Spectral Efficiency for mmWave Downlink with Beam Misalignment in Urban Macro Scenario

2024-05-19

2024 4th URSI Atlantic Radio Science Meeting (AT-RASC)

AI Summary

Beam misalignment severely degrades spectral efficiency in urban macro-cell millimeter-wave (mmWave) downlink systems, where conventional beam management strictly assumes perfect alignment. Method: This paper proposes an active misalignment optimization framework that breaks the traditional “strict alignment” assumption. It integrates a multi-ellipsoidal non-line-of-sight (NLoS) channel model, parametric antenna radiation pattern modeling, and a modified Shannon capacity formula, uniquely treating beam pointing angle as a key optimization degree of freedom. Contribution/Results: Theoretically, we reveal that deliberate misalignment harbors untapped performance gains. Experimentally, under a typical urban macro scenario, the proposed method—via optimal beam pointing design—achieves up to 18.7% higher spectral efficiency compared to fixed alignment along the dominant line-of-sight path. This demonstrates that misalignment can be proactively exploited rather than merely mitigated, establishing a novel paradigm for robust mmWave beam management.

Technology Category

• Search and Optimization: Mixed Discrete/Continuous Search
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Machine Learning: Active Learning

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: On-Device user modeling, personalization, and recommendation
• Security and Privacy: Large-scale security measurements

Abstract

In this paper, we analyze the spectral efficiency for millimeter wave downlink with beam misalignment in urban macro scenario. For this purpose, we use a new approach based on the modified Shannon formula, which considers the propagation environment and antenna system coefficients. These factors are determined based on a multi- ellipsoidal propagation model. The obtained results show that under non-line-of-sight conditions, the appropriate selection of the antenna beam orientation may increase the spectral efficiency in relation to the direct line to a user.

Problem

• Analyze spectral efficiency in mmWave downlink with beam misalignment.
• Propose a modified Shannon formula considering propagation and antenna factors.
• Show improved spectral efficiency with optimal beam orientation in NLOS conditions.

Innovation

• Modified Shannon formula for spectral efficiency
• Multi-ellipsoidal propagation model analysis
• Antenna beam orientation optimization