Robust Radio Resource Allocation in MISO-SCMA Assisted C-RAN in 5G Networks

Abstract

In this paper, by considering multiple slices, a downlink transmission of a sparse code multiple access (SCMA) based cloud-radio access network (C-RAN) is investigated. In this regard, by supposing multiple input and single output (MISO) transmission technology, a novel robust radio resource allocation is proposed where considering uncertain channel state information (CSI), the worst case approach is applied. The main goal of the proposed radio resource allocation is to, maximize the system sum rate with maximum available power at radio remote head (RRH), minimum rate requirement of each slice, maximum frounthaul capacity of each RRH, user association, and SCMA constraints. To solve the proposed optimization problem in an efficient manner, an iterative method is deployed where in each iteration, beamforming and joint codebook allocation and user association subproblem are solved separately. By introducing some auxiliary variables, the joint codebook allocation and user association subproblem is transformed into an integer linear programming, and to solve the beamforming optimization problem, minorization-maximization algorithm (MMA) is applied. Via numerical results, the performance of the proposed system model versus different system parameters and for different channel models are investigated. Index Terms-5G, Sparse code multiple access (SCMA), C-RAN, robust resource allocation.

A Survey on Non-Orthogonal Multiple Access: From the Perspective of Spectral Efficiency and Energy Efficiency

“…Besides the codebook and detector designs, the SE of SCMA-based systems can be improved using resource sharing and UE association in dense-device networks [89,90]. First, the SCMA was employed to enhance the SE in device-to-device (D2D) communication systems, where D2D pairs are allowed to share the same codebook with cellular UEs, and thus the resource allocation and interference management are considered [91][92][93][94]. Kim et al,in [91], proposed a two-stage method based on the combination of graph theory and inner approximation.…”

Throughput Analysis of Multipair Two-Way Replaying Networks With NOMA and Imperfect CSI

“…Furthermore, NOMA provides improved scheme to reduce outage probability [5], [6]. Different from other kinds of multiple access techniques, NOMA users with weaker channel conditions need more allocated power and hence NOMA maintains the user fairness [7]- [9]. Furthermore, due to the ability to provide spatial diversity gain, cooperative commu-nication has been introduced to improve system performance metrics [10], such as coverage and the communication reliability [11].…”

Resource allocation in sparse code multiple access‐based systems for cloud‐radio access network in 5G networks

“…Authors in Reference 11 for an SCMA‐based Heterogeneous cellular Network (HetNet) suggested a joint power and codebook allocation procedure to maximize the total sum rate where the PD‐NOMA is different from the SCMA in the total sum rate and receiver complexity. In Reference 19, the authors for Multiple Input Single Output (MISO)‐based systems investigated user association, codebook assignment, and beamforming in C‐RAN by considering QoS for each slice with four suboptimal levels to solve the optimization problem, which includes the epigraph transform, the iterative algorithm, the approximation of the beamforming subproblem to a convex problem by the Minorization‐Maximization Algorithm, then by solving subproblems with Interior Point Method (IPM). In Reference 20, the authors investigated C‐RAN system with traditional MA methods to optimizing the Quality‐of‐Experience (QoE) of wireless devices by the deployment of cache‐enabled unmanned aerial vehicles (UAVs) when minimizing the transmit power used by the UAVs and to solve the optimization problem conceptor‐based echo state networks has used.…”

“…Due to the above papers, none of the research done so far includes SCMA in C‐RAN based on Single‐Input Single‐Output (SISO) system. Also according to Reference 19, our proposed system model utilized SCMA in C‐RAN based on the SISO system with joint user association, codebook assignment, and power allocation. Compared to Reference 19, in the proposed system model Signal to Interference plus Noise Ratio (SINR) formulation is done using SCMA concepts 11,17,35,36 and the proposed optimization problem is formulated by considering the QoS and power constraints for each user.…”

“…Also according to Reference 19, our proposed system model utilized SCMA in C‐RAN based on the SISO system with joint user association, codebook assignment, and power allocation. Compared to Reference 19, in the proposed system model Signal to Interference plus Noise Ratio (SINR) formulation is done using SCMA concepts 11,17,35,36 and the proposed optimization problem is formulated by considering the QoS and power constraints for each user. As mentioned in Reference 19, due to the four suboptimal levels for solving the optimization problem, the paper has more complexity as well as a more far‐optimal solution than the used method in the proposed algorithm for this paper.…”