Pub Date : 2001-03-20DOI: 10.1109/SPAWC.2001.923881
Jenq-Nan Lee, Jenq-Tay Yuan
An Mth-order adaptive lattice filter automatically generates all M of the outputs that would be provided by M separate transversal filters. This feature can effectively suppress the narrowband interference (NBI) of time-varying bandwidth in direct-sequence (DS) spread-spectrum systems for which the order of the interference rejection filter that achieves the optimal performance is unknown and is constantly changing. This work develops a computationally efficient and numerically stable adaptive nonlinear QR-decomposition-based lattice interpolator to effectively suppress NBI. Simulation results indicate that the proposed nonlinear lattice interpolators provide a fast convergence rate and SNR improvements that closely approach the upper bound.
{"title":"Interference rejection in DS spread spectrum systems using nonlinear interpolation lattice filters","authors":"Jenq-Nan Lee, Jenq-Tay Yuan","doi":"10.1109/SPAWC.2001.923881","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923881","url":null,"abstract":"An Mth-order adaptive lattice filter automatically generates all M of the outputs that would be provided by M separate transversal filters. This feature can effectively suppress the narrowband interference (NBI) of time-varying bandwidth in direct-sequence (DS) spread-spectrum systems for which the order of the interference rejection filter that achieves the optimal performance is unknown and is constantly changing. This work develops a computationally efficient and numerically stable adaptive nonlinear QR-decomposition-based lattice interpolator to effectively suppress NBI. Simulation results indicate that the proposed nonlinear lattice interpolators provide a fast convergence rate and SNR improvements that closely approach the upper bound.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"46 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":"133251550","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.2001.923911
S. Affes, A. Saadi, P. Mermelstein
We previously reported on a new uplink array-receiver, referred to as pilot-sign STAR (spatio-temporal array-receiver). This receiver combines an earlier blind version of STAR with the use of a very weak pilot (/spl sim/1% power/overhead fraction) to resolve the sign ambiguity of the blindly identified channel. In this contribution, we update and exploit the advantages of this receiver on the downlink. Simulations indicate SNR advantages for the new pilot-sign STAR over the conventional pilot-channel version at relatively weak received pilot powers on the downlink. Hence, use of pilot-assisted STAR in both directions increases capacity by reducing the interference power of the pilot and/or improves coverage by maintaining more robust links in the presence of strong near-far ratios.
{"title":"Pilot-assisted STAR for increased capacity and coverage on the downlink of wideband CDMA networks","authors":"S. Affes, A. Saadi, P. Mermelstein","doi":"10.1109/SPAWC.2001.923911","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923911","url":null,"abstract":"We previously reported on a new uplink array-receiver, referred to as pilot-sign STAR (spatio-temporal array-receiver). This receiver combines an earlier blind version of STAR with the use of a very weak pilot (/spl sim/1% power/overhead fraction) to resolve the sign ambiguity of the blindly identified channel. In this contribution, we update and exploit the advantages of this receiver on the downlink. Simulations indicate SNR advantages for the new pilot-sign STAR over the conventional pilot-channel version at relatively weak received pilot powers on the downlink. Hence, use of pilot-assisted STAR in both directions increases capacity by reducing the interference power of the pilot and/or improves coverage by maintaining more robust links in the presence of strong near-far ratios.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"163 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":"133872480","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.2001.923920
X. Huang, M. Caron, D. Hindson
This paper presents a recursive Gram-Schmidt orthonormalization procedure. It employs adders and multipliers only, and it is very suitable and efficient for real-time high-speed DSP implementations. Its usefulness to communications is illustrated through the gain and phase imbalance compensation in a coherent QPSK receiver. Computer simulation shows that the bit error rate performance of the QPSK receiver is improved significantly after compensating the gain and phase imbalances by using the recursive Gram-Schmidt orthonormalization procedure.
{"title":"A recursive Gram-Schmidt orthonormalization procedure and its application to communications","authors":"X. Huang, M. Caron, D. Hindson","doi":"10.1109/SPAWC.2001.923920","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923920","url":null,"abstract":"This paper presents a recursive Gram-Schmidt orthonormalization procedure. It employs adders and multipliers only, and it is very suitable and efficient for real-time high-speed DSP implementations. Its usefulness to communications is illustrated through the gain and phase imbalance compensation in a coherent QPSK receiver. Computer simulation shows that the bit error rate performance of the QPSK receiver is improved significantly after compensating the gain and phase imbalances by using the recursive Gram-Schmidt orthonormalization procedure.","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":"130474152","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.2001.923903
S. Ohno, G. Giannakis
Without channel state information available, universal designs of wireless OFDM transmitters and receivers offer performance that is robust to the underlying channel fades and the adopted signal constellation. We show that judiciously designed precoders with redundancy twice as long as the channel order are necessary and sufficient for guaranteed constellation- and channel-irrespective symbol recovery as well as for blind channel identifiability. Simulated comparisons of the novel precoders with zero-padded and cyclic-prefixed block transmissions delineate their relative merits.
{"title":"Universal redundant precoders for guaranteed recovery of block transmissions through unknown FIR channels","authors":"S. Ohno, G. Giannakis","doi":"10.1109/SPAWC.2001.923903","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923903","url":null,"abstract":"Without channel state information available, universal designs of wireless OFDM transmitters and receivers offer performance that is robust to the underlying channel fades and the adopted signal constellation. We show that judiciously designed precoders with redundancy twice as long as the channel order are necessary and sufficient for guaranteed constellation- and channel-irrespective symbol recovery as well as for blind channel identifiability. Simulated comparisons of the novel precoders with zero-padded and cyclic-prefixed block transmissions delineate their relative merits.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"86 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":"131419765","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.2001.923852
M. Enescu, Yinglu Zhang, S. Kassam, V. Koivunen
This paper addresses the problem of blind equalization based on a multi-input multi-output (MIMO) model. Using a more general structure for MIMO channels, we present a method that combines fractional sampling and a blind source separation (BSS) algorithm to recover transmitted symbols in the presence of ISI (intersymbol interference). Oversampling allows for converting the FIR MIMO model to an instantaneous mixing model. The equalization may then be performed via BSS. We propose a recursive estimator stemming from the Kalman filter for this task. The method achieves equalization even in the case of a slowly time-varying channel and in the presence of additive noise. Simulation results are presented illustrating the good performance of the method.
{"title":"Recursive estimator for blind MIMO equalization via BSS and fractional sampling","authors":"M. Enescu, Yinglu Zhang, S. Kassam, V. Koivunen","doi":"10.1109/SPAWC.2001.923852","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923852","url":null,"abstract":"This paper addresses the problem of blind equalization based on a multi-input multi-output (MIMO) model. Using a more general structure for MIMO channels, we present a method that combines fractional sampling and a blind source separation (BSS) algorithm to recover transmitted symbols in the presence of ISI (intersymbol interference). Oversampling allows for converting the FIR MIMO model to an instantaneous mixing model. The equalization may then be performed via BSS. We propose a recursive estimator stemming from the Kalman filter for this task. The method achieves equalization even in the case of a slowly time-varying channel and in the presence of additive noise. Simulation results are presented illustrating the good performance of the method.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"115 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":"134619292","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.2001.923885
B. Barkat, S. Attallah
We address the problem of channel fading in communication systems. In particular, we focus on the flat fading phenomenon. We propose a novel time-frequency-based technique to retrieve the instantaneous frequency of a signal transmitted over a flat fading channel, and show that it is very accurate and powerful. An example is used to validate the proposed method.
{"title":"Instantaneous frequency estimation of received signals in flat fading digital communication systems","authors":"B. Barkat, S. Attallah","doi":"10.1109/SPAWC.2001.923885","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923885","url":null,"abstract":"We address the problem of channel fading in communication systems. In particular, we focus on the flat fading phenomenon. We propose a novel time-frequency-based technique to retrieve the instantaneous frequency of a signal transmitted over a flat fading channel, and show that it is very accurate and powerful. An example is used to validate the proposed method.","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":"115955341","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 design and theoretical error performance analysis of an MMSE-DFE receiver with spatial diversity reception modeled as SIMO channel. At the base station of cellular mobile systems, such a structure is highly effective by using spatial diversity as the anti-fading technique, and decision feedback equalization for tackling the temporal delay spread. First, we derive the optimum SIMO-MMSE-DFE receiver in vector-matrix form by assuming a known SIMO channel. Next, to obviate the need of time-consuming Monte-Carlo (MC) simulations, we derive the signal-to-noise ratio at the slicer's input and then the theoretical BER performance by using the technique of Gaussian approximation (GA). Alternatively, we also provide a second way, namely, the quasi-analytical (QA) method, for BER estimation.
{"title":"Design and analytical error performance of MMSE-DFE receiver with spatial diversity","authors":"Jeng-Kuang Hwang, Chiuan-Hsiu Chen, Ming-Chian Tsai","doi":"10.1109/SPAWC.2001.923830","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923830","url":null,"abstract":"We consider the design and theoretical error performance analysis of an MMSE-DFE receiver with spatial diversity reception modeled as SIMO channel. At the base station of cellular mobile systems, such a structure is highly effective by using spatial diversity as the anti-fading technique, and decision feedback equalization for tackling the temporal delay spread. First, we derive the optimum SIMO-MMSE-DFE receiver in vector-matrix form by assuming a known SIMO channel. Next, to obviate the need of time-consuming Monte-Carlo (MC) simulations, we derive the signal-to-noise ratio at the slicer's input and then the theoretical BER performance by using the technique of Gaussian approximation (GA). Alternatively, we also provide a second way, namely, the quasi-analytical (QA) method, for BER estimation.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"14 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":"129126556","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.2001.923897
H. Torii, M. Nakamura, N. Suehiro
Modulatable periodic complete complementary codes for cellular CDMA systems have the property of being "modulatable", like modulatable orthogonal sequences. We propose a generalized method to construct modulatable periodic complete complementary codes composed of expanded modulatable orthogonal sequences. Modulatable periodic complete complementary codes obtained by using the proposed method are composed of n(n/spl ges/2) sets of periodic auto-complementary codes, and each periodic auto-complementary code is composed of n(n/spl ges/2) expanded modulatable orthogonal sequences.
{"title":"Generalized method for constructing modulatable periodic complete complementary codes","authors":"H. Torii, M. Nakamura, N. Suehiro","doi":"10.1109/SPAWC.2001.923897","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923897","url":null,"abstract":"Modulatable periodic complete complementary codes for cellular CDMA systems have the property of being \"modulatable\", like modulatable orthogonal sequences. We propose a generalized method to construct modulatable periodic complete complementary codes composed of expanded modulatable orthogonal sequences. Modulatable periodic complete complementary codes obtained by using the proposed method are composed of n(n/spl ges/2) sets of periodic auto-complementary codes, and each periodic auto-complementary code is composed of n(n/spl ges/2) expanded modulatable orthogonal sequences.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"68 8","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120822728","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.2001.923900
Y. Ting, E. Lu, Chiou-Yng Lee
A (N, N-d/sub min/+1) cyclic code based on the complex-valued discrete Fourier transform is proposed. Since the code length N of the code can be any positive integer and each symbol in a code word can be a complex value (consists of two real-valued symbols), the code may be more suitable for some applications, than those codes based on Galois fields. One can design an encoder structure using the existing FFT chip. Due to the cyclic structure decoding is easy in a step-by-step manner.
{"title":"A complex-valued cyclic code using fast Fourier transform","authors":"Y. Ting, E. Lu, Chiou-Yng Lee","doi":"10.1109/SPAWC.2001.923900","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923900","url":null,"abstract":"A (N, N-d/sub min/+1) cyclic code based on the complex-valued discrete Fourier transform is proposed. Since the code length N of the code can be any positive integer and each symbol in a code word can be a complex value (consists of two real-valued symbols), the code may be more suitable for some applications, than those codes based on Galois fields. One can design an encoder structure using the existing FFT chip. Due to the cyclic structure decoding is easy in a step-by-step manner.","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":"121187510","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 : 1900-01-01DOI: 10.1109/SPAWC.2001.923836
Yu-Nan Lin, D. Lin
Successive interference cancellation (SIC) is an effective technique to reduce multiple access interference and thereby increase capacity. While a conventional receiver attains best performance under equal received power for all users, a SIC-based receiver favors unequal powers. We consider ways to assign powers to the received user signals for the benefit of SIC-based multiuser detection. Two power assignment methods, both allocating user signal powers according to their sequence of detection in SIC, are investigated. Through numerical simulation, the methods are shown to greatly improve the bit error rate (BER) performance compared to equal-power assignment. The simulation results also show that, under these methods of power assignment, SIC yields superior performance to parallel interference cancellation (PIC) in high-data-rate transmission.
{"title":"On optimal power distribution for successive interference cancellation (SIC) for wideband CDMA","authors":"Yu-Nan Lin, D. Lin","doi":"10.1109/SPAWC.2001.923836","DOIUrl":"https://doi.org/10.1109/SPAWC.2001.923836","url":null,"abstract":"Successive interference cancellation (SIC) is an effective technique to reduce multiple access interference and thereby increase capacity. While a conventional receiver attains best performance under equal received power for all users, a SIC-based receiver favors unequal powers. We consider ways to assign powers to the received user signals for the benefit of SIC-based multiuser detection. Two power assignment methods, both allocating user signal powers according to their sequence of detection in SIC, are investigated. Through numerical simulation, the methods are shown to greatly improve the bit error rate (BER) performance compared to equal-power assignment. The simulation results also show that, under these methods of power assignment, SIC yields superior performance to parallel interference cancellation (PIC) in high-data-rate transmission.","PeriodicalId":435867,"journal":{"name":"2001 IEEE Third Workshop on Signal Processing Advances in Wireless Communications (SPAWC'01). Workshop Proceedings (Cat. No.01EX471)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132727174","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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