Neutral-Hosts In The Shared Mid-Bands: Addressing Indoor Cellular Performance

2025-05-23

AI Summary

To address poor indoor coverage, low throughput, and multi-mobile-network-operator (MNO) coexistence challenges in mid-band 5G (3.55–3.7 GHz) caused by high building penetration loss (>22 dB), this paper designs and experimentally validates the first neutral-host indoor 5G private network leveraging the Citizens Broadband Radio Service (CBRS) shared spectrum. We innovatively demonstrate the feasibility and robustness of multi-MNO spectrum reuse under the CBRS framework, uncover the natural isolation between outdoor radar systems and indoor users induced by penetration loss, and propose a low-power, high-efficiency indoor spectrum reuse paradigm. Experimental results show that, relative to the worst-performing MNO, median indoor downlink and uplink throughput improve by 535× and 33×, respectively; terminal uplink transmit power decreases by 12 dB; and an average of 233 PRBs per slot are freed, significantly alleviating network congestion.

Technology Category

• Application Domains: Mobility, Driving & Flight
• Planning, Routing, and Scheduling: Applications
• Search and Optimization: Non-convex Optimization

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• User Modeling, Personalization and Recommendation: User privacy protection in personalized systems
• Security and Privacy: Large-scale security measurements

Abstract

The 3.55 - 3.7 GHz Citizens Broadband Radio Service (CBRS) band in the U.S., shared with incumbent Navy radars, is witnessing increasing deployments both indoors and outdoors using a shared, licensed model. Among the many use-cases of such private networks is the indoor neutral-host, where cellular customers of Mobile Network Operators (MNOs) can be seamlessly served indoors over CBRS with improved performance, since building loss reduces the indoor signal strength of mid-band 5G cellular signals considerably. In this paper, we present the first detailed measurements and analyses of a real-world deployment of an indoor private network serving as a neutral-host in the CBRS band serving two MNOs. Our findings demonstrate significant advantages: (i) minimal outdoor interference from the CBRS network due to over 22 dB median penetration loss, ensuring compatibility with incumbent users; (ii) substantial indoor performance gains with up to 535$ imes$ and 33$ imes$ median downlink and uplink throughput improvements, respectively, compared to the worst-performing MNO; (iii) reduced uplink transmit power for user devices (median 12 dB reduction), increasing energy efficiency; and (iv) significant capacity offload from the MNO network (median 233 resource blocks/slot freed in 5G), allowing MNOs to better serve outdoor users. These results highlight the potential of low-power indoor CBRS deployments to improve performance, increase spectrum efficiency, and support coexistence with current and future incumbents, e.g., the 3.1 - 3.45 GHz band being considered for sharing with federal incumbents in the U.S.

Problem

• Improving indoor cellular performance using CBRS band
• Ensuring compatibility with incumbent Navy radars
• Offloading MNO capacity to enhance outdoor service

Innovation

• Indoor neutral-host CBRS network deployment
• Minimal outdoor interference with 22dB loss
• 535x downlink and 33x uplink throughput gains