Link-Level Evaluation of Uplink Cell-Free MIMO in 5G NR Over Frequency-Selective Channels
Cell-free (CF) MIMO has emerged as a promising next-generation technology, primarily due to its ability to provide uniformly high-quality service to all user equipment (UEs), regardless of their location. While existing research has extensively explored various aspects of CF systems–inclu...
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| Format: | Article |
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IEEE
2025-01-01
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| Series: | IEEE Open Journal of the Communications Society |
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| Online Access: | https://ieeexplore.ieee.org/document/11077661/ |
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| author | Mostafa Rahmani Ghourtani Junbo Zhao Yi Chu Hamed Ahmadi David Grace Robert G. Maunder Alister Burr |
| author_facet | Mostafa Rahmani Ghourtani Junbo Zhao Yi Chu Hamed Ahmadi David Grace Robert G. Maunder Alister Burr |
| author_sort | Mostafa Rahmani Ghourtani |
| collection | DOAJ |
| description | Cell-free (CF) MIMO has emerged as a promising next-generation technology, primarily due to its ability to provide uniformly high-quality service to all user equipment (UEs), regardless of their location. While existing research has extensively explored various aspects of CF systems–including scalability, clustering strategies, power control, and precoding designs–there remains a notable gap in the literature concerning the physical-layer performance of 5G New Radio (NR) within CF architectures. This paper addresses this gap by focusing on the Physical Uplink Shared Channel (PUSCH) transmission over frequency-selective channels. We develop a comprehensive, 3GPP-compliant link-level simulator to evaluate the performance of CF MIMO under realistic propagation conditions. First, we generate results for selected modulation and coding schemes (MCSs) to confirm the simulator’s alignment with expected performance. Then, the effects of key physical-layer parameters–such as subcarrier spacing (SCS), the number of distributed radio units (RUs), and the number of RU antennas–are evaluated using Block Error Rate (BLER) as the primary performance metric. We also compare the results of the CF-MIMO system with a co-located antenna scenario, serving as the baseline for a traditional MIMO system, and confirm that the CF-MIMO system achieves superior performance due to its spatial diversity advantages. The results also show that employing higher SCS values effectively exploits frequency diversity, particularly when the signal bandwidth exceeds the channel’s coherence bandwidth. As expected, increasing the number of RUs significantly improves BLER due to enhanced spatial diversity and reduced UE-RU path loss. We further examine the impact of practical channel estimation by evaluating four different DMRS configurations, confirming that Type 1 with length 2 provides superior performance under the tested conditions. Finally, we investigate the effect of carrier frequency, showing that higher frequencies lead to increased path loss and degraded performance. The findings offer valuable insights into spatial, frequency, and estimation-related interactions in CF 5G NR, while guiding MCS selection for target BLER-SNR levels and enabling PHY abstraction for higher-layer simulations. |
| format | Article |
| id | doaj-art-e52185fcb7934d7e9d737cbafa5a975d |
| institution | DOAJ |
| issn | 2644-125X |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IEEE |
| record_format | Article |
| series | IEEE Open Journal of the Communications Society |
| spelling | doaj-art-e52185fcb7934d7e9d737cbafa5a975d2025-08-20T02:46:13ZengIEEEIEEE Open Journal of the Communications Society2644-125X2025-01-0165903592210.1109/OJCOMS.2025.358799011077661Link-Level Evaluation of Uplink Cell-Free MIMO in 5G NR Over Frequency-Selective ChannelsMostafa Rahmani Ghourtani0https://orcid.org/0000-0002-7943-9977Junbo Zhao1https://orcid.org/0000-0003-0019-942XYi Chu2https://orcid.org/0000-0002-5030-9757Hamed Ahmadi3https://orcid.org/0000-0001-5508-8757David Grace4https://orcid.org/0000-0003-4493-7498Robert G. Maunder5https://orcid.org/0000-0002-7944-2615Alister Burr6https://orcid.org/0000-0001-6435-3962School of Physics, Engineering and Technology, University of York, York, U.K.School of Physics, Engineering and Technology, University of York, York, U.K.School of Physics, Engineering and Technology, University of York, York, U.K.School of Physics, Engineering and Technology, University of York, York, U.K.School of Physics, Engineering and Technology, University of York, York, U.K.School of Electronics and Computer Science, University of Southampton, Southampton, U.K.School of Physics, Engineering and Technology, University of York, York, U.K.Cell-free (CF) MIMO has emerged as a promising next-generation technology, primarily due to its ability to provide uniformly high-quality service to all user equipment (UEs), regardless of their location. While existing research has extensively explored various aspects of CF systems–including scalability, clustering strategies, power control, and precoding designs–there remains a notable gap in the literature concerning the physical-layer performance of 5G New Radio (NR) within CF architectures. This paper addresses this gap by focusing on the Physical Uplink Shared Channel (PUSCH) transmission over frequency-selective channels. We develop a comprehensive, 3GPP-compliant link-level simulator to evaluate the performance of CF MIMO under realistic propagation conditions. First, we generate results for selected modulation and coding schemes (MCSs) to confirm the simulator’s alignment with expected performance. Then, the effects of key physical-layer parameters–such as subcarrier spacing (SCS), the number of distributed radio units (RUs), and the number of RU antennas–are evaluated using Block Error Rate (BLER) as the primary performance metric. We also compare the results of the CF-MIMO system with a co-located antenna scenario, serving as the baseline for a traditional MIMO system, and confirm that the CF-MIMO system achieves superior performance due to its spatial diversity advantages. The results also show that employing higher SCS values effectively exploits frequency diversity, particularly when the signal bandwidth exceeds the channel’s coherence bandwidth. As expected, increasing the number of RUs significantly improves BLER due to enhanced spatial diversity and reduced UE-RU path loss. We further examine the impact of practical channel estimation by evaluating four different DMRS configurations, confirming that Type 1 with length 2 provides superior performance under the tested conditions. Finally, we investigate the effect of carrier frequency, showing that higher frequencies lead to increased path loss and degraded performance. The findings offer valuable insights into spatial, frequency, and estimation-related interactions in CF 5G NR, while guiding MCS selection for target BLER-SNR levels and enabling PHY abstraction for higher-layer simulations.https://ieeexplore.ieee.org/document/11077661/Block error ratecell-free systemlink level simulationphysical uplink shared channel5G new radio |
| spellingShingle | Mostafa Rahmani Ghourtani Junbo Zhao Yi Chu Hamed Ahmadi David Grace Robert G. Maunder Alister Burr Link-Level Evaluation of Uplink Cell-Free MIMO in 5G NR Over Frequency-Selective Channels IEEE Open Journal of the Communications Society Block error rate cell-free system link level simulation physical uplink shared channel 5G new radio |
| title | Link-Level Evaluation of Uplink Cell-Free MIMO in 5G NR Over Frequency-Selective Channels |
| title_full | Link-Level Evaluation of Uplink Cell-Free MIMO in 5G NR Over Frequency-Selective Channels |
| title_fullStr | Link-Level Evaluation of Uplink Cell-Free MIMO in 5G NR Over Frequency-Selective Channels |
| title_full_unstemmed | Link-Level Evaluation of Uplink Cell-Free MIMO in 5G NR Over Frequency-Selective Channels |
| title_short | Link-Level Evaluation of Uplink Cell-Free MIMO in 5G NR Over Frequency-Selective Channels |
| title_sort | link level evaluation of uplink cell free mimo in 5g nr over frequency selective channels |
| topic | Block error rate cell-free system link level simulation physical uplink shared channel 5G new radio |
| url | https://ieeexplore.ieee.org/document/11077661/ |
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