Pub Date : 2009-12-28DOI: 10.1109/MASCOT.2009.5366781
Kiron Vijayasankar, L. N. Kannan, M. Tacca, A. Fumagalli
Cooperative link layer protocols are typically used in single hop networks to enhance the link layer capabilities using a special node, called relay. In multi-hop networks, a frame is sent from an original source to the final destination through a series of intermediate nodes. The performance benefits of cooperation at link layer can be channeled into multi-hop networks as well. This paper addresses the challenge in finding multi-hop routes accounting for relays at the link layer by proposing the cooperative expected transmission time (CETT) metric. CETT is used to compute the route, i.e., the sequence of intermediate nodes in terms of the minimum end-to-end average transmission time taking into account the cooperative nature of the link layer.
{"title":"CETT: A cross layer routing metric for cooperative wireless Ad hoc networks","authors":"Kiron Vijayasankar, L. N. Kannan, M. Tacca, A. Fumagalli","doi":"10.1109/MASCOT.2009.5366781","DOIUrl":"https://doi.org/10.1109/MASCOT.2009.5366781","url":null,"abstract":"Cooperative link layer protocols are typically used in single hop networks to enhance the link layer capabilities using a special node, called relay. In multi-hop networks, a frame is sent from an original source to the final destination through a series of intermediate nodes. The performance benefits of cooperation at link layer can be channeled into multi-hop networks as well. This paper addresses the challenge in finding multi-hop routes accounting for relays at the link layer by proposing the cooperative expected transmission time (CETT) metric. CETT is used to compute the route, i.e., the sequence of intermediate nodes in terms of the minimum end-to-end average transmission time taking into account the cooperative nature of the link layer.","PeriodicalId":275737,"journal":{"name":"2009 IEEE International Symposium on Modeling, Analysis & Simulation of Computer and Telecommunication Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125839892","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 : 2009-12-28DOI: 10.1109/MASCOT.2009.5366801
A. Willis, M.J. Zapata, J. Conrad
This article describes a multimedia system consisting of two sensors: (1) a laser range scanner (LIDAR) and (2) a conventional digital camera. Our work specifies a mathematical calibration model that allows for this data to be explicitly integrated. Data integration is accomplished by calibrating the system, i.e., estimating for each variable of the model for a specific LIDAR-and-camera pair. Our approach requires detection of feature points in both the LIDAR scan and the digital images. Using correspondences between feature points, we can then estimate the model variables that specify an explicit mathematical relationship between sensed (x, y, z) LIDAR points and (x, y) digital image positions. Our system is designed for 3D line scanners, i.e., scanners that detect positions that lie in a 3D plane which requires some special theoretical and experimental treatment. Results are provided for simulations of the system in a virtual environment and for a real LIDAR-and-camera system consisting of a SICK LMS200 and an inexpensive USB web-camera. Calibrated systems can integrate the data in real-time which is of particular use for autonomous vehicular and robotic navigation.
本文介绍了一个由两个传感器组成的多媒体系统:(1)激光测距仪(LIDAR)和(2)传统数码相机。我们的工作指定了一个数学校准模型，该模型允许显式集成该数据。数据集成是通过校准系统来完成的，即对特定激光雷达和相机对模型的每个变量进行估计。我们的方法需要在激光雷达扫描和数字图像中检测特征点。利用特征点之间的对应关系，我们可以估计模型变量，这些变量指定了感测(x, y, z)激光雷达点与(x, y)数字图像位置之间的显式数学关系。我们的系统是为3D线扫描仪设计的，即扫描仪检测位于3D平面上的位置，这需要一些特殊的理论和实验处理。给出了该系统在虚拟环境中的仿真结果，以及由SICK LMS200和廉价USB网络摄像机组成的真实激光雷达和摄像机系统的仿真结果。经过校准的系统可以实时整合数据，这在自动驾驶汽车和机器人导航中特别有用。
{"title":"A linear method for calibrating LIDAR-and-camera systems","authors":"A. Willis, M.J. Zapata, J. Conrad","doi":"10.1109/MASCOT.2009.5366801","DOIUrl":"https://doi.org/10.1109/MASCOT.2009.5366801","url":null,"abstract":"This article describes a multimedia system consisting of two sensors: (1) a laser range scanner (LIDAR) and (2) a conventional digital camera. Our work specifies a mathematical calibration model that allows for this data to be explicitly integrated. Data integration is accomplished by calibrating the system, i.e., estimating for each variable of the model for a specific LIDAR-and-camera pair. Our approach requires detection of feature points in both the LIDAR scan and the digital images. Using correspondences between feature points, we can then estimate the model variables that specify an explicit mathematical relationship between sensed (x, y, z) LIDAR points and (x, y) digital image positions. Our system is designed for 3D line scanners, i.e., scanners that detect positions that lie in a 3D plane which requires some special theoretical and experimental treatment. Results are provided for simulations of the system in a virtual environment and for a real LIDAR-and-camera system consisting of a SICK LMS200 and an inexpensive USB web-camera. Calibrated systems can integrate the data in real-time which is of particular use for autonomous vehicular and robotic navigation.","PeriodicalId":275737,"journal":{"name":"2009 IEEE International Symposium on Modeling, Analysis & Simulation of Computer and Telecommunication Systems","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114958309","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 : 2009-12-28DOI: 10.1109/MASCOT.2009.5366693
Sharayu Ghangrekar, J. Conrad
Path planning in robotics deals with developing the logic for the navigation of a robot. The implementation details of most previous algorithms are proprietary to specific organizations. The requirement of a customized strategy for collision free and concerted navigation of an All-Terrain Vehicle (ATV) led to the activities of this research. As a part of this research an algorithm has been developed and visually simulated. The algorithm is evolutionary and capable of path planning for ATVs in the presence of completely known and newly-discovered obstacles. This algorithm helps the ATV model to maneuver in an open field in a specific pattern and avoid obstacles, if any, along its path. The algorithm is implemented and simulated using C and WINAPI. As a result, given the data of known obstacles and the field, the virtually-modeled ATV can maneuver in a systematic and optimum manner towards its goal by avoiding all the obstacles in its path.
{"title":"Modeling and simulating a path planning and obstacle avoidance algorithm for an autonomous robotic vehicle","authors":"Sharayu Ghangrekar, J. Conrad","doi":"10.1109/MASCOT.2009.5366693","DOIUrl":"https://doi.org/10.1109/MASCOT.2009.5366693","url":null,"abstract":"Path planning in robotics deals with developing the logic for the navigation of a robot. The implementation details of most previous algorithms are proprietary to specific organizations. The requirement of a customized strategy for collision free and concerted navigation of an All-Terrain Vehicle (ATV) led to the activities of this research. As a part of this research an algorithm has been developed and visually simulated. The algorithm is evolutionary and capable of path planning for ATVs in the presence of completely known and newly-discovered obstacles. This algorithm helps the ATV model to maneuver in an open field in a specific pattern and avoid obstacles, if any, along its path. The algorithm is implemented and simulated using C and WINAPI. As a result, given the data of known obstacles and the field, the virtually-modeled ATV can maneuver in a systematic and optimum manner towards its goal by avoiding all the obstacles in its path.","PeriodicalId":275737,"journal":{"name":"2009 IEEE International Symposium on Modeling, Analysis & Simulation of Computer and Telecommunication Systems","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122639761","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 : 2009-12-28DOI: 10.1109/MASCOT.2009.5366667
S. Begum, A. Helmy, S. Gupta
We propose a novel framework to critically analyze a given MAC protocol for wireless ad hoc networks with respect to its correctness criteria and performance metrics. The framework is composed of wanted state generation and test scenario generation algorithms. The wanted state generation algorithm generates a set of conditions that meet our study objective. The test generation algorithm then generates complete test scenarios that satisfy our objective, e.g., minimize the value of a particular performance metric. The core of our search engine utilizes novel algorithms that use combinations of goal-oriented backward and forward search and implications as well as heuristics that enable the generation of worst case scenarios in manageable complexity for our practical purposes. We demonstrate the effectiveness of our approach by using our framework to analyze the worst case performance, in terms of throughput and fairness of IEEE 802.11 for ad hoc networks. For all topologies, the worst case scenarios generated by our framework show the worst performance among all scenarios that we generate. The scenarios generated by our framework include the scenarios typically used for performance evaluation of IEEE 802.11 protocol. The case study of IEEE 802.11 shows that the complexity of our novel algorithms are quite practical.
{"title":"Modeling and test generation for worst-case performance evaluation of MAC protocols for wireless ad hoc networks","authors":"S. Begum, A. Helmy, S. Gupta","doi":"10.1109/MASCOT.2009.5366667","DOIUrl":"https://doi.org/10.1109/MASCOT.2009.5366667","url":null,"abstract":"We propose a novel framework to critically analyze a given MAC protocol for wireless ad hoc networks with respect to its correctness criteria and performance metrics. The framework is composed of wanted state generation and test scenario generation algorithms. The wanted state generation algorithm generates a set of conditions that meet our study objective. The test generation algorithm then generates complete test scenarios that satisfy our objective, e.g., minimize the value of a particular performance metric. The core of our search engine utilizes novel algorithms that use combinations of goal-oriented backward and forward search and implications as well as heuristics that enable the generation of worst case scenarios in manageable complexity for our practical purposes. We demonstrate the effectiveness of our approach by using our framework to analyze the worst case performance, in terms of throughput and fairness of IEEE 802.11 for ad hoc networks. For all topologies, the worst case scenarios generated by our framework show the worst performance among all scenarios that we generate. The scenarios generated by our framework include the scenarios typically used for performance evaluation of IEEE 802.11 protocol. The case study of IEEE 802.11 shows that the complexity of our novel algorithms are quite practical.","PeriodicalId":275737,"journal":{"name":"2009 IEEE International Symposium on Modeling, Analysis & Simulation of Computer and Telecommunication Systems","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130352607","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 : 2009-12-28DOI: 10.1109/MASCOT.2009.5366648
F. Guo, T. Chiueh
An emerging class of applications for enterprise wireless LANs (WLAN) is voice over IP (VoIP) applications, which impose a stringent requirement on end-to-end delay. Because access points on an enterprise WLAN tend to be associated with different IP subnets, support for network-layer handoff is indispensable. Moreover, the handoff frequency is expected to be much higher for WLANs than for cellular networks because the coverage of a WLAN access point is much smaller. Although mobile IP is a mature solution to the network-layer handoff problem, no known mobile IP implementation on IEEE 802.11 WLANs can reduce the handoff latency below 100 msec, a nominal requirement for VoIP applications. This paper describes a novel Ethernet-over-IP overlay network architecture that completely does away with network-layer handoff, and thus reduces the end-to-end handoff delay to that of link-layer handoff, which is supported by WLAN hardware directly. In addition, the proposed wireless overlay network (WON) architecture, which has been implemented in a commercial WLAN access point, represents the first mobility solution that allows a mobile device to maintain its network connections while roaming across different IP subnets without requiring any modification on the mobile device. As a result, the proposed architecture can automatically provide seamless network-layer handoff to a wide variety of mobile devices (such as PDA, portable, cell phone) running on different operating systems, as long as they are equipped with 802.11 network interface.
{"title":"Device-transparent network-layer handoff for micro-mobility","authors":"F. Guo, T. Chiueh","doi":"10.1109/MASCOT.2009.5366648","DOIUrl":"https://doi.org/10.1109/MASCOT.2009.5366648","url":null,"abstract":"An emerging class of applications for enterprise wireless LANs (WLAN) is voice over IP (VoIP) applications, which impose a stringent requirement on end-to-end delay. Because access points on an enterprise WLAN tend to be associated with different IP subnets, support for network-layer handoff is indispensable. Moreover, the handoff frequency is expected to be much higher for WLANs than for cellular networks because the coverage of a WLAN access point is much smaller. Although mobile IP is a mature solution to the network-layer handoff problem, no known mobile IP implementation on IEEE 802.11 WLANs can reduce the handoff latency below 100 msec, a nominal requirement for VoIP applications. This paper describes a novel Ethernet-over-IP overlay network architecture that completely does away with network-layer handoff, and thus reduces the end-to-end handoff delay to that of link-layer handoff, which is supported by WLAN hardware directly. In addition, the proposed wireless overlay network (WON) architecture, which has been implemented in a commercial WLAN access point, represents the first mobility solution that allows a mobile device to maintain its network connections while roaming across different IP subnets without requiring any modification on the mobile device. As a result, the proposed architecture can automatically provide seamless network-layer handoff to a wide variety of mobile devices (such as PDA, portable, cell phone) running on different operating systems, as long as they are equipped with 802.11 network interface.","PeriodicalId":275737,"journal":{"name":"2009 IEEE International Symposium on Modeling, Analysis & Simulation of Computer and Telecommunication Systems","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127851167","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 : 2009-12-28DOI: 10.1109/MASCOT.2009.5366131
K. Katsaros, V. Kemerlis, Charilaos Stais, G. Xylomenos
In the past few years numerous P2P file-sharing and content distribution systems have been designed, implemented, and evaluated via simulations, real world measurements, and mathematical analysis. Yet, only few of them have stood the test of time and gained wide user acceptance. BitTorrent is the one that holds the lion's share among them and the reasons behind its success have been studied to a great extent with interesting results. Nevertheless, even though P2P content distribution remains one of the most active research areas, little progress has been made towards the study of the BitTorrent protocol (and its variations), in a fully controllable and realistic simulation environment. In this paper we describe and analyze a full-featured and extensible implementation of BitTorrent for the OMNeT++ simulation platform. Moreover, since we aim at realistic simulations, we present our enhancements on a popular conversion tool for practical Internet topologies, as well as our churn generator that is based on the analysis of real BitTorrent traces. Finally, we set forth the results from the evaluation of our prototype implementation regarding resource demands under different simulation scenarios.
{"title":"A BitTorrent module for the OMNeT++ simulator","authors":"K. Katsaros, V. Kemerlis, Charilaos Stais, G. Xylomenos","doi":"10.1109/MASCOT.2009.5366131","DOIUrl":"https://doi.org/10.1109/MASCOT.2009.5366131","url":null,"abstract":"In the past few years numerous P2P file-sharing and content distribution systems have been designed, implemented, and evaluated via simulations, real world measurements, and mathematical analysis. Yet, only few of them have stood the test of time and gained wide user acceptance. BitTorrent is the one that holds the lion's share among them and the reasons behind its success have been studied to a great extent with interesting results. Nevertheless, even though P2P content distribution remains one of the most active research areas, little progress has been made towards the study of the BitTorrent protocol (and its variations), in a fully controllable and realistic simulation environment. In this paper we describe and analyze a full-featured and extensible implementation of BitTorrent for the OMNeT++ simulation platform. Moreover, since we aim at realistic simulations, we present our enhancements on a popular conversion tool for practical Internet topologies, as well as our churn generator that is based on the analysis of real BitTorrent traces. Finally, we set forth the results from the evaluation of our prototype implementation regarding resource demands under different simulation scenarios.","PeriodicalId":275737,"journal":{"name":"2009 IEEE International Symposium on Modeling, Analysis & Simulation of Computer and Telecommunication Systems","volume":"115 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124158117","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 : 2009-12-28DOI: 10.1109/MASCOT.2009.5366230
G. Pallis, Dimitrios Katsaros, M. Dikaiakos, N. Loulloudes, L. Tassiulas
Vehicular ad hoc networks have emerged recently as a platform to support intelligent inter-vehicle communication and improve traffic safety and performance. The road-constrained and high mobility of the vehicles, their unbounded power source, and the emergence of roadside wireless infrastructures make VANETs a challenging research topic. A key to the development of protocols for intervehicle communication and services lies in the knowledge of the topological characteristics of the VANET communication graph. This article provides answers to the general question: how does a VANET communication graph look like over time and space? This study is the first one that examines a very large-scale VANET graph and conducts a thorough investigation of its topological characteristics using several metrics, not examined in previous studies. Our work characterizes a VANET graph at the connectivity (link) level, quantifies the notion of “qualitative” nodes as required by routing and dissemination protocols, and examines the existence and evolution of communities (dense clusters of vehicles) in the VANET. Several latent facts about the VANET graph are revealed and incentives for their exploitation in protocol design are examined.
{"title":"On the structure and evolution of vehicular networks","authors":"G. Pallis, Dimitrios Katsaros, M. Dikaiakos, N. Loulloudes, L. Tassiulas","doi":"10.1109/MASCOT.2009.5366230","DOIUrl":"https://doi.org/10.1109/MASCOT.2009.5366230","url":null,"abstract":"Vehicular ad hoc networks have emerged recently as a platform to support intelligent inter-vehicle communication and improve traffic safety and performance. The road-constrained and high mobility of the vehicles, their unbounded power source, and the emergence of roadside wireless infrastructures make VANETs a challenging research topic. A key to the development of protocols for intervehicle communication and services lies in the knowledge of the topological characteristics of the VANET communication graph. This article provides answers to the general question: how does a VANET communication graph look like over time and space? This study is the first one that examines a very large-scale VANET graph and conducts a thorough investigation of its topological characteristics using several metrics, not examined in previous studies. Our work characterizes a VANET graph at the connectivity (link) level, quantifies the notion of “qualitative” nodes as required by routing and dissemination protocols, and examines the existence and evolution of communities (dense clusters of vehicles) in the VANET. Several latent facts about the VANET graph are revealed and incentives for their exploitation in protocol design are examined.","PeriodicalId":275737,"journal":{"name":"2009 IEEE International Symposium on Modeling, Analysis & Simulation of Computer and Telecommunication Systems","volume":"139 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114756936","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 : 2009-12-28DOI: 10.1109/MASCOT.2009.5366718
A. Gopinathan, Zongpeng Li, C. Williamson
Recent advances in wireless technology have made it increasingly feasible to equip wireless nodes with multiple radios, thereby allowing each radio to exploit channel diversity in the form of orthogonal, non-overlapping transmission spectrums. Multi-channel operation mitigates interference, but at the same time raises new challenges for network optimization, in terms of judicious channel assignment for efficient bandwidth utilization. While previous research mostly studies optimizing channel assignment for unicast, we focus instead on multicast, which is an efficient mechanism for one-to-many data dissemination. We derive a model for optimal multicast in multi-channel multi-radio wireless networks under the assumption that channel assignment is static. Our model employs network coding as the multicast mechanism of choice, and exploits the broadcast nature of omnidirectional antennas for efficient bandwidth utilization. Based on the model derived, we formulate optimal multicast as a linear integer program. Two accompanying solutions are proposed: a greedy channel assignment scheme and an improved iterative scheme inspired by primal-dual algorithm design. The effectiveness of the two schemes are empirically examined through simulation studies, and are compared to results obtained from solving the integer program as well as its linear programming relaxation. Finally, we present an alternate model for optimal multicast under the assumption that transmission frequencies are not fixed divisions of the usable spectrum.
{"title":"Optimal multicast in multi-channel multi-radio wireless networks","authors":"A. Gopinathan, Zongpeng Li, C. Williamson","doi":"10.1109/MASCOT.2009.5366718","DOIUrl":"https://doi.org/10.1109/MASCOT.2009.5366718","url":null,"abstract":"Recent advances in wireless technology have made it increasingly feasible to equip wireless nodes with multiple radios, thereby allowing each radio to exploit channel diversity in the form of orthogonal, non-overlapping transmission spectrums. Multi-channel operation mitigates interference, but at the same time raises new challenges for network optimization, in terms of judicious channel assignment for efficient bandwidth utilization. While previous research mostly studies optimizing channel assignment for unicast, we focus instead on multicast, which is an efficient mechanism for one-to-many data dissemination. We derive a model for optimal multicast in multi-channel multi-radio wireless networks under the assumption that channel assignment is static. Our model employs network coding as the multicast mechanism of choice, and exploits the broadcast nature of omnidirectional antennas for efficient bandwidth utilization. Based on the model derived, we formulate optimal multicast as a linear integer program. Two accompanying solutions are proposed: a greedy channel assignment scheme and an improved iterative scheme inspired by primal-dual algorithm design. The effectiveness of the two schemes are empirically examined through simulation studies, and are compared to results obtained from solving the integer program as well as its linear programming relaxation. Finally, we present an alternate model for optimal multicast under the assumption that transmission frequencies are not fixed divisions of the usable spectrum.","PeriodicalId":275737,"journal":{"name":"2009 IEEE International Symposium on Modeling, Analysis & Simulation of Computer and Telecommunication Systems","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116284989","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 : 2009-12-28DOI: 10.1109/MASCOT.2009.5366313
A. Symington, P. Kritzinger
The Distributed Coordination Function is one of three channel access control protocols specified by the IEEE 802.11 standard. In this paper we present a method of measuring DCF performance using a test bed built with off-the-shelf hardware. Performance is measured by normalized aggregate throughput as a function of the number of stations contending for channel access. We present measurements for both basic access and RTS/CTS access in fully-connected IEEE 802.11g networks experiencing conditions of saturation. We compare our measurements to results from three analytic models and a simulator, all of which shared the same assumptions about the workload model and operation of DCF. For small networks the analytic models predict a much lower performance than shown through simulation and test bed experiments. As the network grows, so the measured performance deteriorates significantly faster than predicted by the analytic models. We attribute this to inaccuracies in the analytic model, imperfect channels and queuing. The simulation results fit the measured data with more accuracy, as the simulator makes fewer restrictive assumptions about DCF when compared to the analytic models. This is the first paper to provide a cross-comparison of test bed, simulation and analytic results for IEEE 802.11g DCF performance.
{"title":"A hardware test bed for measuring IEEE 802.11g distribution coordination function performance","authors":"A. Symington, P. Kritzinger","doi":"10.1109/MASCOT.2009.5366313","DOIUrl":"https://doi.org/10.1109/MASCOT.2009.5366313","url":null,"abstract":"The Distributed Coordination Function is one of three channel access control protocols specified by the IEEE 802.11 standard. In this paper we present a method of measuring DCF performance using a test bed built with off-the-shelf hardware. Performance is measured by normalized aggregate throughput as a function of the number of stations contending for channel access. We present measurements for both basic access and RTS/CTS access in fully-connected IEEE 802.11g networks experiencing conditions of saturation. We compare our measurements to results from three analytic models and a simulator, all of which shared the same assumptions about the workload model and operation of DCF. For small networks the analytic models predict a much lower performance than shown through simulation and test bed experiments. As the network grows, so the measured performance deteriorates significantly faster than predicted by the analytic models. We attribute this to inaccuracies in the analytic model, imperfect channels and queuing. The simulation results fit the measured data with more accuracy, as the simulator makes fewer restrictive assumptions about DCF when compared to the analytic models. This is the first paper to provide a cross-comparison of test bed, simulation and analytic results for IEEE 802.11g DCF performance.","PeriodicalId":275737,"journal":{"name":"2009 IEEE International Symposium on Modeling, Analysis & Simulation of Computer and Telecommunication Systems","volume":"367 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116449847","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 : 2009-12-28DOI: 10.1109/MASCOT.2009.5366139
D. Feitelson, Edi Shmueli
Computer workloads have many attributes. When modeling these workloads it is often difficult to decide which attributes are important, and which can be abstracted away. In many cases, the modeler only includes attributes that are believed to be important, and ignores the rest. We argue, however, that this can lead to impaired workloads and unreliable system evaluations. Using parallel job scheduling as a case study, and daily cycles of activity as the attribute in dispute, we present two schedulers whose simulated performance seems identical without cycles, but then becomes significantly different when daily cycles are included in the workload. We trace this to the ability of one scheduler to prioritize interactive jobs, which leads to implicitly delaying less critical work to nighttime, when it can utilize resources that otherwise would have been left idle. Notably, this was not a design feature of this scheduler, but rather an emergent property that was not anticipated in advance.
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