Pub Date : 2011-12-01DOI: 10.1109/ISCIT.2011.6092191
C. Vaz, D. G. Daut
In this paper a procedure for deconvolving signals in a Discrete Wavelet Transform (DWT) framework is applied to the estimation of impulse responses of fast-fading communications channels. Specifically, the effects of using several different wavelets on the performance of such wavelet-domain channel estimation is investigated. Monte Carlo simulations are performed using eight different wavelets. The simulations estimate impulse responses having a fast-fading, multipath, Power Delay Profile (PDP), and include Additive White Gaussian Noise (AWGN) resulting in Eb/N0 ratios from 0 dB to 30 dB. Results show that DWT-based deconvolution is especially effective when wavelets corresponding to short-length filters are used.
{"title":"Effects of wavelet choice in fast-fading channel estimation using wavelet transform-based deconvolution","authors":"C. Vaz, D. G. Daut","doi":"10.1109/ISCIT.2011.6092191","DOIUrl":"https://doi.org/10.1109/ISCIT.2011.6092191","url":null,"abstract":"In this paper a procedure for deconvolving signals in a Discrete Wavelet Transform (DWT) framework is applied to the estimation of impulse responses of fast-fading communications channels. Specifically, the effects of using several different wavelets on the performance of such wavelet-domain channel estimation is investigated. Monte Carlo simulations are performed using eight different wavelets. The simulations estimate impulse responses having a fast-fading, multipath, Power Delay Profile (PDP), and include Additive White Gaussian Noise (AWGN) resulting in Eb/N0 ratios from 0 dB to 30 dB. Results show that DWT-based deconvolution is especially effective when wavelets corresponding to short-length filters are used.","PeriodicalId":226552,"journal":{"name":"2011 11th International Symposium on Communications & Information Technologies (ISCIT)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128234529","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 : 2011-12-01DOI: 10.1109/ISCIT.2011.6089754
Yiming Y. Sun, Y. Miyanaga
We propose a noise-robust continuous speech recognition (CSR) method for recognition. In model building, we extract the novel feature vector by using running spectrum analysis (RSA) and dynamic range adjustment (DRA) methods. DRA adjusts the dynamic range on MFCC modulation spectrum domain (MSD). In recognition, the algorithm automatically divides the continuous speech into short sentences and blocks, then we use DRA based on the blocks. The proposed algorithm efficiency is studied for clean and noisy environment. In our experiments, all HMMs have been trained by using the Japanese newspaper article sentence (JNAS) database. The average recognition rate improves under various types of noise and SNR conditions.
{"title":"New continuous speech feature adjustment for a noise-robust CSR system","authors":"Yiming Y. Sun, Y. Miyanaga","doi":"10.1109/ISCIT.2011.6089754","DOIUrl":"https://doi.org/10.1109/ISCIT.2011.6089754","url":null,"abstract":"We propose a noise-robust continuous speech recognition (CSR) method for recognition. In model building, we extract the novel feature vector by using running spectrum analysis (RSA) and dynamic range adjustment (DRA) methods. DRA adjusts the dynamic range on MFCC modulation spectrum domain (MSD). In recognition, the algorithm automatically divides the continuous speech into short sentences and blocks, then we use DRA based on the blocks. The proposed algorithm efficiency is studied for clean and noisy environment. In our experiments, all HMMs have been trained by using the Japanese newspaper article sentence (JNAS) database. The average recognition rate improves under various types of noise and SNR conditions.","PeriodicalId":226552,"journal":{"name":"2011 11th International Symposium on Communications & Information Technologies (ISCIT)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133556567","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}
In this paper, we consider the design of efficient strategies that allow multiple secondary users to choose channels with unknown idle probabilities to sense and access without centralized control. Due to the limited sensing capability of CR, the secondary user cannot sense all the channels simultaneously. How to design intelligent sensing strategy is crucial to track the varying spectrum opportunities. However, the availability probability of each channel is not known a prior. The need to learning the information creates a fundamental trade-off between exploration and exploitation. First, the scenario in which a single cognitive user wishes to opportunistically exploit the availability of idle spectrum is considered. An index based strategy from the classical multi-armed bandit problem is efficient to achieve asymptotically optimal performance. Then, the multiuser case is considered. However, the index based strategy for the single user cannot be applied to multiuser scenario directly. If so, collisions among secondary users degrade the overall network performance greatly. We find that randomized selection of the channel to sense is essential to avoid collisions. We extend the exploration and exploitation idea to the multiuser scenario and come up with a randomization based mixed strategy which takes the activity of other secondary users into consideration in the learning process and at the same time achieves exploration and exploitation tradeoff. Numerical simulation results show that the proposed scheme can achieve near optimal in terms of total network performance as the centralized scenario without any information exchange among cognitive users.
{"title":"Exploration vs exploitation for distributed channel access in cognitive radio networks: A multi-user case study","authors":"Longwei Wang, Xianfu Chen, Zhifeng Zhao, Honggang Zhang","doi":"10.1109/ISCIT.2011.6089953","DOIUrl":"https://doi.org/10.1109/ISCIT.2011.6089953","url":null,"abstract":"In this paper, we consider the design of efficient strategies that allow multiple secondary users to choose channels with unknown idle probabilities to sense and access without centralized control. Due to the limited sensing capability of CR, the secondary user cannot sense all the channels simultaneously. How to design intelligent sensing strategy is crucial to track the varying spectrum opportunities. However, the availability probability of each channel is not known a prior. The need to learning the information creates a fundamental trade-off between exploration and exploitation. First, the scenario in which a single cognitive user wishes to opportunistically exploit the availability of idle spectrum is considered. An index based strategy from the classical multi-armed bandit problem is efficient to achieve asymptotically optimal performance. Then, the multiuser case is considered. However, the index based strategy for the single user cannot be applied to multiuser scenario directly. If so, collisions among secondary users degrade the overall network performance greatly. We find that randomized selection of the channel to sense is essential to avoid collisions. We extend the exploration and exploitation idea to the multiuser scenario and come up with a randomization based mixed strategy which takes the activity of other secondary users into consideration in the learning process and at the same time achieves exploration and exploitation tradeoff. Numerical simulation results show that the proposed scheme can achieve near optimal in terms of total network performance as the centralized scenario without any information exchange among cognitive users.","PeriodicalId":226552,"journal":{"name":"2011 11th International Symposium on Communications & Information Technologies (ISCIT)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125919169","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 : 2011-12-01DOI: 10.1109/ISCIT.2011.6089735
P. Xiao, B. K. Khoo, S. L. Goff, R. Tafazolli
The conventional transmit diversity schemes, such as Alamouti scheme, use several radio frequency (RF) chains to transmit signals simultaneously from multiple antennas. In this paper, we propose a low-complexity repetition time-switched (RTSTD) transmit diversity algorithm, which employs only one RF chain as well as a low-complexity switch for transmission. A mathematical model is developed to assess the performance of the proposed scheme. In order to make it applicable for practical applications, we also investigate its joint application with orthogonal frequency division multiplexing (OFDM) and channel coding techniques to combat frequency selective fading.
{"title":"Theoretical analysis of repetition time-switched transmit diversity scheme","authors":"P. Xiao, B. K. Khoo, S. L. Goff, R. Tafazolli","doi":"10.1109/ISCIT.2011.6089735","DOIUrl":"https://doi.org/10.1109/ISCIT.2011.6089735","url":null,"abstract":"The conventional transmit diversity schemes, such as Alamouti scheme, use several radio frequency (RF) chains to transmit signals simultaneously from multiple antennas. In this paper, we propose a low-complexity repetition time-switched (RTSTD) transmit diversity algorithm, which employs only one RF chain as well as a low-complexity switch for transmission. A mathematical model is developed to assess the performance of the proposed scheme. In order to make it applicable for practical applications, we also investigate its joint application with orthogonal frequency division multiplexing (OFDM) and channel coding techniques to combat frequency selective fading.","PeriodicalId":226552,"journal":{"name":"2011 11th International Symposium on Communications & Information Technologies (ISCIT)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127776766","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 : 2011-12-01DOI: 10.1109/ISCIT.2011.6089714
Ali El Arab, J. Carlach, M. Hélard
This paper proposes a new space-time coding scheme for non-coherent MIMO systems. In this scheme, called Matrix Coded Modulation (MCM), a joint channel error-correcting code and space-time code is considered. Coherent systems are those for which Channel State Information (CSI) is available at the transmitters and/or at the receivers, and their performance strongly depend on the channel estimation. Generally, this CSI estimation requires the insertion of pilot-symbols in the transmitted frame which implies a spectral efficiency loss of the global system. The existing non-coherent MIMO systems like Differential Space Time Modulation (DSTM) suffer not only from the degradation of performance compared to coherent systems, but also from many constraints on the channel and the use of memory at reception. In the proposed MCM scheme, decoding can be achieved with or without CSI at the receiving antennas. Moreover, a low-complexity decoding algorithm is described and compared to the existing differential schemes.
{"title":"A new non-coherent MIMO scheme: Matrix Coded Modulation “MCM”","authors":"Ali El Arab, J. Carlach, M. Hélard","doi":"10.1109/ISCIT.2011.6089714","DOIUrl":"https://doi.org/10.1109/ISCIT.2011.6089714","url":null,"abstract":"This paper proposes a new space-time coding scheme for non-coherent MIMO systems. In this scheme, called Matrix Coded Modulation (MCM), a joint channel error-correcting code and space-time code is considered. Coherent systems are those for which Channel State Information (CSI) is available at the transmitters and/or at the receivers, and their performance strongly depend on the channel estimation. Generally, this CSI estimation requires the insertion of pilot-symbols in the transmitted frame which implies a spectral efficiency loss of the global system. The existing non-coherent MIMO systems like Differential Space Time Modulation (DSTM) suffer not only from the degradation of performance compared to coherent systems, but also from many constraints on the channel and the use of memory at reception. In the proposed MCM scheme, decoding can be achieved with or without CSI at the receiving antennas. Moreover, a low-complexity decoding algorithm is described and compared to the existing differential schemes.","PeriodicalId":226552,"journal":{"name":"2011 11th International Symposium on Communications & Information Technologies (ISCIT)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127795217","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 : 2011-12-01DOI: 10.1109/ISCIT.2011.6089759
K. Xu, Y. Guo, Xiaojing Huang, E. Dutkiewicz
In this paper, a methodology of employing a set of uniform circular arrays to localize the 3D position of a target in sensor networks is presented and the theoretical framework is given. Simulation results demonstrate the validity of the method and illustrate the effect of the element pattern on the accuracy of direction of arrival (DoA) estimation and positioning. A weighted least squares method (WLSM) is proposed as a means to increase the robustness of the method.
{"title":"DoA based positioning employing uniform circular arrays","authors":"K. Xu, Y. Guo, Xiaojing Huang, E. Dutkiewicz","doi":"10.1109/ISCIT.2011.6089759","DOIUrl":"https://doi.org/10.1109/ISCIT.2011.6089759","url":null,"abstract":"In this paper, a methodology of employing a set of uniform circular arrays to localize the 3D position of a target in sensor networks is presented and the theoretical framework is given. Simulation results demonstrate the validity of the method and illustrate the effect of the element pattern on the accuracy of direction of arrival (DoA) estimation and positioning. A weighted least squares method (WLSM) is proposed as a means to increase the robustness of the method.","PeriodicalId":226552,"journal":{"name":"2011 11th International Symposium on Communications & Information Technologies (ISCIT)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115578215","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 : 2011-12-01DOI: 10.1109/ISCIT.2011.6089741
Yingjie Ma, Zheng Zhou, Ping Zeng, Y. Ye
A frequency adaptive detect and avoid (DAA) design method based on frequency band encoding is presented for narrow band interference suppression. Gaussian derivative pulse is considered as the ultra-wideband (UWB) original pulse because of its characteristics of zero DC component, easy generation and meeting with the Federal Communications Commission (FCC) indoor and outdoor spectral mask. Simulation results show that the proposed DAA method can provide stable UWB normal transmit power, have high transmission efficiency and make uninterrupted communication. The adaptive pulses create −40dB notch depth in the frequency band of the WLAN victim system. Furthermore, the adaptive pulses produce arbitrary spectral notches matching the FCC spectral mask.
{"title":"Frequency adaptive DAA design based on frequency band encoding","authors":"Yingjie Ma, Zheng Zhou, Ping Zeng, Y. Ye","doi":"10.1109/ISCIT.2011.6089741","DOIUrl":"https://doi.org/10.1109/ISCIT.2011.6089741","url":null,"abstract":"A frequency adaptive detect and avoid (DAA) design method based on frequency band encoding is presented for narrow band interference suppression. Gaussian derivative pulse is considered as the ultra-wideband (UWB) original pulse because of its characteristics of zero DC component, easy generation and meeting with the Federal Communications Commission (FCC) indoor and outdoor spectral mask. Simulation results show that the proposed DAA method can provide stable UWB normal transmit power, have high transmission efficiency and make uninterrupted communication. The adaptive pulses create −40dB notch depth in the frequency band of the WLAN victim system. Furthermore, the adaptive pulses produce arbitrary spectral notches matching the FCC spectral mask.","PeriodicalId":226552,"journal":{"name":"2011 11th International Symposium on Communications & Information Technologies (ISCIT)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115864756","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 : 2011-12-01DOI: 10.1109/ISCIT.2011.6089733
Pingping Chen, Xiaofeng Zhong, Jing Wang
M2M wireless communications network is a novel research topic, while the green communications is advocated in the subject, which can be reflected by the use of renewable energy. In this paper, we discuss the M2M network together with green communications. We design the flow control and transmission algorithm for the M2M network where there exist nodes using renewable energy. The algorithm need not know about the statistics knowledge of data rate, energy condition and the network condition, and the complexity is low. The aim is to reach an optimal or asymptotically optimal performance together with fairness.
{"title":"Fairness algorithm for renewable M2M network","authors":"Pingping Chen, Xiaofeng Zhong, Jing Wang","doi":"10.1109/ISCIT.2011.6089733","DOIUrl":"https://doi.org/10.1109/ISCIT.2011.6089733","url":null,"abstract":"M2M wireless communications network is a novel research topic, while the green communications is advocated in the subject, which can be reflected by the use of renewable energy. In this paper, we discuss the M2M network together with green communications. We design the flow control and transmission algorithm for the M2M network where there exist nodes using renewable energy. The algorithm need not know about the statistics knowledge of data rate, energy condition and the network condition, and the complexity is low. The aim is to reach an optimal or asymptotically optimal performance together with fairness.","PeriodicalId":226552,"journal":{"name":"2011 11th International Symposium on Communications & Information Technologies (ISCIT)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131592407","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 : 2011-12-01DOI: 10.1109/ISCIT.2011.6092153
Guangchao Zhang, Zhifeng Zhao, Honggang Zhang
Filter Bank Multicarrier (FBMC), so called an evolutionary OFDM, is a multicarrier system which stands out with the feature of lower side-band emission and thus an higher spectrum efficiency than OFDM. However, FBMC is still susceptible to impulse noise interference in time domain like other multicarrier systems. In this article, by using recently well developed Compressive Sensing (CS), we propose a new way to remove impulse noise in FBMC system. Considering the inherent interference in FBMC, first, we eliminate it to get purely available subcarriers. Then, by using these available subcarriers, we develop random construction of observation to guarantee reconstruction with high probability. At last, through simulation, we prove that our scheme can really defend the impulse noise in FBMC.
滤波器组多载波(Filter Bank Multicarrier, FBMC)是一种多载波系统，具有比OFDM更低的边带发射和更高的频谱效率，被称为一种进化OFDM。但是，与其他多载波系统一样，FBMC系统在时域上仍然容易受到脉冲噪声的干扰。本文利用近年来发展良好的压缩感知技术，提出了一种去除FBMC系统中脉冲噪声的新方法。考虑到FBMC固有干扰，首先消除干扰，得到纯可用子载波;然后，利用这些可用的子载波进行观测的随机构造，以保证高概率重构。最后，通过仿真，证明了该方案能够很好地抵御FBMC中的脉冲噪声。
{"title":"Removing impulse noise influence in FBMC system by compressive sensing","authors":"Guangchao Zhang, Zhifeng Zhao, Honggang Zhang","doi":"10.1109/ISCIT.2011.6092153","DOIUrl":"https://doi.org/10.1109/ISCIT.2011.6092153","url":null,"abstract":"Filter Bank Multicarrier (FBMC), so called an evolutionary OFDM, is a multicarrier system which stands out with the feature of lower side-band emission and thus an higher spectrum efficiency than OFDM. However, FBMC is still susceptible to impulse noise interference in time domain like other multicarrier systems. In this article, by using recently well developed Compressive Sensing (CS), we propose a new way to remove impulse noise in FBMC system. Considering the inherent interference in FBMC, first, we eliminate it to get purely available subcarriers. Then, by using these available subcarriers, we develop random construction of observation to guarantee reconstruction with high probability. At last, through simulation, we prove that our scheme can really defend the impulse noise in FBMC.","PeriodicalId":226552,"journal":{"name":"2011 11th International Symposium on Communications & Information Technologies (ISCIT)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131614573","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 : 2011-12-01DOI: 10.1109/ISCIT.2011.6089949
Jin Yi, R. Wu, Juan Li, Qi Xiong, Fajiang Yu, Tao Peng, Zhenyu Yang, Bo Han
With many security events taking place in recent years, scientists have realized vulnerability management is an important field and it brings critical effects to many information systems and services. One topic in this field is to identify similarity relationship between vulnerabilities. It can help us to alarm potential attacks. In this paper, we propose a text mining approach to compute a similarity score between two vulnerabilities based on their text description. It consists of two steps: preprocessing and similarity score computation. Experimental results based on an annotated vulnerability dataset have proved the effectiveness of our approach.
{"title":"Similar vulnerability query based on text mining","authors":"Jin Yi, R. Wu, Juan Li, Qi Xiong, Fajiang Yu, Tao Peng, Zhenyu Yang, Bo Han","doi":"10.1109/ISCIT.2011.6089949","DOIUrl":"https://doi.org/10.1109/ISCIT.2011.6089949","url":null,"abstract":"With many security events taking place in recent years, scientists have realized vulnerability management is an important field and it brings critical effects to many information systems and services. One topic in this field is to identify similarity relationship between vulnerabilities. It can help us to alarm potential attacks. In this paper, we propose a text mining approach to compute a similarity score between two vulnerabilities based on their text description. It consists of two steps: preprocessing and similarity score computation. Experimental results based on an annotated vulnerability dataset have proved the effectiveness of our approach.","PeriodicalId":226552,"journal":{"name":"2011 11th International Symposium on Communications & Information Technologies (ISCIT)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131328932","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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