Simulating a 450 MHz LTE Cell with Simu5G

[Stygiogigantea]

Hello everyone,

I’m working on a project to simulate an eNodeB cell tower for a simulation of the German 450 MHz LTE network (runs on a subset of the 3GPP Band 72). My goal is to configure the simulation to match the following requirements:

• Frequency Bands:

  • Uplink: 451.00–455.74 MHz (instead of 451–456 MHz)
  • Downlink: 461.00–465.74 MHz (instead of 461–466 MHz)

• Coverage Area:

  • The cell tower should serve a radius of approximately 10 km.
  • I need a path loss model that produces valid results for distances between 0 and 10 km.

Question:
Is it possible to simulate this scenario with Simu5G? If so, how should I configure the frequency bands, path loss model, and other parameters to achieve this setup?

[avarga]

AI answer (unverified):

Can Simu5G Simulate a 450 MHz LTE Network?

Short answer: Yes, with caveats. Simu5G can be configured to approximate this scenario, but there are important limitations to understand.

1. Frequency Configuration

Simu5G uses a single carrier frequency per ComponentCarrier, specified in GHz. It does not model separate UL/DL frequencies — FDD duplexing is implicit, and the same carrier frequency value is used in path loss formulas for both directions.

For 450 MHz, you would configure:

# Component Carrier — use the DL center frequency
*.carrierAggregation.componentCarrier[0].carrierFrequency = 0.463GHz
*.carrierAggregation.componentCarrier[0].numBands = 25

The numBands parameter corresponds to Resource Blocks (180 kHz each). For a 5 MHz LTE channel bandwidth, that's 25 RBs. The user mentions 4.74 MHz usable bandwidth, but LTE standardizes channel bandwidths — the closest is 5 MHz (25 RBs), which is the correct setting. The 4.74 MHz figure refers to the occupied bandwidth within the 5 MHz channel.

2. Path Loss Model & Frequency Validity

Simu5G ships three channel model classes, each implementing different 3GPP specifications:

Channel Model	3GPP Spec	Frequency Range	Has RURAL_MACROCELL
LteRealisticChannelModel	TR 36.803	~0.7–3.5 GHz (typical LTE)	Yes
NRChannelModel	TR 36.873	~0.5–6 GHz	Yes
NRChannelModel_3GPP38_901	TR 38.901	0.5–100 GHz	Yes

450 MHz (0.45 GHz) is slightly below all three models' intended ranges. The closest is TR 38.901 which starts at 0.5 GHz. However:

• The code does not enforce frequency range checks — it simply plugs carrierFrequency_ into the formulas
• At 0.45 GHz vs 0.5 GHz, the path loss difference is small (the formulas use log10(f), so the error is marginal)
• The results will be a reasonable approximation, but not strictly validated by 3GPP at this frequency

Recommendation: Use NRChannelModel_3GPP38_901 with RURAL_MACROCELL scenario — it's the closest match for 450 MHz and covers up to 10 km.

3. Distance Limits for RURAL_MACROCELL

From the source code at @/home/andras/projects/Simu5G-fork/simu5g-fork/src/stack/phy/ChannelModel/NRChannelModel_3GPP38_901.cc:215-264:

• LOS: valid up to 10,000 m (10 km) ✓
• NLOS: valid up to 5,000 m only

For a 10 km cell radius, UEs beyond 5 km in NLOS will trigger an error unless you set tolerateMaxDistViolation = true. Also consider using dynamic_los = true so that LOS/NLOS is computed probabilistically based on distance — the RMa LOS probability in TR 38.901 is p(LOS) = exp(-(d-10)/1000) for d > 10m, so at 5 km there's still about 0.7% chance of LOS.

4. Example INI Configuration

[General]
# --- Component Carrier ---
*.carrierAggregation.numComponentCarriers = 1
*.carrierAggregation.componentCarrier[0].carrierFrequency = 0.463GHz   # DL center: (461+466)/2
*.carrierAggregation.componentCarrier[0].numBands = 25                  # 5 MHz = 25 RBs

# --- Channel Model (use TR 38.901) ---
*.gnb.cellularNic.channelModel[0].typename = "NRChannelModel_3GPP38_901"
*.gnb.cellularNic.channelModel[0].scenario = "RURAL_MACROCELL"
*.gnb.cellularNic.channelModel[0].nodeb_height = 40m       # typical rural tower
*.gnb.cellularNic.channelModel[0].ue_height = 1.5m
*.gnb.cellularNic.channelModel[0].building_height = 5m      # low rural buildings
*.gnb.cellularNic.channelModel[0].street_wide = 20m
*.gnb.cellularNic.channelModel[0].dynamic_los = true         # probabilistic LOS/NLOS
*.gnb.cellularNic.channelModel[0].tolerateMaxDistViolation = true  # allow NLOS > 5km
*.gnb.cellularNic.channelModel[0].shadowing = true
*.gnb.cellularNic.channelModel[0].fading = true

# Repeat for UE side
*.ue[*].cellularNic.channelModel[0].typename = "NRChannelModel_3GPP38_901"
*.ue[*].cellularNic.channelModel[0].scenario = "RURAL_MACROCELL"
*.ue[*].cellularNic.channelModel[0].nodeb_height = 40m
*.ue[*].cellularNic.channelModel[0].ue_height = 1.5m
*.ue[*].cellularNic.channelModel[0].building_height = 5m
*.ue[*].cellularNic.channelModel[0].street_wide = 20m
*.ue[*].cellularNic.channelModel[0].dynamic_los = true
*.ue[*].cellularNic.channelModel[0].tolerateMaxDistViolation = true
*.ue[*].cellularNic.channelModel[0].shadowing = true
*.ue[*].cellularNic.channelModel[0].fading = true

# --- Thermal noise adjustment for 5 MHz bandwidth ---
# Default is -104.5 dBm (10 MHz). For 5 MHz: -104.5 - 3 = -107.5 dBm
*.gnb.cellularNic.channelModel[0].thermalNoise = -107.5dBm
*.ue[*].cellularNic.channelModel[0].thermalNoise = -107.5dBm

# --- TX power (typical for 450 MHz rural eNB) ---
*.gnb.cellularNic.phy.txPower = 46dBm

5. Key Caveats

• No separate UL/DL frequencies: Simu5G uses one carrier frequency for path loss. The ~10 MHz UL/DL gap in Band 72 is not modeled — this is acceptable since the path loss difference between 453 MHz and 463 MHz is negligible
• Frequency extrapolation: 0.45 GHz is ~10% below TR 38.901's validated range (0.5 GHz). The formulas will still produce physically reasonable results, but strictly speaking they're extrapolated
• No Band 72-specific features: Simu5G doesn't model band-specific regulatory constraints (e.g., max EIRP, guard bands, specific duplex spacing)
• Antenna gain: At 450 MHz, antennas are physically larger and real-world gains differ from higher-frequency defaults. Adjust antennGainEnB accordingly7