{"title":"Interference alignment based precoder-decoder design for radar-communication co-existence","authors":"Yuanhao Cui, V. Koivunen, Xiaojun Jing","doi":"10.1109/ACSSC.2017.8335561","DOIUrl":"https://doi.org/10.1109/ACSSC.2017.8335561","url":null,"abstract":"Co-existence of radar and communication systems is necessary to facilitate new wireless systems and services due to shortage of useful radio spectrum. Moreover, changes in spectrum regulation will be introduced where spectrum is allocated in larger chunks and different radio systems need to share the spectrum. For example LTE, WI-FI and 5G systems will have to share spectrum with S-band radars. Managing interference is a key task in spectrum sharing and co-existence. In this paper we propose a joint Precoder-Decoder design that maximizes SINRs for co-existing radar and communication systems. Multicarrier waveforms are assumed for both subsystems. Interference Alignment (IA) constraints are imposed to facilitate easier interference cancellation in finding the Precoder and Decoder. Therefore, a maximum Degree of Freedom (DoF) upper bound for K + 1 radar-communication users interference channel can be achieved. Our simulation studies demonstrate that the interference can be practically fully cancelled in both communication and radar systems. This leads to improved detection performance in radar and higher rate in communication subsystems. A significant performance gain over a subspace-based Precoder design is obtained as well.","PeriodicalId":296208,"journal":{"name":"2017 51st Asilomar Conference on Signals, Systems, and Computers","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121658437","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}
Hamidreza Abbaspourazad, Han-Lin Hsieh, M. Shanechi
{"title":"Multiscale modeling of dependencies between spikes and fields","authors":"Hamidreza Abbaspourazad, Han-Lin Hsieh, M. Shanechi","doi":"10.1109/ACSSC.2017.8335438","DOIUrl":"https://doi.org/10.1109/ACSSC.2017.8335438","url":null,"abstract":"Measuring and modeling the brain at multiple spatiotemporal scales are important for studying brain function and developing high-performance brain-machine interfaces. To better understand neural encoding of behavior, the conditional dependencies between different scales of brain activity should be considered in the multiscale modeling framework. Here, we develop a new multiscale model that characterizes the conditional dependence between spikes and fields during behavior. We modeled this mutual dependence by incorporating the effect of field features on each neuron's firing rate function. To reduce the number of model parameters to be learned, we assumed that the strength of dependency between a pair of neuron and field feature is a function of the distance between electrodes from which they are recorded. We then constructed the shape of this unknown spatial dependency function with a weighted sum of Gaussian kernels. We devised an unsupervised learning algorithm using expectation-maximization to learn the kernel weights as well as other model parameters. Using simulated data, we show that this learning algorithm accurately identifies the multiscale model parameters and the conditional dependency functions. This modeling and learning framework can help study spike-field encoding and dependencies and could enhance future neurotechnologies.","PeriodicalId":296208,"journal":{"name":"2017 51st Asilomar Conference on Signals, Systems, and Computers","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121196000","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 efficient software implementation of correctly rounded operations extending FMA: A + b + c and a × b + c × d","authors":"C. Lauter","doi":"10.1109/ACSSC.2017.8335379","DOIUrl":"https://doi.org/10.1109/ACSSC.2017.8335379","url":null,"abstract":"In its 2008 revision, the IEEE754 Standard for Floating-Point Arithmetic added the Fused-Multiply-And-Add (FMA) operation, computing a × b + c without intermediate rounding. This operation enables faster scalar products and doubled-precision arithmetic. The IEEE754 Standard is again undergoing revision. We propose an efficient software implementation of two additional operations: Fused-Multiply-Twice-And-Add, a × b + c × d and Fused-Add-Add a + b + c. Our implementation guarantees correct rounding in all rounding modes and IEEE754 compliant signaling. Although intended for reference purposes, with a 94 resp. 104 cycle latency, our software implementations are pretty fast.","PeriodicalId":296208,"journal":{"name":"2017 51st Asilomar Conference on Signals, Systems, and Computers","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121347917","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}
S. Venkatakrishnan, E. Cakmak, Hassina Billheux, P. Bingham, Richard Archibald
{"title":"Model-based iterative reconstruction for neutron laminography","authors":"S. Venkatakrishnan, E. Cakmak, Hassina Billheux, P. Bingham, Richard Archibald","doi":"10.1109/ACSSC.2017.8335686","DOIUrl":"https://doi.org/10.1109/ACSSC.2017.8335686","url":null,"abstract":"Neutron-based parallel-beam laminography is an important 3D characterization tool because it can image thick specimens with unique shapes and provides a complimentary contrast to X-rays for several elements relevant to the material sciences and biology. However, the inversion of neutron laminography data is complicated because of the non-traditional geometry of the set-up, the presence of noise and the occurrence of gamma hits on the detector during the course of an experiment. In this paper, we present a model-based/regularized-inversion reconstruction algorithm for neutron laminography. We introduce a new forward-model/data fitting term and combine it with a flexible regularizer function to formulate the reconstruction as minimizing a cost-function. We then present a novel optimization algorithm that is based on combining a majorization-minimization technique with a first-order method that is amenable to simple parallelization on multi-core architectures. Using simulated and experimental data, we demonstrate that it is possible to acquire high quality reconstructions compared to the typically used filtered-back projection algorithm and algebraic reconstruction techniques.","PeriodicalId":296208,"journal":{"name":"2017 51st Asilomar Conference on Signals, Systems, and Computers","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122258845","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":"Physical layer security in massive MIMO systems","authors":"R. Schaefer, Gayan Amarasuriya, H. Poor","doi":"10.1109/ACSSC.2017.8335124","DOIUrl":"https://doi.org/10.1109/ACSSC.2017.8335124","url":null,"abstract":"An overview over secure communication in massive multiple-input multiple-output (MIMO) systems is presented. A massive MIMO base-station serves multiple user nodes by provisioning physical layer security techniques to secure the confidential transmissions against an eavesdropper. The eavesdropper can either be passively eavesdropping upon the communication or can actively contaminate the channel estimates. The achievable secrecy rates for these settings are reviewed, and their asymptotic behavior is discussed. Finally, a detection scheme for active pilot contamination attacks is discussed.","PeriodicalId":296208,"journal":{"name":"2017 51st Asilomar Conference on Signals, Systems, and Computers","volume":"113 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127041887","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":"Noncoherent multi-user MIMO communications using covariance CSIT","authors":"C. Thomas, Wassim Tabikh, D. Slock, Yuan-Wu Yi","doi":"10.1109/ACSSC.2017.8335551","DOIUrl":"https://doi.org/10.1109/ACSSC.2017.8335551","url":null,"abstract":"The Multi-User downlink, particularly in a Multi-Cell Massive MIMO setting, requires enormous amounts of instantaneous CSIT (Channel State Information at the Trans-mitter(s)), iCSIT. Here we focus on exploiting channel covariance CSIT (coCSIT) only. In particular multipath induced structured low rank covariances are considered that arise in Massive MIMO and mmWave settings, which we call pathwise CSIT (pwC-SIT). The resulting non-Kronecker MIMO channel covariance structures lead to a split between the roles of transmitters and receivers in MIMO systems. For the beamforming optimization, we consider a minorization approach applied to the Massive MIMO limit of the Expected Weighted Sum Rate. Simulations indicate that the pwCSIT based designs may lead to limited spectral efficiency loss compared to iCSIT based designs, while trading fast fading CSIT for slow fading CSIT. We also point out that the pathwise approach may lead to distributed designs with only local pwCSIT, and analyze the sum rates for iCSIT and pwCSIT in the low and high SNR limits.","PeriodicalId":296208,"journal":{"name":"2017 51st Asilomar Conference on Signals, Systems, and Computers","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127137153","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-parametric learning to infer wireless relays, routes and traffic patterns from time series of spectrum activity","authors":"S. Kokalj-Filipovic, P. Spasojevic, A. Poylisher","doi":"10.1109/ACSSC.2017.8335484","DOIUrl":"https://doi.org/10.1109/ACSSC.2017.8335484","url":null,"abstract":"Non-parametric inference techniques are proposed to understand latent structure behind sequences of spectral activity indicators, i.e. packet start and stop times, of networked wireless transmitters. We aim to infer the latent network structure and characterize information flow between spectrally monitored nodes. The practical aspect of learning is to aid the reasoning of a cognitive network about its unknown and dynamic spectrum environment. We first segment the observed on-off time series into temporal segments of statistically discernible behavioral states. Each state segment has distinct emission statistics and a specific duration, learned by using a Bayesian non-parametric method, referred to as HDP-HSMM [1] in our prior work [2]. The end result is that new times series of state segments are derived from the observations of each nodes activity. We propose test statistics, loosely related to Granger-causality between per-node sequences of state segments, to trace the impact of one nodes traffic to another. We define extendable statistical models of causality in which not only state changes are considered as events, but also the nature of those changes, i.e. whether the new state has similar observation statistics in both nodes. Our approach is non-parametric as it does not require knowledge about underlying network protocols.","PeriodicalId":296208,"journal":{"name":"2017 51st Asilomar Conference on Signals, Systems, and Computers","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127262201","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":"Feature based order recognition of continuous-phase FSK using principal component analysis","authors":"Ambaw B. Ambaw, M. Doroslovački","doi":"10.1109/ACSSC.2017.8335157","DOIUrl":"https://doi.org/10.1109/ACSSC.2017.8335157","url":null,"abstract":"Principal component analysis (PCA) is a technique that performs a linear transformation on the input space to align directions of maximum variation with the directions of the axises. In this paper, we study the feasibility of principal component analysis based order recognition of continuous phase FSK. The approximate entropy (ApEn) of the received signal, ApEn of the phase of the received signal, and ApEn of the instantaneous frequency of the received signal are used as a set of distinguishing features. The work aims in devising an unsupervised learning algorithm under noisy, carrier frequency offset and fast fading channel conditions. The instantaneous frequency is shaped by using root raised cosine pulses. Performance of principal component based method is compared to stacked autoencoder (SAE) based approach which is more computationally complex technique that can model relatively complicated relationships and non-linearities. For fair comparison both the PCA and SAE based methods use approximate entropy features. The benefit of employing PCA is that after PCA transformations the computation cost can really be decreased a lot. Also in both methods, no a priori information is required about carrier phase, symbol rate and carrier amplitude. The PCA based method shows higher accuracy than the SAE method.","PeriodicalId":296208,"journal":{"name":"2017 51st Asilomar Conference on Signals, Systems, and Computers","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126423887","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}
Sven Jacobsson, G. Durisi, M. Coldrey, Christoph Studer
{"title":"On out-of-band emissions of quantized precoding in massive MU-MIMO-OFDM","authors":"Sven Jacobsson, G. Durisi, M. Coldrey, Christoph Studer","doi":"10.1109/ACSSC.2017.8335128","DOIUrl":"https://doi.org/10.1109/ACSSC.2017.8335128","url":null,"abstract":"We analyze out-of-band (OOB) emissions in the massive multi-user (MU) multiple-input multiple-output (MIMO) downlink. We focus on systems in which the base station (BS) is equipped with low-resolution digital-to-analog converters (DACs) and orthogonal frequency-division multiplexing (OFDM) is used to communicate to the user equipments (UEs) over frequency-selective channels. We demonstrate that analog filtering in combination with simple frequency-domain digital predistortion (DPD) at the BS enables a significant reduction of OOB emissions, but degrades the signal-to-interference-noise-and-distortion ratio (SINDR) at the UEs and increases the peak-to-average power ratio (PAR) at the BS. We use Bussgang's theorem to characterize the tradeoffs between OOB emissions, SINDR, and PAR, and to study the impact of analog filters and DPD on the error-rate performance of the massive MU-MIMO-OFDM downlink. Our results show that by carefully tuning the parameters of the analog filters, one can achieve a significant reduction in OOB emissions with only a moderate degradation of error-rate performance and PAR.","PeriodicalId":296208,"journal":{"name":"2017 51st Asilomar Conference on Signals, Systems, and Computers","volume":"461 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124352211","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":"Physics-driven deep training of dictionary-based algorithms for MR image reconstruction","authors":"S. Ravishankar, Il Yong Chun, J. Fessler","doi":"10.1109/ACSSC.2017.8335685","DOIUrl":"https://doi.org/10.1109/ACSSC.2017.8335685","url":null,"abstract":"Techniques involving learned dictionaries can outperform conventional approaches involving (nontrained) analytical sparsifying models for MR image reconstruction. Inspired by iterative dictionary learning-based reconstruction methods, we propose a novel efficient image reconstruction framework involving multiple iterations (or layers). Each layer involves applying a transformation to image patches, thresholding, and then reconstructing the patches in a dictionary, followed by an update of the image using observed k-space measurements. We train the transforms, thresholds, and dictionaries within the multi-layer algorithm to minimize reconstruction errors. Our experiments demonstrate that for highly undersampled k-space data, such trained reconstruction algorithms provide high quality results.","PeriodicalId":296208,"journal":{"name":"2017 51st Asilomar Conference on Signals, Systems, and Computers","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127525784","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}