# Resource Allocation for Reconfigurable Intelligent Surface Assisted Dual Connectivity
###### Abstract  
The next generation 6G wireless systems are envisioned to have higher reliability and capacity than the existing cellular systems. The reconfigurable intelligent surfaces (RISs)-assisted wireless networks are one of the promising solutions to control the wireless channel by altering the electromagnetic properties of the signal. The dual connectivity (DC) increases the per-user throughput by utilizing radio resources from two different base stations. In this work, we propose the RIS-assisted DC system to improve the per-user throughput of the users by utilizing resources from two base stations (BSs) in proximity via different RISs. Given an \(\alpha\)-fair utility function, the joint resource allocation and the user scheduling of a RIS-assisted DC system is formulated as an optimization problem and the optimal user scheduling time fraction is derived. A heuristic is proposed to solve the formulated optimization problem with the derived optimal user scheduling time fractions. Exhaustive simulation results for coverage and throughput of the RIS-assisted DC system are presented with varying user, BS, blockage, and RIS densities for different fairness values. Further, we show that the proposed RIS-assisted DC system provides significant throughput gain of 52% and 48% in certain scenarios when compared to the existing benchmark and DC systems. b 2022 29 July 20211 August 202  
systems. A comprehensive analysis of main operating principles of RISs and the current research challenges of these RISs has been discussed in detail in [3]. The far-field path loss model using optical techniques has been derived by authors in [4]. Further, they also explained how the small elements of the surface can be advantageous when jointly beamforming the signal in the desired direction. Two types of implementation of RIS based on reflect arrays or metasurfaces, and their prospective channel modeling and path loss models, have been discussed in [5]. The joint optimization of coordinated transmit beamforming at BS and the reflective beamforming vector at the RIS by maximizing signal-to-interference- plus-noise ratio (SINR) at the users, subject to transmit power constraints, have been considered in [6]. The RIS with multicell communication, in order to avoid inter cell interference of the cell-edge users, has been proposed in [7]. This inter cell interference has been eliminated by destructively combining the reflected signal from RIS. The multiple RISs aided wireless communication system, where multiple RISs jointly assist the link between BS and cell edge users, has been investigated in [8]. The joint RIS deployment and the design of reflection coefficients have been jointly considered in [9]. Some of the multiple access schemes, such as non orthogonal multiple access (NOMA), frequency division multiple access, and time division multiple access (TDMA) have also been considered during joint optimization in [9]. The joint optimization problem of channel, resource allocation, power allocation, and the reflection coefficients for a downlink (DL) RIS based NOMA has been investigated by authors in [10]. The RIS-aided coordinated multipoint (CoMP) with joint processing has been proposed and discussed in [11] where the deployed RIS serves the cell-edge users by utilizing the signal from multiple BSs in proximity. The resource allocation for RIS aided vehicular communications based on slowly varying large-scale fading channel has been studied in [12]. The optimization of rate, energy efficiency, and their trade-off in a RIS based system along with overhead estimation has been presented in [13]. The optimization of RIS passive beamforming and orthogonal frequency division multiple access (OFDMA) in a RIS based system has been proposed in [14]. A novel approach to enhance the achievable rate of a ODPM system using RIS has been presented in [15]. The detailed investigation of RIS-associated NOMA and orthogonal multiple access (OMA) schemes have been studied in [16].