence containing one or multiple moving objects without strong constraints on their shape or motion, thus clearly outperforming any existing super-resolution techniques that perform poorly on depth data and are either restricted to global motions or not precise because of an implicit estimation of motion. The proposed approach is based on a new data model that leads to a robust registration of all depth frames after a dense upsampling. The textureless nature of depth images allows to robustly handle sequences with multiple moving objects as confirmed by our experiments.
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