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Sökning: swepub > Ottersten Björn 1961 > (2000-2004) > (2000)

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1.
  • Jansson, Magnus, et al. (författare)
  • Structured Covariance Matrix Estimation : A Parametric Approach
  • 2000
  • Ingår i: Proceedings IEEE International Conference on Acoustics, Speech, and Signal Processing. - IEEE. ; s. 3172-3175
  • Konferensbidrag (refereegranskat)abstract
    • The problem of estimating a positive semi-definite Toeplitz covariance matrix consisting of a low rank matrix plus a scaled identity from noisy data arises in many applications. We propose a computationally attractive (noniterative) covariance matrix estimator with certain optimality properties. For example, under suitable assumptions the proposed estimator achieves the Cramer-Rao lower bound on the covariance matrix parameters. The resulting covariance matrix estimate is also guaranteed to possess all of the structural properties of the true covariance matrix. Previous approaches to this problem have either resulted in computationally unattractive iterative solutions or have provided estimates that only satisfy some of the structural relations
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2.
  • Jöngren, George, et al. (författare)
  • Structured Spatial Interference Rejection Combining
  • 2000
  • Ingår i: Proceedings European Signal Processing Conference.
  • Konferensbidrag (refereegranskat)abstract
    • Modern communication systems are often interferencelimited. By modeling the co-channel interference asspatially colored, temporally white Gaussian noise, itis straightforward to incorporate interference rejectionin the metric of a sequence estimator. In general, estimates of both the channels and the spatial color of theco-channel interference and the noise are needed. In thiswork, a structured model for the spatial noise covariancematrix is proposed and maximum likelihood estimates ofthe parameters are derived. The choice of model orderis also addressed. Simulation results show large gains due to the use of these structured estimates compared with the conventional, unstructured, approach.
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3.
  • Martin, Cristoff, et al. (författare)
  • Joint Channel Estimation and Detection for Interference Cancellation in Multi-Channel Systems
  • 2000
  • Ingår i: The 10th IEEE Workshop on Statistical Signal and Array Processing. - IEEE. ; s. 186-190
  • Konferensbidrag (refereegranskat)abstract
    • Interference from other users and interference due to multipath propagation limit the capacity of wireless communication networks. As the number of users and the demand for new services in the networks increases, co-channel interference will be a limiting factor. This paper proposes an iterative structured multichannel receiver algorithm that jointly estimates the communication channels and desired data while cancelinginterference. A general way of adding training redundancy to a data frame is also introduced. From simulations the proposed method is shown to achieve low bit error rates also in the presence of strong interference. These simulations also show that by distributing the training information in a data burst elaborately further improvements in performance are achievable.
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4.
  • Martin, Cristoff, et al. (författare)
  • On Robustness Against Burst Unsynchronized Co-Channel Interference in Semi-Blind Detection
  • 2000
  • Ingår i: Proceedings Asilomar Conference on Signals, Systems & Computers. - IEEE. ; s. 946-950
  • Konferensbidrag (refereegranskat)abstract
    • Interference from other users and interference due to multi-path propagation limit the capacity of wireless communication networks. As the number of users and the demand for new services in the networks increases, co-channel interference will be a limiting factor. This paper investigates the effects of burst unsynchronized co-channel interference on the performance of a joint channel estimation and detection algorithm. Further, the paper tries to give some insight in how to add training redundancy to a data frame in order to provide robustness against unsynchronized co-channel interference. From simulations and Cramér-Rao bound calculation we find that by using distributing training information elaborately it is possible to increase the robustness against unsynchronized co-channel interferers.
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5.
  • Nilsson, Martin, et al. (författare)
  • A Cluster Approach to Spatio-Temporal Channel Estimation
  • 2000
  • Ingår i: IEEE International Conference on Acoustics, Speech, and Signal Processing. - IEEE. ; s. 2757-2760
  • Konferensbidrag (refereegranskat)abstract
    • In a severe multipath environment the antenna receives multiple copies of the same transmitted signal. To solve for all waves is difficult if possible at all. In this paper we use the approach of grouping the spatio-temporalreflections into clusters. We study how the aperture and bandwidth affects the cluster resolution using experimental data. The measurements were obtained by transmitting linear FM (chirp) signals of 150 MHz bandwidth, in the 1800 MHz band. An antenna array of 16 elements was used as a receiver.
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6.
  • Stridh, Rickard, et al. (författare)
  • Spatial Characterization of Indoor Radio Channel Measurements at 5 GHz
  • 2000
  • Ingår i: Proceedings IEEE Sensor Array and Multichannel Signal Processing Workshop. - IEEE. ; s. 58-62
  • Konferensbidrag (refereegranskat)abstract
    • Multiple transmitters and receivers can be used to provide high link capacity in future wireless systems. Herein analysis of real indoor environment multiple-input-multiple-output measurements on the 5.8 GHz band is performed. The possible increase in capacity, utilizing multiple transmit and receive elements is examined. The gain possible when using channel knowledge at both transmitter and receiver is shown and the capacity dependence on the intra-element distance is examined for the experimental system and compared to simulations
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7.
  • KRISTENSSON, Martin, et al. (författare)
  • Co-channel interference rejection in a digital receiver
  • 2000
  • Patentabstract
    • The present invention relates to a method for a digital receiver and a receiver exploiting second order statistics for adaptive co-channel interference rejection in wireless communication. It uses digitally I, in phase, and Q, quadrature, branches of a received transmitted signal as input to the receiver, a coarse synchronization and a coarse frequency offset compensation have being performed on the signal. It comprises a means for derotation, means for separation, means for filtering, means for estimating and means for detecting transmitted symbols in the received signal. The invention thereby improving co-channel rejection in wireless communication, thus making it possible to increase the number of communication channels for frequencies used.
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