Pub Date : 2011-03-17DOI: 10.1109/NCC.2011.5734698
Diwakar Sharma, Sriram N. Kizhakkemadam
We propose and evaluate the performance of a cascaded THP and BD system (THP-BD) for a MIMO downlink in which BD is used to mitigate multi-user interference and THP is used to mitigate spatial interference. We show that at moderate to high SNR, the cascaded THP-BD system achieves the same error performance as the system employing THP on a multi-user MIMO (MU-MIMO) downlink. Also, symbol error rate (SER) of the THP-BD precoding technique is at least 3 dB better than a linear precoding scheme when perfect CSIT is available. We also evaluate the performance of this scheme for channels with noisy feedback and with temporal correlation. Significantly, we find that while THP is sensitive to temporal correlation of the channel, THP-BD is more resilient.
{"title":"Cascaded tomlinson harashima precoding and block diagonalization for multi-user MIMO","authors":"Diwakar Sharma, Sriram N. Kizhakkemadam","doi":"10.1109/NCC.2011.5734698","DOIUrl":"https://doi.org/10.1109/NCC.2011.5734698","url":null,"abstract":"We propose and evaluate the performance of a cascaded THP and BD system (THP-BD) for a MIMO downlink in which BD is used to mitigate multi-user interference and THP is used to mitigate spatial interference. We show that at moderate to high SNR, the cascaded THP-BD system achieves the same error performance as the system employing THP on a multi-user MIMO (MU-MIMO) downlink. Also, symbol error rate (SER) of the THP-BD precoding technique is at least 3 dB better than a linear precoding scheme when perfect CSIT is available. We also evaluate the performance of this scheme for channels with noisy feedback and with temporal correlation. Significantly, we find that while THP is sensitive to temporal correlation of the channel, THP-BD is more resilient.","PeriodicalId":158295,"journal":{"name":"2011 National Conference on Communications (NCC)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115766587","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 : 2011-03-17DOI: 10.1109/NCC.2011.5734723
A. Jagannatham
An Expectation-Maximization (EM) based scheme is presented in the context of compressed image transmission for blind Multiple-Input Multiple-Output (MIMO) wireless channel estimation. This cross-layer content-aware algorithm employs a combination of hard and soft (HS) symbol information from the header blocks of the scalable JPEG compressed image to estimate the complex baseband MIMO wireless channel. The proposed HS-EM scheme can significantly reduce the overhead for communication by avoiding the transmission of dedicated pilot symbols which constitute a considerable overhead in a MIMO wireless system. Further, the unique blend of HS information makes the algorithm ideally suited for scalable image transmission in the fast-fading wireless environment, while it simultaneously avoids the convergence problems typically associated with conventional blind estimation algorithms. Simulation results are presented in the end which demonstrate the performance of the proposed estimation scheme in terms of mean-squared error (MSE), BER, block error rate and PSNR in a MIMO wireless system.
{"title":"HS-EM based blind MIMO channel estimation for dynamically scalable JPEG transmission","authors":"A. Jagannatham","doi":"10.1109/NCC.2011.5734723","DOIUrl":"https://doi.org/10.1109/NCC.2011.5734723","url":null,"abstract":"An Expectation-Maximization (EM) based scheme is presented in the context of compressed image transmission for blind Multiple-Input Multiple-Output (MIMO) wireless channel estimation. This cross-layer content-aware algorithm employs a combination of hard and soft (HS) symbol information from the header blocks of the scalable JPEG compressed image to estimate the complex baseband MIMO wireless channel. The proposed HS-EM scheme can significantly reduce the overhead for communication by avoiding the transmission of dedicated pilot symbols which constitute a considerable overhead in a MIMO wireless system. Further, the unique blend of HS information makes the algorithm ideally suited for scalable image transmission in the fast-fading wireless environment, while it simultaneously avoids the convergence problems typically associated with conventional blind estimation algorithms. Simulation results are presented in the end which demonstrate the performance of the proposed estimation scheme in terms of mean-squared error (MSE), BER, block error rate and PSNR in a MIMO wireless system.","PeriodicalId":158295,"journal":{"name":"2011 National Conference on Communications (NCC)","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124123272","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 : 2011-03-17DOI: 10.1109/NCC.2011.5734760
P. Verma, Ziping Hu
This paper investigates the implications of topologies on the average path length of networks, which is the dominant parameter affecting performance. Based on the available literature, classic network topologies are reviewed and analyzed. Furthermore, a new class of communication networks is introduced, and a topology design algorithm is proposed to improve network performance in terms of average path length.
{"title":"Impact of topology on the performance of communication networks","authors":"P. Verma, Ziping Hu","doi":"10.1109/NCC.2011.5734760","DOIUrl":"https://doi.org/10.1109/NCC.2011.5734760","url":null,"abstract":"This paper investigates the implications of topologies on the average path length of networks, which is the dominant parameter affecting performance. Based on the available literature, classic network topologies are reviewed and analyzed. Furthermore, a new class of communication networks is introduced, and a topology design algorithm is proposed to improve network performance in terms of average path length.","PeriodicalId":158295,"journal":{"name":"2011 National Conference on Communications (NCC)","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120977565","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 : 2011-03-17DOI: 10.1109/NCC.2011.5734774
S. Dey, R. Rajan, R. Padmanabhan, H. Murthy
In this paper we describe the utilisation of the diversity of different feature representations for speaker, emotion and language verification. The underlying principle behind the method is that some features are better at discriminating some classes and other features for other classes. Studies are done on four features and their combinations. An information theoretic procedure is described which can be used to determine the feature most suitable for a given class. Based on this, we propose the method of feature-switching, which uses different features for verifying different classes. Experiments show that feature-switching improves the accuracy for all three tasks.
{"title":"Feature diversity for emotion, language and speaker verification","authors":"S. Dey, R. Rajan, R. Padmanabhan, H. Murthy","doi":"10.1109/NCC.2011.5734774","DOIUrl":"https://doi.org/10.1109/NCC.2011.5734774","url":null,"abstract":"In this paper we describe the utilisation of the diversity of different feature representations for speaker, emotion and language verification. The underlying principle behind the method is that some features are better at discriminating some classes and other features for other classes. Studies are done on four features and their combinations. An information theoretic procedure is described which can be used to determine the feature most suitable for a given class. Based on this, we propose the method of feature-switching, which uses different features for verifying different classes. Experiments show that feature-switching improves the accuracy for all three tasks.","PeriodicalId":158295,"journal":{"name":"2011 National Conference on Communications (NCC)","volume":"287 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116527485","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 : 2011-03-17DOI: 10.1109/NCC.2011.5734757
R. U. Uma Mahesh, A. Chaturvedi
This paper addresses the estimation of fractional timing offset and channel response in orthogonal frequency division multiplexing (OFDM) systems. Timing offset and channel estimator is derived based on maximum likelihood criterion. Closed form Cramer Rao bound (CRB) expressions for fractional timing offset and channel response are derived. We consider flat fading channel throughout this paper. Simulation results have been used to cross-check the accuracy of the proposed estimation algorithm.
{"title":"Fractional timing offset and channel estimation in OFDM systems over flat fading channels","authors":"R. U. Uma Mahesh, A. Chaturvedi","doi":"10.1109/NCC.2011.5734757","DOIUrl":"https://doi.org/10.1109/NCC.2011.5734757","url":null,"abstract":"This paper addresses the estimation of fractional timing offset and channel response in orthogonal frequency division multiplexing (OFDM) systems. Timing offset and channel estimator is derived based on maximum likelihood criterion. Closed form Cramer Rao bound (CRB) expressions for fractional timing offset and channel response are derived. We consider flat fading channel throughout this paper. Simulation results have been used to cross-check the accuracy of the proposed estimation algorithm.","PeriodicalId":158295,"journal":{"name":"2011 National Conference on Communications (NCC)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116568664","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 : 2011-03-17DOI: 10.1109/NCC.2011.5734732
P. Lehana, Prem C. Pandey
Speaker transformation uses a mapping between the signal parameters derived from a set of phrases spoken by two speakers to modify the speech signal of one speaker to make it perceptually similar to that of the other speaker. In spectral warping and interpolation technique, the transformation function can be estimated using lesser data, but it needs a different transformation function for each acoustic class. Earlier reported investigations have used class dependent multivariate linear regression or univariate cubic interpolation. In this paper, a technique for modifying spectral characteristics, using a multivariate polynomial modeling for source-target mapping of the spectral parameters, is presented. Harmonic plus Noise Model (HNM) has been used for analysis-synthesis because of ease of the time and frequency scaling.
{"title":"Transformation of short-term spectral envelope of speech signal using multivariate polynomial modeling","authors":"P. Lehana, Prem C. Pandey","doi":"10.1109/NCC.2011.5734732","DOIUrl":"https://doi.org/10.1109/NCC.2011.5734732","url":null,"abstract":"Speaker transformation uses a mapping between the signal parameters derived from a set of phrases spoken by two speakers to modify the speech signal of one speaker to make it perceptually similar to that of the other speaker. In spectral warping and interpolation technique, the transformation function can be estimated using lesser data, but it needs a different transformation function for each acoustic class. Earlier reported investigations have used class dependent multivariate linear regression or univariate cubic interpolation. In this paper, a technique for modifying spectral characteristics, using a multivariate polynomial modeling for source-target mapping of the spectral parameters, is presented. Harmonic plus Noise Model (HNM) has been used for analysis-synthesis because of ease of the time and frequency scaling.","PeriodicalId":158295,"journal":{"name":"2011 National Conference on Communications (NCC)","volume":"115 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124824018","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 : 2011-03-17DOI: 10.1109/NCC.2011.5734736
F. Ali, S. Ray
Specific Absorption Rate (SAR) averaged over 10 g, 1 g and 0.1 g mass of head tissue induced inside a realistic grounded human head in the near-field of a half-wave radiating dipole antenna has been computed using Finite Difference in Time Domain (FDTD) method. The head is modeled using voxel based anthropomorphic phantom data considering the electrical parameters of different anatomical internal structures of the human body. Results obtained from the simulation show that maximum local SAR increases significantly for smaller mass average. Maximum 0.1-g SAR of 3.75 W/kg is obtained for 4 mm distance between head and antenna with 0.6 W radiated power.
利用时域有限差分(FDTD)方法计算了半波辐射偶极子天线近场中真实接地人头组织在10g、1g和0.1 g质量上的平均比吸收率(SAR)。考虑到人体不同解剖内部结构的电参数，使用基于体素的拟人化幻像数据对头部进行建模。模拟结果表明，质量平均值越小，局部SAR最大值显著增大。当头与天线距离为4mm，辐射功率为0.6 W时，最大0.1 g SAR为3.75 W/kg。
{"title":"SAR analysis in a realistic grounded human head for radiating dipole antenna","authors":"F. Ali, S. Ray","doi":"10.1109/NCC.2011.5734736","DOIUrl":"https://doi.org/10.1109/NCC.2011.5734736","url":null,"abstract":"Specific Absorption Rate (SAR) averaged over 10 g, 1 g and 0.1 g mass of head tissue induced inside a realistic grounded human head in the near-field of a half-wave radiating dipole antenna has been computed using Finite Difference in Time Domain (FDTD) method. The head is modeled using voxel based anthropomorphic phantom data considering the electrical parameters of different anatomical internal structures of the human body. Results obtained from the simulation show that maximum local SAR increases significantly for smaller mass average. Maximum 0.1-g SAR of 3.75 W/kg is obtained for 4 mm distance between head and antenna with 0.6 W radiated power.","PeriodicalId":158295,"journal":{"name":"2011 National Conference on Communications (NCC)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127249209","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 : 2011-03-17DOI: 10.1109/NCC.2011.5734765
A. Vijaya Krishna, V. Shashank
The use of multiple antennas at both the transmitter and receiver is well motivated by the substantial performance gains that can be realized, both in terms of an increase in achievable data rate and a decrease in error rate. The achievable data rate is characterized by the mutual information of the channel. In case of frequency selective multiple input multiple output (MIMO) channels, expressions for mutual information are obtained by using a block transmission model. In this paper, we consider a filterbank equalization framework, which is an attractive alternative to the block processing approach. We derive expressions for mutual information with the minimum mean-squared error (MMSE) filterbank receiver, for both joint detection and symbol-wise detection. It is shown that the filterbank approach provides much better information rates than the block processing approach. Simulation results are provided to validate our analysis.1
{"title":"Mutual information with filterbank equalization for MIMO frequency selective channels","authors":"A. Vijaya Krishna, V. Shashank","doi":"10.1109/NCC.2011.5734765","DOIUrl":"https://doi.org/10.1109/NCC.2011.5734765","url":null,"abstract":"The use of multiple antennas at both the transmitter and receiver is well motivated by the substantial performance gains that can be realized, both in terms of an increase in achievable data rate and a decrease in error rate. The achievable data rate is characterized by the mutual information of the channel. In case of frequency selective multiple input multiple output (MIMO) channels, expressions for mutual information are obtained by using a block transmission model. In this paper, we consider a filterbank equalization framework, which is an attractive alternative to the block processing approach. We derive expressions for mutual information with the minimum mean-squared error (MMSE) filterbank receiver, for both joint detection and symbol-wise detection. It is shown that the filterbank approach provides much better information rates than the block processing approach. Simulation results are provided to validate our analysis.1","PeriodicalId":158295,"journal":{"name":"2011 National Conference on Communications (NCC)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126359526","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 : 2011-03-17DOI: 10.1109/NCC.2011.5734776
Vidhyadhari Gondle, J. Sivaswamy
Segmentation in echo-cardiographic images is a difficult task due to the presence of speckle noise, low contrast and blurring. We present a novel method based on clustering performed in the feature space. A new feature-based image representation is proposed. It is obtained by computing a local feature descriptor at every pixel location. This descriptor is derived using the Radon-Transform to effectively characterise local image context. Next, an un-supervised clustering is performed in the feature space to segment regions in the image. The performance of the proposed method is tested on both synthetic and real images. A comparison against well established feature descriptors is carried out to demonstrate the strengths and applicability of the proposed representation. Overall, the results indicate promise in the strategy of doing segmentation of noisy data in image descriptor space.
{"title":"Echo-cardiographic segmentation: Via feature-space clustering","authors":"Vidhyadhari Gondle, J. Sivaswamy","doi":"10.1109/NCC.2011.5734776","DOIUrl":"https://doi.org/10.1109/NCC.2011.5734776","url":null,"abstract":"Segmentation in echo-cardiographic images is a difficult task due to the presence of speckle noise, low contrast and blurring. We present a novel method based on clustering performed in the feature space. A new feature-based image representation is proposed. It is obtained by computing a local feature descriptor at every pixel location. This descriptor is derived using the Radon-Transform to effectively characterise local image context. Next, an un-supervised clustering is performed in the feature space to segment regions in the image. The performance of the proposed method is tested on both synthetic and real images. A comparison against well established feature descriptors is carried out to demonstrate the strengths and applicability of the proposed representation. Overall, the results indicate promise in the strategy of doing segmentation of noisy data in image descriptor space.","PeriodicalId":158295,"journal":{"name":"2011 National Conference on Communications (NCC)","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127468952","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 : 2011-03-17DOI: 10.1109/NCC.2011.5734768
K. Vasu, S. Maheshwari, S. Mahapatra, C. S. Kumar
Increasing demands of ubiquitous services in wireless networks and evolution towards heterogeneous solutions has driven the necessity of developing efficient QoS aware vertical handoff (handoff between different networks) mechanisms. This paper proposes a QoS aware fuzzy rule based vertical handoff mechanism that makes a multi-criteria based decision, found to be effective for meeting the requirements of different applications. The QoS parameters considered are available bandwidth, end-to-end delay, jitter, and bit error rate (BER). A new evaluation model is proposed using a non birth-death Markov chain, in which the states correspond to the available networks. Simulation results show that compared to other vertical handoff algorithms, the proposed algorithm gives better performance for different traffic classes.
{"title":"QoS aware fuzzy rule based vertical handoff decision algorithm for wireless heterogeneous networks","authors":"K. Vasu, S. Maheshwari, S. Mahapatra, C. S. Kumar","doi":"10.1109/NCC.2011.5734768","DOIUrl":"https://doi.org/10.1109/NCC.2011.5734768","url":null,"abstract":"Increasing demands of ubiquitous services in wireless networks and evolution towards heterogeneous solutions has driven the necessity of developing efficient QoS aware vertical handoff (handoff between different networks) mechanisms. This paper proposes a QoS aware fuzzy rule based vertical handoff mechanism that makes a multi-criteria based decision, found to be effective for meeting the requirements of different applications. The QoS parameters considered are available bandwidth, end-to-end delay, jitter, and bit error rate (BER). A new evaluation model is proposed using a non birth-death Markov chain, in which the states correspond to the available networks. Simulation results show that compared to other vertical handoff algorithms, the proposed algorithm gives better performance for different traffic classes.","PeriodicalId":158295,"journal":{"name":"2011 National Conference on Communications (NCC)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127002823","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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