Pub Date : 2012-02-16DOI: 10.1109/WONS.2012.6152222
A. Coluccia, F. Ricciato
In this paper we present a Maximum Likelihood (ML) trajectory estimation of a mobile node from Received Signal Strength (RSS) measurements. The reference scenario includes a number of nodes in fixed and known positions (anchors) and a target node (blind) in motion whose instantaneous position is unknown. We first consider the dynamic estimation of the channel parameters from anchor-to-anchor measurements, statistically modeled according to the well-known Path-Loss propagation model. Then, we address the ML estimation problem for the position and velocity of the blind node based on a set of blind-to-anchor RSS measurements. We compare also the algorithm with a ML-based single-point localization algorithm, and discuss the applicability of both methods for slowly moving nodes. We present simulation results to assess the accuracy of the proposed solution in terms of localization error and velocity estimation (modulus and angle). The distribution of the localization error on the initial and final point is analyzed and closed-form expressions are derived.
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Pub Date : 2012-02-16DOI: 10.1109/WONS.2012.6152233
Sanpetch Chupisanyarote, S. T. Kouyoumdjieva, Ó. Helgason, G. Karlsson
In this paper we examine opportunistic content distribution. We design and evaluate a caching strategy where a node will fetch and share contents on behalf of other nodes, although the contents are not of its own interest. We propose three caching options for improving the use of network resources: relay request on demand, hop-limit, and greedy relay request. The proposed strategies are implemented in the OMNeT++ simulator and evaluated on mobility traces from Legion Studio that have churn. We also compare our strategies with a strategy from the literature. The results are analyzed and they show that the use of opportunistic caching for a community of nodes may enhance the performance marginally while overhead increases significantly.
{"title":"Caching in opportunistic networks with churn","authors":"Sanpetch Chupisanyarote, S. T. Kouyoumdjieva, Ó. Helgason, G. Karlsson","doi":"10.1109/WONS.2012.6152233","DOIUrl":"https://doi.org/10.1109/WONS.2012.6152233","url":null,"abstract":"In this paper we examine opportunistic content distribution. We design and evaluate a caching strategy where a node will fetch and share contents on behalf of other nodes, although the contents are not of its own interest. We propose three caching options for improving the use of network resources: relay request on demand, hop-limit, and greedy relay request. The proposed strategies are implemented in the OMNeT++ simulator and evaluated on mobility traces from Legion Studio that have churn. We also compare our strategies with a strategy from the literature. The results are analyzed and they show that the use of opportunistic caching for a community of nodes may enhance the performance marginally while overhead increases significantly.","PeriodicalId":309036,"journal":{"name":"2012 9th Annual Conference on Wireless On-Demand Network Systems and Services (WONS)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124635938","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 : 2012-02-16DOI: 10.1109/WONS.2012.6152246
Michele Segata, R. Cigno
The goal of this work is to highlight and explain the limitations of traditional physical channel models used in network simulators for wireless LANs, with particular reference to VANETs, where these limitations may jeopardize the validity of results, specially for safety applications. The fundamental tradeoff is between simulation time and realism. Indeed, a simulator should provide realistic results as fast as possible, even if several nodes (i.e., hundreds) are considered. Our final goal, beyond this initial contribution, is the development of a stochastic channel model which improves reliability of simulations while increasing computational complexity only marginally. The design of our model is based on the representation of the packet decoding procedure as a Markov Decision (Stochastic) Process (MDP), thus avoiding the computational complexity of the simulation of the entire transmission - propagation - decoding chain bit-by-bit, which can surely provide enough accuracy, but at the price of unacceptable computational (and model) complexity. The paper identifies the key phenomena such as preamble detection, central-frequency misalignment, channel captures, vehicles relative speed, that represent the `state' of the MDP modeling the transmission chain, and propose an MDP structure to exploit it. The focus is on 802.11p and OFDM-based PHY layers, but the model is extensible to other transmission techniques easily. The design is tailored for implementation in ns-3, albeit the modeling principle is general and suitable for every event-driven simulator.
{"title":"Simulation of 802.11 PHY/MAC: The quest for accuracy and efficiency","authors":"Michele Segata, R. Cigno","doi":"10.1109/WONS.2012.6152246","DOIUrl":"https://doi.org/10.1109/WONS.2012.6152246","url":null,"abstract":"The goal of this work is to highlight and explain the limitations of traditional physical channel models used in network simulators for wireless LANs, with particular reference to VANETs, where these limitations may jeopardize the validity of results, specially for safety applications. The fundamental tradeoff is between simulation time and realism. Indeed, a simulator should provide realistic results as fast as possible, even if several nodes (i.e., hundreds) are considered. Our final goal, beyond this initial contribution, is the development of a stochastic channel model which improves reliability of simulations while increasing computational complexity only marginally. The design of our model is based on the representation of the packet decoding procedure as a Markov Decision (Stochastic) Process (MDP), thus avoiding the computational complexity of the simulation of the entire transmission - propagation - decoding chain bit-by-bit, which can surely provide enough accuracy, but at the price of unacceptable computational (and model) complexity. The paper identifies the key phenomena such as preamble detection, central-frequency misalignment, channel captures, vehicles relative speed, that represent the `state' of the MDP modeling the transmission chain, and propose an MDP structure to exploit it. The focus is on 802.11p and OFDM-based PHY layers, but the model is extensible to other transmission techniques easily. The design is tailored for implementation in ns-3, albeit the modeling principle is general and suitable for every event-driven simulator.","PeriodicalId":309036,"journal":{"name":"2012 9th Annual Conference on Wireless On-Demand Network Systems and Services (WONS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122877186","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 : 2012-02-16DOI: 10.1109/WONS.2012.6152231
S. Saleem, Ning Zhang
Limited availability of computing devices and broadband access are among the biggest hurdles in bringing many data rich applications, to the masses in developing countries. Ad-hoc Mobile Collaborative Community (MCC) has been proposed as a solution to address these hurdles. MCC enables two or more persons to aggregate their mobile phone/PDA network channels for collaborative data transfer across the Internet. These channels may be heterogeneous and are characterized with frequent Quality of Service (QoS) fluctuations. Further, data to be transferred may contain multiple streams each having distinct, possibly conflicting security and QoS requirements. These factors make scheduling of data over multiple channels, a challenging task. In addition, battery and processing power limitations of mobile nodes imply that scheduler should be energy and processing cost efficient. This paper proposes a novel lightweight scheduler, a Risk-Aware Workload (RAW) scheduler, to support secure and efficient collaborative data transfer in MCC.
计算设备的有限可用性和宽带接入是向发展中国家大众提供许多数据丰富的应用程序的最大障碍之一。特设移动协作社区(Ad-hoc Mobile Collaborative Community, MCC)已被提出作为解决这些障碍的解决方案。MCC使两个或更多的人能够聚合他们的移动电话/PDA网络通道，以便在互联网上协作传输数据。这些信道可能是异构的，其特点是服务质量(QoS)波动频繁。此外，要传输的数据可能包含多个流，每个流具有不同的、可能相互冲突的安全性和QoS需求。这些因素使得通过多个通道调度数据成为一项具有挑战性的任务。此外，移动节点的电池和处理能力的限制意味着调度程序应该是能源和处理成本有效的。本文提出了一种新的轻量级调度器——风险感知工作负载(RAW)调度器，以支持MCC中安全高效的协同数据传输。
{"title":"A Risk-Aware Workload scheduler to support secure and efficient collaborative data transfer in mobile communities","authors":"S. Saleem, Ning Zhang","doi":"10.1109/WONS.2012.6152231","DOIUrl":"https://doi.org/10.1109/WONS.2012.6152231","url":null,"abstract":"Limited availability of computing devices and broadband access are among the biggest hurdles in bringing many data rich applications, to the masses in developing countries. Ad-hoc Mobile Collaborative Community (MCC) has been proposed as a solution to address these hurdles. MCC enables two or more persons to aggregate their mobile phone/PDA network channels for collaborative data transfer across the Internet. These channels may be heterogeneous and are characterized with frequent Quality of Service (QoS) fluctuations. Further, data to be transferred may contain multiple streams each having distinct, possibly conflicting security and QoS requirements. These factors make scheduling of data over multiple channels, a challenging task. In addition, battery and processing power limitations of mobile nodes imply that scheduler should be energy and processing cost efficient. This paper proposes a novel lightweight scheduler, a Risk-Aware Workload (RAW) scheduler, to support secure and efficient collaborative data transfer in MCC.","PeriodicalId":309036,"journal":{"name":"2012 9th Annual Conference on Wireless On-Demand Network Systems and Services (WONS)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130536593","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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