Progressive Integrated Access and Backhaul Network Augmentation

Integrated access and backhaul (IAB) has been envisioned as a fast and flexible solution for deploying 5G and beyond networks. However, the growth and spatial imbalance of user demand could cause bottlenecks in wireless backhauls, particularly at nodes near the gateway. In this letter, we propose a progressive network augmentation strategy to address these bottlenecks by interconnecting backhaul nodes with fiber, allowing them to leverage their neighbors for traffic offloading. The objective is to ensure that each IAB node’s outbound rate exceeds its inbound rate to prevent congestion at the minimum fiber deployment cost. To achieve this, we introduce a two-step optimization algorithm that first optimizes backhaul routing topology and then strategically deploys fiber to eliminate congestion. Simulation results demonstrate that the proposed solution significantly outperforms two baseline methods.