Blind detection of on-off keying for free-space optical communications

Riediger, M.L.B.; Schober, Robert; Lampe, Lutz

doi:10.1109/ccece.2008.4564763

Cited by 33 publications

(19 citation statements)

References 9 publications

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“…The main drawback of this method is the trade-off between throughput and performance. A blind detection scheme for the case where there is no channel knowledge with the background-noise limited and a sub-optimum maximum-likelihood detection based Rxs was studied in [13] and [14], respectively. However, the performances of these schemes are rather poor for small observation windows.…”

Section: Introductionmentioning

confidence: 99%

Impact of Link Parameters and Channel Correlation on the Performance of FSO Systems With the Differential Signaling Technique

Abadi¹,

Ghassemlooy²,

Zvánovec

et al. 2017

J. Opt. Commun. Netw.

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Abstract-We investigate the effects of link parameters and the channel correlation coefficient on the detection threshold, -factor, and bit-errorrate (BER) of a free space optical system employing the differential signalling scheme. In systems employing differential signalling scheme, the mean value of the signal is used as the detection threshold level, provided that differential links are identical or highly correlated. However, in reality the underlying links are not essentially identical and have a low level of correlation. To show the significance of the link parameters as well as the correlation coefficient, we derive analytical relations describing the effect of weak turbulence and we determine the improvement of -factor with the channel correlation. Further, for the same signal-to-noise ratio, we demonstrate that a link with a higher extinction ratio offers improved performance. We also propose a closed-form expression of the system BER. We present experimental results showing improved -factor for the correlated channel case, compared to the uncorrelated channel.

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Section: Introductionmentioning

confidence: 99%

Impact of Link Parameters and Channel Correlation on the Performance of FSO Systems With the Differential Signaling Technique

Abadi¹,

Ghassemlooy²,

Zvánovec

et al. 2017

J. Opt. Commun. Netw.

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“…After using the likelihood function for MIMO OW systems, as in (9), the log-likelihood function for the complete data in vector form is obtained by (10) After dropping some unnecessary terms, (10) reduces to (11) or equivalently (12) At the E-step of the th iteration of the algorithm, the log-likelihood function for the complete data is calculated, conditioned on the received sequence and the th estimate of the transmitted sequence . Hence, based on (11) or (12) we obtain (13) where (14) and is the number of the bits of the th estimate of the transmitted sequence that correspond to the ON-state. A better estimate of the transmitted sequence, , is obtained at the second step of the th iteration of the algorithm, the M-step. M-step performs the maximization of (13), which yields (15) Since the transmitted data bits are randomly chosen, i.e., no coding scheme is employed, maximizing (15) over the -bit sequences is equivalent to making symbol-by-symbol decisions on each bit.…”

Section: Em-based Sequence Detectionmentioning

confidence: 99%

“…In this paper, we propose EM algorithm as a low-complexity solution for MLSD in the MIMO OW system under consideration. As benchmarks, we also investigate the performance of symbol-by-symbol ML detector, blind detector of [14], PSAM, and MLSD in a MIMO scenario. The proposed detector outperforms symbol-by-symbol ML detector, blind detector, and PSAM methods.…”

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confidence: 99%

“…To address the complexity issue, suboptimal, yet of low complexity, MLSD metrics have been proposed in [12] and [13] for different detection models; still, these metrics require knowledge of the channel's statistics. Other detection methods such as pilot-symbol assisted modulation (PSAM) or blind detection, which both do not require knowledge of the channel's fading statistics have been also applied to SISO OW systems in [11] and [14], respectively.…”

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confidence: 99%

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Iterative Near Maximum-Likelihood Sequence Detection for MIMO Optical Wireless Systems

Chatzidiamantis

Uysal

Tsiftsis³

et al. 2010

J. Lightwave Technol.

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Abstract-A major performance-limiting factor in terrestrial optical wireless (OW) systems is turbulence-induced fading. Exploiting the additional degrees of freedom in the spatial dimension, multiple laser transmitters combined with multiple receive apertures provide an effective solution for fading mitigation. Although multiple-input multiple-output (MIMO) OW systems have been extensively studied in recent years, most of these works are mainly limited to symbol-by-symbol decoding. MLSD exploits the temporal correlation of turbulence-induced fading and promises further performance gains. In this paper, we investigate MLSD for intensity-modulation/direct-detection MIMO OW systems over log-normal atmospheric turbulence channels. Even with a low-order modulation scheme such as OOK, which is typically used in OW systems, the complexity of MLSD might be prohibitive. We therefore present an iterative sequence detector based on the expectation-maximization (EM) algorithm. The complexity of the proposed algorithm is considerably less than a direct evaluation of the log-likelihood function, and it is independent of the channel's fading statistics. The Monte Carlo simulation results demonstrate that the EM-based algorithm outperforms the symbol-by-symbol decoder and achieves a performance, which lies within 0.3 dB of that of the optimal MLSD.

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“…This requirement results in a complex receiver design [26], [34]. Signal detection can rely on a maximum likelihood (ML) detector to achieve optimal performance for the fading case [19].…”

Section: Literature Reviewmentioning

confidence: 99%

MIMO UV NLOS Communications

Gupta

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AcknowledgmentsI would like to thank all these people who have made this thesis possible and because of whom my graduate experience has been one that I will cherish forever.I would like to express my sincere gratitude to my advisor Prof. Maite Brandt-Pearce for her continuous guidance during my study and research.She is a source of constant encouragement and inspiration and I thank her for believing in me. I could not have imagined having a better mentor for my graduate study. Since UV NLOS communications rely on directed communications, the research explores sectoring the scattering atmosphere into non-overlapping volumes defined by the transmit/receive angles and using this as a multiplex-

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Blind detection of on-off keying for free-space optical communications

Cited by 33 publications

References 9 publications

Impact of Link Parameters and Channel Correlation on the Performance of FSO Systems With the Differential Signaling Technique

Impact of Link Parameters and Channel Correlation on the Performance of FSO Systems With the Differential Signaling Technique

Iterative Near Maximum-Likelihood Sequence Detection for MIMO Optical Wireless Systems

MIMO UV NLOS Communications

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