2007 IEEE International Conference on Portable Information Devices最新文献

{"title":"Recognizing User Context Using Mobile Handsets with Acceleration Sensors","authors":"Y. Kawahara, H. Kurasawa, H. Morikawa","doi":"10.1109/PORTABLE.2007.12","DOIUrl":"https://doi.org/10.1109/PORTABLE.2007.12","url":null,"abstract":"User context recognition is one of the important technologies for realizing context aware services. Conventional multi sensor based approach has advantages in that it can generate variety of contexts with less computation resources by using many different sensors. However, such systems tend to be complex and cumbersome and, thus, do not fit in well with mobile environment. In this sense, a single sensor based approach is suitable for mobile environments. In this paper, we show a context inference scheme that realizes a user posture inference with only one acceleration sensor embedded in a mobile handset. Our system automatically detects the sensor position on the user's body and selects the most relevant inference method dynamically. Our experimental results show that the system can infer a user's posture (sitting, standing, walking, and running) with an accuracy of more than 96%.","PeriodicalId":426585,"journal":{"name":"2007 IEEE International Conference on Portable Information Devices","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125358989","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}

{"title":"Economical Methods for Accurate Vehicle Tracking","authors":"J. D. Jackson, D. Callahan, P. Wang","doi":"10.1109/PORTABLE.2007.48","DOIUrl":"https://doi.org/10.1109/PORTABLE.2007.48","url":null,"abstract":"Accurate vehicle localization is frequently a requirement of tracking applications. Cost, however, often becomes a limiting factor rather than tolerable error in applications requiring better than 1 meter of accuracy. In this paper methods are proposed to provide accurate vehicle localization using off the shelf components, with the goal being accuracy down to 4 cm at 80 km/hr. The technologies proposed include the use of regular GPS, laser and ultrasonic rangefinders, optical mouse sensors, and accelerometers. Methods will also be discussed for calculating position from accelerometer data with a discussion of current results and future plans for combining GPS and accelerometer data.","PeriodicalId":426585,"journal":{"name":"2007 IEEE International Conference on Portable Information Devices","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117039986","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}

{"title":"Dynamic Channel Assignment in IEEE 802.11 Networks","authors":"R. Akl, Anurag Arepally","doi":"10.1109/PORTABLE.2007.63","DOIUrl":"https://doi.org/10.1109/PORTABLE.2007.63","url":null,"abstract":"We design a dynamic channel assignment algorithm for IEEE 802.11 wireless networks. Our algorithm assigns channels dynamically in a way that minimizes channel interference generated by neighboring access points (APs) on a reference access point, resulting in higher throughput. We implement and simulate our algorithm using two versions (I: pick rand and II: pick first) and different number of APs (4, 9, 16, and 25). Analysis of our algorithm shows an improvement by a factor of 4 (by lowering the total interference on an AP by 6 dBm on average) over default settings of having all APs use the same channel. As the number of APs is increased in a given service area, dynamic channel assignment becomes crucial; otherwise overlapping channel interference becomes a limiting factor.","PeriodicalId":426585,"journal":{"name":"2007 IEEE International Conference on Portable Information Devices","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125717604","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}

{"title":"A Novel Equalizer Structure for Direct Sequence Ultra Wideband (DS-UWB) System","authors":"Jin Ren, M. Lim","doi":"10.1109/PORTABLE.2007.44","DOIUrl":"https://doi.org/10.1109/PORTABLE.2007.44","url":null,"abstract":"In this paper we present a transceiver scheme based on a novel equalizer for indoor DS-UWB systems. The proposed scheme consists of a transmitter, a receiver with a novel equalizer which can reduce the overhead during the training phase and reduce the computation complexity without inducing loss of the BER performance. Furthermore, we evaluate performance on convergence rate, complexity and robustness for adaptive algorithm, and then compare the proposed scheme with the conventional structure under the realistic IEEE 802.15.3a channel model. Simulation results support the theoretical analysis and show that the proposed scheme can achieve higher throughput than a conventional one without loss of BER performance.","PeriodicalId":426585,"journal":{"name":"2007 IEEE International Conference on Portable Information Devices","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127957306","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}

{"title":"Gain & Size Considerations of Satellite Subscriber Terminals on Earth in Future Intelligent Satellites","authors":"G. Tomar, S. Verma","doi":"10.1109/PORTABLE.2007.60","DOIUrl":"https://doi.org/10.1109/PORTABLE.2007.60","url":null,"abstract":"This paper presents an advanced satellite-imaging concept that could have impact on the development of satellite technology in coming years. The proposed intelligent satellite system is a space based architecture for the dynamic and comprehensive on-board integration of Earth observing sensors, data processors and communication systems to enable simultaneous, global measurement and timely analysis of the Earth's environment for real-time, mobile and common users in the remote sensing, photogrammetry, GIS, and other communities. This is because user's demands in the GIS, mapping, natural resources, environmental science, Earth monitoring, etc., communities have migrated from basic Imagery to temporal, site specific, update mapping products/image-based information. Data and information revisions will be requested more frequently, that is, in many ways analogous to today's weather updates. In addition, common consumers will be less concerned with the technical complexities of image processing, requiring imagery providers to use different strategies to directly provide users with value-added images (e.g., orthorectification, feature enhancement, radiometric intensification, etc.) and value-added products (e.g., orthoimage mosaics) in order to meet real-time, mobile needs. The proposed architectures form a seamless integration of diverse components into a smart, adaptable and robust Earth observation satellite system.","PeriodicalId":426585,"journal":{"name":"2007 IEEE International Conference on Portable Information Devices","volume":"47 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117042228","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}

{"title":"Optimal Channel Changing Delay for Mobile TV Over DVB-H","authors":"M. Rezaei, Imed Bouazizi, V. Vadakital, M. Gabbouj","doi":"10.1109/PORTABLE.2007.15","DOIUrl":"https://doi.org/10.1109/PORTABLE.2007.15","url":null,"abstract":"This paper provides an analysis on the optimal channel changing delay in DVB-H (Digital Video Broadcasting for Handhelds) channels for Mobile Television. DVB-H uses a time-sliced transmission scheme to reduce the power consumption used for radio reception in DVB-H receivers. Channel changing delay, i.e. changing from one audio-visual service to another, is increased due to the time slicing scheme in DVB-H. One of the significant factors in channel changing delay is the Decoder Refresh Delay. The Decoder Refresh Delay is the time from the start of video decoding to the start of correct output from decoder. This delay is minimized when a time-slice starts with a random access point picture such as an instantaneous decoding refresh (IDR) picture in H.264/AVC standard. In DVB-H, encapsulation into time-slices is performed independently from content encoding. At the time of encoding, the exact time-slice boundaries are typically unknown, and therefore it is impossible to align the location of IDR pictures to time-slice boundaries. The average decoder refresh delay can decrease by frequent IDR pictures in the bit stream. However, using very frequent IDR pictures drops the compression efficiency and the quality of compressed video dramatically. Another factor in channel changing delay is the delay required to compensate the variation in bit rate. In video streaming over DVB-H the improved quality and compression efficiency obtained by using variable bit rate should be exploited. Higher quality and compression performance can be provided by higher delay. Moreover, when changing channels, a delay is required until the start of the desired time-slice and a further delay is incurred to complete the reception of the entire time-slice. These delays depend on the time-slicing parameters that define the power saving percentage obtained as the result of the time-slice scheme. The lower the receiver power consumption, the higher delay is required. Therefore, there is a strong multilateral relationship between the quality of compressed video, the channel changing delay and the power consumption in the receiver. Simulations were conducted and based on the simulation results an optimal operating area is proposed.","PeriodicalId":426585,"journal":{"name":"2007 IEEE International Conference on Portable Information Devices","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114403271","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}