Pub Date : 2004-11-07DOI: 10.1109/ACSSC.2004.1399508
Wei Liu, Stephan Weiss
In this paper, two subband implementations of a frequency invariant beamformer (FIB) are studied. In the first structure, the received array signals are split into subbands and an FIB is operated in each of the corresponding decimated subbands, with a potential of achieving a lower computational complexity. As the spatio-temporal distribution of the subband signals is different from the original fullband signal, a modified design method of the FIB is proposed. Based on the subband implementation, we then change the sensor spacings of different subband signals so that lower frequency bands have a larger spacing, which results in a class of FIBs with scaled aperture with improved performance in lower frequencies. Several design examples are given to show the performance of our new structures.
{"title":"Frequency invariant beamforming in subbands","authors":"Wei Liu, Stephan Weiss","doi":"10.1109/ACSSC.2004.1399508","DOIUrl":"https://doi.org/10.1109/ACSSC.2004.1399508","url":null,"abstract":"In this paper, two subband implementations of a frequency invariant beamformer (FIB) are studied. In the first structure, the received array signals are split into subbands and an FIB is operated in each of the corresponding decimated subbands, with a potential of achieving a lower computational complexity. As the spatio-temporal distribution of the subband signals is different from the original fullband signal, a modified design method of the FIB is proposed. Based on the subband implementation, we then change the sensor spacings of different subband signals so that lower frequency bands have a larger spacing, which results in a class of FIBs with scaled aperture with improved performance in lower frequencies. Several design examples are given to show the performance of our new structures.","PeriodicalId":396779,"journal":{"name":"Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, 2004.","volume":"211 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124738677","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 : 2004-11-07DOI: 10.1109/ACSSC.2004.1399589
N. Owsley, J. Tague
Adaptive beamforming (ABF) using a conventional beamformer (CBF) output interference estimator-subtractor (ES) is known as sidelobe cancellation (SC). SC forms a very low dimensional data vector, called the auxiliary vector, as an input to the adaptive ES function. After a treatment of robust and steering invariant SC background, the frequency dependent auxiliary vector formation from geometrically thinned, sparse array apertures is considered. The corresponding auxiliary aperture spans the full array aperture and consequently does not sacrifice the potential for mainlobe interference rejection while still maintaining essentially optimum SC. Robust steering invariant (SI) SC is compared to a full element space ABF.
{"title":"Steering invariant robust sidelobe cancellation implementation for large arrays","authors":"N. Owsley, J. Tague","doi":"10.1109/ACSSC.2004.1399589","DOIUrl":"https://doi.org/10.1109/ACSSC.2004.1399589","url":null,"abstract":"Adaptive beamforming (ABF) using a conventional beamformer (CBF) output interference estimator-subtractor (ES) is known as sidelobe cancellation (SC). SC forms a very low dimensional data vector, called the auxiliary vector, as an input to the adaptive ES function. After a treatment of robust and steering invariant SC background, the frequency dependent auxiliary vector formation from geometrically thinned, sparse array apertures is considered. The corresponding auxiliary aperture spans the full array aperture and consequently does not sacrifice the potential for mainlobe interference rejection while still maintaining essentially optimum SC. Robust steering invariant (SI) SC is compared to a full element space ABF.","PeriodicalId":396779,"journal":{"name":"Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, 2004.","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129896870","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 : 2004-11-07DOI: 10.1109/ACSSC.2004.1399249
H. A. Schmitt, D. E. Waagen, G. Barbastathis, I. Streinu
We describe one approach for the development of generation-after-next microsystems that have on-the-fly sensing and processing adaptivity. These microsystems function as the lowest level in a multitiered network. Ideas for the development of these microsystems borrow from several evolving fields, including origami folding, computational geometry, topology, and three-dimensional nanofabrication techniques. This work is driven by the "geometry of computation and sensing". In other words, how do the spatial structures of computational and sensing devices define their properties, and, more importantly, can we use geometry as a design tool? Ultimately we envision families of microbots, built from cell-like modules analogous to stem cells, which can not only learn and adjust to their environment but furthermore can adapt their form and function to accommodate possibly changing environments.
{"title":"Computational origami for sensor configuration and control","authors":"H. A. Schmitt, D. E. Waagen, G. Barbastathis, I. Streinu","doi":"10.1109/ACSSC.2004.1399249","DOIUrl":"https://doi.org/10.1109/ACSSC.2004.1399249","url":null,"abstract":"We describe one approach for the development of generation-after-next microsystems that have on-the-fly sensing and processing adaptivity. These microsystems function as the lowest level in a multitiered network. Ideas for the development of these microsystems borrow from several evolving fields, including origami folding, computational geometry, topology, and three-dimensional nanofabrication techniques. This work is driven by the \"geometry of computation and sensing\". In other words, how do the spatial structures of computational and sensing devices define their properties, and, more importantly, can we use geometry as a design tool? Ultimately we envision families of microbots, built from cell-like modules analogous to stem cells, which can not only learn and adjust to their environment but furthermore can adapt their form and function to accommodate possibly changing environments.","PeriodicalId":396779,"journal":{"name":"Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, 2004.","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128486073","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 : 2004-11-07DOI: 10.1109/ACSSC.2004.1399149
Yik-Chung Wu, K. Yip, T. Ng, E. Serpedin
Based on the maximum-likelihood principle and the preamble structure of IEEE 802.11a WLAN standard, this paper proposes a new symbol synchronization algorithm for IEEE 802.11a WLANs over frequency-selective fading channels. In addition to the physical channel, the effects of filtering and unknown sampling phase offset are also considered. Loss in system performance due to synchronization error is used as a performance criterion. Computer simulations show that the proposed algorithm has comparable performances to the algorithm based on the generalized Akaike information criterion (GAIC), but the proposed algorithm exhibits reduced complexity.
{"title":"ML symbol synchronization for OFDM-based WLANs in unknown frequency-selective fading channels","authors":"Yik-Chung Wu, K. Yip, T. Ng, E. Serpedin","doi":"10.1109/ACSSC.2004.1399149","DOIUrl":"https://doi.org/10.1109/ACSSC.2004.1399149","url":null,"abstract":"Based on the maximum-likelihood principle and the preamble structure of IEEE 802.11a WLAN standard, this paper proposes a new symbol synchronization algorithm for IEEE 802.11a WLANs over frequency-selective fading channels. In addition to the physical channel, the effects of filtering and unknown sampling phase offset are also considered. Loss in system performance due to synchronization error is used as a performance criterion. Computer simulations show that the proposed algorithm has comparable performances to the algorithm based on the generalized Akaike information criterion (GAIC), but the proposed algorithm exhibits reduced complexity.","PeriodicalId":396779,"journal":{"name":"Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, 2004.","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127305965","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 : 2004-11-07DOI: 10.1109/ACSSC.2004.1399485
Jo Ebergen, Ivan Sutherland, Ajanta Chakraborty
This paper offers two new division algorithms by digit recurrence. Compared to the standard radix-2 division algorithms with carry-save addition, the new division algorithms trade off a simpler selection logic for more alternatives in the basic repetition step. Our final division algorithm is potentially faster and more energy efficient than radix-2 division with carry-save addition, because the selection logic has less delay and the repetition steps on average perform fewer additions and subtractions.
{"title":"New division algorithms by digit recurrence","authors":"Jo Ebergen, Ivan Sutherland, Ajanta Chakraborty","doi":"10.1109/ACSSC.2004.1399485","DOIUrl":"https://doi.org/10.1109/ACSSC.2004.1399485","url":null,"abstract":"This paper offers two new division algorithms by digit recurrence. Compared to the standard radix-2 division algorithms with carry-save addition, the new division algorithms trade off a simpler selection logic for more alternatives in the basic repetition step. Our final division algorithm is potentially faster and more energy efficient than radix-2 division with carry-save addition, because the selection logic has less delay and the repetition steps on average perform fewer additions and subtractions.","PeriodicalId":396779,"journal":{"name":"Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, 2004.","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130783297","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 : 2004-11-07DOI: 10.1109/ACSSC.2004.1399093
Y. Pointurier, M. Brandt-Pearce
In all-optical networks, signals are propagated through switches with no electrical regeneration. The switches used in all-optical networks (called optical crossconnects, or OXC) are prone to signal leaking; due to the absence of electrical regeneration, these leaked signals, called crosstalk signals, may therefore propagate through hundreds to several thousands of kilometers. Moreover, crosstalk may be enhanced by fiber nonlinearities during the propagation, hence severely impairing network performance. In this paper, we present a simulation study that highlights the issues of crosstalk-impaired all-optical networks. We show that crosstalk cannot be ignored while designing all-optical networks and routing and wavelength assignment (RWA) algorithms and we show how network design and RWA could account for the presence of crosstalk.
{"title":"Effects of crosstalk on the performance and design of all-optical networks with fiber nonlinearities","authors":"Y. Pointurier, M. Brandt-Pearce","doi":"10.1109/ACSSC.2004.1399093","DOIUrl":"https://doi.org/10.1109/ACSSC.2004.1399093","url":null,"abstract":"In all-optical networks, signals are propagated through switches with no electrical regeneration. The switches used in all-optical networks (called optical crossconnects, or OXC) are prone to signal leaking; due to the absence of electrical regeneration, these leaked signals, called crosstalk signals, may therefore propagate through hundreds to several thousands of kilometers. Moreover, crosstalk may be enhanced by fiber nonlinearities during the propagation, hence severely impairing network performance. In this paper, we present a simulation study that highlights the issues of crosstalk-impaired all-optical networks. We show that crosstalk cannot be ignored while designing all-optical networks and routing and wavelength assignment (RWA) algorithms and we show how network design and RWA could account for the presence of crosstalk.","PeriodicalId":396779,"journal":{"name":"Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, 2004.","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132979921","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 : 2004-11-07DOI: 10.1109/ACSSC.2004.1399341
M. Brown, M. Jamali
One of today's problems in signal processing is the identification of direction of arrival (DOA). The need for estimating direction-of-arrival (DOA) of energy wave fields within a three-dimensional medium has led to great interest in areas outside of military use. For most real-world applications however, a target tends to lie within three-dimensional medium. A method for detection and tracking of multiple moving targets within a three-dimensional medium has been developed.
{"title":"Detection and tracking of multiple targets within a three-dimensional medium","authors":"M. Brown, M. Jamali","doi":"10.1109/ACSSC.2004.1399341","DOIUrl":"https://doi.org/10.1109/ACSSC.2004.1399341","url":null,"abstract":"One of today's problems in signal processing is the identification of direction of arrival (DOA). The need for estimating direction-of-arrival (DOA) of energy wave fields within a three-dimensional medium has led to great interest in areas outside of military use. For most real-world applications however, a target tends to lie within three-dimensional medium. A method for detection and tracking of multiple moving targets within a three-dimensional medium has been developed.","PeriodicalId":396779,"journal":{"name":"Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, 2004.","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130994779","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 : 2004-11-07DOI: 10.1109/ACSSC.2004.1399296
D. Bartolomé, A. Pérez-Neira, C. Ibars
This paper deals with practical multiantenna multiuser OFDM systems. With the additional degrees of freedom of multiple antennas and multiple subcarriers, the performance might be enhanced, but the scheduling complexity might increase exponentially. Since the scheduling with realistic integer signal mappings is an NP-complete combinatorial problem, suboptimum solutions based on the scalar product are good candidates to yield a fast and realizable practical implementation. We propose afterwards a power reuse strategy to lower the computational complexity and show that the amount of signaling can be reduced by forcing an equal mapping for all the users at the same subcarrier.
{"title":"Practical bit loading schemes for multiantenna multiuser wireless OFDM systems","authors":"D. Bartolomé, A. Pérez-Neira, C. Ibars","doi":"10.1109/ACSSC.2004.1399296","DOIUrl":"https://doi.org/10.1109/ACSSC.2004.1399296","url":null,"abstract":"This paper deals with practical multiantenna multiuser OFDM systems. With the additional degrees of freedom of multiple antennas and multiple subcarriers, the performance might be enhanced, but the scheduling complexity might increase exponentially. Since the scheduling with realistic integer signal mappings is an NP-complete combinatorial problem, suboptimum solutions based on the scalar product are good candidates to yield a fast and realizable practical implementation. We propose afterwards a power reuse strategy to lower the computational complexity and show that the amount of signaling can be reduced by forcing an equal mapping for all the users at the same subcarrier.","PeriodicalId":396779,"journal":{"name":"Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, 2004.","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129195901","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 : 2004-11-07DOI: 10.1109/ACSSC.2004.1399222
Y. Zhou, W. Chan, T. Falk
We consider multiple description communication over Rayleigh fading channels with binary phase-shift keying (BPSK) modulators at the transmitter and soft-decision detectors at the receiver. The multiple-channel optimized quantizer design (MCOQD) method, introduced in Y. Zhou et al., (2004) for multiple discrete memoryless channels, is extended to multiple Rayleigh fading channels. The decision thresholds of the soft-decision detectors are optimized to achieve minimum end-to-end distortion. Simulation results show that MCOQD provides more robust quantizers than multiple description scalar quantizers V. Vaishampayan (1993) over Rayleigh fading channels, when both the encoder and decoder are matched to channel statistics and when only the decoder is matched to channel statistics.
{"title":"Multiple-channel optimized quantizers for Rayleigh fading channels","authors":"Y. Zhou, W. Chan, T. Falk","doi":"10.1109/ACSSC.2004.1399222","DOIUrl":"https://doi.org/10.1109/ACSSC.2004.1399222","url":null,"abstract":"We consider multiple description communication over Rayleigh fading channels with binary phase-shift keying (BPSK) modulators at the transmitter and soft-decision detectors at the receiver. The multiple-channel optimized quantizer design (MCOQD) method, introduced in Y. Zhou et al., (2004) for multiple discrete memoryless channels, is extended to multiple Rayleigh fading channels. The decision thresholds of the soft-decision detectors are optimized to achieve minimum end-to-end distortion. Simulation results show that MCOQD provides more robust quantizers than multiple description scalar quantizers V. Vaishampayan (1993) over Rayleigh fading channels, when both the encoder and decoder are matched to channel statistics and when only the decoder is matched to channel statistics.","PeriodicalId":396779,"journal":{"name":"Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, 2004.","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129259740","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 : 2004-11-07DOI: 10.1109/ACSSC.2004.1399316
J. Sun, M. Valenti
This paper introduces an optimum maximum a posteriori (MAP) frame synchronization method for packet-based turbo coded communication systems. The synchronizer maximizes the probability of frame synchronization by observing the received signal sequences. This method is based on the low-density parity-check properties of turbo codes and does not require insertion of sync words or preambles.
{"title":"Optimum frame synchronization for preamble-less packet transmission of turbo codes","authors":"J. Sun, M. Valenti","doi":"10.1109/ACSSC.2004.1399316","DOIUrl":"https://doi.org/10.1109/ACSSC.2004.1399316","url":null,"abstract":"This paper introduces an optimum maximum a posteriori (MAP) frame synchronization method for packet-based turbo coded communication systems. The synchronizer maximizes the probability of frame synchronization by observing the received signal sequences. This method is based on the low-density parity-check properties of turbo codes and does not require insertion of sync words or preambles.","PeriodicalId":396779,"journal":{"name":"Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, 2004.","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121534963","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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