Power reduction techniques for multiple-subcarrier modulated diffuse wireless optical channels

Kang, Weiwei; Hranilovic, Steve

doi:10.1109/tcomm.2008.060609

Cited by 28 publications

(9 citation statements)

References 22 publications

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“…The authors of [12] addressed the same issue by employing in-band coding to use with symbol-by-symbol bias. A novel approach of using out-of-band subcarriers to reduce transmit power was proposed in [13]. The use of the selected mapping technique was investigated in [14] to achieve reduction in average transmit optical power.…”

Section: Average Transmit Power Issue In Multi-carrier Optical Wirelementioning

confidence: 99%

Transmit power reduction through subcarrier selection for MC-CDMA-based indoor optical wireless communications with IM/DD

Farooqui

Saengudomlert

2013

J Wireless Com Network

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This research addresses the issue of average transmit optical power reduction in multi-carrier code division multiple access (MC-CDMA)-based indoor optical wireless communications employing intensity modulation with direct detection. The problem is treated in a novel way by investigating pre-and post-equalization-based subcarrier selection for transmit power reduction in downlink transmissions. Analytical expressions are derived for upper bounds of the required fixed DC bias for both cases. The fixed DC bias is used to reduce the system complexity on one hand and to devise optimal subcarrier selection criteria on the other. Simulation results based on the proposed subcarrier selection reveal significant power reduction subject to the 10 −4 bit error rate (BER) requirement for 10-Mbps 64-subcarrier MC-CDMA-based indoor optical wireless communication systems. In addition, the BER performance obtained from pre-equalization is shown to be no higher than that obtained from post-equalization for the same transmit power.light. The key advantages of such optical wireless systems are usage of flexible unlicensed spectrum, high data rate support, energy efficiency, no electromagnetic interference, low-cost front ends, and inherent security. Major issues are eye and skin safety problems which can be dealt with by limiting the average transmit optical power.The contributions of this research, which are not reported previously to the best of the authors' knowledge, are highlighted as follows:1. Average transmit optical power reduction is accomplished by subcarrier selection for the first time in MC-CDMA-based indoor optical wireless communication systems employing intensity modulation with direct detection (IM/DD). Expressions for upper bounds of a fixed DC biasusing pre-and post-equalization-based subcarrier selection are analytically derived for MC-CDMA-based IM/DD system. 3. Optimal subcarrier selection algorithms that minimizes the bit error rate (BER) for a fixed transmit optical power are proposed for both pre-and post-equalization.

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Section: Average Transmit Power Issue In Multi-carrier Optical Wirelementioning

confidence: 99%

Transmit power reduction through subcarrier selection for MC-CDMA-based indoor optical wireless communications with IM/DD

Farooqui

Saengudomlert

2013

J Wireless Com Network

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“…A number of techniques to mitigate the high PAPR requirement in O-OFDM have been reported in the literature including amplitude clipping [8], trellis coding, which reduces the average optical power [9], and block coding, which maps the vector of k-information bits to be transmitted and the vector of symbol amplitudes modulated onto the N-subcarrier [10] at the cost of increased transmission bandwidth. Signal transformation based on selected mapping (SLM) has also been used to reduce the signal peak values in O-OFDM systems [11].…”

Section: Introductionmentioning

confidence: 99%

The Novel PAPR Reduction Schemes for O‐OFDM‐Based Visible Light Communications

Zhang¹,

Yao²,

Guo³

2017

Visible Light Communications

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In this chapter, we propose two novel peak-to-average power ratio (PAPR) reduction schemes for the asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) scheme used in the visible light communications (VLC) system. In the first scheme, we implement the Toeplitz matrix based Gaussian blur method to reduce the high PAPR of ACO-OFDM at the transmitter and use the orthogonal matching pursuit algorithm to recover the original ACO-OFDM frame at the receiver. Simulation results show that for the 256-subcarrier ACO-OFDM system a~6 dB improvement in PAPR is achieved compared with the original ACO-OFDM in terms of the complementary cumulative distribution function (CCDF), while maintaining a competitive bit-error rate performance compared with the ideal ACO-OFDM lower bound. In the second scheme, we propose an improved hybrid optical orthogonal frequency division multiplexing (O-OFDM) and pulse-width modulation (PWM) scheme to reduce the PAPR for ACO-OFDM. The bipolar O-OFDM signal without negative clipping is converted into a PWM format where the leading and trailing edges carry the frame synchronization and modulated information, respectively. The simulation and experimental results demonstrate that the proposed OFDM-PWM scheme offers a significant PAPR reduction compared to the ACO-OFDM with an improved bit error rate.

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“…An OWC system relies on optical radiations to convey information in free space, with wavelengths ranging from InfraRed (IR) to UltraViolet (UV), including the visible light spectrum. In the latter spectrum range, the concept of Visible Light Communications (VLC) relies on the assumption that in the near future all lighting systems may be expected to Mauro Biagi and be based on Light Emitting Diodes (LEDs), due to their energy efficiency and reliability [3]. Nowadays, these light sources can be modulated, and in the future, they are expected to be modulated at a higher rate than now.…”

Section: Introductionmentioning

confidence: 99%

LAST: A Framework to Localize, Access, Schedule, and Transmit in Indoor VLC Systems

Biagi

Pergoloni

Vegni

2015

J. Lightwave Technol.

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The need allowing indoor access to the Internet services requires to reduce the electromagnetic pollution. Recently, the scientific community is looking for alternatives to the use of radio frequency communication, leading to propose and study the new paradigm of Visible Light Communications. In order to present a system implementing transmission and access procedures, we propose a logical stream starting from user localization, so as to decide which LEDs can provide access, thus basically performing a space division multiple access by scheduling data on the basis of the bits to be transmitted. For this aim, a 2-bands access scheme is proposed and implemented through the use of a separated channel where signaling specifies where, in the wavelength domain, the reception must be operated by the different users. A Multiple Input Multiple Output scheme is considered for data transmission, in order to increase rate with a reliable error rate performance. Performance is evaluated for what concerns localization and access tasks, so as to show the effectiveness of the proposed scheme. Performance comparison with recent literature has been also reported.

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Power reduction techniques for multiple-subcarrier modulated diffuse wireless optical channels

Cited by 28 publications

References 22 publications

Transmit power reduction through subcarrier selection for MC-CDMA-based indoor optical wireless communications with IM/DD

Transmit power reduction through subcarrier selection for MC-CDMA-based indoor optical wireless communications with IM/DD

The Novel PAPR Reduction Schemes for O‐OFDM‐Based Visible Light Communications

LAST: A Framework to Localize, Access, Schedule, and Transmit in Indoor VLC Systems

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