Pub Date : 2007-12-04DOI: 10.1109/ISCIT.2007.4392139
M. Hedley, P. Ho, D. Humphrey, A. Kajan, A. Grancea, J. Pathikulangara
Accurate and low-cost localisation is an essential requirement in many sensor and ad hoc network applications. This paper presents a platform, both hardware and software, that has been developed as a flexible tool for research in ubiquitous localisation in applications such as emergency services. The system has also been designed to be small and with sufficiently long battery life to be suitable for field trials in a range of applications.
{"title":"A platform for radio location research in Ad Hoc and sensor networks","authors":"M. Hedley, P. Ho, D. Humphrey, A. Kajan, A. Grancea, J. Pathikulangara","doi":"10.1109/ISCIT.2007.4392139","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392139","url":null,"abstract":"Accurate and low-cost localisation is an essential requirement in many sensor and ad hoc network applications. This paper presents a platform, both hardware and software, that has been developed as a flexible tool for research in ubiquitous localisation in applications such as emergency services. The system has also been designed to be small and with sufficiently long battery life to be suitable for field trials in a range of applications.","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115872586","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 : 2007-12-04DOI: 10.1109/ISCIT.2007.4392196
K. Nguyen, U. Gunawardana, R. Liyana-Pathirana
The design of space-time turbo trellis codes (ST Turbo TC) for improving the bandwidth efficiency and the reliability of wireless data networks, which is based on the turbo structure, has been proposed in the literature. However, like other turbo based coding schemes, the fundamental problems with the ST Turbo TC decoder are its complexity and decoding delay. In some cases the decoding delay may be so long that the use of ST Turbo TC system is unattractive for time sensitive applications. The aim of this paper is to propose a simplified ST Turbo TC decoder using the sliding window technique in order to achieve memory savings and reduce decoding delay. In particular, we consider the performance of QPSK ST Turbo TC schemes on fast fading channels for various system parameters. Different window sizes are employed and investigated. Through computer simulation, the optimum window sizes are defined for different system parameters.
{"title":"Optimization of sliding window algorithm for space-time turbo trellis codes","authors":"K. Nguyen, U. Gunawardana, R. Liyana-Pathirana","doi":"10.1109/ISCIT.2007.4392196","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392196","url":null,"abstract":"The design of space-time turbo trellis codes (ST Turbo TC) for improving the bandwidth efficiency and the reliability of wireless data networks, which is based on the turbo structure, has been proposed in the literature. However, like other turbo based coding schemes, the fundamental problems with the ST Turbo TC decoder are its complexity and decoding delay. In some cases the decoding delay may be so long that the use of ST Turbo TC system is unattractive for time sensitive applications. The aim of this paper is to propose a simplified ST Turbo TC decoder using the sliding window technique in order to achieve memory savings and reduce decoding delay. In particular, we consider the performance of QPSK ST Turbo TC schemes on fast fading channels for various system parameters. Different window sizes are employed and investigated. Through computer simulation, the optimum window sizes are defined for different system parameters.","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131397518","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 : 2007-12-04DOI: 10.1109/ISCIT.2007.4392032
Aimin Yang, G. Xie, Ranran Zhang, B. Tang, Yuan’an Liu
This paper proposes an adaptive modulation (AM) algorithm for multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems with Vertical Bell Laboratories Layered Space-Time (V-BLAST) and orthogonal-triangular decomposition (QR) detection firstly. Then performance analysis is derived in closed form. Simulation results show that the theoretic bit error rate (BER) and spectral efficiency are very accordant to the simulated ones, respectively. Through the simulation, it is also seen that the adaptive modulation algorithm can improve not only the spectral efficiency but also the BER performance, remarkably.
{"title":"Performance analysis for AM in MIMO-OFDM systems","authors":"Aimin Yang, G. Xie, Ranran Zhang, B. Tang, Yuan’an Liu","doi":"10.1109/ISCIT.2007.4392032","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392032","url":null,"abstract":"This paper proposes an adaptive modulation (AM) algorithm for multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems with Vertical Bell Laboratories Layered Space-Time (V-BLAST) and orthogonal-triangular decomposition (QR) detection firstly. Then performance analysis is derived in closed form. Simulation results show that the theoretic bit error rate (BER) and spectral efficiency are very accordant to the simulated ones, respectively. Through the simulation, it is also seen that the adaptive modulation algorithm can improve not only the spectral efficiency but also the BER performance, remarkably.","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130684261","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 : 2007-12-04DOI: 10.1109/ISCIT.2007.4392052
F. P. Wathan, R. Hoshyar, R. Tafazolli
The performance of various iterated soft-input soft-output (SISO) multiuser detection (MUD) techniques is evaluated and compared for the case of overloaded condition for symbol-synchronous uncoded Code-Division Multiple Access (CDMA) systems over Additive White Gaussian Noise (AWGN) channel. We show that, via computer simulation, while the Bit-Error Rate (BER) performance of the serial version of the Symbol-Level iterated (SLi) SISO MUD technique is inferior to its parallel counterpart, its convergence rate is the faster between the two. Yet, the Chip-Level iterated (CLi) SISO MUD performs the best. Moreover, the Max-Log-MAP version of the CLi SISO MUD complementing the recently proposed Low-Density Signature (LDS) structure is introduced and compared to its Log-MAP version. The sensitivity of the various CLi SISO MUD techniques to the existence of the short-cycles in the underlying factor graph of the LDS structure is also analyzed. Our simulations confirm that the Max-Log-MAP version performs better compared to its more complex Log-MAP version in higher system loading condition. We also show that a performance close to single-user bound can be achieved at higher Signal-to-Noise Ratio (SNR) regime for system loading of up to 250%.
{"title":"Iterated SISO MUD for synchronous uncoded CDMA systems over AWGN channel: performance evaluation in overloaded condition","authors":"F. P. Wathan, R. Hoshyar, R. Tafazolli","doi":"10.1109/ISCIT.2007.4392052","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392052","url":null,"abstract":"The performance of various iterated soft-input soft-output (SISO) multiuser detection (MUD) techniques is evaluated and compared for the case of overloaded condition for symbol-synchronous uncoded Code-Division Multiple Access (CDMA) systems over Additive White Gaussian Noise (AWGN) channel. We show that, via computer simulation, while the Bit-Error Rate (BER) performance of the serial version of the Symbol-Level iterated (SLi) SISO MUD technique is inferior to its parallel counterpart, its convergence rate is the faster between the two. Yet, the Chip-Level iterated (CLi) SISO MUD performs the best. Moreover, the Max-Log-MAP version of the CLi SISO MUD complementing the recently proposed Low-Density Signature (LDS) structure is introduced and compared to its Log-MAP version. The sensitivity of the various CLi SISO MUD techniques to the existence of the short-cycles in the underlying factor graph of the LDS structure is also analyzed. Our simulations confirm that the Max-Log-MAP version performs better compared to its more complex Log-MAP version in higher system loading condition. We also show that a performance close to single-user bound can be achieved at higher Signal-to-Noise Ratio (SNR) regime for system loading of up to 250%.","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"2016 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133332360","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 : 2007-12-04DOI: 10.1109/ISCIT.2007.4392070
Dong Hoi Kim, H. Kim, D. Lee
This paper considers a packet scheduling algorithm using two different priority metrics specified for each service to support integrated services of real-time (RT) and non-realtime (NRT) applications. In particular, as a packet scheduling algorithm for NRT service, this paper proposes a new minimum guaranteed throughput scheduling (MGBRS) algorithm with two priority metrics based on average throughput and the minimum guaranteed throughput requirement and its design objective is to increase the number of NRT service users satisfying the required minimum guaranteed throughput. For the performance evaluation of the proposed MGBRS scheme in a wireless communication system, this paper adopts a transmission structure of an orthogonal frequency division multiple access (OFDMA) system. The simulation results show that the proposed algorithm can provide a significant improvement in terms of increase of the number of NRT service users satisfying the target outage probability and the per-cell total throughput performance by the number of NRT service users meeting the target outage probability is improved.
{"title":"Packet scheduling algorithm for NRT service in wireless system supporting integrated services of RT and NRT applications","authors":"Dong Hoi Kim, H. Kim, D. Lee","doi":"10.1109/ISCIT.2007.4392070","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392070","url":null,"abstract":"This paper considers a packet scheduling algorithm using two different priority metrics specified for each service to support integrated services of real-time (RT) and non-realtime (NRT) applications. In particular, as a packet scheduling algorithm for NRT service, this paper proposes a new minimum guaranteed throughput scheduling (MGBRS) algorithm with two priority metrics based on average throughput and the minimum guaranteed throughput requirement and its design objective is to increase the number of NRT service users satisfying the required minimum guaranteed throughput. For the performance evaluation of the proposed MGBRS scheme in a wireless communication system, this paper adopts a transmission structure of an orthogonal frequency division multiple access (OFDMA) system. The simulation results show that the proposed algorithm can provide a significant improvement in terms of increase of the number of NRT service users satisfying the target outage probability and the per-cell total throughput performance by the number of NRT service users meeting the target outage probability is improved.","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"92 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124591727","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 : 2007-12-04DOI: 10.1109/ISCIT.2007.4392072
M. Kang, B. Jung, D. Sung
In this paper, we mathematically analyze the performance of four different relaying schemes in cellular systems. We assume a downlink cellular system with fixed relays and a mobile station is either directly connected to a base station and/or connected to a relay station. We consider four different downlink data relaying schemes: a direct scheme, a relay scheme, a selection scheme, and a cooperative scheme. Under the environment, we derive a closed-form solution or upper bound of the ergodic and outage capacities. We also analyze the system capacity in a multiuser diversity environment in which a maximum signal-to-noise ratio (SNR) scheduler is used at a base station. The analytical results agree well with computer simulation results. The result shows that the selection scheme outperforms the other three schemes in terms of link ergodic capacity, link outage capacity, and system ergodic capacity.
{"title":"Performance analysis of four different downlink data relaying schemes in cellular systems","authors":"M. Kang, B. Jung, D. Sung","doi":"10.1109/ISCIT.2007.4392072","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392072","url":null,"abstract":"In this paper, we mathematically analyze the performance of four different relaying schemes in cellular systems. We assume a downlink cellular system with fixed relays and a mobile station is either directly connected to a base station and/or connected to a relay station. We consider four different downlink data relaying schemes: a direct scheme, a relay scheme, a selection scheme, and a cooperative scheme. Under the environment, we derive a closed-form solution or upper bound of the ergodic and outage capacities. We also analyze the system capacity in a multiuser diversity environment in which a maximum signal-to-noise ratio (SNR) scheduler is used at a base station. The analytical results agree well with computer simulation results. The result shows that the selection scheme outperforms the other three schemes in terms of link ergodic capacity, link outage capacity, and system ergodic capacity.","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114991141","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 : 2007-12-04DOI: 10.1109/ISCIT.2007.4392141
F. Engel, M. Hedley
Sensor networks allow monitoring, tracking, and controlling various aspects of the physical world. Any data retrieved or generated is only useful if considered in relation to its time and space coordinates. CSIRO's ICT Centre is currently developing a platform for distributed ad-hoc sensor networks. This paper describes the evaluation of various cooperative localisation techniques and their suitability for this sensor networks platform. Simulation results comparing different algorithms are presented and discussed.
{"title":"A comparison of cooperative localisation techniques for wireless mobile sensor networks","authors":"F. Engel, M. Hedley","doi":"10.1109/ISCIT.2007.4392141","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392141","url":null,"abstract":"Sensor networks allow monitoring, tracking, and controlling various aspects of the physical world. Any data retrieved or generated is only useful if considered in relation to its time and space coordinates. CSIRO's ICT Centre is currently developing a platform for distributed ad-hoc sensor networks. This paper describes the evaluation of various cooperative localisation techniques and their suitability for this sensor networks platform. Simulation results comparing different algorithms are presented and discussed.","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117219291","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 : 2007-12-04DOI: 10.1109/ISCIT.2007.4392118
Yi Wang, Fuhuei Lin
It is well know that red-eye is the appearance of an unnatural red blot in the pupils of a flash photography subject. Though plenty of solutions exist for this red-eye problem, some of them require some special speed-light apparatus, some deal with this problem by post-capture red-eye correction software, and others require the user intervention. A new approach is presented in this paper to automatically detect and correct redeye by combining flash image and preview frame which can be obtained easily as almost all of the cameras have preview function. It can be implemented in the existing cameras easily and such a camera would eliminate red-eye immediately after capture. Unlike previous approaches, proposed method is economic, fast, and accurate in both red-eye detection and correction since the artful use of the preview frame.
{"title":"A novel automatic red-eye detection and removal method","authors":"Yi Wang, Fuhuei Lin","doi":"10.1109/ISCIT.2007.4392118","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392118","url":null,"abstract":"It is well know that red-eye is the appearance of an unnatural red blot in the pupils of a flash photography subject. Though plenty of solutions exist for this red-eye problem, some of them require some special speed-light apparatus, some deal with this problem by post-capture red-eye correction software, and others require the user intervention. A new approach is presented in this paper to automatically detect and correct redeye by combining flash image and preview frame which can be obtained easily as almost all of the cameras have preview function. It can be implemented in the existing cameras easily and such a camera would eliminate red-eye immediately after capture. Unlike previous approaches, proposed method is economic, fast, and accurate in both red-eye detection and correction since the artful use of the preview frame.","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124663742","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 : 2007-12-04DOI: 10.1109/ISCIT.2007.4392227
I. Alony, Albert Munoz
This paper reviews the various methods of modelling the dynamics of supply chains. We then present recently documented causes of the Bullwhip effect in production supply chains, and the methodologies used to describe and measure the importance of these causes. We examine the limitations of these methodologies and suggest a combined approach discrete event-continuous simulation modelling approach to further study this phenomenon in complex production supply chains.
{"title":"The bullwhip effect in complex supply chains","authors":"I. Alony, Albert Munoz","doi":"10.1109/ISCIT.2007.4392227","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392227","url":null,"abstract":"This paper reviews the various methods of modelling the dynamics of supply chains. We then present recently documented causes of the Bullwhip effect in production supply chains, and the methodologies used to describe and measure the importance of these causes. We examine the limitations of these methodologies and suggest a combined approach discrete event-continuous simulation modelling approach to further study this phenomenon in complex production supply chains.","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124697057","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 : 2007-12-04DOI: 10.1109/ISCIT.2007.4392254
Kazuto Nishi, S. Yoshizawa, Yoshikazu Miyanaga
Cognitive radio recognizes frequency use in space and time domains and improves frequency utilization efficiency and communication performance by selecting an optimal communication mode. This paper proposes a new method reducing circuit area for reconfigurable FFT processors with multiple communication modes in OFDM based cognitive radio. The proposed method offers the FFT stages with two dimensional arrays and dynamically changes the data path connections in the butterfly and FIFO memory blocks. In the CMOS implementation, this structure has reduced circuit area by 35% compared with the conventional circuit.
{"title":"A study of dynamic reconfigurable FFT processor for OFDM based cognitive radio","authors":"Kazuto Nishi, S. Yoshizawa, Yoshikazu Miyanaga","doi":"10.1109/ISCIT.2007.4392254","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392254","url":null,"abstract":"Cognitive radio recognizes frequency use in space and time domains and improves frequency utilization efficiency and communication performance by selecting an optimal communication mode. This paper proposes a new method reducing circuit area for reconfigurable FFT processors with multiple communication modes in OFDM based cognitive radio. The proposed method offers the FFT stages with two dimensional arrays and dynamically changes the data path connections in the butterfly and FIFO memory blocks. In the CMOS implementation, this structure has reduced circuit area by 35% compared with the conventional circuit.","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130208554","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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