24 research outputs found
Closed-form SER expression for APSK based on the kite structure
Abstract: Please refer to full text to view abstrac
On the indoor VLC link evaluation based on the racian K-factor
Abstract: In visible light communications (VLC) technology, the channel is generally modeled as a multi-path propagation environment. This is due to the presence, on the photo-detector (PD), of specular and non-specular signal components. The Racian K-factor is exploited in such environments to measure the dominance of the line-of-sight (LoS) signal power over that of the non-LoS (NLoS) link. In this paper, K is exploited in the evaluation of the VLC link. Examples of the use of K is underlined in the computation of few link evaluation metrics including the signal-to-noise ratio (SNR), , the channel capacity, C, and the outage probabilit
AF cooperative VLC communication systems : cascaded channel analysis
Abstract: Visible light communications (VLC) technology is a relatively new emerging telecommunication paradigm. It offers the opportunity to design cost-effective communication systems due to the dual use of the light sources, which are exploited as illumination devices and as communication antennas. However, this technology is mostly deployed in short-range communication applications because of the light diffusion range, which is short by nature. One good response to this dilemma is the imple- mentation of relay-assisted cooperative communication systems. Cooperative VLC systems provide three advantages, which are an increase in the transmission range, an improvement of the detection, hence of the bit error rate (BER), and an improved lighting system. In this paper, we analyze the channel response of a single-relay indoor VLC system based on an amplify-and- forward (AF) strategy. The system takes into account the fact that the relay also receives a reflected message. Results show the influence of the room’s reflection index, Lambertian index, the number of scattered rays on the overall channel response and confirms the importance of relay-assisted strategies in improving systems’ reliability
Energy efficient subchannel and power allocation in cooperative VLC systems
This letter studies the energy efficiency (EE) optimization of cooperative visible light communication (VLC) systems while considering the inter-cell interference and the lineof-sight blockage problems. Specifically, the optimization problem of subchannel and power allocation to maximize EE under transmit power budgets and users' minimum rate constraints is considered. The formulated problem turns out to be a difficult nonlinear fractional program for which a low-complexity iterative solution based on fractional programming theory and the quadratic transform approach is proposed. Extensive simulations are conducted to show the efficacy of the proposed scheme over conventional approaches. In addition, the outage analysis and impacts of varying the transmit power and the subchannel bandwidth on the EE performance are investigated.This work was supported by the Natural Science and Engineering Research Council of Canada (NSERC) through its Discovery Program, the Memorial University VPR Program, and the Spanish National Project TERESA-ADA (TEC2017-90093-C3-2-R) (MINECO/AEI/FEDER, UE). The associate editor coordinating the review of this letter and approving it for publication was H. Zhang
Constellation design for cascaded MPSK-CSK systems
Abstract: This paper proposes a constellation design for color shift keying (CSK) based on phase shift keying (PSK) conversion, to be used in cascaded power line communications (PLC) and visible light communications (VLC) systems integration. We optimize the design of MPSK-CSK constellations and analyze the performance of MPSK-CSK systems based on the optimized Euclidean distance calculated on the red-green-blue (RGB) color space
VLC-Based Networking: Feasibility and Challenges
VLC has emerged as a prominent technology to address the radio spectrum shortage. It is characterized by the unlicensed and unexploited high bandwidth, and provides the system with cost-effective advantages because of the dual-use of light bulbs for illumination and communication and the low complexity design. It is considered to be utilized in various telecommunication systems, including 5G, and represents the key technology for light-fidelity. To this end, VLC has to be integrated into the existing telecommunication networks. Therefore, its analysis as a network technology is momentous. In this article, we consider the feasibility of using VLC as a network technology and discuss the challenges related to the implementation of a VLC-based network, as well as the integration of VLC into existing conventional networks and its inclusion in standards