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4G LTE Outperforms 5G SA: Surprising Peak Performance Results from a Controlled Testbed

The transition to 5G Standalone (SA) is expected to deliver a massive increase in throughput, but our side-by-side testing reveals a counter-intuitive result: LTE significantly outperforms the n78 band 5G SA (SISO) configuration in both downlink and uplink peak speeds.

This data suggests that while 5G NR has theoretical advantages, achieving superior real-world performance is highly dependent on the deployment configuration of Radio Access Network (RAN) components, even in a controlled environment.

Test Environment and Methodology 

To ensure a fair comparison focused on peak throughput, all measurements were conducted in a highly controlled setup:

  • Test Equipment: Both networks utilized the same test hardware (USRP B200-mini) as the SDR base station. The core network and software for the base station modules were hosted on an Intel i9 server with 16 GB of RAM, running Ubuntu 24.04 LTS. This testbed uses open source software Open5GS as the 5G core with srsRAN for the 5G and srsRAN srsEPC and srsENB for the 4G.
  • Test Device: A Quectel 520 module was used as the User Equipment (UE). The sim card used is sysmoISIM-SJA5 and the testbed PLMN is 99970.
  • Distance: The distance between the test device and the base station was kept constant at 1 meter (line-of-sight) to eliminate channel impairments.
  • 5G Band: 5G SA utilized the n78 band. n78 operates in TDD mode.
Channel Bandwidth (MHz)
5G SA (n78) Downlink (Mbps)
LTE Downlink (Mbps)
5G SA (n78) Uplink (Mbps)
LTE Uplink (Mbps)
10 MHz
23.0
46.6
9.65
21.5
15 MHz
34.6
N/A
14.8
N/A
20 MHz
55.1
91.6
9.43
47.6
30 MHz
58.2
N/A
2.90
N/A
40 MHz
95.2
2.89
2.89
N/A
50 MHz
121.0
N/A
2.59
N/A
60 MHz
115.0
N/A
3.67
N/A

Key Findings: LTE Downlink Advantage at 20 MHz

The measurement results reveal a notable performance disparity between LTE and 5G SA when both operate under comparable 20 MHz channel conditions. In this bandwidth—commonly used as a baseline reference for mid-band deployments—LTE demonstrated a significantly higher downlink throughput:

  • LTE Downlink: 91.6 Mbps
  • 5G SA (n78) Downlink: 55.1 Mbps

This represents a 66% performance advantage in favor of LTE, despite 5G NR’s inherently more advanced physical layer and frame structure.The data suggests that within the constraints of the current SDR testbed, the LTE implementation is more effectively optimized for peak throughput. Several technical factors may contribute to this outcome, including:

  • Power allocation efficiency: LTE may be utilizing transmit power more effectively under SISO conditions.
  • Scheduler maturity: LTE MAC and HARQ scheduling algorithms are highly refined after years of commercial deployment, potentially outperforming early-stage NR scheduler implementations.
  • Software and PHY layer tuning: Specific build configurations, numerology settings, or modulation/coding scheme selections may be favoring LTE under the tested conditions.
  • RAN parameter alignment: Even small deviations in NR parameter tuning can significantly impact achievable throughput in SA mode.

Overall, while 5G NR offers superior capabilities on paper—especially with wider bandwidths, MIMO configurations, and advanced NR features—the results demonstrate that real-world (or testbed-specific) performance remains highly dependent on implementation maturity and configuration quality.

 

Uplink Performance: A Major Discrepancy

The most striking contrast is observed in the Uplink (UL) performance, where 5G SA significantly trails the optimized LTE network across all bandwidths:

  • LTE Uplink (UL): Recorded a strong peak speed of 47.6 Mbps.
  • 5G SA Uplink (UL): The peak was only 14.8 Mbps (at 15 MHz), dropping to a low of 2.59 Mbps at 50 MHz.

     

The LTE uplink is more than three times faster (47.6 Mbps vs. 14.8 Mbps) than the best 5G SA result, and over ten times faster than the 5G SA result at 50 MHz bandwidth.

 

Why 5G SA Underperforms LTE in This Setup

The inability of 5G SA to surpass the LTE speeds, even when utilizing wider bandwidths (up to 60 MHz), points to constraints within the implementation rather than the technology’s theoretical limits. Potential reasons include:

  1. UE Constraints: The Quectel 520 test device may not be fully optimized or configured to support the massive bandwidth utilization and complex scheduling required by the 5G SA network stack.
  2. Resource Allocation Overhead: The 5G New Radio (NR) protocol introduces greater complexity and control signaling overhead compared to the relatively simpler LTE protocol, especially in early-stage SDR implementations like srsRAN. This overhead may be consuming valuable airtime that is better utilized for data transfer in the optimized LTE setup.
  3. Software Optimization: The srsRAN LTE stack, having been developed over a longer period, is likely more mature and robustly optimized for these specific SDR hardware constraints (USRP B200-mini) than the newer srsRAN Project 5G stack.

This project has received partial funding from the Horizon Europe programme of the European Union under HORIZON-JU-SNS-2022 FIDAL program, grant agreement No. 101096146

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