Adaptive Transceivers for Mobile Free-Space Optical Communications

Minch, J.; Gervais, David R.; Townsend, Daniel J.

doi:10.1109/milcom.2006.302152

Cited by 18 publications

(6 citation statements)

References 7 publications

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“…About previous works, related to the first problem, in [2], a fixed pulse-width was pointed out, considering the rate and the modulation agility. A tunable pulse-width management was proposed in [3], according to tuning the captured voltage on a phase modulator, jointly using a tunable dispersion element.…”

Section: Mimo Cdma-based Opticalmentioning

confidence: 99%

MIMO CDMA-based optical SATCOMs: A new solution

Zamanipour¹,

Mohammadi

2015

2015 IEEE Power, Communication and Information Technology Conference (PCITC)

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Abstract-A new scheme for MIMO CDMA-based optical satellite communications (OSATCOMs) is presented. Three independent problems are described for up-link and downlink in terms of two distinguished optimization problems. At first, in up-link, Pulse-width optimization is proposed to reduce dispersions over fibers as the terrestrial part. This is performed for return-to-zero (RZ) modulation that is supposed to be used as an example in here. This is carried out by solving the first optimization problem, while minimizing the probability of overlapping for the Gaussian pulses that are used to produce RZ. Some constraints are assumed such as a threshold for the peak-to-average power ratio (PAPR). In down-link, the second and the third problems are discussed as follows, jointly as a closed-form solution. Solving the second optimization problem, an objective function is obtained, namely the MIMO CDMA-based satellite weight-matrix as a conventional adaptive beam-former. The Satellite link is stablished over flat un-correlated Nakagami-m/Suzuki fading channels as the second problem. On the other hand, the mentioned optimization problem is robustly solved as the third important problem, while considering inter-cell interferences in the multi-cell scenario. Robust solution is performed due to the partial knowledge of each cell from the others in which the link capacity is maximized. Analytical results are conducted to investigate the merit of system.

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Section: Mimo Cdma-based Opticalmentioning

confidence: 99%

MIMO CDMA-based optical SATCOMs: A new solution

Zamanipour¹,

Mohammadi

2015

2015 IEEE Power, Communication and Information Technology Conference (PCITC)

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“…[5][6][7] In addition, rate-adaptive modem designs have been demonstrated [8][9][10][11][12] which can be used to optimize system performance over the highly variable channel associated with mobile free-space optical communication links. [13][14][15] Some of these designs have been implemented with near quantum-limited performance. 9-12 Figure 1 shows a block diagram of a typical preamplified DPSK communication modem that is capable of performing near the theoretically best performance.…”

Section: Importance Of Frequency Stabilitymentioning

confidence: 99%

Frequency stabilization of laser diodes in an aggressive thermal environment

et al. 2015

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Mobile free-space laser communication systems must reconcile the requirements of low size, weight, and power with the ability to both survive and operate in harsh thermal and mechanical environments. In order to minimize the aperture size and amplifier power requirements of such systems, communication links must exhibit performance near theoretical limits. Such performance requires laser transmitters and receiver filters and interferometers to maintain frequency accuracy to within a couple hundred MHz of the design frequency. We demonstrate an approach to achieving high frequency stability over wide temperature ranges by using conventional DFB lasers, tuned with TEC and current settings, referenced to an HCN molecular frequency standard. A HCN cell absorption line is scanned across the TEC set-point to adjust the DFB laser frequency. Once the center of the line is determined, the TEC set-point is offset as required to obtain frequency agility. To obtain large frequency offsets from an HCN absorption line, as well as continuous laser source operation, a second laser is offset from the reference laser and the resulting beat tone is detected in a photoreceiver and set to the desired offset using a digital frequency-locked loop. Using this arrangement we have demonstrated frequency accuracy and stability of better than 8 MHz RMS over an operational temperature range of 0ºC to 50º C, with operation within minutes following 8 hour soaks at -40º C and 70º C.

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“…Conventional FSO has been categorized stationary telecommunication technology rather than ubiquitous one as it is applied to fixed point-topoint communication. [4][5][6][7][8][9] FSO terminal is rigidly attached to some stiff and sturdy structure enough to avoid vibration due to weather or traffic, even though the installation requires labor and time. [10][11][12][13][14] Another drawback of conventional FSO is vulnerability to disturbance to aerial laser transmission.…”

Section: Introductionmentioning

confidence: 99%

Initial alignment method for free space optics laser beam

Shimada

Tashiro

Izumi

et al. 2016

Jpn. J. Appl. Phys.

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The authors have newly proposed and constructed an active free space optics transmission system. It is equipped with a motor driven laser emitting mechanism and positioning photodiodes, and it transmits a collimated thin laser beam and accurately steers the laser beam direction. It is necessary to introduce the laser beam within sensible range of the receiver in advance of laser beam tracking control. This paper studies an estimation method of laser reaching point for initial laser beam alignment. Distributed photodiodes detect laser luminescence at respective position, and the optical axis of laser beam is analytically presumed based on the Gaussian beam optics. Computer simulation evaluates the accuracy of the proposed estimation methods, and results disclose that the methods help us to guide the laser beam to a distant receiver.

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Adaptive Transceivers for Mobile Free-Space Optical Communications

Cited by 18 publications

References 7 publications

MIMO CDMA-based optical SATCOMs: A new solution

MIMO CDMA-based optical SATCOMs: A new solution

Frequency stabilization of laser diodes in an aggressive thermal environment

Initial alignment method for free space optics laser beam

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