On the Upper Mid-Band 8 × 8 and 8 × 4 Device MIMO Performance Based on Applying Compact Backcover Four-Antenna Modules for 6G Smartphones With Increased Data Rates
For future six-generation (6G) upper mid-band mobile communications, the higher-order device multi-input-multi-output (MIMO) such as the <inline-formula> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> or <inline-formula> <tex-math notat...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
IEEE
2025-01-01
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| Series: | IEEE Access |
| Subjects: | |
| Online Access: | https://ieeexplore.ieee.org/document/10980293/ |
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| Summary: | For future six-generation (6G) upper mid-band mobile communications, the higher-order device multi-input-multi-output (MIMO) such as the <inline-formula> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> or <inline-formula> <tex-math notation="LaTeX">$8\times 4$ </tex-math></inline-formula> MIMO is envisioned for the smartphone to achieve increased data rates for the user. However, it is worth noting that the <inline-formula> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> MIMO requires twice the transmitted power of current fifth-generation (5G) <inline-formula> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> MIMO and has a much more complex system architecture. Thus, whether it is cost effective to apply the <inline-formula> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> MIMO for increased data rates is not clear. In this study, we demonstrate that the <inline-formula> <tex-math notation="LaTeX">$8\times 4$ </tex-math></inline-formula> MIMO (8 receive antennas for 4 spatial streams) with the same transmitted power as the 5G <inline-formula> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> MIMO can outperform the <inline-formula> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> MIMO to achieve increased data rates and lower energy per bit as well. In the outdoor scenario testing, the <inline-formula> <tex-math notation="LaTeX">$8\times 4$ </tex-math></inline-formula> MIMO shows a spectral efficiency of about 31 or 26 bps/Hz, while that of the <inline-formula> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> MIMO is only about 22 bps/Hz. Additionally, the required energy per bit transmitted in the <inline-formula> <tex-math notation="LaTeX">$8\times 4$ </tex-math></inline-formula> MIMO is less than one-half that of the <inline-formula> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> MIMO. The is mainly because the <inline-formula> <tex-math notation="LaTeX">$8\times 4$ </tex-math></inline-formula> MIMO uses only one-half transmitted power and has a much larger MIMO efficiency (measured system capacity/ideal system capacity) than the <inline-formula> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> MIMO. Thus, the <inline-formula> <tex-math notation="LaTeX">$8\times 4$ </tex-math></inline-formula> MIMO can support a higher signal modulation of 256 or 1024 Quadrature Amplitude Modulation (QAM), while the <inline-formula> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> MIMO supports only 16 QAM. Hence, although the <inline-formula> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> MIMO has a potentially much larger system channel capacity, its actual data throughput cannot be proportionally larger. We experimentally evaluate the MIMO performance in the 7.1 GHz band by applying compact backcover four-antenna (B4A) modules as receive antennas in the smartphone-like device covering 6.425-8.4 GHz in the upper mid-band, which is promising to be a prime 6G mobile spectrum. The applied compact B4A module provides a promising solution for the challenge in embedding at least 8 MIMO antennas in 6G smartphones for upper mid-band MIMO communications. We present details of the <inline-formula> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">$8\times 4$ </tex-math></inline-formula> MIMO performance testing and the applied B4A modules for promising 6G smartphone applications. |
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| ISSN: | 2169-3536 |