End-to-End Network SLA Quality Assurance for C-RAN: A Closed-Loop Management Method Based on Digital Twin Network

To enable intelligent and low-cost End-to-End (E2E) network service deployment and Service Level Agreement (SLA) quality management in the two-level Cloud Radio Access Network (C-RAN), this paper studies a DTN-based SLA quality closed-loop management scheme, which mainly includes acquisition module, base module, deployment module, and monitoring module. The deployment module is responsible for constructing the service deployment optimization model with the goal of minimizing the average E2E delay of packets, and quickly obtain deployment decisions through a Weighted GraphSAGE (WGraphSAGE)-assisted Double Deep Q-network (DDQN)-based two-stage service deployment (WDTSD) algorithm. The monitoring module uses the state monitoring model based on Bayesian Convolutional Neural Network (BCNN) to complete the abnormal detection of physical devices. The modular closed-loop interaction provides a virtual environment for network service deployment, verification, monitoring, and policy revision, achieving SLA quality assurance. Extensive results validate the effectiveness of the WDTSD algorithm, state monitoring model, and DTN. WDTSD outperforms existing solutions in terms of memory overhead, computing speed, E2E delay, and service access ratio. The state monitoring model has better performance in indicators such as accuracy. The results under different data acquisition periods show that the service deployment effect is better when the DTN is closer to the physical network.

I. Introduction

To meet the requirements of agility, flexibility, and scalability of the network for diversified services, the transformation of the network to virtualization and cloudification is an inevitable trend. The Cloud Radio Access Network (C-RAN) replaces the Distributed RAN, and has been widely favored by global operators. C-RAN gathers the Baseband Unit (BBU) in the base station together to form a BBU pool, and pulls the Remote Radio Unit (RRU) far away to make it close to the base station antenna. The BBU pool and distributed RRUs communicate through the Fronthaul (FH). The application of Network Function Virtualization (NFV) technology further splits the BBU into Centralized Unit (CU) and Distributed Unit (DU), and transforms the End-to-End (E2E) network service deployment problem into the Service Function Chain (SFC) orchestration problem, which consists of Virtual Network Functions (VNFs) and Virtual Links (VLs). Complete the flexible placement, monitoring, and adjustment of VNFs and VLs in the physical network, and realize on-demand service customization with Service Level Agreement (SLA) guarantee, all of which put forward higher requirements for the network closed-loop management and intelligent Operation and Maintenance (O&M) capabilities.