The QR-decomposition-based least-squares lattice (QRD-LSL) algorithm is one of the most attractive choices for adaptive filters applications, mainly due to its fast convergence rate and good numerical properties. In practice, the square-root-free QRD-LSL (SRF-QRD-LSL) algorithms are frequently employed, especially when fixed- point digital signal processors (DSPs) are used for implementation. In this context, there are some major limitations regarding the large dynamic range of the algorithm's cost functions. Consequently, hard scaling operations are required, which further reduce the precision of numerical representation and lead to performance degradation. In this paper we propose a SRF-QRD-LSL algorithm based on a modified update of the cost functions, which offers improved numerical robustness. Simulations performed in fixed-point and logarithmic number system (LNS) implementation support the theoretical findings.
{"title":"Square-Root-Free QRD-LSL Adaptive Algorithm with Improved Numerical Robustness","authors":"C. Paleologu, F. Albu, A. Enescu, S. Ciochină","doi":"10.1109/ICN.2008.48","DOIUrl":"https://doi.org/10.1109/ICN.2008.48","url":null,"abstract":"The QR-decomposition-based least-squares lattice (QRD-LSL) algorithm is one of the most attractive choices for adaptive filters applications, mainly due to its fast convergence rate and good numerical properties. In practice, the square-root-free QRD-LSL (SRF-QRD-LSL) algorithms are frequently employed, especially when fixed- point digital signal processors (DSPs) are used for implementation. In this context, there are some major limitations regarding the large dynamic range of the algorithm's cost functions. Consequently, hard scaling operations are required, which further reduce the precision of numerical representation and lead to performance degradation. In this paper we propose a SRF-QRD-LSL algorithm based on a modified update of the cost functions, which offers improved numerical robustness. Simulations performed in fixed-point and logarithmic number system (LNS) implementation support the theoretical findings.","PeriodicalId":250085,"journal":{"name":"Seventh International Conference on Networking (icn 2008)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130055806","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}
A Wireless Sensor Network (WSN) is a power constrained system, because nodes run on limited power batteries. When a node switches between modes (i.e., transmit, receive, and sleep), there are also changes related to the transition process. Although the switching energy is considered negligible most of the time, it is strongly dependent on the technology (e.g., the radio) deployed on the nodes. Most of the time, the switching energy is neglected to simplify the simulation process. To better understand energy consumption in a WSN, it is necessary to adopt a more realistic battery model. Network simulators usually employ the linear discharge model. This model is simple, but far from reality, leading to wrong conclusions like, for example, that switching energy necessarily implies on energy consumption. Getting a more accurate measure for the energy consumption of a sensor network may lead to better estimates for the network lifetime. To better understand the impact of a more realistic battery model on the simulation of a WSN, we compare the results for blind flooding using the standard battery model (i.e., linear model) to the results obtained using the Rakhmatov-Vrudhula battery model which captures the non-linear battery behavior.
{"title":"Simulation of Blind Flooding over Wireless Sensor Networks Based on a Realistic Battery Model","authors":"M. Spohn, P. Sausen, F. Salvadori, M. Campos","doi":"10.1109/ICN.2008.100","DOIUrl":"https://doi.org/10.1109/ICN.2008.100","url":null,"abstract":"A Wireless Sensor Network (WSN) is a power constrained system, because nodes run on limited power batteries. When a node switches between modes (i.e., transmit, receive, and sleep), there are also changes related to the transition process. Although the switching energy is considered negligible most of the time, it is strongly dependent on the technology (e.g., the radio) deployed on the nodes. Most of the time, the switching energy is neglected to simplify the simulation process. To better understand energy consumption in a WSN, it is necessary to adopt a more realistic battery model. Network simulators usually employ the linear discharge model. This model is simple, but far from reality, leading to wrong conclusions like, for example, that switching energy necessarily implies on energy consumption. Getting a more accurate measure for the energy consumption of a sensor network may lead to better estimates for the network lifetime. To better understand the impact of a more realistic battery model on the simulation of a WSN, we compare the results for blind flooding using the standard battery model (i.e., linear model) to the results obtained using the Rakhmatov-Vrudhula battery model which captures the non-linear battery behavior.","PeriodicalId":250085,"journal":{"name":"Seventh International Conference on Networking (icn 2008)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131615223","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}
We present a thorough investigation of four issues with the destination set in IP-level topology measurement. (1) To evaluate the completeness of the destination set, we measured by brute force and found that a half of edges will be missed by the uniform random selection (URS) method which was adopted by well-known CAIDA' skitter. (2) Two potential reasons for edge missing, the short-term routing dynamics and the subnetting technique, were investigated with the last-hop selection method and the bisection selection method respectively. And the results showed that the subnetting technique is the main reason. (3) To select destinations efficiently, we presented the minimum cover selection (MCS) method which performed better than the URS method on 75% of networks over three months. (4) Finally, to investigate the bias of topology characterization, we measured a destination set larger than before and discovered a Chinese topology whose size is 5 times as large as that discovered by skitter. The comparison between characteristics of skitter's topology and ours indicated that the small destination set trends to miss the information on marginal networks.
{"title":"On Destination Set in IP-Level Topology Measurement","authors":"Yu Zhang, Binxing Fang, Hongli Zhang","doi":"10.1109/ICN.2008.54","DOIUrl":"https://doi.org/10.1109/ICN.2008.54","url":null,"abstract":"We present a thorough investigation of four issues with the destination set in IP-level topology measurement. (1) To evaluate the completeness of the destination set, we measured by brute force and found that a half of edges will be missed by the uniform random selection (URS) method which was adopted by well-known CAIDA' skitter. (2) Two potential reasons for edge missing, the short-term routing dynamics and the subnetting technique, were investigated with the last-hop selection method and the bisection selection method respectively. And the results showed that the subnetting technique is the main reason. (3) To select destinations efficiently, we presented the minimum cover selection (MCS) method which performed better than the URS method on 75% of networks over three months. (4) Finally, to investigate the bias of topology characterization, we measured a destination set larger than before and discovered a Chinese topology whose size is 5 times as large as that discovered by skitter. The comparison between characteristics of skitter's topology and ours indicated that the small destination set trends to miss the information on marginal networks.","PeriodicalId":250085,"journal":{"name":"Seventh International Conference on Networking (icn 2008)","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132813092","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}
An efficient operation of modern network services in packet networks is often conditional on complex quality-of-service (QoS) support. Because of its relative simplicity the mechanism of differentiated services (DiffServ) has recently come to be the most widely used QoS support technology in IP networks. One of the biggest disadvantages of this mechanism is the inability to cooperate with end-stations and end-user applications. This paper introduces a solution which allows end-stations to automatically retrieve DiffServ- related information from a network. As a result, end-users can control traffic policing in the DiffServ domain provided the predefined traffic conditions are not violated.
{"title":"DiffServ-Based User-Manageable Quality of Service Control System","authors":"K. Molnar, V. Vrba","doi":"10.1109/ICN.2008.9","DOIUrl":"https://doi.org/10.1109/ICN.2008.9","url":null,"abstract":"An efficient operation of modern network services in packet networks is often conditional on complex quality-of-service (QoS) support. Because of its relative simplicity the mechanism of differentiated services (DiffServ) has recently come to be the most widely used QoS support technology in IP networks. One of the biggest disadvantages of this mechanism is the inability to cooperate with end-stations and end-user applications. This paper introduces a solution which allows end-stations to automatically retrieve DiffServ- related information from a network. As a result, end-users can control traffic policing in the DiffServ domain provided the predefined traffic conditions are not violated.","PeriodicalId":250085,"journal":{"name":"Seventh International Conference on Networking (icn 2008)","volume":"215 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132194949","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}
For iterative detection/decoding turbo schemes List Sequential (LISS) detection is an effective technique which contrary to a posteriori probability (APP) equalization offers a much smaller complexity almost independent of the number of states. It uses a metric containing a priori and channel values, a metric length bias term for speeding up the tree-search, a soft extension of paths without increasing the stack size and soft weighting to obtain a soft-output. Using a length bias term calculated via an auxiliary stack has been shown to substantially narrow the tree search and thus reduce detection complexity. In this paper we propose a novel approach to determine an approximation of the bias term. It is based on the information available during the tree search in the main stack of the LISS detector. This approach further reduces the detection computational load without significant loss of performances.
{"title":"LISS Algorithm with Modified Length Bias Term in Turbo Equalization","authors":"A. Paun, S. Ciochină, C. Paleologu","doi":"10.1109/ICN.2008.49","DOIUrl":"https://doi.org/10.1109/ICN.2008.49","url":null,"abstract":"For iterative detection/decoding turbo schemes List Sequential (LISS) detection is an effective technique which contrary to a posteriori probability (APP) equalization offers a much smaller complexity almost independent of the number of states. It uses a metric containing a priori and channel values, a metric length bias term for speeding up the tree-search, a soft extension of paths without increasing the stack size and soft weighting to obtain a soft-output. Using a length bias term calculated via an auxiliary stack has been shown to substantially narrow the tree search and thus reduce detection complexity. In this paper we propose a novel approach to determine an approximation of the bias term. It is based on the information available during the tree search in the main stack of the LISS detector. This approach further reduces the detection computational load without significant loss of performances.","PeriodicalId":250085,"journal":{"name":"Seventh International Conference on Networking (icn 2008)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128820566","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}
Anand Pulicat Gopalakrishnan, H. Yousefi’zadeh, H. Jafarkhani
In this article, we study the performance of transmitting H.264 video sequences over hybrid networks formed by a collection of wired and wireless links. We use the Gilbert-Elliott error model to simulate the wireless transmission channel. Taking the effects of fading into consideration, our numerical results show that the quality of the reconstructed video sequences is seriously degraded. We then investigate how the addition of FEC techniques like the Reed-Solomon codes and the use of MIMO techniques help improve the performance of wireless links and consequently the quality of reconstructed video transmitted over such links.
{"title":"A Performance Evaluation of H.264 FGS Sequences over Hybrid Networks","authors":"Anand Pulicat Gopalakrishnan, H. Yousefi’zadeh, H. Jafarkhani","doi":"10.1109/ICN.2008.91","DOIUrl":"https://doi.org/10.1109/ICN.2008.91","url":null,"abstract":"In this article, we study the performance of transmitting H.264 video sequences over hybrid networks formed by a collection of wired and wireless links. We use the Gilbert-Elliott error model to simulate the wireless transmission channel. Taking the effects of fading into consideration, our numerical results show that the quality of the reconstructed video sequences is seriously degraded. We then investigate how the addition of FEC techniques like the Reed-Solomon codes and the use of MIMO techniques help improve the performance of wireless links and consequently the quality of reconstructed video transmitted over such links.","PeriodicalId":250085,"journal":{"name":"Seventh International Conference on Networking (icn 2008)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116169423","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}
In order to evaluate the behavior and performance of protocols for wireless networks, simulations are a good compromise between cost and complexity, on the one hand, and accuracy of the results, on the other hand. Since there are many simulators for wireless networks, it is often difficult to decide which simulator to choose. To help shed light on this issue, we present a case study in which four popular wireless network simulators were used to evaluate a well-known topology control protocol (SPAN). Within the case study, we describe outstanding and desirable but missing features of the simulators, outlining their strengths and weaknesses. Further, we compare the amount of effort needed for installation, familiarization, implementation (needed lines of code and lines for configuration) and visualization. As opposed to other simulator comparisons, we do not focus on the correlation of the individual simulation results, but try to compare the simulators from feature and usability point of view. This paper can help other researchers to quickly identify which simulator is most suitable for their needs.
{"title":"Comparative Study of Wireless Network Simulators","authors":"J. Lessmann, P. Janacik, Lazar Lachev, D. Orfanus","doi":"10.1109/ICN.2008.97","DOIUrl":"https://doi.org/10.1109/ICN.2008.97","url":null,"abstract":"In order to evaluate the behavior and performance of protocols for wireless networks, simulations are a good compromise between cost and complexity, on the one hand, and accuracy of the results, on the other hand. Since there are many simulators for wireless networks, it is often difficult to decide which simulator to choose. To help shed light on this issue, we present a case study in which four popular wireless network simulators were used to evaluate a well-known topology control protocol (SPAN). Within the case study, we describe outstanding and desirable but missing features of the simulators, outlining their strengths and weaknesses. Further, we compare the amount of effort needed for installation, familiarization, implementation (needed lines of code and lines for configuration) and visualization. As opposed to other simulator comparisons, we do not focus on the correlation of the individual simulation results, but try to compare the simulators from feature and usability point of view. This paper can help other researchers to quickly identify which simulator is most suitable for their needs.","PeriodicalId":250085,"journal":{"name":"Seventh International Conference on Networking (icn 2008)","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124846191","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}
We propose a formal model to represent and solve the Constraint-Based Routing problem in networks. To attain this, we model the network adapting it to a weighted or graph (unicast delivery) or and-or graph (multicast delivery), where the weight on a connector corresponds to the cost of sending a packet on the network link modelled by that connector. We use the Soft Constraint Logic Programming (SCLP) framework as a convenient declarative programming environment in which to solve the routing problem. In particular, we show how the semantics of an SCLP program computes the best route in the corresponding graph. At last, we provide an implementation of the framework over scale-free networks.
{"title":"A Formal and Practical Framework for Constraint-Based Routing","authors":"Stefano Bistarelli, Francesco Santini","doi":"10.1109/ICN.2008.12","DOIUrl":"https://doi.org/10.1109/ICN.2008.12","url":null,"abstract":"We propose a formal model to represent and solve the Constraint-Based Routing problem in networks. To attain this, we model the network adapting it to a weighted or graph (unicast delivery) or and-or graph (multicast delivery), where the weight on a connector corresponds to the cost of sending a packet on the network link modelled by that connector. We use the Soft Constraint Logic Programming (SCLP) framework as a convenient declarative programming environment in which to solve the routing problem. In particular, we show how the semantics of an SCLP program computes the best route in the corresponding graph. At last, we provide an implementation of the framework over scale-free networks.","PeriodicalId":250085,"journal":{"name":"Seventh International Conference on Networking (icn 2008)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131232292","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}
As multi-core systems begin to appear, their possible applications, parallel performance and on-chip interconnection networks have to be clarified, analyzed and optimized. The paper investigates an impact of collective communication (CC) overhead that may be critical for performance of parallel applications. Two potential topologies of networks on chip (NoC) are investigated, a ring-based network and 2D-mesh, due to their easy manufacturability on a chip. The wormhole switching, full duplex links and 1-port non-combining as well as combining nodes are considered. The lower bounds on the number of communication steps and upper bounds of CC times based on real CC algorithms are given. They can be evaluated for any given start-up time and link bandwidth. This enables performance prediction of applications with CCs among computing nodes.
{"title":"Communication Performance of Mesh- and Ring-Based NoCs","authors":"V. Dvorák","doi":"10.1109/ICN.2008.53","DOIUrl":"https://doi.org/10.1109/ICN.2008.53","url":null,"abstract":"As multi-core systems begin to appear, their possible applications, parallel performance and on-chip interconnection networks have to be clarified, analyzed and optimized. The paper investigates an impact of collective communication (CC) overhead that may be critical for performance of parallel applications. Two potential topologies of networks on chip (NoC) are investigated, a ring-based network and 2D-mesh, due to their easy manufacturability on a chip. The wormhole switching, full duplex links and 1-port non-combining as well as combining nodes are considered. The lower bounds on the number of communication steps and upper bounds of CC times based on real CC algorithms are given. They can be evaluated for any given start-up time and link bandwidth. This enables performance prediction of applications with CCs among computing nodes.","PeriodicalId":250085,"journal":{"name":"Seventh International Conference on Networking (icn 2008)","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128813710","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}
In this paper, we propose an algorithm of video transmission adaptation by automatic selection of variation based on the calculation of the score value that depends closely on the preferences user, networks conditions, and applications requirements (in terms of image quality and fidelity). This function of score value reflects the quality of satisfaction of the user preference and network condition with the adapted strategy. Numeric some results prove the efficiency of the solution proposed well.
{"title":"Best Video Stream Variation Selection in Wireless Networks","authors":"A. Kamoun, F. Zarai, L. Kamoun","doi":"10.1109/ICN.2008.13","DOIUrl":"https://doi.org/10.1109/ICN.2008.13","url":null,"abstract":"In this paper, we propose an algorithm of video transmission adaptation by automatic selection of variation based on the calculation of the score value that depends closely on the preferences user, networks conditions, and applications requirements (in terms of image quality and fidelity). This function of score value reflects the quality of satisfaction of the user preference and network condition with the adapted strategy. Numeric some results prove the efficiency of the solution proposed well.","PeriodicalId":250085,"journal":{"name":"Seventh International Conference on Networking (icn 2008)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122235883","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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