New state-of-the-art handheld antenna models pave the way for 6G

As outlined in our recent blog post, "The 6G Train Has Left the Station," 3GPP has begun the standardization process for 6G technology. A crucial component of 6G Radio (6GR) will be the MIMO (Multiple Input Multiple Output) solution, designed to deliver significant performance gains over today’s 5G networks. This improvement will be achieved through a streamlined and efficient 6G MIMO design, featuring a unified Transmission Control Information (TCI) framework that supports a greater number of MIMO layers and ports.

To define the most effective 6G MIMO solutions, 3GPP will evaluate multiple design options using extensive simulations. But for these simulations to guide sound design decisions, they must be built on accurate models that capture all critical influencing factors. Realistic mobile terminal modeling, particularly for multi-antenna smartphone systems, is therefore essential. This blog focuses on that aspect. 

Why an upgrade was necessary

The old user equipment (UE) antenna model was based on overly idealized assumptions, namely a dual-polarized Uniform Linear Array (ULA) with uniform isotropic radiation patterns and perfect isolation between all elements. This approach, while mathematically convenient, fails to capture the complexities of real-world handheld devices. Specifically, it neglects the following:

• Highly directive antenna radiation patterns: Real-world antennas exhibit maximum gain in different angular directions.
• Non-orthogonal antenna pairs: Single-port antennas in handheld devices are rarely perfectly orthogonal. 
• Irregular antenna spacing: Antenna placement in actual devices is far from uniform.
• User interaction effects: The way users hold devices greatly impacts antenna performance, creating power imbalances not reflected in the old model's simplistic near-field blockage model.

These limitations would have hindered the accuracy of simulations, ultimately forcing an erroneous optimization space to improve the performance of 6G technologies.

New state-of-the-art UE antenna model:

The new state-of-art UE antenna and blockage model introduced by Nokia, addresses these shortcomings head-on. Based on a realistic smartphone form factor dimension (150x70x0 mm), it incorporates eight potential antenna locations with non-uniform spacings, as shown in Figure 1:

A new UE antenna radiation pattern with a directivity of 5.3 dBi is placed at each location with a unique orientation. This ensures that the maximum gain direction differs for each antenna position, accurately reflecting realistic antenna behavior influenced by the device form factor. The model also decomposes the gain pattern into orthogonal Theta and Phi field components, providing a more comprehensive representation of polarization effects.

Furthermore, the enhanced near-field blockage model uses varying attenuation values for different antenna locations and user scenarios, including free space, Cellular Telephone Industries Association (CTIA) defined right-hand browsing, Nokia dual-hand browsing, and CTIA defined right-hand/head-talk. This granular approach captures blockage variations across antenna ports, leading to significantly more accurate simulations.

The Impact:

• Uplink MIMO: New MIMO codebooks and procedures will be optimized based on realistic antenna behavior.
• CSI Acquisition: Sounding Reference Signal (SRS)-based acquisition for both uplink and downlink MIMO will be more accurate.
• Mobility: The highly directive nature of the new antennas will lead to a more sectorized user experience pattern, allowing enhancements in mobility management.
• Power Control: Algorithms can be refined for greater precision.
• RAN4 Requirements: This includes over-the-air conformance testing.
• Simulation Accuracy: Both link-level and system-level simulations will yield more reliable results.

In conclusion, the new 3GPP state-of-the-art UE antenna model proposed by Nokia marks an important leap forward in problem modelling for next-generation mobile communications. By integrating realistic antenna characteristics and user interaction effects, it enables more accurate simulations, smarter optimizations, and ultimately, higher performing 6G systems. This advancement underscores Nokia’s commitment to pushing the boundaries of connectivity and shaping the future of wireless communication.