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- Eriksson, Håkan, et al.
(författare)
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A robust correlation receiver for distance estimation
- 1994
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Ingår i: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. - New York : Institute of Electrical and Electronics Engineers (IEEE). - 0885-3010 .- 1525-8955. ; 41:5, s. 596-603
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Tidskriftsartikel (refereegranskat)abstract
- Many methods for distance estimation, such as the ultrasonic pulse-echo method, involve the estimation of a time-of-flight (TOF). In this paper, a signal model is developed that, apart from the TOF, accounts for an unknown, linear frequency dependent distortion as well as for additive noise. We derive a TOF estimator for this model based on the criteria of maximum likelihood. The resulting receiver can be seen as an extension or generalization of the well known cross-correlation, or "matched filter", estimator described, e.g., by Nilsson. The novel receiver is found to be more robust against unknown pulse shape distortion than the cross-correlation estimator, giving less biased TOF estimates. Also, bias versus noise sensitivity can be controlled by proper model order selection
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| 4. |
- Eriksson, Håkan B., et al.
(författare)
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A genie-aided detector with a probabilistic description of the side information
- 1995
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Ingår i: Proceedings. - Piscataway, NJ : IEEE Communications Society. - 0780324536 ; , s. 332-
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Konferensbidrag (refereegranskat)abstract
- Building on Forney's concept of the genie (1972), and introducing the idea of an explicit statistical description of the side information provided to the genie-aided detector, we develop a generic tool for derivation of lower bounds on the bit-error rate of any actual receiver. With this approach, the side information statistics become design parameters, which may be chosen to give the resulting bound a desired structure. To illustrate this, we choose statistics in order to obtain a special case: the lower bound derived by Mazo (1975). The statistical description of the side information makes the lower bounding a transparent application of Bayesian theory
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| 5. |
- Eriksson, Håkan B., et al.
(författare)
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Simultaneous time of flight and channel estimation using a stochastic channel model
- 1993
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Ingår i: Radiovetenskaplig konferens på Lunds tekniska högskola 5-7 april 1993. - Lund : Lunds tekniska högskola. ; , s. 43-46
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Konferensbidrag (refereegranskat)abstract
- In this paper we address the problem of estimating the Time-of-Flight of a transmitted signal when the shape of the received waveform is stochastic. Specifically, we examine the case when the transmission system model is stochastic, linear and time discrete, with additive Gaussian noise, and where the transmitted waveform is known to the receiver. The joint estimation is couched in terms of Maximum a Posteriori (MAP) and Maximum Likelihood estimation. When deriving the MAP estimator we assume a priori knowledge of the probability density of the transmission system impulse response. The MAP estimator is then compared to estimators derived using less a priori information and lower order system models. The ordinary correlation based Time-of-Flight estimator assumes knowledge of the received waveform, that is has a one-dimensional transmission system model. This investigation indicates that a more complex model structure is worthwhile when distortion in excess of low additive noise is present.
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- Nilsson, Rickard, et al.
(författare)
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A low complexity threshold detector making MLSD decisions in a multiuser environment
- 1998
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Ingår i: Pathway to a global wireless revolution. - Piscataway, NJ : IEEE Communications Society. - 0780343204 ; , s. 333-337
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a pipelined implementation of an iterative threshold detector, which makes the same decisions as a maximum likelihood sequence detector (MLSD) on some, but not necessarily all, bits. We apply this as a first stage detector in a direct sequence code division multiple access (DS-CDMA) interference-limited multiuser system. In combination with the single-user matched filter (MF) detector we obtain improved performance and lower complexity than with the decorrelating receiver for a limited number of simultaneous users, e.g. up to 25 users with a spreading factor of 127.
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| 8. |
- Sundström, Nils, et al.
(författare)
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Combined linear-Viterbi equalizers : a comparative study and a minimax design
- 1994
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Ingår i: Creating tomorrow's mobile systems. - Piscataway, NJ : IEEE Communications Society. - 0780319273 ; , s. 1263-1267
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Konferensbidrag (refereegranskat)abstract
- Combined linear-Viterbi equalizer (CLVE) is a term often used for a class of digital receivers reducing the complexity of the Viterbi detector by assuming an approximate channel model together with linear pre-equalization of the received data. The authors reconsider a weighted least squares design technique for CLVEs by introducing a minimax criterion for suppressing the strongest component of the residual intersymbol interference. Odling (1993) studied the performance of some proposed CLVE design methods and evaluated them by simulated bit error rates. The present authors investigate the performance of the minimax design and of the CLVE designs found in literature for two GSM test channels. They also present a comparison of the CLVE designs based on a common quadratic optimization criterion for the selection of the channel prefilter and the desired impulse response
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- Ödling, Per, et al.
(författare)
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Making MLSD-decisions on some individual symbols in a sequence by thresholding the matched filter output
- 1997
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Ingår i: [Host publication title missing]. - : Institute of Electrical and Electronics Engineers (IEEE). - 0780339568 ; , s. 75-75
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Konferensbidrag (refereegranskat)abstract
- We present a detector that, by thresholding the output of the matched filter, gives MLSD-decisions on binary, antipodally modulated symbols that have been corrupted by intersymbol interference and additive Gaussian noise. The detector is simple in structure, consisting of a whitened matched filter and two variable thresholds for each symbol to be detected. The detector will make decisions on some, but most often not all, of the symbols in a transmitted sequence, and those decisions will be the same decisions as the maximum likelihood sequence detector (MLSD) would have made. The number of symbols that are detected is stochastic, varying from sequence to sequence. The basis of the detector is a bound on a cross-product of the quadratic form in the log-likelihood function for the transmitted sequence
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| 10. |
- Ödling, Per, et al.
(författare)
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Making MLSD-decisions on some individual symbols thresholding the matched filter output
- 1997
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Ingår i: Proceedings. - Piscataway, NJ : IEEE Communications Society. - 0780339568 ; , s. 75-
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Konferensbidrag (refereegranskat)abstract
- We present a detector that, by thresholding the output of the matched filter, gives MLSD-decisions on binary, antipodally modulated symbols that have been corrupted by intersymbol interference and additive Gaussian noise. The detector is simple in structure, consisting of a whitened matched filter and two variable thresholds for each symbol to be detected. The detector will make decisions on some, but most often not all, of the symbols in a transmitted sequence, and those decisions will be the same decisions as the maximum likelihood sequence detector (MLSD) would have made. The number of symbols that are detected is stochastic, varying from sequence to sequence. The basis of the detector is a bound on a cross-product of the quadratic form in the log-likelihood function for the transmitted sequence
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