Optimum resource allocation in optical wireless systems with energy-efficient fog and cloud architectures

Abstract

<jats:p>Optical wireless communication (OWC) is a promising technology that can provide high data rates while supporting multiple users. The optical wireless (OW) physical layer has been researched extensively, however, less work was devoted to multiple access and how the OW front end is connected to the network. In this paper, an OWC system which employs a wavelength division multiple access (WDMA) scheme is studied, for the purpose of supporting multiple users. In addition, a cloud/fog architecture is proposed for the first time for OWC to provide processing capabilities. The cloud/fog-integrated architecture uses visible indoor light to create high data rate connections with potential mobile nodes. These OW nodes are further clustered and used as fog mini servers to provide processing services through the OW channel for other users. Additional fog-processing units are located in the room, the building, the campus and at the metro level. Further processing capabilities are provided by remote cloud sites. Two mixed-integer linear programming (MILP) models were proposed to numerically study networking and processing in OW systems. The first MILP model was developed and used to optimize resource allocation in the indoor OWC systems, in particular, the allocation of access points (APs) and wavelengths to users, while the second MILP model was developed to optimize the placement of processing tasks in the different fog and cloud nodes available. The optimization of tasks placement in the cloud/fog-integrated architecture was analysed using the MILP models. Multiple scenarios were considered where the mobile node locations were varied in the room and the amount of processing and data rate requested by each OW node was varied. The results help to identify the optimum colour and AP to use for communication for a given mobile node location and OWC system configuration, the optimum location to place processing and the impact of the network architecture.</jats:p> <jats:p>This article is part of the theme issue ‘Optical wireless communication’.</jats:p>

Optimum Resource Allocation in 6G Optical Wireless Communication Systems

“…Each of the four branches of the ADR has a narrow field of view (FOV) to reduce interference from other users and inter-symbol interference (ISI). The design of the ADR is similar to [9], [22], [38]. Each branch of the ADR covers different areas in the indoor environment by orienting the branch to that area based on Azimuth and Elevation angles.…”

“…Wavelength division multiple access (WDMA) has been a subject of interest in many studies in OWC systems to support multiple users by sharing wavelengths among users [6], [38] - [41]. A multiplexer is used at the transmitter to aggregate wavelengths into a single optical beam.…”

“…This section presents a MILP model developed to optimize resource allocation based on maximizing the sum of SINRs for all possible users [38]. This MILP model is used to assign users or devices to access points (APs) and wavelengths while maximizing the sum of SINRs over all users.…”

“…12,4 The first part of Equation (6) consists of interference and background noise which is a nonlinear part composed of the multiplication of a continuous variable and a binary variable. To linearize this part, the same equations as [38], [43] were utilized which introduces a linearization variable that is non-negative; 12,1@,4,A 56,96,7 = 12,4…”

“…However, users assigned to the Yellow wavelength have a lower SINR compared to those assigned to Red wavelength. The reason for that is that the Yellow wavelength has a lower transmitted power (needed to ensure the version of white colour desired [38]) and receiver responsivity compared to the Red wavelength. In terms of data rate, all users can support a data rate above 7 Gbps.…”