Traffic-Aware Cost-Optimized Fronthaul Planning for Ultra-Dense Networks

TL;DR

Traffic-Aware Cost-Optimized Fronthaul Planning for Ultra-Dense Networks addresses the fronthaul bottleneck in cell-free MIMO deployments by introducing a traffic-aware hybrid design that jointly selects fiber or mmWave links. The approach is formulated as a MILP that minimizes the total cost of ownership while enforcing per-AP capacity thresholds and per-DU backhaul constraints, using a mmWave channel model grounded in 3GPP specifications and a detailed fiber cost model. Key contributions include a Gaussian hotspot traffic model to set AP thresholds, a two-technology cost framework, and QoS-constrained selection rules that outperform single-technology and heuristic baselines. Numerical results demonstrate that a carefully planned mix of fiber and mmWave yields lower TCO and higher surplus capacity, enabling scalable, future-proof fronthaul planning for ultra-dense networks.

Abstract

The cost and limited capacity of fronthaul links pose significant challenges for the deployment of ultra-dense networks (UDNs), specifically for cell-free massive MIMO systems. Hence, cost-effective planning of reliable fronthaul networks is crucial for the future deployment of UDNs. We propose an optimization framework for traffic-aware hybrid fronthaul network planning, aimed at minimizing total costs through a mixed-integer linear program (MILP) that considers fiber optics and mmWave, along with optimizing key performance metrics. The results demonstrate superiority of the proposed approach, highlighting the cost-effectiveness and performance advantages when compared to different deployment schemes. Moreover, our results also reveal different trends that are critical for Service Providers (SPs) during the fronthaul planning phase of future-proof networks that can adapt to evolving traffic demands.

Figures (5)

• Figure 1: Sample network realization with optimized DUs placement and APs traffic thresholds assignment.
• Figure 2: Network samples with optimized mixed-technologies selection for different traffic distributions and numbers of DUs.
• Figure 3: Comparison of fronthaul technologies and network TCO for different numbers of deployed DUs.
• Figure 4: Average TCO per AP vs. fronthaul sum traffic thresholds across different numbers of deployed DUs ($W$) and benchmarks.
• Figure 5: Network surplus capacity vs. fronthaul sum traffic across different number of deployed DUs ($W$) and benchmarks.