Pub Date : 2007-12-04DOI: 10.1109/ISCIT.2007.4392144
Alexandre P. Almeida, Rui Dinis, F. Cercas
This paper introduces an efficient acquisition/correlation technique for DS-CDMA systems using a frequency-domain approach employing TCH-based training blocks (Tomlison, Cercas and Hughes). The classical time-domain active acquisition technique is compared with the proposed passive matched-filter type frequency domain technique. Moreover using the fact that an N-point discrete Fourier transform (DFT) can be partitioned into M smaller DFTs, we present a procedure for simultaneous decoding/despreading and synchronization that switch between 16 bit-length and 256 bit-length cyclic codes thus providing code rate variability.
{"title":"An FFT-based acquisition scheme for DS-CDM a systems","authors":"Alexandre P. Almeida, Rui Dinis, F. Cercas","doi":"10.1109/ISCIT.2007.4392144","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392144","url":null,"abstract":"This paper introduces an efficient acquisition/correlation technique for DS-CDMA systems using a frequency-domain approach employing TCH-based training blocks (Tomlison, Cercas and Hughes). The classical time-domain active acquisition technique is compared with the proposed passive matched-filter type frequency domain technique. Moreover using the fact that an N-point discrete Fourier transform (DFT) can be partitioned into M smaller DFTs, we present a procedure for simultaneous decoding/despreading and synchronization that switch between 16 bit-length and 256 bit-length cyclic codes thus providing code rate variability.","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":"130603174","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.2007.4392119
S. Majid, K. Ahmed
Disasters in last decade have rapidly increased the research activities related to emergency communications. This paper presents a model for cognitive identification of post-disaster situation. A two-state model for mobile handsets along with a software based identification module is introduced for the said purpose. This paper also discusses implementation solutions based on: traditional cellular network features, cognitive radio using game theory and artificial neural networks. At the end of paper we present analysis considering the time taken for the identification of emergency situation and probability of false alarming of such situations.
{"title":"CIP - cognitive identification of post-disaster communications","authors":"S. Majid, K. Ahmed","doi":"10.1109/ISCIT.2007.4392119","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392119","url":null,"abstract":"Disasters in last decade have rapidly increased the research activities related to emergency communications. This paper presents a model for cognitive identification of post-disaster situation. A two-state model for mobile handsets along with a software based identification module is introduced for the said purpose. This paper also discusses implementation solutions based on: traditional cellular network features, cognitive radio using game theory and artificial neural networks. At the end of paper we present analysis considering the time taken for the identification of emergency situation and probability of false alarming of such situations.","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"9 3 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":"116863019","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.2007.4392208
R. Chrabieh, S. Soliman
WiMedia UWB is a high data rate OFDM system for wireless personal area networks. The design philosophy is a mixture of high throughput and low power consumption. The standard uses special time and frequency domain spreading to enable low power consumption for the low data rates and for low-end devices. A loss of channel diversity is observed in certain scenarios. First we describe an efficient frequency domain spreading implementation in time domain. Then using this key idea, we propose new spreading schemes, either to recover the diversity loss or to achieve additional power and hardware savings for low-end devices.
{"title":"Enhanced frequency domain spreading for WiMedia UWB","authors":"R. Chrabieh, S. Soliman","doi":"10.1109/ISCIT.2007.4392208","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392208","url":null,"abstract":"WiMedia UWB is a high data rate OFDM system for wireless personal area networks. The design philosophy is a mixture of high throughput and low power consumption. The standard uses special time and frequency domain spreading to enable low power consumption for the low data rates and for low-end devices. A loss of channel diversity is observed in certain scenarios. First we describe an efficient frequency domain spreading implementation in time domain. Then using this key idea, we propose new spreading schemes, either to recover the diversity loss or to achieve additional power and hardware savings for low-end devices.","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"100 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":"134229552","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.2007.4392130
A. Allwright, Dennis Perisa, P. Pourbeik
There have been many studies in recent years reporting the performance and survivability of mobile ad-hoc networks (MANETs). These studies invariably consider the network as covering a relatively small geographic area. However, in many crises, such as may occur during disaster relief and military operations, a wide geographic area may require network coverage. In these circumstances, the infrastructure free mobile wireless communications features of MANETs may be critical in forming a satisfactory network. Given transmission range limitations within current MANET proposals, it is likely that providing network coverage to a wide geographic area would be problematic. This paper presents the results of a study on clustering in the spatial distribution of communication nodes. A realistic environment (e.g. topography and organisational limitations) and operating procedures are introduced through the use of the results of war games. The spatial distribution of nodes is used as the basis for MANET internetwork topology generation.
{"title":"Analytical support for MANET internetworks from war game data","authors":"A. Allwright, Dennis Perisa, P. Pourbeik","doi":"10.1109/ISCIT.2007.4392130","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392130","url":null,"abstract":"There have been many studies in recent years reporting the performance and survivability of mobile ad-hoc networks (MANETs). These studies invariably consider the network as covering a relatively small geographic area. However, in many crises, such as may occur during disaster relief and military operations, a wide geographic area may require network coverage. In these circumstances, the infrastructure free mobile wireless communications features of MANETs may be critical in forming a satisfactory network. Given transmission range limitations within current MANET proposals, it is likely that providing network coverage to a wide geographic area would be problematic. This paper presents the results of a study on clustering in the spatial distribution of communication nodes. A realistic environment (e.g. topography and organisational limitations) and operating procedures are introduced through the use of the results of war games. The spatial distribution of nodes is used as the basis for MANET internetwork topology generation.","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"129 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134259995","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.2007.4392259
Qin Zheng, Dan-li Xu
Traditional software system is always designed with characters like tight-coupling, which is difficult to be replanted and so on. A new design of credit scoring information system(CSIS) has been proposed in this paper, which includes the framework of CSIS based on service-oriented architecture (SOA), (the) seven-layer macro-SOA, three types of flow units in micro-SOA, and four-layer credits data warehouse. Some key issues and the solutions for implementation of the CSIS are also discussed in the paper. The new CSIS is loose-coupling. It is of flexibility and is easy to replant. Thus it is feasible for customization [2].
{"title":"A new design of the credits scoring information System","authors":"Qin Zheng, Dan-li Xu","doi":"10.1109/ISCIT.2007.4392259","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392259","url":null,"abstract":"Traditional software system is always designed with characters like tight-coupling, which is difficult to be replanted and so on. A new design of credit scoring information system(CSIS) has been proposed in this paper, which includes the framework of CSIS based on service-oriented architecture (SOA), (the) seven-layer macro-SOA, three types of flow units in micro-SOA, and four-layer credits data warehouse. Some key issues and the solutions for implementation of the CSIS are also discussed in the paper. The new CSIS is loose-coupling. It is of flexibility and is easy to replant. Thus it is feasible for customization [2].","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"88 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":"133132835","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.2007.4392153
Chiu-Kuo Liang, Yu-Jie Huang, J. Lin
In wireless sensor networks, it is an important task to periodically collect data from an area of interest for time-sensitive applications. The sensed data must be gathered and transmitted to a base station for further processing to meet the end-user queries. Since the network consists of low-cost nodes with limited battery power, it is a challenging task to design an efficient routing scheme that can minimize delay and offer good performance in energy efficiency, and long network lifetimes. In this paper, we propose a new routing protocol, called Degree-Constrained Minimal Spanning Tree (DCMST), to collect information efficiently. DCMST is efficient in the ways that it ensures maximal utilization of network energy, it makes the lifetime of the network longer, as well as it takes much lower time to complete a round. Simulation results show that DCMST achieves around 20% better performance than that of COSEN in respect of delay time. It also shows that DCMST can perform better than COSEN in total transmission distance, which implies the less total energy consumption. Therefore, our DCMST scheme gives a good compromise between energy efficiency and latency.
{"title":"Energy efficient routing for achieving shorter latency in sensor networks","authors":"Chiu-Kuo Liang, Yu-Jie Huang, J. Lin","doi":"10.1109/ISCIT.2007.4392153","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392153","url":null,"abstract":"In wireless sensor networks, it is an important task to periodically collect data from an area of interest for time-sensitive applications. The sensed data must be gathered and transmitted to a base station for further processing to meet the end-user queries. Since the network consists of low-cost nodes with limited battery power, it is a challenging task to design an efficient routing scheme that can minimize delay and offer good performance in energy efficiency, and long network lifetimes. In this paper, we propose a new routing protocol, called Degree-Constrained Minimal Spanning Tree (DCMST), to collect information efficiently. DCMST is efficient in the ways that it ensures maximal utilization of network energy, it makes the lifetime of the network longer, as well as it takes much lower time to complete a round. Simulation results show that DCMST achieves around 20% better performance than that of COSEN in respect of delay time. It also shows that DCMST can perform better than COSEN in total transmission distance, which implies the less total energy consumption. Therefore, our DCMST scheme gives a good compromise between energy efficiency and latency.","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"7 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":"123021111","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.2007.4392182
T.T. Nguyen, H. Tuan, T.Q. Nguyen
This paper presents a robust approach for spread spectrum (SS) based watermarking process. Unlike the traditional SS or other improvements, this method can work properly in case of absence of watermark and achieve good performance. If the channel has no noise, the error probability of the new design is zero, which is not existed in almost SS-based watermarking systems. Based on analysis by theory, the optimal threshold is calculated. Moreover, the simulations are implemented to verify to the theory.
{"title":"Robust watermarking with improved modified spread spectrum","authors":"T.T. Nguyen, H. Tuan, T.Q. Nguyen","doi":"10.1109/ISCIT.2007.4392182","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392182","url":null,"abstract":"This paper presents a robust approach for spread spectrum (SS) based watermarking process. Unlike the traditional SS or other improvements, this method can work properly in case of absence of watermark and achieve good performance. If the channel has no noise, the error probability of the new design is zero, which is not existed in almost SS-based watermarking systems. Based on analysis by theory, the optimal threshold is calculated. Moreover, the simulations are implemented to verify to the theory.","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":"129086713","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.2007.4392114
K. Gopalan
A method of implementing image steganography in a color image for applications such as covert communication via the Internet and authentication of an employee carrying a picture identification card is described. By converting the color image to a one-dimensional signal in red, green, or blue, audibly masked frequencies in the 1-D signal are determined for each segment or block. Embedding of secure or confidential data is carried out by modifying the spectral power at a pair of commonly occurring masked frequencies. Compressing the data-embedded image to standard JPEG coding enables its transmission via the Internet. Experimental results show that the technique is simple to implement and causes barely noticeable distortion in the stego image. Using an oblivious technique and a key consisting of the frequencies where the spectrum is modified, successful data retrieval even at low level noise levels and at low-loss compression has been achieved. Higher payload of hidden data can be obtained at a cost of perceptibility of embedding. Lossy JPEG compression, however, leads to low payloads.
{"title":"An image steganography implementation for JPEG-compressed images","authors":"K. Gopalan","doi":"10.1109/ISCIT.2007.4392114","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392114","url":null,"abstract":"A method of implementing image steganography in a color image for applications such as covert communication via the Internet and authentication of an employee carrying a picture identification card is described. By converting the color image to a one-dimensional signal in red, green, or blue, audibly masked frequencies in the 1-D signal are determined for each segment or block. Embedding of secure or confidential data is carried out by modifying the spectral power at a pair of commonly occurring masked frequencies. Compressing the data-embedded image to standard JPEG coding enables its transmission via the Internet. Experimental results show that the technique is simple to implement and causes barely noticeable distortion in the stego image. Using an oblivious technique and a key consisting of the frequencies where the spectrum is modified, successful data retrieval even at low level noise levels and at low-loss compression has been achieved. Higher payload of hidden data can be obtained at a cost of perceptibility of embedding. Lossy JPEG compression, however, leads to low payloads.","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":"129348222","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.2007.4392108
Jinsheng Sun, M. Zukerman, M. Palaniswami
Active queue management (AQM) mechanisms have been proposed to support end-to-end congestion control mechanisms of transmission control protocol (TCP) in TCP/IP networks. This paper introduces a new AQM based on a stable adaptive proportional-integral (SAPI) controller. SAPI adaptively adjusts the PI controller parameters based on estimated network parameters to improve the transient performance of a fixed-gain PI controller. We present the SAPI scheme in detail, and provide guidelines for the selection of its parameters. Through extensive simulations, we demonstrate that SAPI maintains satisfactory transient and steady-state performance independent of traffic loads, round trip propagation delay, and bottleneck capacity. The simulation results also demonstrate that SAPI is robust to non-responsive UDP traffic and HTTP traffic, and it is effective for networks with multiple bottlenecks. Comparison with other well-known AQM algorithms like PI, REM and Q-SAPI shows that SAPI achieves faster convergence to queue length target and smaller queue length jitter.
{"title":"A stable adaptive PI controller for AQM","authors":"Jinsheng Sun, M. Zukerman, M. Palaniswami","doi":"10.1109/ISCIT.2007.4392108","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4392108","url":null,"abstract":"Active queue management (AQM) mechanisms have been proposed to support end-to-end congestion control mechanisms of transmission control protocol (TCP) in TCP/IP networks. This paper introduces a new AQM based on a stable adaptive proportional-integral (SAPI) controller. SAPI adaptively adjusts the PI controller parameters based on estimated network parameters to improve the transient performance of a fixed-gain PI controller. We present the SAPI scheme in detail, and provide guidelines for the selection of its parameters. Through extensive simulations, we demonstrate that SAPI maintains satisfactory transient and steady-state performance independent of traffic loads, round trip propagation delay, and bottleneck capacity. The simulation results also demonstrate that SAPI is robust to non-responsive UDP traffic and HTTP traffic, and it is effective for networks with multiple bottlenecks. Comparison with other well-known AQM algorithms like PI, REM and Q-SAPI shows that SAPI achieves faster convergence to queue length target and smaller queue length jitter.","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"43 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":"116942190","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.2007.4391986
H. Ryu, Chengxiang Wang, Sang-Burm Ryu
Orthogonal frequency division multiplexing (OFDM) has been used widely in many communication systems. However, the major drawback of OFDM is the high peak-to-average-power ratio (PAPR) which results in the bit error rate (BER) performance degradation in nonlinear environments. In this paper, we introduce a new phase weighting method to reduce the nonlinear distortion of OFDM signals in the nonlinear high power amplifier, which is different from the well-known PAPR reduction method. Especially, the proposed method is based on the nonlinear distortion reduction criterion rather than the conventional PAPR reduction criterion so that we can improve the BER performance more effectively. The simulation results show that the BER performance of the OFDM system using the proposed method is better than that of the ordinary OFDM and other OFDM systems using the PAPR reduction criterion.
{"title":"Nonlinear distortion reduction for the improvement of the BER performance in OFDM communication systems","authors":"H. Ryu, Chengxiang Wang, Sang-Burm Ryu","doi":"10.1109/ISCIT.2007.4391986","DOIUrl":"https://doi.org/10.1109/ISCIT.2007.4391986","url":null,"abstract":"Orthogonal frequency division multiplexing (OFDM) has been used widely in many communication systems. However, the major drawback of OFDM is the high peak-to-average-power ratio (PAPR) which results in the bit error rate (BER) performance degradation in nonlinear environments. In this paper, we introduce a new phase weighting method to reduce the nonlinear distortion of OFDM signals in the nonlinear high power amplifier, which is different from the well-known PAPR reduction method. Especially, the proposed method is based on the nonlinear distortion reduction criterion rather than the conventional PAPR reduction criterion so that we can improve the BER performance more effectively. The simulation results show that the BER performance of the OFDM system using the proposed method is better than that of the ordinary OFDM and other OFDM systems using the PAPR reduction criterion.","PeriodicalId":331439,"journal":{"name":"2007 International Symposium on Communications and Information Technologies","volume":"35 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":"117070263","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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