Pub Date : 2011-05-08DOI: 10.1109/CTS.2011.5898954
R. Radeke, Stefan Türk, R. Lehnert
Many localization algorithms require that at least some nodes in a network know their correct real position. Anchor-free localization algorithms manage to assign to all nodes virtual coordinates (VC) without knowledge of real location information. This is mostly done by node cooperation. These algorithms provide VCs for the usage of geographic routing in environments where real coordinate localization is impossible due to cost, time, energy, space or line of sight restrictions. This paper proposes improvements in generating VCs for wireless ad-hoc networks without location information. We present algorithms for improving the preparatory phase, which is used to obtain initial VCs as well as for the working phase, which adapts to network changes and node movement. Using simulations for different node densities and network sizes, we compare different approaches and show which algorithms outperform others.
{"title":"Optimization of 2d virtual node coordinates in anchor-free localization algorithms for geographic routing in ad-hoc networks","authors":"R. Radeke, Stefan Türk, R. Lehnert","doi":"10.1109/CTS.2011.5898954","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898954","url":null,"abstract":"Many localization algorithms require that at least some nodes in a network know their correct real position. Anchor-free localization algorithms manage to assign to all nodes virtual coordinates (VC) without knowledge of real location information. This is mostly done by node cooperation. These algorithms provide VCs for the usage of geographic routing in environments where real coordinate localization is impossible due to cost, time, energy, space or line of sight restrictions. This paper proposes improvements in generating VCs for wireless ad-hoc networks without location information. We present algorithms for improving the preparatory phase, which is used to obtain initial VCs as well as for the working phase, which adapts to network changes and node movement. Using simulations for different node densities and network sizes, we compare different approaches and show which algorithms outperform others.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129773211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-08DOI: 10.1109/CTS.2011.5898939
Bin Li, Yumei Wang, Qing Huang, Yu Liu
Low-density Parity-Check (LDPC) code is widely used in distributed video coding (DVC) to realizing Wyner-Ziv (WZ) coding for its better performance than other channel codes. However, during the LDPC decoding process, most of DVC solutions do not make use of the video character to help decoding. In this paper, we propose an improved LDPC decoding scheme for DVC by utilizing the movement of the objects in the video sequence to partition different confidence areas for the side information (SI). The pixels in the SI correspond to different confidence areas, and the corresponding binary representations of the pixels will have different likelihood-ratio (LLR) initialization methods which are used to generate the LLR values for LDPC iterative decoding. The experimental results show that with the proposed decoding scheme the PSNR gain can reach up to 0.8 db without increasing the decoding complexity.
{"title":"An LDPC-based improved decoding scheme for distributed video codec","authors":"Bin Li, Yumei Wang, Qing Huang, Yu Liu","doi":"10.1109/CTS.2011.5898939","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898939","url":null,"abstract":"Low-density Parity-Check (LDPC) code is widely used in distributed video coding (DVC) to realizing Wyner-Ziv (WZ) coding for its better performance than other channel codes. However, during the LDPC decoding process, most of DVC solutions do not make use of the video character to help decoding. In this paper, we propose an improved LDPC decoding scheme for DVC by utilizing the movement of the objects in the video sequence to partition different confidence areas for the side information (SI). The pixels in the SI correspond to different confidence areas, and the corresponding binary representations of the pixels will have different likelihood-ratio (LLR) initialization methods which are used to generate the LLR values for LDPC iterative decoding. The experimental results show that with the proposed decoding scheme the PSNR gain can reach up to 0.8 db without increasing the decoding complexity.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128599623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-08DOI: 10.1109/CTS.2011.5898902
Alton MacDonald, R. Cartas, J. Incera
Digital convergence is becoming increasingly imortant to both network operators and end users. Network operators look to Next Generation Network (NGN) solutions to meet the ever growing user demand and to the IP Multimedia Subsystem (IMS) as a catalyzer for attractive and innovative services which aim at improving user Quality of Experience (QoE). IMS, presented as the first working implementation of a Service Delivery Platform (SDP), takes great strides to ease migration to NGN as well as help the network become transparent to the end user. Location Based Services (LBS) also play an important role in QoE by supplying relevant information on the user's whereabouts directly enhancing their day-to-day activities. The combination of LBS within IMS holds great promise for future services where service delivery mimics a network responding directly to user activities. This helps dissolve the difference between the network and the User Equipment (UE), thus increasing user adoption through a transparent network and service delivery. This paper presents two personalized LBS implemented within an IMS test bed acting as a proof of concept for providing improved QoE on an IMS infrastructure as well as demonstrating that service creation is relatively easy to achieve in IMS.
{"title":"Custom tailored location based services: An IMS implementation","authors":"Alton MacDonald, R. Cartas, J. Incera","doi":"10.1109/CTS.2011.5898902","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898902","url":null,"abstract":"Digital convergence is becoming increasingly imortant to both network operators and end users. Network operators look to Next Generation Network (NGN) solutions to meet the ever growing user demand and to the IP Multimedia Subsystem (IMS) as a catalyzer for attractive and innovative services which aim at improving user Quality of Experience (QoE). IMS, presented as the first working implementation of a Service Delivery Platform (SDP), takes great strides to ease migration to NGN as well as help the network become transparent to the end user. Location Based Services (LBS) also play an important role in QoE by supplying relevant information on the user's whereabouts directly enhancing their day-to-day activities. The combination of LBS within IMS holds great promise for future services where service delivery mimics a network responding directly to user activities. This helps dissolve the difference between the network and the User Equipment (UE), thus increasing user adoption through a transparent network and service delivery. This paper presents two personalized LBS implemented within an IMS test bed acting as a proof of concept for providing improved QoE on an IMS infrastructure as well as demonstrating that service creation is relatively easy to achieve in IMS.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127516484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-08DOI: 10.1109/CTS.2011.5898979
Zhiyuan Yin, H. Alnuweiri, A. L. Narasimha Reddy, H. Çelebi, K. Qaraqe
Early Retransmission (ER) has already been shown to improve TCP-SACK's performance in delivering time sensitive media. In this paper, we integrate the ER scheme into a delay-based TCP variant, namely TCP-PERT, and performs extensive ns2 simulation. Our results show that ER can also improve PERT's performance in delivering real time media by reducing the latency caused by retransmission timeouts. Furthermore, we also explored the improvement brought by employing a finegrained retransmission timer, and compared it with ER. We find out a) ER outperforms fine grained timer in a variety of conditions and b) the combination of the two can further improve performance.
{"title":"Improving the performance of delay based protocol in delivering real time media via early retransmission","authors":"Zhiyuan Yin, H. Alnuweiri, A. L. Narasimha Reddy, H. Çelebi, K. Qaraqe","doi":"10.1109/CTS.2011.5898979","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898979","url":null,"abstract":"Early Retransmission (ER) has already been shown to improve TCP-SACK's performance in delivering time sensitive media. In this paper, we integrate the ER scheme into a delay-based TCP variant, namely TCP-PERT, and performs extensive ns2 simulation. Our results show that ER can also improve PERT's performance in delivering real time media by reducing the latency caused by retransmission timeouts. Furthermore, we also explored the improvement brought by employing a finegrained retransmission timer, and compared it with ER. We find out a) ER outperforms fine grained timer in a variety of conditions and b) the combination of the two can further improve performance.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120956973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-08DOI: 10.1109/CTS.2011.6024144
S. M. Zabihi-Maddah, M. M. Kakhki
Increasing the number of simultaneous users is one of the challenging issues in incoherent and asynchronous optical CDMA systems. One solution is to increase the value of cross- correlation, λc. In neglecting the effect of noise, optimum value of λcwas obtained. In this work, with considering noise, the simultaneous effect of λc and transmitted power on the probability of bit error (pbe) is investigated. Our investigation is performed by employing OOC (λc =1) and prime code (λc =2) and active correlator is chosen for its robustness against the noise. The performance is analyzed for three common receiver structures, namely soft receiver (without optical hard limiter), single optical hard limiter (SHL) and double optical hard limiters (DHL). Our results show that under the same bandwidth efficiency, increasing λc in high power regimes decreases the pbe but increasing λc in low power regimes will increase pbe.
{"title":"Code cross-correlation effects on the performance of optical cdma systems in the presence of receiver noises","authors":"S. M. Zabihi-Maddah, M. M. Kakhki","doi":"10.1109/CTS.2011.6024144","DOIUrl":"https://doi.org/10.1109/CTS.2011.6024144","url":null,"abstract":"Increasing the number of simultaneous users is one of the challenging issues in incoherent and asynchronous optical CDMA systems. One solution is to increase the value of cross- correlation, λ<sub>c</sub>. In neglecting the effect of noise, optimum value of λ<sub>c</sub>was obtained. In this work, with considering noise, the simultaneous effect of λ<sub>c</sub> and transmitted power on the probability of bit error (pbe) is investigated. Our investigation is performed by employing OOC (λ<sub>c</sub> =1) and prime code (λ<sub>c</sub> =2) and active correlator is chosen for its robustness against the noise. The performance is analyzed for three common receiver structures, namely soft receiver (without optical hard limiter), single optical hard limiter (SHL) and double optical hard limiters (DHL). Our results show that under the same bandwidth efficiency, increasing λ<sub>c</sub> in high power regimes decreases the pbe but increasing λ<sub>c</sub> in low power regimes will increase pbe.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115306373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-08DOI: 10.1109/CTS.2011.5898987
Ruohan Cao, Tiejun Lv, Hui Gao, Pengfei Chang
This paper proposes two detection schemes based on a novel strategy associated with ant colony optimization (ACO) for multiple-input multiple-output (MIMO) systems. By employing heuristic values and pheromone levels, we jointly exploit local and global information about solution space to constitute transition probability. The proposed constitution rule evaluates the reliability of possible solution more efficiently than previous research. Besides, the unreliable solutions in terms of pheromone levels are deleted before each iteration for reducing the scale of solution space. Both simulations and analysis confirm that the proposed schemes provide improved tradeoff between complexity and performance over traditional detectors.
{"title":"A novel detection strategy based on ant colony optimization for MIMO systems","authors":"Ruohan Cao, Tiejun Lv, Hui Gao, Pengfei Chang","doi":"10.1109/CTS.2011.5898987","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898987","url":null,"abstract":"This paper proposes two detection schemes based on a novel strategy associated with ant colony optimization (ACO) for multiple-input multiple-output (MIMO) systems. By employing heuristic values and pheromone levels, we jointly exploit local and global information about solution space to constitute transition probability. The proposed constitution rule evaluates the reliability of possible solution more efficiently than previous research. Besides, the unreliable solutions in terms of pheromone levels are deleted before each iteration for reducing the scale of solution space. Both simulations and analysis confirm that the proposed schemes provide improved tradeoff between complexity and performance over traditional detectors.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121634998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-08DOI: 10.1109/CTS.2011.5898959
Z. Zinonos, Ricardo M. Silva, V. Vassiliou, J. Silva
Wireless sensor and actuator networks (WSANs) have been studied for about ten years now. However, a gap between research and real applications and implementations remains. The lack of an integrated solution, capable of providing the reliability levels of monitoring and actuation required by critical applications, have postponed the replacement and extension of the existing inflexible and expensive wired solutions with the low-cost, easy-to-deploy, and portable wireless options. In order to assist this transition this paper presents a new method for supporting mobility in WSANs specifically designed for time-critical scenarios. The method is being targeted for a critical application located in a real oil refinery, in which a WSAN has been implemented in the scope of a European research project.
{"title":"Mobility solutions for wireless sensor and actuator networks with performance guarantees","authors":"Z. Zinonos, Ricardo M. Silva, V. Vassiliou, J. Silva","doi":"10.1109/CTS.2011.5898959","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898959","url":null,"abstract":"Wireless sensor and actuator networks (WSANs) have been studied for about ten years now. However, a gap between research and real applications and implementations remains. The lack of an integrated solution, capable of providing the reliability levels of monitoring and actuation required by critical applications, have postponed the replacement and extension of the existing inflexible and expensive wired solutions with the low-cost, easy-to-deploy, and portable wireless options. In order to assist this transition this paper presents a new method for supporting mobility in WSANs specifically designed for time-critical scenarios. The method is being targeted for a critical application located in a real oil refinery, in which a WSAN has been implemented in the scope of a European research project.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121105230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-08DOI: 10.1109/CTS.2011.5898935
Yu Liu, Xuqi Zhu, Cong Ma, Lin Zhang
Event Detection is one of the main applications of wireless sensor networks (WSN). However, due to the noisy sensed data of sensors and the wireless channel noise, it's difficult to guarantee the accuracy of detection, especially in multiple event detection. In this paper, we proposed a multiple event detection scheme using compressed sensing (CS). By analogy with CS problem, the efficient recovery algorithms of CS can be used to reconstruct the source signal that contains multiple simultaneous events. Moreover, the events may not change much, so the source signals at two adjacent time instants have high redundancy. This temporal correlation is also utilized in our scheme to improve the detection accuracy. In the proposed scheme, not only the position but also the value of an event can be achieved. Three algorithms of CS are used in our scheme to show the advantages on detection probability over the traditional decentralized detection methods using Bayesian.
{"title":"Multiple event detection in wireless sensor networks using compressed sensing","authors":"Yu Liu, Xuqi Zhu, Cong Ma, Lin Zhang","doi":"10.1109/CTS.2011.5898935","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898935","url":null,"abstract":"Event Detection is one of the main applications of wireless sensor networks (WSN). However, due to the noisy sensed data of sensors and the wireless channel noise, it's difficult to guarantee the accuracy of detection, especially in multiple event detection. In this paper, we proposed a multiple event detection scheme using compressed sensing (CS). By analogy with CS problem, the efficient recovery algorithms of CS can be used to reconstruct the source signal that contains multiple simultaneous events. Moreover, the events may not change much, so the source signals at two adjacent time instants have high redundancy. This temporal correlation is also utilized in our scheme to improve the detection accuracy. In the proposed scheme, not only the position but also the value of an event can be achieved. Three algorithms of CS are used in our scheme to show the advantages on detection probability over the traditional decentralized detection methods using Bayesian.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121040766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-08DOI: 10.1109/CTS.2011.5898908
Hamidreza Aghasi, M. Hashemi, B. Khalaj
In this paper we present a method of localizing multiple wideband acoustic sources based on both signal attenuation pattern and delays in the reception of the signal. Moreover, an additional order of flexibility is added to the problem by considering the attenuation model as an unknown function with reasonable prior assumptions about its functional space. Such approach is capable of enhancing the localization performance compared to when only the signal attenuation data or the time delays are used. A cost function is then formed in terms of the sources locations and the attenuation model parameters. Having different types of unknowns in the cost function, convergence concerns, and the advantage of using trust region methods encourages using the Levenberg-Marquardt algorithm. Accordingly, to simplify the implementation of the proposed algorithm, methods of calculating the Jacobian are provided. Finally the validity of the proposed method is verified by providing simulation results.
{"title":"Source localization through adaptive signal attenuation model and time delay estimation","authors":"Hamidreza Aghasi, M. Hashemi, B. Khalaj","doi":"10.1109/CTS.2011.5898908","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898908","url":null,"abstract":"In this paper we present a method of localizing multiple wideband acoustic sources based on both signal attenuation pattern and delays in the reception of the signal. Moreover, an additional order of flexibility is added to the problem by considering the attenuation model as an unknown function with reasonable prior assumptions about its functional space. Such approach is capable of enhancing the localization performance compared to when only the signal attenuation data or the time delays are used. A cost function is then formed in terms of the sources locations and the attenuation model parameters. Having different types of unknowns in the cost function, convergence concerns, and the advantage of using trust region methods encourages using the Levenberg-Marquardt algorithm. Accordingly, to simplify the implementation of the proposed algorithm, methods of calculating the Jacobian are provided. Finally the validity of the proposed method is verified by providing simulation results.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"119 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116317223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-08DOI: 10.1109/CTS.2011.5898963
Andoena Balla, A. Stassopoulou, M. Dikaiakos
In this paper we present a methodology for detecting web crawlers in real time. We use decision trees to classify requests in real time, as originating from a crawler or human, while their session is ongoing. For this purpose we used machine learning techniques to identify the most important features that differentiate humans from crawlers. The method was tested in real time with the help of an emulator, using only a small number of requests. Our results demonstrate the effectiveness and applicability of our approach.
{"title":"Real-time web crawler detection","authors":"Andoena Balla, A. Stassopoulou, M. Dikaiakos","doi":"10.1109/CTS.2011.5898963","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898963","url":null,"abstract":"In this paper we present a methodology for detecting web crawlers in real time. We use decision trees to classify requests in real time, as originating from a crawler or human, while their session is ongoing. For this purpose we used machine learning techniques to identify the most important features that differentiate humans from crawlers. The method was tested in real time with the help of an emulator, using only a small number of requests. Our results demonstrate the effectiveness and applicability of our approach.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"144 11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129512951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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