Impact of Receiver FOV and Orientation on Dense Optical Networks

Abdalla, Iman; Rahaim, Michael; Little, Thomas D. C.

doi:10.1109/glocom.2018.8647842

Cited by 11 publications

(11 citation statements)

References 9 publications

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“…In addition, three baseline schemes, SD-OFDM, DCO-OFDM with index modulation (DCO-OFDM-IM) and HD-OFDM, are also simulated for comparisons. In this work, an avalanche photodiode (ThorLabs unit (#APD120A2)) positioned on a servo is assumed, and with the help of the lens mounted on the receiver surface, the value of 1/2 can be adjusted from 20 • to 90 • [33]. To ensure that the PD can receive signals from multiple LEDs, 1/2 = 80 • is set in this work.…”

Section: Numerical and Simulation Resultsmentioning

confidence: 99%

A Dimmable OFDM Scheme With Dynamic Subcarrier Activation for VLC

et al. 2020

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Dimmable optical orthogonal frequency division multiplexing (D-OFDM) is challenging to design for visible light communications, due to the high peak-to-average power ratio (PAPR) of OFDM signals and limited dynamic range of LEDs. Current D-OFDM schemes focused on the time domain and spatial domain designs of OFDM signals. This paper proposes a novel dynamic subcarrier activation based OFDM (DSA-OFDM) scheme. In DSA-OFDM, the number of activated subcarriers, as well as the signal's DC bias and the number of activated LEDs, is adjusted to provide both flexible dimming control and reliable communication. A generalized index modulation in both spatial domain and frequency domain is designed to select the activated subcarriers and activated LEDs. To show the influence of frequency domain design analytically, the closed-form expressions of the PAPR and the clipping noise of the DSA-OFDM signals are derived, and the optimized signal form is obtained accordingly. Simulation and numerical results show that the proposed scheme can outperform conventional dimming control schemes at various illumination levels in terms of the bit-error rate performance.

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Section: Numerical and Simulation Resultsmentioning

confidence: 99%

A Dimmable OFDM Scheme With Dynamic Subcarrier Activation for VLC

et al. 2020

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“…Based on the real measurements in [24], we set the system parameters to the values summarized in Table 1. The handover execution time is set to 800 ms, within which the throughput is zero.…”

Section: Case Studymentioning

confidence: 99%

Optimizing Handover Parameters by Q-Learning for Heterogeneous Radio-Optical Networks

et al. 2020

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Existing literature studying the access point (AP)-user association problem of heterogeneous radio-optical networks either investigates quasi-static network selection or only considers vertical handover (VHO) dwell time from optical to radio. The quasi-static assumption can result in outdated decisions for highly mobile scenarios. Solely focusing on the optical to radio handover ignores the importance of dwell time for VHO from radio to optical. In this paper, we propose a flexible and holistic framework, that runs a self-optimizing algorithm at the centralized coordinator (CC). This CC resides in the LTE eNodeB and controls the handover parameters of all the visible light communication (VLC) APs under the coverage of the LTE eNodeB. Based on Q-learning approach, the algorithm optimizes the time-to-trigger (T T T) values for VHO between LTE and VLC. Case studies are performed to validate the considerable gain in terms of average throughput by optimizing T T T s. We evaluate the impact of learning parameters on the optimal throughput and convergence speed through trace-driven simulations. The simulation results reveal that the Q-learning based algorithm improves the average throughput of mobile device by 25% when compared to the fixed T T T scheme. Furthermore, this algorithm is capable of self-optimizing handover parameters in an online manner.

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“…Figure 2 illustrates this property through various receivers pointed in different directions, rotations and FOVs with respect to a transmitter. This directionality implies that the relative orientation of the transmitter and receiver has a significant effect on the communication quality [9]. Sub-gigahertz (sub-GHz) RF is modelled as omnidirectional.…”

Section: (A) Characteristics Of Optical Mediamentioning

confidence: 99%

“…Each of the works indicate that improvements in SINR can be achieved at a receiver by employing more PDs. However, they do not account for the variations in receiver orientation, which is critical to link performance [9,71,72].…”

Section: (Iii) Angle Diversity Receiversmentioning

confidence: 99%

Interference in multi-user optical wireless communications systems

Abdalla

Rahaim

Little

2020

Phil. Trans. R. Soc. A.

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Visible light communications (VLC) (including LiFi) represent a subset of the broader field of optical wireless communications. Where narrow beams, typical of free space optical communications are largely free from interference. VLC encompasses use cases involving combined illumination and data access and supporting a wireless access point (AP) model. The use of many units provides scaling of spatial coverage for both lighting and data access. However, AP replication in close proximity creates many interference challenges that motivate the investigation embodied in this paper. In particular, we frame the interference challenge in the context of existing strategies for driving improvements in link performance and consider the impacts of multiple users, multiple sources and multiple cells. Lastly, we review the state of existing research in this area and recommend areas for further study. This article is part of the theme issue ‘Optical wireless communication’.

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Impact of Receiver FOV and Orientation on Dense Optical Networks

Cited by 11 publications

References 9 publications

A Dimmable OFDM Scheme With Dynamic Subcarrier Activation for VLC

A Dimmable OFDM Scheme With Dynamic Subcarrier Activation for VLC

Optimizing Handover Parameters by Q-Learning for Heterogeneous Radio-Optical Networks

Interference in multi-user optical wireless communications systems

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