In this work a simple scheduling scheme is proposed for wireless sensor networks in presence of a maximum tolerable delay constraint. The scheduler performs the dual task of scheduling the users experiencing high channel gains to minimize the energy consumption while at the same time, it takes into account the maximum allowed buffer length of each user to provide an upper bound on the maximum tolerable delay. The idea of a threshold depending on the buffer occupancy is proposed to schedule the users opportunistically unless the deadline for transmission is reached. A maximum delay guarantee is provided in the proposed scheme in addition to average delay guarantee at almost no additional energy cost. The results show that multilevel recursive optimization can minimize energy subject to maximum bounded delay for schedulers that empty the buffer.
{"title":"Provision of Maximum Delay Guarantee at Low Energy in a Multi-User Environment","authors":"M. Butt, K. Kansanen, R. Muller","doi":"10.1109/ISSSTA.2008.101","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.101","url":null,"abstract":"In this work a simple scheduling scheme is proposed for wireless sensor networks in presence of a maximum tolerable delay constraint. The scheduler performs the dual task of scheduling the users experiencing high channel gains to minimize the energy consumption while at the same time, it takes into account the maximum allowed buffer length of each user to provide an upper bound on the maximum tolerable delay. The idea of a threshold depending on the buffer occupancy is proposed to schedule the users opportunistically unless the deadline for transmission is reached. A maximum delay guarantee is provided in the proposed scheme in addition to average delay guarantee at almost no additional energy cost. The results show that multilevel recursive optimization can minimize energy subject to maximum bounded delay for schedulers that empty the buffer.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123032524","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}
A K-user direct-sequence spread-spectrum code- division multiple-access (CDMA) system with (q << log2 K) -bit baseband signal quantization at the demodulator is considered. It is shown that additionally quantizing the K + 1 level output signal of the CDMA modulator into q bits improves significantly the average bit-error performance in a non-negligible regime of noise variance, sigma2, and user load, beta, under various system settings, like additive white Gaussian noise (AWGN), Rayleigh fading, single-user detection, multi-user detection, random and orthogonal spreading codes. For the case of single-user detection in random spreading AWGN-CDMA, this regime is identified explicitly as sigma < gamma(q)yradicbeta, where gamma(q) is a certain pre-factor depending on q, and the associated BER improvement is derived analytically for q = 1, 2. For the other examined system settings, computer simulations are provided, corroborating this interesting behavior.
{"title":"Dual-Transceiver Quantization Can Improve Error Performance in CDMA","authors":"H. Efraim, N. Yacov, I. Kanter, O. Shental","doi":"10.1109/ISSSTA.2008.21","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.21","url":null,"abstract":"A K-user direct-sequence spread-spectrum code- division multiple-access (CDMA) system with (q << log2 K) -bit baseband signal quantization at the demodulator is considered. It is shown that additionally quantizing the K + 1 level output signal of the CDMA modulator into q bits improves significantly the average bit-error performance in a non-negligible regime of noise variance, sigma2, and user load, beta, under various system settings, like additive white Gaussian noise (AWGN), Rayleigh fading, single-user detection, multi-user detection, random and orthogonal spreading codes. For the case of single-user detection in random spreading AWGN-CDMA, this regime is identified explicitly as sigma < gamma(q)yradicbeta, where gamma(q) is a certain pre-factor depending on q, and the associated BER improvement is derived analytically for q = 1, 2. For the other examined system settings, computer simulations are provided, corroborating this interesting behavior.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121887640","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}
In this paper, a proposed model based on in-place wavelet transform (IP-WT) was suggested to improve the performance of the orthogonal frequency division multiplexing (OFDM) under the additive white Gaussian noise (AWGN), and flat fading channel. The proposed model does not require additional arrays at each sweep such as in the ordered Haar wavelet transform; this ensures fast processing time with minimum memory size. The results extracted by a computer simulation and compared with the performance of the conventional model based on fast Fourier transform (FFT). As a result, it can be seen that the proposed technique has high performance improvement over the conventional OFDM system based FFT, where the bit error rate (BER) is widely reduced under these models of channels.
{"title":"Performance Study of OFDM Based on In-Place Wavelet Transform","authors":"S. M. Salih, A. Mansour","doi":"10.1109/ISSSTA.2008.96","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.96","url":null,"abstract":"In this paper, a proposed model based on in-place wavelet transform (IP-WT) was suggested to improve the performance of the orthogonal frequency division multiplexing (OFDM) under the additive white Gaussian noise (AWGN), and flat fading channel. The proposed model does not require additional arrays at each sweep such as in the ordered Haar wavelet transform; this ensures fast processing time with minimum memory size. The results extracted by a computer simulation and compared with the performance of the conventional model based on fast Fourier transform (FFT). As a result, it can be seen that the proposed technique has high performance improvement over the conventional OFDM system based FFT, where the bit error rate (BER) is widely reduced under these models of channels.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117009446","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}
The radio frequency identification (RFID) systems are exhibiting an immense growth and ubiquity. In future there will be a large number of RFID tags attached to objects and persons and dense deployment of the RFID readers, which will be interconnected in reader networks. The performance of the reading of such large volumes of tags requires efficient arbitration protocols for resolving the collisions among the tags that attempt to send information to the reader network. In this paper we introduce a framework for arbitration protocols that makes provisions for cooperative arbitration performed by the network of readers. We introduce the notion of arbitration space, which is a generalization of the recently recently introduced framework for collision resolution with running multiplicity estimation. The usefulness of the concept of arbitration space is illustrated through several examples. The presented ideas on generalized arbitration space set interesting directions for future work.
{"title":"Tree Protocols for RFID Tags with Generalized Arbitration Spaces","authors":"P. Popovski","doi":"10.1109/ISSSTA.2008.10","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.10","url":null,"abstract":"The radio frequency identification (RFID) systems are exhibiting an immense growth and ubiquity. In future there will be a large number of RFID tags attached to objects and persons and dense deployment of the RFID readers, which will be interconnected in reader networks. The performance of the reading of such large volumes of tags requires efficient arbitration protocols for resolving the collisions among the tags that attempt to send information to the reader network. In this paper we introduce a framework for arbitration protocols that makes provisions for cooperative arbitration performed by the network of readers. We introduce the notion of arbitration space, which is a generalization of the recently recently introduced framework for collision resolution with running multiplicity estimation. The usefulness of the concept of arbitration space is illustrated through several examples. The presented ideas on generalized arbitration space set interesting directions for future work.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130305040","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}
B. M. Zaidel, R. Muller, R. de Miguel, A. L. Moustakas
The spectral efficiency of practically oriented vector precoding schemes for the Gaussian multiple-input multiple-output (MIMO) broadcast channel is analyzed in the large system limit. Considering discrete complex input alphabets, the transmitter is assumed to comprise a linear front-end combined with nonlinear precoding, that minimizes the transmit energy penalty imposed by the linear front-end. The energy penalty is minimized by relaxing the input alphabet to a larger alphabet set prior to precoding. The so-called "replica method" of statistical physics is employed to derive the limiting empirical distribution of the precoder's output, as well as the limiting energy penalty. Particularizing to a "zero-forcing" (ZF) linear front-end, and non- cooperative users, a decoupling result is derived according to which the channel observed by each of the individual receivers can be characterized by the Markov chain u-x-y, where u is the channel input, x is the equivalent precoder output, and y is the channel output. A comparative spectral efficiency analysis of two illustrative examples reveals significant performance gains compared to linear ZF precoding in the medium to high Et/No region. In particular, we demonstrate that convex extended alphabets, amenable to efficient energy minimization algorithms, provide an attractive alternative to alphabets based on the discrete Gaussian integer lattice, for which the energy minimization problem is NP-hard.
{"title":"On Spectral Efficiency of Vector Precoding for Gaussian MIMO Broadcast Channels","authors":"B. M. Zaidel, R. Muller, R. de Miguel, A. L. Moustakas","doi":"10.1109/ISSSTA.2008.48","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.48","url":null,"abstract":"The spectral efficiency of practically oriented vector precoding schemes for the Gaussian multiple-input multiple-output (MIMO) broadcast channel is analyzed in the large system limit. Considering discrete complex input alphabets, the transmitter is assumed to comprise a linear front-end combined with nonlinear precoding, that minimizes the transmit energy penalty imposed by the linear front-end. The energy penalty is minimized by relaxing the input alphabet to a larger alphabet set prior to precoding. The so-called \"replica method\" of statistical physics is employed to derive the limiting empirical distribution of the precoder's output, as well as the limiting energy penalty. Particularizing to a \"zero-forcing\" (ZF) linear front-end, and non- cooperative users, a decoupling result is derived according to which the channel observed by each of the individual receivers can be characterized by the Markov chain u-x-y, where u is the channel input, x is the equivalent precoder output, and y is the channel output. A comparative spectral efficiency analysis of two illustrative examples reveals significant performance gains compared to linear ZF precoding in the medium to high Et/No region. In particular, we demonstrate that convex extended alphabets, amenable to efficient energy minimization algorithms, provide an attractive alternative to alphabets based on the discrete Gaussian integer lattice, for which the energy minimization problem is NP-hard.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121666584","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}
J. Samuel, P. Rosson, L. Maret, C. Dehos, A. Valkanas
This paper analyses the impact of RF impairments in a new wireless environment where relays are introduced to improve performances. Thanks to a simulation chain supporting theoretical RF impairments models, different techniques are evaluated. The transmission chain can simulate amplify-and-forward or decode-and-forward protocols in either simple relaying or cooperative scenarios. The results of these simulations show BER degradations versus several realistic sets of RF impairments.
{"title":"Impact of RF Impairments in Cellular Wireless Metropolitan Area Networks","authors":"J. Samuel, P. Rosson, L. Maret, C. Dehos, A. Valkanas","doi":"10.1109/ISSSTA.2008.149","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.149","url":null,"abstract":"This paper analyses the impact of RF impairments in a new wireless environment where relays are introduced to improve performances. Thanks to a simulation chain supporting theoretical RF impairments models, different techniques are evaluated. The transmission chain can simulate amplify-and-forward or decode-and-forward protocols in either simple relaying or cooperative scenarios. The results of these simulations show BER degradations versus several realistic sets of RF impairments.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127996252","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}
The high level of flexibility achievable with software defined radio (SDR) technology generates interest in the industry of mass market receivers, but represents also a valuable tool for research-oriented analysis. This paper exploits this last aspect and demonstrates how it is possible to assess the performance of different digital estimators of C/N0 (i.e., the carrier power to noise power spectral density ratio) using a real time SDR Global Navigation Satellite System (GNSS) receiver. In a GNSS receiver the measure of C/N0 is not only a measure of the strength of the received signal, but is also used to determine the lock condition of the carrier and tracking loops and to control the channel scheduling. This paper investigates the possibility of implementing various low complexity C/N0 estimators, properly adapted from the digital communications world. After a theoretical analysis, the performance of such estimation techniques are assessed through both simulated and real GPS signals.
{"title":"Performance Evaluation of C/N0 Estimators Using a Real Time GNSS Software Receiver","authors":"M. Pini, E. Falletti, M. Fantino","doi":"10.1109/ISSSTA.2008.12","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.12","url":null,"abstract":"The high level of flexibility achievable with software defined radio (SDR) technology generates interest in the industry of mass market receivers, but represents also a valuable tool for research-oriented analysis. This paper exploits this last aspect and demonstrates how it is possible to assess the performance of different digital estimators of C/N0 (i.e., the carrier power to noise power spectral density ratio) using a real time SDR Global Navigation Satellite System (GNSS) receiver. In a GNSS receiver the measure of C/N0 is not only a measure of the strength of the received signal, but is also used to determine the lock condition of the carrier and tracking loops and to control the channel scheduling. This paper investigates the possibility of implementing various low complexity C/N0 estimators, properly adapted from the digital communications world. After a theoretical analysis, the performance of such estimation techniques are assessed through both simulated and real GPS signals.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128054734","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}
Navid Hassanpour, J. E. Smee, Jilei Hou, Soriaga Joseph Binamira
This paper presents a distributed beamforming technique that addresses the effect of inter-cell interference on the downlink of cellular communications systems. The beamforming weights are computed in a distributed manner at each transmit sector antenna array without the need for inter-sector communication. The beamforming weights are chosen to compromise between maximizing the power to the served user from each sector while minimizing the interference caused to users served in adjacent sectors. The extensions of this method for variable levels of channel state information feedback and multiple receiver antennas are introduced. Beamforming codebooks with power variations across antennas are presented. We show how users can additionally feed back the fraction of interference caused by each interfering sector to incorporate the urgency of interference avoidance into the transmitter optimization.
{"title":"Distributed Beamforming Based on Signal-to Caused-Interference Ratio","authors":"Navid Hassanpour, J. E. Smee, Jilei Hou, Soriaga Joseph Binamira","doi":"10.1109/ISSSTA.2008.81","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.81","url":null,"abstract":"This paper presents a distributed beamforming technique that addresses the effect of inter-cell interference on the downlink of cellular communications systems. The beamforming weights are computed in a distributed manner at each transmit sector antenna array without the need for inter-sector communication. The beamforming weights are chosen to compromise between maximizing the power to the served user from each sector while minimizing the interference caused to users served in adjacent sectors. The extensions of this method for variable levels of channel state information feedback and multiple receiver antennas are introduced. Beamforming codebooks with power variations across antennas are presented. We show how users can additionally feed back the fraction of interference caused by each interfering sector to incorporate the urgency of interference avoidance into the transmitter optimization.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"110 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127981813","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}
In this paper approximated expressions for the pull- out probability of digital tracking loops are derived. The analysis is done for a PLL and for a UFA-PLL recently introduced in P.A. Roncagliolo and J.G. Garcia (2007), as a structure for high dynamic applications. The considered dynamics is modeled as acceleration steps and the loop filter used is designed with a fully digital technique presented previously. These expressions allow to quantify the role of the different loop parameters, such as the integration time and loop bandwidth, at the design stage and to choose them more efficiently. Monte Carlo simulations for 20 g acceleration steps showing the usefulness and limitations of these approximations are presented.
{"title":"Pull-Out Probability Considerations in High Dynamics GNSS Tracking Loops Design","authors":"P. A. Roncagliolo, J. G. Garcia, C. Muravchik","doi":"10.1109/ISSSTA.2008.17","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.17","url":null,"abstract":"In this paper approximated expressions for the pull- out probability of digital tracking loops are derived. The analysis is done for a PLL and for a UFA-PLL recently introduced in P.A. Roncagliolo and J.G. Garcia (2007), as a structure for high dynamic applications. The considered dynamics is modeled as acceleration steps and the loop filter used is designed with a fully digital technique presented previously. These expressions allow to quantify the role of the different loop parameters, such as the integration time and loop bandwidth, at the design stage and to choose them more efficiently. Monte Carlo simulations for 20 g acceleration steps showing the usefulness and limitations of these approximations are presented.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130191733","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}
A low-complexity, decision-directed, iterative scheme is proposed for severe phase noise mitigation in OFDM modulation over frequency-selective as well as flat channels. The proposed approach relies on two modeling steps: first, an alternative model formulation in the time domain; second, a maximum likelihood (ML)-inspired estimator which incorporates SNR-maximizing concepts. The resulting scheme is shown to outperform already proposed approaches in terms of achievable error rate and to do so with comparatively reduced complexity.
{"title":"Robust Phase Noise Compensation in OFDM via a Dual-Model Approach","authors":"I. Dagres, A. Polydoros, K. Nikitopoulos","doi":"10.1109/ISSSTA.2008.91","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.91","url":null,"abstract":"A low-complexity, decision-directed, iterative scheme is proposed for severe phase noise mitigation in OFDM modulation over frequency-selective as well as flat channels. The proposed approach relies on two modeling steps: first, an alternative model formulation in the time domain; second, a maximum likelihood (ML)-inspired estimator which incorporates SNR-maximizing concepts. The resulting scheme is shown to outperform already proposed approaches in terms of achievable error rate and to do so with comparatively reduced complexity.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"100 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131759809","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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