| 1. |
- Aziz, Maryam, et al.
(författare)
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Mobility impact on the end-to-end delay performance for VoIP over LTE
- 2012
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Ingår i: Procedia Engineering. - Coimbatore : Elsevier. - 1877-7058. ; , s. 491-498
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Konferensbidrag (refereegranskat)abstract
- Long Term Evolution (LTE) is the last step towards the 4th generation of cellular networks. This revolution is necessitated by the unceasing increase in demand for high speed connection on LTE networks. This paper focuses on the performance evaluation of End-to-End delay under variable mobility speed for VoIP (Voice over IP) in the LTE network. In the course of E2E performance evaluation, realizing simulation approach three scenarios have been modeled using OPNET 16.0. The first one is the baseline network while among other two, one consists of VoIP traffic solely and the other consists of FTP along with VoIP. E2E delay has been measured for both scenarios in various cases under the varying mobility speed of the node. Simulation results have been studied and presented in terms of comparative performance analysis of the three network scenarios. In light of the result analysis, the performance quality of a VoIP network (with and without the presence of additional network traffic) in LTE has been determined and discussed. The simulation results for baseline VoIP network (non-congested) congested VoIP network and congested VoIP with FTP network show that as the speed of node is gradually increased, E2E delay slightly increases.
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| 2. |
- Bartunek, Josef Ström, et al.
(författare)
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Adaptive Fingerprint Binarization by Frequency Domain Analysis
- 2006
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents a new approach for fingerprint enhancement by using directional filters and binarization. A straightforward method for automatically tuning the size of local area is obtained by analyzing entire fingerprint image in the frequency domain. Hence, the algorithm will adjust adaptively to the local area of the fingerprint image, independent on the characteristics of the fingerprint sensor or the physical appearance of the fingerprints. Frequency analysis is carried out in the local areas to design directional filters. Experimental results are presented.
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| 3. |
- Bartunek, Josef Ström, et al.
(författare)
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Improved Adaptive Fingerprint Binarization
- 2008
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Konferensbidrag (refereegranskat)abstract
- In this paper improvements to a previous work are presented. Removing the redundant artifacts in the fingerprint mask is introduced enhancing the final result. The proposed method is entirely adaptive process adjusting to each fingerprint without any further supervision of the user. Hence, the algorithm is insensitive to the characteristics of the fingerprint sensor and the various physical appearances of the fingerprints. Further, a detailed description of fingerprint mask generation not fully described in the previous work is presented. The improved experimental results are presented.
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| 4. |
- Bartunek, Josef Ström, et al.
(författare)
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Neural Network based Minutiae Extraction from Skeletonized Fingerprints
- 2006
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Human fingerprints are rich in details denoted minutiae. In this paper a method of minutiae extraction from fingerprint skeletons is described. To identify the different shapes and types of minutiae a neural network is trained to work as a classifier. The proposed neural network is applied throughout the fingerprint skeleton to locate various minutiae. A scheme to speed up the process is also presented. Extracted minutiae can then be used as identification marks for automatic fingerprint matching.
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| 5. |
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| 6. |
- Dam, Hai Huyen, et al.
(författare)
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Complex Spreading Sequence Design
- 2002
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Konferensbidrag (refereegranskat)abstract
- The performance of code division multiple access system depends on the correlation of the employed spreading code. Low cross-correlation values between spreading sequences are desired to suppress multiple access interference. An auto-correlation function with with a distinct peak enables proper synchronization and suppresses intersymbol interference. However, these requirements contradict each other and a trade-off needs to be established. In this paper, a global two dimensional optimization method is proposed to minimize auto-correlation with cross-correlation being allowed to lie within a fixed region. This approach is applied to design a set of complex valued spreading sequences.
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| 7. |
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| 8. |
- Dam, Hai Huyen, et al.
(författare)
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Non-Causal Delayless Subband Adaptive Equalizer
- 2002
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Konferensbidrag (refereegranskat)abstract
- In wireless communication, multiple versions of the transmitted signals arrive at the receiver with different attenuations and time delays. Thus, an equalizer with long filter is required at the receiver to reverse the multipath effects. In this paper, a new non-causal delayless subband equalizer structure is proposed to reduce the computational complexity of the equalizer and to improve the channel tracking capability. This structure avoids the additional delays usually associated with the subband schemes. A design method is formulated to minimize the aliasing effect of the filter bank in the subbands. The significance of employing a non-causal equalizer is also emphasized. Simulation results show that the performance of the new structure is significantly improved by using the design method. Moreover, the complexity of the new subband equalizer is a fraction of the equivalent fullband at the expense of small degradation in the performance.
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| 9. |
- Dam, Hai Huyen, et al.
(författare)
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Spreading Code Design Using a Global Optimization Method
- 2005
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Ingår i: Annals of Operations Research. - : Springer. - 0254-5330 .- 1572-9338. ; 133:1-4, s. 249-264
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Tidskriftsartikel (refereegranskat)abstract
- The performance of a code division multiple access system depends on the correlation properties of the employed spreading code. Low cross-correlation values between spreading sequences are desired to suppress multiple access interference and to improve bit error performance. An auto-correlation function with a distinct peak enables proper synchronization and suppresses intersymbol interference. However, these requirements contradict each other and a trade-off needs to be established. In this paper, a global two dimensional optimization method is proposed to minimize the out-of-phase average mean-square aperiodic auto-correlation with average mean-square aperiodic cross-correlation being allowed to lie within a fixed region. This approach is applied to design sets of complex spreading sequences. A design example is presented to illustrate the relation between various correlation characteristics. The correlations of the obtained sets are compared with correlations of other known sequences.
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| 10. |
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