{"title":"Receiver implementation for MIMO-OFDM with AMC and precoding","authors":"Johanna Ketonen, M. Juntti, Joseph R. Cavallaro","doi":"10.1109/ACSSC.2009.5469950","DOIUrl":"https://doi.org/10.1109/ACSSC.2009.5469950","url":null,"abstract":"Receivers for horizontally encoded LTE based MIMO-OFDM systems are considered in this paper. Adaptive modulation and coding (AMC) is used as well as precoding. The linear minimum mean square error (LMMSE), successive interference cancellation (SIC) and K-best list sphere detectors (LSD) are compared. The receivers were designed and implemented for 2×2 and 4×4 antenna systems and meet the decoding rate requirement in LTE, i.e, 210 Mb/s in 2×2 and 405 Mb/s in 4×4 antenna systems. The results show that the performance of the receivers is similar in low SNR but the performance difference increases when a higher rank transmission is used. The K-best LSD has the highest performance and complexity. A simpler receiver could be used in the low SNRs to save power and a more complex receiver in the high SNRs when a higher goodput is needed.","PeriodicalId":224492,"journal":{"name":"2009 Conference Record of the Forty-Third Asilomar Conference on Signals, Systems and Computers","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122804005","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}
{"title":"Non-pilot based synchronization for ACO-OFDM","authors":"Sarah Kate Wilson","doi":"10.1109/ACSSC.2009.5470192","DOIUrl":"https://doi.org/10.1109/ACSSC.2009.5470192","url":null,"abstract":"Cyclic-prefix-based synchronization has been used in radio-frequency OFDM for tracking both the timing and frequency offset. The idea behind cyclic-prefix based synchronization is to use the redundancy that is already inherent in the symbol and avoid additional pilots. Asymmetrically-clipped Optical Orthogonal Frequency Division Multiple Access (ACO-OFDM) is a power-efficient form of intensity-modulated/direct-detection (IM/DD) OFDM that avoids the use of a DC-bias. Like OFDM, ACO-OFDM has a cyclic prefix, but it also has additional redundancy in the signal due to the fact that information is transmitted only on the odd carriers. This paper introduces a way to exploit this additional redundancy along with the cyclic-prefix for time-synchronization in ACO-OFDM systems.","PeriodicalId":224492,"journal":{"name":"2009 Conference Record of the Forty-Third Asilomar Conference on Signals, Systems and Computers","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129441676","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}
{"title":"A novel autofocusing approach for estimating directions-of-arrival of wideband signals","authors":"P. Pal, P. Vaidyanathan","doi":"10.1109/ACSSC.2009.5469796","DOIUrl":"https://doi.org/10.1109/ACSSC.2009.5469796","url":null,"abstract":"We propose a novel approach to the design of focusing matrices which play important role in the coherent methods for wideband direction-of-arrival estimation. We call this ‘autofocusing’ because unlike the conventional methods, our technique constructs the focusing matrices entirely by processing the received signal and does not require any preliminary DOA estimates. In this way, it overcomes the major drawback of the coherent methods which otherwise possess many desirable properties. Through computer simulations, the proposed method is found to exhibit satisfactory performance in comparison to the existing wideband DOA estimation algorithms. 1","PeriodicalId":224492,"journal":{"name":"2009 Conference Record of the Forty-Third Asilomar Conference on Signals, Systems and Computers","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126913203","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}
{"title":"Broadcast-based dynamic consensus propagation in wireless sensor networks","authors":"V. Schwarz, Clemens Novak, G. Matz","doi":"10.1109/ACSSC.2009.5470109","DOIUrl":"https://doi.org/10.1109/ACSSC.2009.5470109","url":null,"abstract":"Consensus propagation (CP) is an attractive distributed asynchronous averaging algorithm. In this paper, we develop a modified CP protocol for wireless sensor networks (WSN) that uses message broadcast instead of bilateral message exchange, thereby significantly reducing transmit energy. Furthermore, we extend CP to dynamic environments. We show that the distributed nature of the algorithm causes an inherent tracking delay which we propose to compensate by incorporating an appropriately designed linear predictor. The performance of dynamic broadcast CP is assessed via numerical simulations for severalWSN topologies.","PeriodicalId":224492,"journal":{"name":"2009 Conference Record of the Forty-Third Asilomar Conference on Signals, Systems and Computers","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123643721","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}
{"title":"A simplified channel model for MIMO communications with polarization","authors":"Xiayu Zheng, E. Lindskog","doi":"10.1109/ACSSC.2009.5469860","DOIUrl":"https://doi.org/10.1109/ACSSC.2009.5469860","url":null,"abstract":"We present a simple, yet general channel model for MIMO communications with polarization. The channel model is based on covariance matrices and can model a MIMO channel for an arbitrary spatial antenna configuration with arbitrary polarization angles for each antenna element. We also present a method for deriving equivalent spatial transmit and receive covariance matrices that can be used to understand the statistical impacts of the polarization on the channel correlations. This simplified model can be very useful in design work as it is easy to implement and reasonably can capture the most important aspects of the channel.","PeriodicalId":224492,"journal":{"name":"2009 Conference Record of the Forty-Third Asilomar Conference on Signals, Systems and Computers","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114615693","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}
Maximilian Riemensberger, Ines Abdelghani, Johannes Lenz, W. Utschick
{"title":"Weighted sum rate maximization on two user Gaussian interference channels with rate splitting","authors":"Maximilian Riemensberger, Ines Abdelghani, Johannes Lenz, W. Utschick","doi":"10.1109/ACSSC.2009.5470049","DOIUrl":"https://doi.org/10.1109/ACSSC.2009.5470049","url":null,"abstract":"In interference limited networks treating interference as noise leads to performance degradation at high transmit powers. This can be avoided with rate splitting schemes (Han-Kobayashi region) where portions of the interference are decoded and removed at each receiver. We propose an algorithmic framework for solving the weighted sum rate maximization problem for the two user case of Gaussian interference channels. The polyblock outer approximation algorithm is used to solve the problem despite its nonconvexity. Contrary to usual brute force sampling approaches this framework may be extended to more users and other Gaussian interference models such as the X channel.","PeriodicalId":224492,"journal":{"name":"2009 Conference Record of the Forty-Third Asilomar Conference on Signals, Systems and Computers","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121584623","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}
{"title":"Optimized DFT-FB transceivers over LTV channels","authors":"Chih-Hao Liu, P. Vaidyanathan","doi":"10.1109/ACSSC.2009.5470167","DOIUrl":"https://doi.org/10.1109/ACSSC.2009.5470167","url":null,"abstract":"In this work, we consider the optimization of DFT modulated filterbank transceiver (DFT-FBT) over linear time varying (LTV) channels. The DFT-FBT is a generalization of the Affine Fourier transform based OFDM (Affine OFDM) and the chirped OFDM, which are suggested in recent literature for the transmission over LTV channels. For both known LTV channels and unknown wide sense stationary uncorrelated scattering (WSSUS) statistical channels, we show how to optimize the transmitting and receiving prototypes of DFT-FBT such that the signal to interference and noise ratio (SINR) at the receiver is maximized. After the optimization, the channel dependent part, like OFDM, is a set of scalar multipliers at the receiver end that adapts to the equivalent memoryless channel on a block basis. Simulation results show that the bit error rate (BER) performance of the optimized DFT-FBT over LTV channels is superior to the Affine OFDM. 1","PeriodicalId":224492,"journal":{"name":"2009 Conference Record of the Forty-Third Asilomar Conference on Signals, Systems and Computers","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114812095","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}
{"title":"Performance analysis of slotted ALOHA with periodic server vacations for energy-efficient medium access","authors":"T. O. Walker, M. Tummala, J. McEachen","doi":"10.1109/ACSSC.2009.5469850","DOIUrl":"https://doi.org/10.1109/ACSSC.2009.5469850","url":null,"abstract":"Slotted ALOHA is one of the earliest proposed contention-based medium access solutions for wireless networks and it remains a common approach in literature. In this paper, we present the throughput and delay performance analysis for a slotted ALOHA system with periodic server vacations. By this, we mean that the service is governed by a fixed cycle composed of alternating active and inactive periods, representative of an energy-efficient medium access solution that implements sleep cycles. To our knowledge, ours is the first work to fully develop this analysis.","PeriodicalId":224492,"journal":{"name":"2009 Conference Record of the Forty-Third Asilomar Conference on Signals, Systems and Computers","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124455038","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}
{"title":"Automatic segmentation of Drosophila neurons for content based retrieval using a minimum spanning tree approach","authors":"S. Basu, Alla Aksel, B. Condron, S. Acton","doi":"10.1109/ACSSC.2009.5470190","DOIUrl":"https://doi.org/10.1109/ACSSC.2009.5470190","url":null,"abstract":"A critical part in our knowledge of the brain is the understanding of the structure and morphology of neurons. In recent years, we have witnessed a tremendous effort in developing libraries of neuronal structures that can be used for multiple purposes. These critical studies include modeling the brain connectivity and understanding how cellular structure regulates brain function. Presently, methods for tracing neuronal structures from microscopy images of neurons are not only tedious, but prone to user bias; hence they are not suitable for practical purposes. State of the art automatic neuron tracing algorithms fail to give satisfactory results for neuron images with low contrast, discontinuous filaments, and complex branching. In this paper, we develop Tree2Tree, an automatic neuron segmentation and morphology generation algorithm. Our algorithm uses a global tree linking strategy to connect smaller medial trees of visible components of the neuron in order to give an optimal explanation of the brightness patterns of the neuron branches. We intend to utilize these graph-based segmentation results in the retrieval of similar neurons from an extensive database of segmented neurons. We have tested our algorithm on confocal microscopy images of Drosophila neurons and our segmentation results are congruent with (within ±5.3 pixel RMSE) the manually obtained ground truth.","PeriodicalId":224492,"journal":{"name":"2009 Conference Record of the Forty-Third Asilomar Conference on Signals, Systems and Computers","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126207323","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}
{"title":"An EM-based beamforming algorithm for WCDMA downlink signals","authors":"Sheng-Luen Wei, J. Shynk","doi":"10.1109/ACSSC.2009.5469824","DOIUrl":"https://doi.org/10.1109/ACSSC.2009.5469824","url":null,"abstract":"Multipath propagation causes intersymbol interference and results in a loss of orthogonality between the pilot channel and the user signals in wideband code-division multiple-access (WCDMA) systems. Consequently, an adaptive beamformer using only the pilot signal as the training sequence may not provide adequate error-rate performance. Although a conventional maximum likelihood (ML) beamformer gives improved performance, its computational complexity is relatively high. In this paper, we present a reduced-complexity ML beamformer based on the expectation-maximization (EM) algorithm that utilizes information about the unknown user signals. For comparison purposes, we describe another reduced-complexity ML beamformer based on a Gaussian model for base station self-interference. These beamformers improve the performance of the pilot-only beamformer as demonstrated in a computer simulation example.","PeriodicalId":224492,"journal":{"name":"2009 Conference Record of the Forty-Third Asilomar Conference on Signals, Systems and Computers","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125777444","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}