Pub Date : 2008-12-01DOI: 10.1109/ISITA.2008.4895635
K. Gowda, C. Yuen, Sumei Sun
This paper proposes a class of space-time (ST) codes for supporting applications that demand unequal error protection. Traditionally, an ST code is designed to support a single information stream aiming to achieve a point on the fundamental rate versus diversity trade-off curve. The construction in this paper is based on the diversity-embedded codes recently proposed by Diggavi et.al., where-in ST codes need to encode multiple information streams, with each stream demanding a different level of reliability. In this paper, we propose to use an existing class of ST codes with low maximum-likelihood decoding complexity, as diversity embedded codes. For this class of codes, we are able to characterize the different diversity levels achievable for every message symbol.
{"title":"Diversity embedded space-time code from quasi-orthogonal designs","authors":"K. Gowda, C. Yuen, Sumei Sun","doi":"10.1109/ISITA.2008.4895635","DOIUrl":"https://doi.org/10.1109/ISITA.2008.4895635","url":null,"abstract":"This paper proposes a class of space-time (ST) codes for supporting applications that demand unequal error protection. Traditionally, an ST code is designed to support a single information stream aiming to achieve a point on the fundamental rate versus diversity trade-off curve. The construction in this paper is based on the diversity-embedded codes recently proposed by Diggavi et.al., where-in ST codes need to encode multiple information streams, with each stream demanding a different level of reliability. In this paper, we propose to use an existing class of ST codes with low maximum-likelihood decoding complexity, as diversity embedded codes. For this class of codes, we are able to characterize the different diversity levels achievable for every message symbol.","PeriodicalId":338675,"journal":{"name":"2008 International Symposium on Information Theory and Its Applications","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132526393","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 : 2008-12-01DOI: 10.1109/ISITA.2008.4895449
Xiaoyan Xu, M. Flanagan, C. Koller, N. Goertz
In cooperative communications, the technique of algebraic code superposition (or network coding) may efficiently utilize limited communications resources to produce spatial diversity. In this paper, we propose a simple cooperative diversity scheme for the scenario of two sources sharing a single relay. No cooperative coding is required at the sources, and only very simple interleave-and-superpose operations are performed at the relay. We propose a novel computationally efficient message passing algorithm at the destination's decoder which utilizes spatial diversity gathered over multiple transmission frames. We show that despite the simplicity of the proposed scheme, diversity gains are efficiently leveraged by the simple combination of channel coding at the sources and network coding at the relay.
{"title":"A shared-relay cooperative diversity scheme based on joint channel and network coding","authors":"Xiaoyan Xu, M. Flanagan, C. Koller, N. Goertz","doi":"10.1109/ISITA.2008.4895449","DOIUrl":"https://doi.org/10.1109/ISITA.2008.4895449","url":null,"abstract":"In cooperative communications, the technique of algebraic code superposition (or network coding) may efficiently utilize limited communications resources to produce spatial diversity. In this paper, we propose a simple cooperative diversity scheme for the scenario of two sources sharing a single relay. No cooperative coding is required at the sources, and only very simple interleave-and-superpose operations are performed at the relay. We propose a novel computationally efficient message passing algorithm at the destination's decoder which utilizes spatial diversity gathered over multiple transmission frames. We show that despite the simplicity of the proposed scheme, diversity gains are efficiently leveraged by the simple combination of channel coding at the sources and network coding at the relay.","PeriodicalId":338675,"journal":{"name":"2008 International Symposium on Information Theory and Its Applications","volume":"135 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132728676","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 : 2008-12-01DOI: 10.1109/ISITA.2008.4895484
Y. Yanagihara
For an observation system assisted for diagnosis of 3-D CT images consisting of time-sequenced multi slice tomograms, the refinement method to obtain the more precise region detection on which noise areas are reduced is proposed. The experimental results show that noise areas are reduced effectively. And also the system model refined by code refactoring is also proposed to be able to make the system having flexibility, also for that the proposed method is implemented.
{"title":"A study of region extraction and system model on an observation system of time-sequenced 3-D CT images","authors":"Y. Yanagihara","doi":"10.1109/ISITA.2008.4895484","DOIUrl":"https://doi.org/10.1109/ISITA.2008.4895484","url":null,"abstract":"For an observation system assisted for diagnosis of 3-D CT images consisting of time-sequenced multi slice tomograms, the refinement method to obtain the more precise region detection on which noise areas are reduced is proposed. The experimental results show that noise areas are reduced effectively. And also the system model refined by code refactoring is also proposed to be able to make the system having flexibility, also for that the proposed method is implemented.","PeriodicalId":338675,"journal":{"name":"2008 International Symposium on Information Theory and Its Applications","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131792159","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 : 2008-12-01DOI: 10.1109/ISITA.2008.4895469
Takahiro Yoshida, T. Matsushima, H. Imai
In this paper, we consider a ramp scheme for Key Predistribution System (KPS). In the ramp scheme, it can be regarded as one kind of generalization of KPS, and the required resources can be reduced at the cost of a security degradation which depends on the size of users. We define a ramp scheme for KPS, show lower bound on the amount of user' s information needed to generate a common key, and design a protocol that realize a ramp scheme for KPS.
{"title":"A ramp scheme for Key Predistribution System against collusion of users and centers","authors":"Takahiro Yoshida, T. Matsushima, H. Imai","doi":"10.1109/ISITA.2008.4895469","DOIUrl":"https://doi.org/10.1109/ISITA.2008.4895469","url":null,"abstract":"In this paper, we consider a ramp scheme for Key Predistribution System (KPS). In the ramp scheme, it can be regarded as one kind of generalization of KPS, and the required resources can be reduced at the cost of a security degradation which depends on the size of users. We define a ramp scheme for KPS, show lower bound on the amount of user' s information needed to generate a common key, and design a protocol that realize a ramp scheme for KPS.","PeriodicalId":338675,"journal":{"name":"2008 International Symposium on Information Theory and Its Applications","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134235246","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 : 2008-12-01DOI: 10.1109/ISITA.2008.4895622
H. Yoshikawa
An analytical bound to bit error probability of turbo codes can be derived by weight distribution of recursive systematic convolutional codes. In this paper, the conditional weight enumerating function of terminated recursive systematic convolutional codes is computed. This form can be expressed as a function of number of information bits, and can reduce the computational complexity of calculation of error bounds. Applying these results, it is shown that improved error bound can be obtained by the conditional weight enumerating function of parallel concatenated convolutional codes.
{"title":"On the weight distribution of recursive systematic convolutional codes","authors":"H. Yoshikawa","doi":"10.1109/ISITA.2008.4895622","DOIUrl":"https://doi.org/10.1109/ISITA.2008.4895622","url":null,"abstract":"An analytical bound to bit error probability of turbo codes can be derived by weight distribution of recursive systematic convolutional codes. In this paper, the conditional weight enumerating function of terminated recursive systematic convolutional codes is computed. This form can be expressed as a function of number of information bits, and can reduce the computational complexity of calculation of error bounds. Applying these results, it is shown that improved error bound can be obtained by the conditional weight enumerating function of parallel concatenated convolutional codes.","PeriodicalId":338675,"journal":{"name":"2008 International Symposium on Information Theory and Its Applications","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134373888","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 : 2008-12-01DOI: 10.1109/ISITA.2008.4895613
Haewoon Nam, Mohamed-Slim Alouini
This paper investigates a simple analytical approach that yields the optimal switching thresholds for multi-branch switched diversity systems. It also presents a performance optimization based on these optimal thresholds. For multi-branch switched diversity systems, the optimal fixed switching threshold is not only a function of the average channel SNR but also a function of the number of diversity branches. Conventional multi-branch switched diversity systems use a single fixed switching threshold, where computing this optimal threshold is not a simple task when the number of diversity branches is high. We propose a novel multi-branch switched diversity system that is based on a set of adaptive switching thresholds instead of a single fixed switching threshold, where a different switching threshold is used every switching. Thanks to the fact that each switching threshold in the set depends only on the remaining diversity branches, the proposed system allows a simple optimization for these switching thresholds. Furthermore, numerical and simulation results show that the proposed adaptive switched diversity system outperforms the conventional system.
{"title":"Multi-branch switched diversity with adaptive switching thresholds","authors":"Haewoon Nam, Mohamed-Slim Alouini","doi":"10.1109/ISITA.2008.4895613","DOIUrl":"https://doi.org/10.1109/ISITA.2008.4895613","url":null,"abstract":"This paper investigates a simple analytical approach that yields the optimal switching thresholds for multi-branch switched diversity systems. It also presents a performance optimization based on these optimal thresholds. For multi-branch switched diversity systems, the optimal fixed switching threshold is not only a function of the average channel SNR but also a function of the number of diversity branches. Conventional multi-branch switched diversity systems use a single fixed switching threshold, where computing this optimal threshold is not a simple task when the number of diversity branches is high. We propose a novel multi-branch switched diversity system that is based on a set of adaptive switching thresholds instead of a single fixed switching threshold, where a different switching threshold is used every switching. Thanks to the fact that each switching threshold in the set depends only on the remaining diversity branches, the proposed system allows a simple optimization for these switching thresholds. Furthermore, numerical and simulation results show that the proposed adaptive switched diversity system outperforms the conventional system.","PeriodicalId":338675,"journal":{"name":"2008 International Symposium on Information Theory and Its Applications","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115337660","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 : 2008-12-01DOI: 10.1109/ISITA.2008.4895475
H. Kostadinov, H. Morita, N. Iijima, N. Manev
A new construction of double error correctable integer codes and their application to QAM scheme are presented. Soft decoding algorithm for multiple error correctable integer code which are suited to any modulation scheme (QAM, PSK, ASK) will be introduced. Comparison of bit error rate (BER) versus signal-to-noise ratio (SNR) between soft and hard decoding using integer coded modulation (ICM) shows us that we can obtain approximately 2 dB coding gain.
{"title":"Double error correctable integer code and its application to QAM","authors":"H. Kostadinov, H. Morita, N. Iijima, N. Manev","doi":"10.1109/ISITA.2008.4895475","DOIUrl":"https://doi.org/10.1109/ISITA.2008.4895475","url":null,"abstract":"A new construction of double error correctable integer codes and their application to QAM scheme are presented. Soft decoding algorithm for multiple error correctable integer code which are suited to any modulation scheme (QAM, PSK, ASK) will be introduced. Comparison of bit error rate (BER) versus signal-to-noise ratio (SNR) between soft and hard decoding using integer coded modulation (ICM) shows us that we can obtain approximately 2 dB coding gain.","PeriodicalId":338675,"journal":{"name":"2008 International Symposium on Information Theory and Its Applications","volume":"195 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115647827","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 : 2008-12-01DOI: 10.1109/ISITA.2008.4895437
M. Nomura, K. Nakamura
In this paper, we propose a scheme that enhances the security of long-term private key lID used in the tripartite authenticated key agreement protocol. In this scheme, we use (H(lIDPmacr)lID)P (H: hash function) instead of lIDP (P: a rational point of the defined elliptic curve over Fp) as a static public key and tauID1, tauID2 as two ephemeral private keys. From this, even though the bit length of p (p's security parameter) is more lessened, we can preserve equal security to conventional schemes in respect of the secrecy of the long-term private key.
{"title":"On security enhancement of long-term private key for the tripartite authenticated key agreement protocol","authors":"M. Nomura, K. Nakamura","doi":"10.1109/ISITA.2008.4895437","DOIUrl":"https://doi.org/10.1109/ISITA.2008.4895437","url":null,"abstract":"In this paper, we propose a scheme that enhances the security of long-term private key l<sub>ID</sub> used in the tripartite authenticated key agreement protocol. In this scheme, we use (H(l<sub>ID</sub>Pmacr)l<sub>ID</sub>)P (H: hash function) instead of l<sub>ID</sub>P (P: a rational point of the defined elliptic curve over F<sub>p</sub>) as a static public key and tau<sub>ID1</sub>, tau<sub>ID2</sub> as two ephemeral private keys. From this, even though the bit length of p (p's security parameter) is more lessened, we can preserve equal security to conventional schemes in respect of the secrecy of the long-term private key.","PeriodicalId":338675,"journal":{"name":"2008 International Symposium on Information Theory and Its Applications","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114487168","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 : 2008-12-01DOI: 10.1109/ISITA.2008.4895406
Su-Wan Park, Dohee Yi, Sanguk Shin
This paper proposes a practical key management scheme using the frame-based feature in order to efficiently manage multi-keys used for layered access control of H.264/SVC. The efficiency of the proposed scheme is summarized in the following three points. 1) It offers implicit authentication in video content encryption/decryption. 2) It provides the security in key transmission through the network, and 3) has the robustness against brute-force attack as using all different NAL unit keys in the video sequence.
{"title":"A practical key management scheme using the frame-based features for layered access control of H.264/SVC","authors":"Su-Wan Park, Dohee Yi, Sanguk Shin","doi":"10.1109/ISITA.2008.4895406","DOIUrl":"https://doi.org/10.1109/ISITA.2008.4895406","url":null,"abstract":"This paper proposes a practical key management scheme using the frame-based feature in order to efficiently manage multi-keys used for layered access control of H.264/SVC. The efficiency of the proposed scheme is summarized in the following three points. 1) It offers implicit authentication in video content encryption/decryption. 2) It provides the security in key transmission through the network, and 3) has the robustness against brute-force attack as using all different NAL unit keys in the video sequence.","PeriodicalId":338675,"journal":{"name":"2008 International Symposium on Information Theory and Its Applications","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121756044","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 : 2008-12-01DOI: 10.1109/ISITA.2008.4895551
Chanhong Kim, Jungwoo Lee
Multiple-input multiple-output (MIMO) systems give high data rates through spatial multiplexing or diversity using space-time codes. We propose a rate-adaptive modulation scheme combined with mode switching between spatial multiplexing and orthogonal space-time block coding. We first find out which modulation level and mode maximize the spectral efficiency with a given target bit error ratio (BER). If the rates of the two MIMO modes are the same, we select one mode which gives lower BER than the other. We also propose a simple mode switching algorithm using effective SNR and constellation specific constant. Numerical results demonstrate improvement over each fixed mode with adaptive modulation in terms of average spectral efficiency.
{"title":"Rate adaptive modulation with MIMO mode switching between spatial multiplexing and diversity","authors":"Chanhong Kim, Jungwoo Lee","doi":"10.1109/ISITA.2008.4895551","DOIUrl":"https://doi.org/10.1109/ISITA.2008.4895551","url":null,"abstract":"Multiple-input multiple-output (MIMO) systems give high data rates through spatial multiplexing or diversity using space-time codes. We propose a rate-adaptive modulation scheme combined with mode switching between spatial multiplexing and orthogonal space-time block coding. We first find out which modulation level and mode maximize the spectral efficiency with a given target bit error ratio (BER). If the rates of the two MIMO modes are the same, we select one mode which gives lower BER than the other. We also propose a simple mode switching algorithm using effective SNR and constellation specific constant. Numerical results demonstrate improvement over each fixed mode with adaptive modulation in terms of average spectral efficiency.","PeriodicalId":338675,"journal":{"name":"2008 International Symposium on Information Theory and Its Applications","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121037700","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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