Pub Date : 2001-03-20DOI: 10.1109/SPAWC.2001.923849
T. Tung, K. Yao, R. E. Hudson
We describe several techniques for the analysis and design of OFDM multiple-antenna systems, which include channel estimation and tracking, optimal training sequences for initial channel acquisition, and adaptive power allocation with closed-loop updating of channel state information for capacity improvement.
{"title":"Channel estimation and adaptive power allocation for performance and capacity improvement of multiple-antenna OFDM systems","authors":"T. Tung, K. Yao, R. E. Hudson","doi":"10.1109/SPAWC.2001.923849","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923849","url":null,"abstract":"We describe several techniques for the analysis and design of OFDM multiple-antenna systems, which include channel estimation and tracking, optimal training sequences for initial channel acquisition, and adaptive power allocation with closed-loop updating of channel state information for capacity improvement.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123107760","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 : 2001-03-20DOI: 10.1109/SPAWC.2001.923899
Zhengdao Wang, G. Giannakis
Orthogonal frequency division multiplexing (OFDM) converts a dispersive channel into parallel subchannels and thus facilitates equalization. But when the channel has nulls close to or on the FFT grid, OFDM faces serious symbol recovery problems. As an alternative to various error-control coding techniques that have been proposed to ameliorate the problem, we linearly precode (LP) symbols before they are multiplexed. We identify the maximum achievable diversity order for iid or correlated Rayleigh fading channels and also provide design rules for achieving maximum diversity gains with LP-OFDM. Simulated performance comparisons of LP-OFDM with existing block and convolutionally coded OFDM alternatives favor LP-OFDM in a HiperLan2 experiment.
{"title":"Linearly precoded or coded OFDM against wireless channel fades?","authors":"Zhengdao Wang, G. Giannakis","doi":"10.1109/SPAWC.2001.923899","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923899","url":null,"abstract":"Orthogonal frequency division multiplexing (OFDM) converts a dispersive channel into parallel subchannels and thus facilitates equalization. But when the channel has nulls close to or on the FFT grid, OFDM faces serious symbol recovery problems. As an alternative to various error-control coding techniques that have been proposed to ameliorate the problem, we linearly precode (LP) symbols before they are multiplexed. We identify the maximum achievable diversity order for iid or correlated Rayleigh fading channels and also provide design rules for achieving maximum diversity gains with LP-OFDM. Simulated performance comparisons of LP-OFDM with existing block and convolutionally coded OFDM alternatives favor LP-OFDM in a HiperLan2 experiment.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"2007 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127306925","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 : 2001-03-20DOI: 10.1109/SPAWC.2001.923844
J. Manton, Y. Hua, Xiren Cao
A single input single output finite impulse response channel driven by a linear precoder can at best be identified up to an unknown complex-valued scaling factor. Although this scale ambiguity can be removed by setting the first channel coefficient to one, if its true value is very close to zero then the resulting channel estimate will be grossly inaccurate. This paper shows that an alternative is to treat the channel vector as a point in complex projective space. A novel optimisation algorithm is derived for estimating the channel vector by minimising the squared error on complex projective space.
{"title":"Precoder assisted channel estimation in complex projective space","authors":"J. Manton, Y. Hua, Xiren Cao","doi":"10.1109/SPAWC.2001.923844","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923844","url":null,"abstract":"A single input single output finite impulse response channel driven by a linear precoder can at best be identified up to an unknown complex-valued scaling factor. Although this scale ambiguity can be removed by setting the first channel coefficient to one, if its true value is very close to zero then the resulting channel estimate will be grossly inaccurate. This paper shows that an alternative is to treat the channel vector as a point in complex projective space. A novel optimisation algorithm is derived for estimating the channel vector by minimising the squared error on complex projective space.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126629870","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 : 2001-03-20DOI: 10.1109/SPAWC.2001.923894
Xiaotong Lin, Rick S. Blum
Analytical expressions bounding the performance of serially concatenated space-time codes are provided for quasi-static and rapid flat fading models. These expressions lead to guidelines for achieving large interleaving gains through serial concatenation for space-time codes in wireless fading channels. The performance of an example serially concatenated space-time code designed for a rapid fading channel is analyzed numerically. Simulation results show agreement with the guidelines provided. An iterative decoding scheme is used at the receiver. For applications which can tolerate delay, significant gain can be achieved with the proposed approach.
{"title":"Guidelines for serially concatenated space-time code design in flat Rayleigh fading channels","authors":"Xiaotong Lin, Rick S. Blum","doi":"10.1109/SPAWC.2001.923894","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923894","url":null,"abstract":"Analytical expressions bounding the performance of serially concatenated space-time codes are provided for quasi-static and rapid flat fading models. These expressions lead to guidelines for achieving large interleaving gains through serial concatenation for space-time codes in wireless fading channels. The performance of an example serially concatenated space-time code designed for a rapid fading channel is analyzed numerically. Simulation results show agreement with the guidelines provided. An iterative decoding scheme is used at the receiver. For applications which can tolerate delay, significant gain can be achieved with the proposed approach.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116223744","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 : 2001-03-20DOI: 10.1109/SPAWC.2001.923850
H. Mathis
Beside being a renowned parameter in signal classification, the kurtosis of a source signal is an indicator of the separation difficulty in blind signal separation and deconvolution. Whereas the maximum kurtosis is unbounded, the lower bound on the minimum kurtosis is -2. This means that the family of sub-Gaussian signals, to which most modulated communication signals belong, have an inherent limit in their suitability for blind techniques. Furthermore, the kurtosis of a composite signal has bounds which depend on the kurtoses of the constituent signals. Exact expressions for the kurtoses for a number of digital modulation formats are derived, and the influence of sampling-time accuracy to the kurtosis of the sampled signal is investigated.
{"title":"On the kurtosis of digitally modulated signals with timing offsets","authors":"H. Mathis","doi":"10.1109/SPAWC.2001.923850","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923850","url":null,"abstract":"Beside being a renowned parameter in signal classification, the kurtosis of a source signal is an indicator of the separation difficulty in blind signal separation and deconvolution. Whereas the maximum kurtosis is unbounded, the lower bound on the minimum kurtosis is -2. This means that the family of sub-Gaussian signals, to which most modulated communication signals belong, have an inherent limit in their suitability for blind techniques. Furthermore, the kurtosis of a composite signal has bounds which depend on the kurtoses of the constituent signals. Exact expressions for the kurtoses for a number of digital modulation formats are derived, and the influence of sampling-time accuracy to the kurtosis of the sampled signal is investigated.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122295506","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 : 2001-03-20DOI: 10.1109/SPAWC.2001.923917
X. Huang, Ke-Lin Du, A. Lai, Kai-Mao Cheng
Software radio, one cornerstone technique for the third-generation mobile communications, will provide inexpensive regional and global communications. We develop a general-purpose software radio architecture for the development and evaluation of software components such as software structures, algorithms and protocols. The system incorporates the state-of-the art chipset, and can provide a most powerful computation capability. We also provide a comprehensive software library for this platform, and demonstrate the methodology of implementation in two examples.
{"title":"A unified software radio architecture","authors":"X. Huang, Ke-Lin Du, A. Lai, Kai-Mao Cheng","doi":"10.1109/SPAWC.2001.923917","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923917","url":null,"abstract":"Software radio, one cornerstone technique for the third-generation mobile communications, will provide inexpensive regional and global communications. We develop a general-purpose software radio architecture for the development and evaluation of software components such as software structures, algorithms and protocols. The system incorporates the state-of-the art chipset, and can provide a most powerful computation capability. We also provide a comprehensive software library for this platform, and demonstrate the methodology of implementation in two examples.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129775528","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 : 2001-03-20DOI: 10.1109/SPAWC.2001.923865
V. Prabhakaran, V. Umapathi Reddy
Block transmission systems which consist of a precoder transmit-filterbank and a block receiver have been used to combat frequency-selective fading in wireless channels. Several authors have addressed the problem of decision feedback equalizer (DFE) receivers for such systems. We attempt this problem in a general framework and obtain the optimal solution for the minimum mean-square error (MMSE) DFE of finite complexity. We show that several previously derived results are special cases of our general solution.
{"title":"Optimal MSE DFE for multicarrier communication systems","authors":"V. Prabhakaran, V. Umapathi Reddy","doi":"10.1109/SPAWC.2001.923865","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923865","url":null,"abstract":"Block transmission systems which consist of a precoder transmit-filterbank and a block receiver have been used to combat frequency-selective fading in wireless channels. Several authors have addressed the problem of decision feedback equalizer (DFE) receivers for such systems. We attempt this problem in a general framework and obtain the optimal solution for the minimum mean-square error (MMSE) DFE of finite complexity. We show that several previously derived results are special cases of our general solution.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116324609","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 : 2001-03-20DOI: 10.1109/SPAWC.2001.923841
Hongbing Zhang, H. Fan, A. Lindsey
Wavelet packets have found many applications in communications. Promising results have been obtained for a number of modulation schemes based on wavelet packets. However, effects of multipath and time-varying wireless communication channels on these wavelet packet signature waveforms have not been seriously dealt with. We present a method to model complex time-varying wireless communication channels using wavelet packets as bases. This model has the advantages of flexibility, efficiency, and accuracy. Test results using field measurement data show the effectiveness of our model.
{"title":"A wavelet packet based model for time-varying wireless communication channels","authors":"Hongbing Zhang, H. Fan, A. Lindsey","doi":"10.1109/SPAWC.2001.923841","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923841","url":null,"abstract":"Wavelet packets have found many applications in communications. Promising results have been obtained for a number of modulation schemes based on wavelet packets. However, effects of multipath and time-varying wireless communication channels on these wavelet packet signature waveforms have not been seriously dealt with. We present a method to model complex time-varying wireless communication channels using wavelet packets as bases. This model has the advantages of flexibility, efficiency, and accuracy. Test results using field measurement data show the effectiveness of our model.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128202836","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 : 2001-03-20DOI: 10.1109/SPAWC.2001.923910
K. Yang, T. Ohira, Yimin D. Zhang
Space-time multiuser detection (STMD) is an emerging technique for wideband CDMA mobile communication systems, where the problems of multiuser access interference (MUAI) and intersymbol interference (ISI) can be solved simultaneously. However, complexity becomes one of the key problems in its practical implementation because of the exponential increment of computation burden due to the increased number of users. In this paper, we propose the sectorized STMD scheme that confines detection within a given sector. In the proposed scheme, the number of users in the sector becomes smaller, and, consequently, the system complexity becomes lower. Due to the sectorized beamforming, the signal-to-noise ratios of the users' multipath rays are enhanced, leading to performance improvements in the signature waveforms' estimation and detection.
{"title":"Sectorized space-time multiuser detection for CDMA systems","authors":"K. Yang, T. Ohira, Yimin D. Zhang","doi":"10.1109/SPAWC.2001.923910","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923910","url":null,"abstract":"Space-time multiuser detection (STMD) is an emerging technique for wideband CDMA mobile communication systems, where the problems of multiuser access interference (MUAI) and intersymbol interference (ISI) can be solved simultaneously. However, complexity becomes one of the key problems in its practical implementation because of the exponential increment of computation burden due to the increased number of users. In this paper, we propose the sectorized STMD scheme that confines detection within a given sector. In the proposed scheme, the number of users in the sector becomes smaller, and, consequently, the system complexity becomes lower. Due to the sectorized beamforming, the signal-to-noise ratios of the users' multipath rays are enhanced, leading to performance improvements in the signature waveforms' estimation and detection.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134361738","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 : 2001-03-20DOI: 10.1109/SPAWC.2001.923839
Takahiro Matsumoto, Y. Tanada, T. Watanabe
A real-valued shift-orthogonal finite-length sequence has a sharp autocorrelation function with zero sidelobes except at shift ends, and can be synthesized by element sequences. We propose the structure of a digital matched filter for M-ary direct sequence spread spectrum (M-ary/DS-SS) system using the sequences and the reduction of operation elements of the digital matched filter. It is shown that this digital matched filter for M-ary/DS-SS systems can be constructed by multipliers and adders proportional to sequence length.
{"title":"Digital matched filter of reduced operation elements for M-ary/DS-SS system using real-valued shift-orthogonal finite-length sequences","authors":"Takahiro Matsumoto, Y. Tanada, T. Watanabe","doi":"10.1109/SPAWC.2001.923839","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923839","url":null,"abstract":"A real-valued shift-orthogonal finite-length sequence has a sharp autocorrelation function with zero sidelobes except at shift ends, and can be synthesized by element sequences. We propose the structure of a digital matched filter for M-ary direct sequence spread spectrum (M-ary/DS-SS) system using the sequences and the reduction of operation elements of the digital matched filter. It is shown that this digital matched filter for M-ary/DS-SS systems can be constructed by multipliers and adders proportional to sequence length.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114910826","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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