Throughput comparison (LTE vs 5G NSA)

Hello Experts.

If we tested throughput for LTE connection vs NSA connection having identical bandwidths (20 MHz each or 3CA 60MHz vs 60 MHz in NSA… etc) and we kept all other factors constant so similar radio conditions, traffic, modulation… etc.

Is NSA going to reflect higher throughput value or it will be identical to that of LTE too?

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It’ll be higher on NSA as it will be more spectral efficient.
Simply, each LTE carrier will have 18 MHz of useful bandwidth, 2 MHz are guard intervals, so in total 54 MHz for LTE, while for 5G you’ll have around 58 MHz.

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That’s a great highlight @georgest . Is there any reference for the guard band used against BW and SCS selection for NSA?
Also, allow me to deviate a little bit, does that mean we’re assuming data is being transferred 100% on the SCG rather than being splited to MCG as well?

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Assuming B1 band:

3CA 60MHz with 20MHz each 2x2MIMO, 256QAM will have max. ~640Mbps
60 MHz in NSA (30Khz) will have max. 1.04Gbps

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You can calculate guard band on your own, no need for some document. For LTE technology PRB size is fixed, i.e. 180 kHz, so just by multiplying with number of PRBs for each BW size you can get useful bandwidth and the rest is guard interval. I gave you an example for BW=20 MHz, which has 100 PRBs, so multiplying 100 PRBs x 180 kHz = 18000 kHz (18MHz) and the rest of 2 MHz is guard band. The same approach applies for other BW sizes and also for 5G. But in 5G you have to consider SCS, so if SCS=30 kHz you have to multiply the number of PRBs for particular BW size and SCS with 360 kHz.

For the second question assumption is what would be the peak DL spectral efficency performance for both LTE and NR cases.

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Hi everyone, I have a query.

If we have a 15 MHz FDD band in both LTE and 5G, with support for 2x2 MIMO and 256QAM in both technologies, will the theoretical downlink throughput be the same or different?

The throughput will be the same or slightly higher in 5G due to improved spectral efficiency.

Hi, you are not considering the advantages of 5G, such as:

  1. Subcarrier spacing
  2. Bits per symbol
  3. Symbols per second

These factors contribute to better spectral efficiency in 5G.

SCS does not provide efficiency gains in 5G – any savings from a shorter TTI are offset by the longer resource elements (RE). For example, if SCS = 30 kHz, each RE spans 30 kHz instead of 15 kHz.

Take a look at this picture:

So, NR offers some improvements, but the advantage is not significant.

Higher throughput in NR is primarily achieved through increased bandwidth.

If LTE and NR cells operate with the same bandwidth, there is no significant improvement in NR compared to LTE.

1024QAM in NR can further boost throughput, but it is rarely achievable in real-world networks. Additionally, both the UE and the network must support it.

I meant that the gain in 5G comes from improved spectral efficiency.

Here is the 3GPP calculation that addresses the same concept.

This is a complex topic that requires careful consideration of several factors, including:

Key Considerations:

  1. Massive MIMO or Non-Massive MIMO
  • With Massive MIMO: Additional overheads impact efficiency.
  • Without Massive MIMO: Different performance characteristics.
  1. Overhead Contributions (With Massive MIMO)
  • SSB Overhead:
    • 4 SSB → 0.5%
    • 7 SSB → 1.05%
  • Control Channel & Reference Signal Overheads:
    • PDCCH + DMRS7.1%
    • PDSCH + DMRS7.1% to 14.2% (depends on Additional Position DMRS for MIMO).
  1. TDD vs. FDD Comparisons
  • Differences in guard period calculations impact efficiency.
  • Performance depends on scheduling and interference management.
  1. Slot Structure Selection
  • 10:2:2 (DL: 73%)
  • 6:6:2 (DL: 70%)
  • Different structures influence spectral efficiency.
  1. Subcarrier Spacing Impact
  • 15 kHz vs. 30 kHz: Guard band calculations differ (as specified in 3GPP 38.101-1).
  • Selection depends on deployment scenario and network optimization.
  1. Modulation Scheme (256 QAM)
  • Consider the maximum MCS value allocated for realistic throughput estimation.

Final Assessment:

  • If all factors are considered, NR has an advantage over legacy systems due to better guard band efficiency (1-3% gain).
  • However, the correct requirements and assumptions must be defined before drawing conclusions.

:point_right: Recommendation: Ensure a well-defined requirement before raising this question.