Two-dimensional binary halftoned optical intensity channels

Mohamed, Mohamed D. A.; Hranilovic, Steve

doi:10.1049/iet-com:20060385

Cited by 14 publications

(16 citation statements)

References 30 publications

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“…MIMO links have been used in a variety of applications including 2D barcodes [78,79], page-oriented recording [80,81], holographic storage [71,72,82,83], and MIMO OW communications [27,66,84,85]. With respect to the 2D barcodes, OW MIMO links are currently used on a wide array of cellular telephones in the form of barcode readers.…”

Section: Point-to-point Linksmentioning

confidence: 99%

A review of communication-oriented optical wireless systems

Borah

Boucouvalas

Davis

et al. 2012

J Wireless Com Network

187

104

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This article presents an overview of optical wireless (OW) communication systems that operate both in the short-(personal and indoor systems) and the long-range (outdoor and hybrid) regimes. Each of these areas is discussed in terms of (a) key requirements, (b) their application framework, (c) major impairments and applicable mitigation techniques, and (d) current and/or future trends. Personal communication systems are discussed within the context of point-to-point ultra-high speed data transfer. The most relevant application framework and related standards are presented, including the next generation Giga-IR standard that extends personal communication speeds to over 1 Gb/s. As far as indoor systems are concerned, emphasis is given on modeling the dispersive nature of indoor OW channels, on the limitations that dispersion imposes on user mobility and dispersion mitigation techniques. Visible light communication systems, which provide both illumination and communication over visible or hybrid visible/ infrared LEDs, are presented as the most important representative of future indoor OW systems. The discussion on outdoor systems focuses on the impact of atmospheric effects on the optical channel and associated mitigation techniques that extend the realizable link lengths and transfer rates. Currently, outdoor OW is commercially available at 10 Gb/s Ethernet speeds for Metro networks and Local-Area-Network interconnections and speeds are expected to increase as faster and more reliable optical components become available. This article concludes with hybrid optical wireless/radio-frequency (OW/RF) systems that employ an additional RF link to improve the overall system reliability. Emphasis is given on cooperation techniques between the reliable RF subsystem and the broadband OW system.

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Section: Point-to-point Linksmentioning

confidence: 99%

A review of communication-oriented optical wireless systems

Borah

Boucouvalas

Davis

et al. 2012

J Wireless Com Network

187

104

View full text Add to dashboard Cite

show abstract

“…The noise power shaping function, |1 − J(k 1 , k 2 )| 2 , is designed to shape the quantizer error power to the out-of-band region [9]. In order for this model to be consistent and for the modulator to remain stable, the average electrical power of the input SDMT signal, σ 2 x , must be limited as justified in [9].…”

Section: A Digital Image Halftoningmentioning

confidence: 99%

“…Due to the equalization in (3), the image can be considered as an array of independent parallel complex Gaussian channels in frequency domain. Notice, however, that half the complex channels are dependent on the other half due to conjugate symmetry [9]. Therefore the capacity, C, is maximized by using the water pouring algorithm to define the electrical power, Φ x (k 1 , k 2 ), allocated to bin (k 1 , k 2 ) such that the total input electrical power constraint is met [9].…”

Section: B Halftoned Spatial Discrete Multitone Modulationmentioning

confidence: 99%

“…Notice, however, that half the complex channels are dependent on the other half due to conjugate symmetry [9]. Therefore the capacity, C, is maximized by using the water pouring algorithm to define the electrical power, Φ x (k 1 , k 2 ), allocated to bin (k 1 , k 2 ) such that the total input electrical power constraint is met [9]. The non-negativity constraint is no longer an issue during the water pouring power allocation, as was the case in [8], since the output image is a binary one.…”

Section: B Halftoned Spatial Discrete Multitone Modulationmentioning

confidence: 99%

“…The size of the imager receiver was assumed constant in [9], and hence increasing the number of receiving pixels was achieved by decreasing the pixel size. Moreover, the effect of the frame rate on channel capacity was not studied.…”

Section: Introductionmentioning

confidence: 99%

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MIMO Optical Wireless Channels Using Halftoning

Mohamed

Dabbo

Hranilovic

2008

2008 IEEE International Conference on Communications

Self Cite

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Abstract-Two-dimensional (2D) optical intensity channels exist in a variety of applications including holographic storage, page-oriented memories, optical interconnects, 2D barcodes, as well as MIMO wireless optical links. This paper considers the capacity of such channels when the transmitted signal is binarylevel. Strict spatial alignment between transmitter and receiver is not required nor is independence among the spatial channels. Spatial discrete multitone modulation is combined with digital image halftoning to produce a binary-level transmit image. Unlike earlier work, this paper considers imagers with pixels of fixed size and quantifies the tradeoff between frame rate, array size and capacity per frame. An experimental prototype pixelated wireless optical channel is constructed, and the channel parameters are measured. With a measured channel model, rates on the order of 450 Mbps are predicted for a 1 m link using 0.5 megapixel arrays at a frame rate of 7 kfps.

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Performance analysis of spatial OFDM for pixelated optical wireless systems

Mondal

Panta

2015

Trans. Emerging Tel. Tech.

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Pixelated optical wireless systems can transmit at high speed by encoding data in transmitted images using spatial orthogonal frequency division multiplexing (spatial OFDM) but are susceptible to a number of limiting factors including defocus, linear fractional misalignment (LFM) and vignetting. This paper investigates the effects of these impairments on the performance of both forms of spatial OFDM: spatial DC-biased optical OFDM (SDCO-OFDM) and spatial asymmetrically clipped optical OFDM (SACO-OFDM). The novelty of this paper is in the theoretical analysis of the effect of defocus on a spatial OFDM based pixelated system. The theoretical results for defocus are found to be in agreement with the simulation results reported in the literature. Furthermore, the joint effects of defocus, LFM and vignetting are mathematically described. Analytical and simulation results show that these three factors are largely independent of each other. Simulation results indicate that these impairments and their associated mitigation techniques influence the optimum choice of DC bias for SDCO-OFDM. Finally, it is shown that for the case of the joint impairments and for a given data rate, the bit error rate performance of SDCO-OFDM with the optimum bias is slightly better than that of SACO-OFDM. ], which is an extension of the concept of conventional OFDM [18][19][20] to the 2-D spatial domain. For spatial OFDM, data are encoded in the spatial-frequency domain, the frequency representation of the 2-D image space, using a number of orthogonal 2-D subcarriers. Each of the encoded spatial frames is converted to a pixelated image before transmission. Spatial OFDM has several advantages for pixelated communication. Compared with systems that encode data directly in the spatial domain, a spatial OFDM scheme is less affected by a number of distortions occurring in the spatial domain [7,8,21,22]. Moreover, the formation of the data-carrying transmitted images can be well-designed. This means that, by using spatial OFDM algorithms at the transmitter side, the images can be generated in a way that makes them much robust to distortions. The receiver can then decode the

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Two-dimensional binary halftoned optical intensity channels

Cited by 14 publications

References 30 publications

A review of communication-oriented optical wireless systems

A review of communication-oriented optical wireless systems

MIMO Optical Wireless Channels Using Halftoning

Performance analysis of spatial OFDM for pixelated optical wireless systems

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