Highly dynamic and mobile applications, such as vehicular networks, require stable connectivity, which is often challenging to achieve. Network densification is a key approach to address this issue and can be achieved cost-effectively through mobile base stations and wireless relaying. However, existing solutions rely on rigid and complex architectures that hinder deployment in dynamic scenarios. The recently standardized Wireless Access Backhaul (WAB) architecture represents a key evolution, enabling flexible and modular wireless relay networks with native support for mobility and multi-technology wireless backhaul. This paper presents the first experimental realization of a multi-band WAB testbed, combining an FR2 backhaul and an FR1 access link using open-source software and commercial off-the-shelf components. The proposed framework validates end-to-end WAB operation under mobility and demonstrates the extension of FR2 coverage while maintaining compatibility with legacy FR1 user equipment. Experimental campaigns in vehicular and outdoor-to-indoor scenarios confirm that WAB effectively mitigates FR2 limitations, particularly in uplink and Non-Line-of-Sight conditions. These results highlight WAB as a practical and scalable approach for vehicular and next-generation wireless networks.

翻译：高度动态和移动化的应用（如车载网络）需要稳定的连接，而这往往难以实现。网络密集化是解决该问题的关键方法，可通过移动基站和无线中继以经济高效的方式达成。然而，现有方案依赖僵化复杂的架构，阻碍了其在动态场景中的部署。近期标准化的无线接入回传（WAB）架构代表了一项关键演进，支持灵活模块化的无线中继网络，具备对移动性和多技术无线回传的原生支持。本文首次实现了多频段WAB实验平台，利用开源软件和商用现成组件结合FR2回传链路与FR1接入链路。所提框架验证了WAB在移动性下的端到端运行，并展示了在保持与遗留FR1用户设备兼容的同时扩展FR2覆盖范围的能力。在车载和室外至室内场景中的实验证实，WAB有效缓解了FR2的局限性，特别是在上行链路和非视距条件下。这些结果凸显了WAB作为车载及下一代无线网络的一种实用且可扩展方案的潜力。