The achievable rate of a coherent coded modulation (CM) digital communication system with data-aided channel estimation and a discrete, equiprobable symbol alphabet is derived under the assumption that the system operates on a flat fading MIMO channel and uses an interleaver to combat the bursty nature of the channel. It is shown that linear minimum mean square error (LMMSE) channel estimation directly follows from the derivation, and links average mutual information to the channel dynamics. Based on the assumption that known training symbols are transmitted, the achievable rate of the system is optimized with respect to the amount of training information needed.
{"title":"Achievable rate of MIMO channels with data-aided channel estimation","authors":"J. Baltersee, G. Fock, H. Meyr","doi":"10.1109/ITW.2001.955167","DOIUrl":"https://doi.org/10.1109/ITW.2001.955167","url":null,"abstract":"The achievable rate of a coherent coded modulation (CM) digital communication system with data-aided channel estimation and a discrete, equiprobable symbol alphabet is derived under the assumption that the system operates on a flat fading MIMO channel and uses an interleaver to combat the bursty nature of the channel. It is shown that linear minimum mean square error (LMMSE) channel estimation directly follows from the derivation, and links average mutual information to the channel dynamics. Based on the assumption that known training symbols are transmitted, the achievable rate of the system is optimized with respect to the amount of training information needed.","PeriodicalId":288814,"journal":{"name":"Proceedings 2001 IEEE Information Theory Workshop (Cat. No.01EX494)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121363533","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}
It has recently been shown that at high signal-to-noise ratios (SNR) the capacity of multi-antenna systems over flat fading channels (without receiver or transmitter side-information) typically grows only double-logarithmically in the SNR. Here we further refine the analysis and study the "fading number" /spl chi/, which we define as the limit of the difference between channel capacity and log(1+log(1+SNR)). It is suggested that at high SNR, i.e., at rates that significantly exceed the fading number, a capacity increase of one bit per channel use requires the squaring of the SNR, or equivalently, the doubling of the SNR as expressed in decibels. In this loose sense, the fading number can be viewed as the channel limiting rate for power-efficient communication. Note, however, that the fading number may be negative. While the use of multiple antennas does not typically change the double-logarithmic asymptotic dependence of channel capacity on the SNR, multiple antennas do typically increase the fading number, albeit at times (e.g., in the Rayleigh fading case) only in an additive way that grows only logarithmically with the number of antennas.
{"title":"On the fading number of multi-antenna systems","authors":"A. Lapidoth, S. M. Moser","doi":"10.1109/ITW.2001.955154","DOIUrl":"https://doi.org/10.1109/ITW.2001.955154","url":null,"abstract":"It has recently been shown that at high signal-to-noise ratios (SNR) the capacity of multi-antenna systems over flat fading channels (without receiver or transmitter side-information) typically grows only double-logarithmically in the SNR. Here we further refine the analysis and study the \"fading number\" /spl chi/, which we define as the limit of the difference between channel capacity and log(1+log(1+SNR)). It is suggested that at high SNR, i.e., at rates that significantly exceed the fading number, a capacity increase of one bit per channel use requires the squaring of the SNR, or equivalently, the doubling of the SNR as expressed in decibels. In this loose sense, the fading number can be viewed as the channel limiting rate for power-efficient communication. Note, however, that the fading number may be negative. While the use of multiple antennas does not typically change the double-logarithmic asymptotic dependence of channel capacity on the SNR, multiple antennas do typically increase the fading number, albeit at times (e.g., in the Rayleigh fading case) only in an additive way that grows only logarithmically with the number of antennas.","PeriodicalId":288814,"journal":{"name":"Proceedings 2001 IEEE Information Theory Workshop (Cat. No.01EX494)","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131595375","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}
Bit-interleaved turbo-coded modulations (BITCM) have been shown to achieve bit error rate performance very close to the capacity limit over both additive white Gaussian noise (AWGN) channels and Rayleigh fading channels. So far, most studies have been done on BITCM systems designed using rectangular QAM signal sets. In this paper, we address the problem of finding some constellations that would be more suitable than rectangular QAM for designing power efficient BITCM. When the parameter M is in the form M=2/sup 2p/ where p is an integer, we show that rectangular QAM constellations are surprisingly the most attractive signal sets for the design of power-efficient BITCM schemes over AWGN channels. This is not necessarily true with Rayleigh fading channels.
{"title":"On the design of bit-interleaved turbo-coded modulation","authors":"S. L. Goff, Faisal Obaid Al-Ayyan","doi":"10.1109/ITW.2001.955140","DOIUrl":"https://doi.org/10.1109/ITW.2001.955140","url":null,"abstract":"Bit-interleaved turbo-coded modulations (BITCM) have been shown to achieve bit error rate performance very close to the capacity limit over both additive white Gaussian noise (AWGN) channels and Rayleigh fading channels. So far, most studies have been done on BITCM systems designed using rectangular QAM signal sets. In this paper, we address the problem of finding some constellations that would be more suitable than rectangular QAM for designing power efficient BITCM. When the parameter M is in the form M=2/sup 2p/ where p is an integer, we show that rectangular QAM constellations are surprisingly the most attractive signal sets for the design of power-efficient BITCM schemes over AWGN channels. This is not necessarily true with Rayleigh fading channels.","PeriodicalId":288814,"journal":{"name":"Proceedings 2001 IEEE Information Theory Workshop (Cat. No.01EX494)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127743494","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}
We design low-density parity-check (LDPC) codes for bandwidth efficient modulation using a multilevel coding (MLC) technique. We develop a method to analyze the asymptotic performance of the LDPC codes using message-passing decoding at each level of the MLC scheme as the codeword length goes to infinity. Simulation of very large block size LDPC codes verifies the accuracy of the analytical results. We jointly optimize the code rates and code parameters of the LDPC codes at each level of the MLC scheme, and the asymptotic performance of the optimized irregular LDPC codes is very close to the channel capacity of the additive white Gaussian noise (AWGN) channel.
{"title":"Design of low-density parity-check codes for bandwidth efficient modulation","authors":"J. Hou, P. Siegel, L. Milstein, H. Pfister","doi":"10.1109/ITW.2001.955124","DOIUrl":"https://doi.org/10.1109/ITW.2001.955124","url":null,"abstract":"We design low-density parity-check (LDPC) codes for bandwidth efficient modulation using a multilevel coding (MLC) technique. We develop a method to analyze the asymptotic performance of the LDPC codes using message-passing decoding at each level of the MLC scheme as the codeword length goes to infinity. Simulation of very large block size LDPC codes verifies the accuracy of the analytical results. We jointly optimize the code rates and code parameters of the LDPC codes at each level of the MLC scheme, and the asymptotic performance of the optimized irregular LDPC codes is very close to the channel capacity of the additive white Gaussian noise (AWGN) channel.","PeriodicalId":288814,"journal":{"name":"Proceedings 2001 IEEE Information Theory Workshop (Cat. No.01EX494)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133509322","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}
We present results on multipath channel estimation and detection for space-time coded systems used in conjunction with orthogonal frequency-division multiplexing (OFDM). An expectation-maximization (EM) based algorithm is introduced and is shown to be more robust to multipath channel delay profile variations and can be implemented more efficiently compared to a recently proposed alternative algorithm at similar or better performance.
{"title":"Some results on channel estimation and detection for space-time OFDM systems","authors":"Y. Xie, C. Georghiades","doi":"10.1109/ITW.2001.955156","DOIUrl":"https://doi.org/10.1109/ITW.2001.955156","url":null,"abstract":"We present results on multipath channel estimation and detection for space-time coded systems used in conjunction with orthogonal frequency-division multiplexing (OFDM). An expectation-maximization (EM) based algorithm is introduced and is shown to be more robust to multipath channel delay profile variations and can be implemented more efficiently compared to a recently proposed alternative algorithm at similar or better performance.","PeriodicalId":288814,"journal":{"name":"Proceedings 2001 IEEE Information Theory Workshop (Cat. No.01EX494)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125590523","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}
Three-dimensional spectral null constraints for two dimensional storage devices are studied. These constraints may be useful when we use circular pits to store information on physical devices.
研究了二维存储器件的三维谱零约束。当我们使用圆形凹坑在物理设备上存储信息时，这些约束可能很有用。
{"title":"Three directional spectral null constraints for two-dimensional storage devices","authors":"H. Kamabe, T. Ichihashi","doi":"10.1109/ITW.2001.955147","DOIUrl":"https://doi.org/10.1109/ITW.2001.955147","url":null,"abstract":"Three-dimensional spectral null constraints for two dimensional storage devices are studied. These constraints may be useful when we use circular pits to store information on physical devices.","PeriodicalId":288814,"journal":{"name":"Proceedings 2001 IEEE Information Theory Workshop (Cat. No.01EX494)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127147162","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}
We discuss the design of new low-complexity turbo-like codes based on a multiple parallel concatenation of 4-state and 2-state constituent codes. The new code designs take advantage of the big-numerator/little-denominator principle along with specially designed interleavers to outperform previously designed turbo codes over the entire range of signal-to-noise ratios. Puncturing at the encoder is used to produce low-complexity codes with excellent performance at code rates of 1/2 and 1/3. The multiple parallel concatenation and puncturing results in turbo-like encoders which are either partially systematic or completely nonsystematic. Comparisons with the proposed 8-state turbo coding standard and with other low-complexity alternative code designs are included.
{"title":"New low-complexity turbo-like codes","authors":"P. Massey, D. Costello","doi":"10.1109/ITW.2001.955139","DOIUrl":"https://doi.org/10.1109/ITW.2001.955139","url":null,"abstract":"We discuss the design of new low-complexity turbo-like codes based on a multiple parallel concatenation of 4-state and 2-state constituent codes. The new code designs take advantage of the big-numerator/little-denominator principle along with specially designed interleavers to outperform previously designed turbo codes over the entire range of signal-to-noise ratios. Puncturing at the encoder is used to produce low-complexity codes with excellent performance at code rates of 1/2 and 1/3. The multiple parallel concatenation and puncturing results in turbo-like encoders which are either partially systematic or completely nonsystematic. Comparisons with the proposed 8-state turbo coding standard and with other low-complexity alternative code designs are included.","PeriodicalId":288814,"journal":{"name":"Proceedings 2001 IEEE Information Theory Workshop (Cat. No.01EX494)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130408025","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}
Many imaging techniques, including magnetic resonance imaging and interferometric synthetic aperture radar, produce "phase-wrapped" images. In a phase-wrapped image, the original image values are measured modulus a known wavelength, A. The goal of phase unwrapping is to produce an estimate of the original image using an a priori preference for smooth images. We formulate phase unwrapping as the problem of computing a vector field that is an estimate of the gradient field of the original image. A preference for smooth images is obtained using a Gaussian prior on the vector field. For a vector field to be a gradient field, it must satisfy the constraint that the sum of the vectors around every closed loop is zero. We enforce this constraint using "zero-curl checks" in a factor graph on the vector field. The sum-product algorithm in this factor graph is used to approximately compute the posterior probabilities of the vectors. Hard decisions are used to produce a vector field, which is integrated to obtain the unwrapped image. Experimental results show that this method can work significantly better than existing techniques for phase unwrapping. Although phase unwrapping for general image priors is NP-hard, we conjecture that the sum-product algorithm in an appropriate factor graph will lead to a near-optimal unwrapping algorithm for Gaussian process sources.
{"title":"\"Codes\" on images and iterative phase unwrapping","authors":"B. Frey, R. Koetter, Nemanja Petrović","doi":"10.1109/ITW.2001.955119","DOIUrl":"https://doi.org/10.1109/ITW.2001.955119","url":null,"abstract":"Many imaging techniques, including magnetic resonance imaging and interferometric synthetic aperture radar, produce \"phase-wrapped\" images. In a phase-wrapped image, the original image values are measured modulus a known wavelength, A. The goal of phase unwrapping is to produce an estimate of the original image using an a priori preference for smooth images. We formulate phase unwrapping as the problem of computing a vector field that is an estimate of the gradient field of the original image. A preference for smooth images is obtained using a Gaussian prior on the vector field. For a vector field to be a gradient field, it must satisfy the constraint that the sum of the vectors around every closed loop is zero. We enforce this constraint using \"zero-curl checks\" in a factor graph on the vector field. The sum-product algorithm in this factor graph is used to approximately compute the posterior probabilities of the vectors. Hard decisions are used to produce a vector field, which is integrated to obtain the unwrapped image. Experimental results show that this method can work significantly better than existing techniques for phase unwrapping. Although phase unwrapping for general image priors is NP-hard, we conjecture that the sum-product algorithm in an appropriate factor graph will lead to a near-optimal unwrapping algorithm for Gaussian process sources.","PeriodicalId":288814,"journal":{"name":"Proceedings 2001 IEEE Information Theory Workshop (Cat. No.01EX494)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114436880","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}
We consider the impact of transmit diversity on the capacity of synchronous, randomly-spread code-division multiple-access, in the presence of frequency-flat fading. For large user populations, we characterize the spectral efficiency (capacity per chip) of two systems that use different spreading sequences on each antenna: a theoretically optimal system in which each transmit antenna is fed by independent data streams, and a code sequence diversity scheme that transmits the same data on each antenna.
{"title":"On the spectral efficiency of CDMA with multiple antennas","authors":"P. Sudarshan, B. Hughes","doi":"10.1109/ITW.2001.955150","DOIUrl":"https://doi.org/10.1109/ITW.2001.955150","url":null,"abstract":"We consider the impact of transmit diversity on the capacity of synchronous, randomly-spread code-division multiple-access, in the presence of frequency-flat fading. For large user populations, we characterize the spectral efficiency (capacity per chip) of two systems that use different spreading sequences on each antenna: a theoretically optimal system in which each transmit antenna is fed by independent data streams, and a code sequence diversity scheme that transmits the same data on each antenna.","PeriodicalId":288814,"journal":{"name":"Proceedings 2001 IEEE Information Theory Workshop (Cat. No.01EX494)","volume":"2016 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125727860","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}
We investigate the consequences of lossy compression, i.e., description with distortion, on the model selection of the minimum description length (MDL) criterion. Our basic observation is that for a finite data sequence and sufficiently large distortion, a two-stage universal lossy encoder tends to under-estimate the model order of the source. We demonstrate this property by examining the behavior of a two-stage universal lossy encoder, based on pre/post-filtered entropy-coded dithered quantization, over some parametric classes of stationary Gaussian sources.
{"title":"The effect of distortion on the MDL model","authors":"Yoram Gronich, R. Zamir","doi":"10.1109/ITW.2001.955169","DOIUrl":"https://doi.org/10.1109/ITW.2001.955169","url":null,"abstract":"We investigate the consequences of lossy compression, i.e., description with distortion, on the model selection of the minimum description length (MDL) criterion. Our basic observation is that for a finite data sequence and sufficiently large distortion, a two-stage universal lossy encoder tends to under-estimate the model order of the source. We demonstrate this property by examining the behavior of a two-stage universal lossy encoder, based on pre/post-filtered entropy-coded dithered quantization, over some parametric classes of stationary Gaussian sources.","PeriodicalId":288814,"journal":{"name":"Proceedings 2001 IEEE Information Theory Workshop (Cat. No.01EX494)","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127125627","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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