Introduction

The 5G NTN library supports end-to-end, full-stack, packet-level simulation of 5G NTN based LEO/MEO satellite networks. The features supported include:

LEO satellite orbits
- Altitude: User configurable between 160 to 2000 kms.
- Standard options: LEO 600, LEO 1200
MEO satellite orbits
- Altitude: User configurable between 2000 to 35876 kms.
- Standard options: MEO 10000, MEO 20000
Bands
- S-band and L-band: n254, n255, n256 (FR1 bands released in 3GPP standards)
- Ka Band, Ku Band: n510, n511, n512 (FR2 bands proposed in 3GPP standards)
Earth satellite link and satellite earth link
- Channel model and path losses (per TR 38.811)
- Propagation delay based on slant distance
Devices
- UEs
  - VSAT with directive antennas
  - Handhelds (or informally mobiles)
- Ground stations, gNBs
- 5G core and remote servers
Downlink transmissions (Remote server > gNB > Satellite > UE)
- Uplink transmissions are currently not supported and is under development
Antenna models
- Omni directional antenna for Handheld HEs
- Circular aperture antenna for VSATs and Satellites
Satellite spot beams with earth fixed cells (explained later)
Architecture
- Transparent satellite (also termed “bent pipe” operation)

Similar to the NetSim (terrestrial) 5G library, the NTN satellite library would allow users to simulate the transmission of data, voice, video, etc., over a LEO/MEO satellite network. After simulation, users can assess key output metrics such as delay, latency, and errors. These results can be viewed in both tabular and graphical formats, from a network-wide overview down to individual links and devices. For in-depth studies, the NetSim can log detailed radio measurements and resource allocations as well as trace individual packet flow and individual event execution.

Single transparent satellite fixed in a LEO orbit with terrestrial UEs and gNB

Single satellite simulation per 3GPP TR 38.821
The satellite remains fixed in orbit; users can configure the orbital height.
UE elevation angle is determined based on the UE's position.
Fixed-earth spot beams. UEs will connect to the beam with the highest PDSCH SNR.
Ground station and gNB located at an arbitrary point outside the service beams, and communicates to the satellite via a feeder link.
UEs transmit/receive data from remote servers. Connectivity is UE <> Satellite <>Gateway <> gNB <> 5G Core <> Remote servers.
UEs can be mobile and inter beam handovers can occur
UEs are handheld devices (e.g., Power Class 3) operating in FR1, in particular S or L band. VSAT terminals can connect in FR1 or FR2 bands.
The UE terminal are assumed to be equipped with a GNSS receiver, thus able to estimate its location.

RAN Architecture with a transparent satellite (NTN A1 mode)

The diagrams below show a satellite NTN typical scenario based on transparent payload architecture

Figure-1: Architecture of 5G Non terrestrial network with LEO/MEO satellites. The satellite communication with the ground station is over a feeder link having 1-spot beam and communication with the UEs is over a service link having multiple spot beams. UEs can be placed within these beams (or cells). The telemetry and telecommand (TTC) link is out of scope of 3GPP realm. (source TR 38.821)

Figure-2: A simplified illustration of the transparent payload architecture. In Phase-1 the satellite is assumed fixed in the LEO/MEO orbit, and the UE is assumed to be stationary on earth.

A feeder link is a radio communication link between a gateway and the satellite. It is a single beam of full bandwidth.
A service link is a radio communication link between the user equipment and the satellite. Multiple spot beams to cover a given area. The bandwidth of the beams depends on the frequency reuse factor.

Figure-3: Top view of four tessellated spot beams on the service link. In NetSim, UEs will associate to the beam which provides the highest signal strength. Per 3GPP standards, the mapping of satellite beams to terrestrial cells is one-to-one. Each beam is one physical cell. Thus, we will refer to cells and spotbeams interchangeably.

A satellite, which implements a transparent payload performs radio frequency filtering, frequency conversion and amplification; hence, the waveform signal repeated by the payload is un-changed except for frequency translation and transmit power.

Figure-4: 5G NTN User plane and control plane protocol stacks. Source TR 38.821.

Earth fixed spot beams and cells

The satellite beams point towards the ground in a hexagonal manner similar to the canonical evaluation setup with hexagonal tessellation used for terrestrial cellular networks. NetSim supports earth fixed beams

In earth-fixed beams, the satellite beams are steered such that they always point to the same location on earth.
The ability to adjust these beams is constrained by the satellite's elevation angle. It must stay above a specified minimum value on either side of the horizon for uninterrupted connectivity. Practically, when the elevation hits its limit, the beams shift to another Earth location. The beams stay fixed on that location for a set duration before moving to another, and this cycle repeats.
The adjustment of these beams is limited by the satellite's beam radius and the number of beams configured by the user.
The fixed-beam scenario yields the maximum time a UE may remain under the coverage area of the same satellite. This time is the time the satellite remains above the horizon relative to the UE location. This usually of the order of 7 to 10 minutes.
As against fixed beams, “Moving beams” move over the Earth’s surface that follow the motion of the satellite. This is not currently supported in NetSim.
Mapping of satellite beams to terrestrial cells is one-to-one. Each beam is one physical cell.
Number of spot beams.

NetSim can presently support configurations of 1, 7, or 19 spot beams.

The 7-cell setup consists of a central hexagonal cell surrounded by 6 adjacent cells.

The 19-cell configuration has two layers of surrounding cells around a central hexagonal cell

NetSim will automatically compute the tessellated beams (cells) based on number of spot beams.
NetSim supports the NR-Uu radio interface on the service link between the satellite and the UE.

Cell/Beam Layouts

NetSim will support 1 cell, 7 cell and 19 cell layouts. The beam diameter which is also the inter-beam distance on earth is a user input. The beams would be circular, but the tessellation would be hexagonal. The centre of all the cells can be calculated from basic trigonometry.

Beam diameter to inter-cell distance

Let the beam diameter be \(D\), which is a user input. Then the distance between the centre of two adjacent hexagons whose circumcircle has a diameter \(D\) can be obtained from basic trigonometry. Since \(\frac{\frac{ISD}{2}}{\frac{D}{2}} = \cos{(30)},\) we obtain \(ISD = \frac{\sqrt{3} \times D}{2}\).

Feeder Link

The feeder link is used for communication between the satellite and the terrestrial gNB. The frequency reuse options discussed are pertinent to the service link. For the feeder link, NetSim models a single spot beam of full bandwidth pointed towards the terrestrial gNB. NetSim supports Satellite Radio Interface (SRI) on the feeder link between the NTN gateway and the satellite. The SRI transports the F1 protocol.

Per TR 38821, Table 6.1.1.1-5, NOTE 1, “Typical impairment values (additional frequency error, SNR loss) due to the feeder link except for delay can be considered to be negligible”. Therefore, in NetSim, we assume the feeder link to have NIL SNR losses. The only factor we consider and model over this link is latency.

Bent pipe operation

Bent pipe satellites are typically used to relay information. Data received by the satellite on its reception interface is simply transmitted by the satellite on its transmission interface without modifying the data. Given that we model NIL SNR loss on the feeder link the link budget computations are only carried out on the service link.

Angle between the antenna boresight to the line joining the UE and the satellite

The cell diameter \(D\) is a user-defined parameter. The beam positions are based on the cell diameter and the number of beams configured. \(\theta\) is defined as the angle subtended between the selected beam and the UE from the satellite. It is computed by forming vectors:

Satellite-to-Beam (centre) vector \(\overrightarrow{\rho_{c}}\)
Satellite-to-UE vector \(\overrightarrow{\rho_{u}}\)

The angle \(\theta\) is determined using the dot product formula:

\[\theta = \cos^{- 1}\left( \frac{\overrightarrow{\rho_{c}} \cdot \overrightarrow{\rho_{u}}}{\|\overrightarrow{\rho_{c}}\|\|\overrightarrow{\rho_{u}}\|} \right)\]

where:

\(\overrightarrow{\rho_{c}} \cdot \overrightarrow{\rho_{u}}\) is the dot product of the vectors, and

\(\left\| \overrightarrow{\rho_{c}} \right\|,\ \|\overrightarrow{\rho_{u}}\|\) are the magnitude of the respective vectors.

Bands

Release 17 has two new bands for LEO NTN

n256 (S-Band): UL 1980 – 2010 MHz, DL: 2170 – 2200 MHz. FDD
n255 (L-Band): UL 1626.5 – 1660.5 MHz, DL: 1525 – 1559 MHz. FDD
n254: UL 1610 – 1626.5 MHz, DL: 2483.5–2500 MHz. FDD

Release 18 NTN bands in FR2

n512: UL 27.5–30.0 GHz; DL 17.3–20.2 GHz FDD
n511: UL 28.35–30.0 GHz; DL17.3–20.2 GHz FDD
n510: UL 27.5–28.35 GHz; DL 17.3–20.2 GHz FDD

With 3GPP Rel- 18 additional spectrum in Ka band offers much higher speed – to the order of hundreds of Mbps - to non-handheld devices using small dish antennas, similar to that offered by SpaceX’s Starlink service (need to check the standard for the exact frequency and bandwidths)

Note that:

UEs can connect only on FR1 bands
VSAT terminals can connect on FR1 and FR2 bands

Sub carrier spacing

Rel 17 allows for SCS of UL signals lower than 60 KHz (in FR1)

GUI parameters

Grid size:
- Min: 50km * 50 km
- Max: 150 km * 150 km
- Square or rectangular configurations
Satellite type:
- Options: LEO, MEO
- Altitude (per Table 4.5.1, 38.811)
- LEO: 160 km to 2000 km. Standard options: 600 km, 1200 km.
- MEO: 2000 km to 35876 km. Standard options: 10000 km, 20000km.
Service link
- Number of beams on the service link
Options: 1, 7, 19
- Frequency reuse factor
  Options: 1, 3
- Beam diameter // Reference Tabel 4.6.1, 38.811
  LEO: 5km to 200 km. Default: 50 km
  
  MEO: 100 km to 500 km. Default: 200 km.
- \(EIRP\) is the effective isotropic radiated power in dBW
- \(\frac{G_{rx}}{T}\) is the antenna-gain-to-noise temperature in dB/K of the receiver
- k is the Boltzmann constant with the value of -228.6 dBW/K/Hz. Fixed.
- Channel
  Pathloss model. Fixed to Free Space. Using this model we obtain, \(PL_{FS}\ \)the free space path loss (FSPL) in dB.
  
  Shadow Margin, \(PL_{SM}\) in dB. Enable and disable options in the GUI. If enabled then the log normal shadowing model is applied; the standard deviation of the distribution is obtained from tables available at section 6.6.2 of 3GPP 38.811, based on the LOS probability, elevation angle, and scenario type (urban, rural, or dense urban).
  
  Scintillation loss, \(PL_{SL}\) in dB. Range [0.0, 10.0]. Default [1.1]
  
  Additional loss, \(PL_{AD}\) in dB. Range [0.0, 10.0]. Default [8]
  
  Interference. Enable and disable options in the GUI. If enabled then Carrier to Interference Ratio, CIR in dB. Range [-30, +50]. Default [5]
- Channel bandwidth, \(BW\) in Hz from which we obtain \(B,\) is the channel bandwidth in dBHz (i.e., \(10\log_{10}{BW},\) where \(BW\ \)is bandwidth in Hz). Options
  FR1 – 5, 10, 15, 20, 30 (MHz)
  
  FR2 – 50, 100, 200, 400 (MHz)
- Antenna
  Satellite Max Receive Gain
  
  Note that transmit gain is assumed to be included in the EIRP
- UE Transmit power: 23 dBm
Terrestrial environment: Dense urban, urban, rural
Frequency Reuse

In the NETSIM GUI, users can configure the number of beams and select the frequency reuse factor accordingly. This selection determines the channel ID assignment for all beams.

Once configured, the NetSim GUI generates a csv file containing the beam ID, beam centre coordinates, and assigned channel ID. This file is then passed to the NTN simulation engine. An option is available for the user to directly modify this csv file through the GUI.

Band Frequency Information

NR operating band	Uplink (UL) operating band BS receive / UE transmit F_{UL_low} – F_{UL_high}	Downlink (DL) operating band BS transmit / UE receive F_{DL_low} – F_{DL_high}	Duplex Mode
n256	1980 MHz – 2010 MHz	2170 MHz – 2200 MHz	FDD
n255	1626.5 MHz – 1660.5 MHz	1525 MHz – 1559 MHz	FDD
n254	1610 MHz – 1626.5 MHz	2483.5 MHz – 2500 MHz	FDD
n512	27500 MHz – 30000 MHz	17300 MHz – 20200 MHz	FDD
n511	28350 MHz – 30000 MHz	17300 MHz – 20200 MHz	FDD
n510	27500 MHz – 28350 MHz	17300 MHz – 20200 MHz	FDD

Table-1: Frequency Bands with Uplink/Downlink Allocations

Maximum transmission bandwidth configuration

The maximum transmission bandwidth configuration NRB for each UE channel bandwidth and subcarrier spacing is specified below.

SCS (kHz)	5 MHz	10 MHz	15 MHz	20 MHz	30 MHz
SCS (kHz)	N_RB	N_RB	N_RB	N_RB	N_RB
15	25	52	79	106	160
30	11	24	38	51	78

Table-2: Maximum transmission bandwidth configuration for FR1

SCS (kHz)	50 MHz	100 MHz	200 MHz	400 MHz
SCS (kHz)	N_RB	N_RB	N_RB	N_RB
60	66	132	264	N/A
120	32	66	132	264

Table-3: Maximum transmission bandwidth configuration for FR2

Minimum guard band and transmission bandwidth configuration

SCS (kHz)

5

MHz

10 MHz

15 MHz

20 MHz

30

MHz

15

242.5

312.5

382.5

452.5

592.5

30

505

665

645

805

945

60

N/A

1010

990

1330

1290

Table-4:Minimum guard band for each UE channel bandwidth and SCS (KHz)

SCS (kHz)

50

MHz

100 MHz

200 MHz

400

MHz

60

1210

2450

4930

945

120

1900

2420

4900

9860

Table-5: Minimum guard band for each UE channel bandwidth and SCS (KHz)

Simulation GUI

In the New simulation window select New Simulation→ Non-Terrestrial Networks

Figure-5: NTN in New simulation window

Configure Non-Terrestrial Networks

Users can choose how the beam parameters can be configured.

Standard Setup: Allows you to create a scenario with predefined parameters based on 3GPP standards.
Custom Excel/CSV File: Allows you to define the beam configuration in your own Excel or CSV file.
Manual Placement: Allows you to manually place devices and beams. In this mode, no devices are automatically placed.

Figure-6: Configuring the Non-Terrestrial Network

Set device properties

Figure-7: Network scenario created using Standard set up

The following are main properties of Satellite device in PHY and MAC layer. To configure any properties in device, click on the device, expand the property panel on change the properties.

Figure-8: PHY layer properties of Satellite (Feeder link)

Configure an application by clicking on set traffic tab on top ribbon.

Figure-9: Set traffic tab from top ribbon

Application settings can be modified from Application properties tab on right panel.

Figure-10: Application settings from right panel

Configure reports

Check Packet Trace / Event Trace option from the Configure Reports tab. To get detailed help, please refer to sections 8.4 and 8.5 in User Manual.

Figure-11: Enabling Packet trace and Event trace from Configure reports tab

Enable protocol-specific logs such as NTN Radio Measurement Logs, NTN UE Beam Association Logs, NTN Resource Allocation Logs, and others. Additionally, view NTN Radio Measurement plots such as MCS Index vs Time, Shadow Fading Loss vs Time, SNR vs Time, Total Loss vs Time, and more.

Figure-12: Enable NTN Radio Measurements plots

Figure-13: Enable NTN Radio Measurements logs.

GUI Parameters

Interface (Feeder link) – Physical Layer
Parameter	Type	Range	Description
Frame Duration (ms)	Fixed	10ms	The length of the frame in milliseconds. The FRAME DURATION is a non-editable parameter whose value is fixed at 10 ms.
Sub Frame Duration (ms)	Fixed	1ms	The length of the frame in milliseconds. The SUBFRAME DURATION is a non-editable parameter whose value is fixed at 1 ms.
Subcarrier Number Per PRB	Fixed	12	The number of Subcarriers per PRB is a non-editable parameter whose value is fixed at 12.
Duplex Mode	Local	FDD	Frequency Division Duplexing: There are different frequency bands for UL and for DL. Hence UL and DL transmissions can occur simultaneously. As per 3GPP document, NetSim supports FDD bands and various CA configurations and Operating bands, FR1 and FR2 are available.
CA Type	Local	SINGLE_BAND	The single band drop-down options are per TS 38.101-5.
CA Configuration	Local	Depends on CA Type	The drop shows the frequency band options for the user to choose from.
CA Count	Fixed	Depends on CA Type and CA Configurations	This is a non-editable parameter that shows the number of component carriers based on the CA configuration. CA count would be 1 for Single Band configuration.
NOTE: For detailed information to Frequency Range (FR1 & FR2), Please, refer PHY Layer
Slot Type	Local	Downlink, Uplink	Slot type can be Uplink, or Downlink. Uplink: In uplink slot type, there are only uplink slots, and the DL:UL ratio will be fixed by NetSim as 0:1. Downlink: In downlink slot type, there are only downlink slots and the DL:UL ratio will be fixed by NetSim as 1:0.
Frequency Range	Local	FR1 & FR2	The frequency bands for NTN is separated into two frequency ranges. First, is Frequency Range 1 (FR1) which includes sub-6 GHz, frequency bands. The other is Frequency Range 2 (FR2) which includes frequency bands in the mmWave range. FR1: 1525 MHz – 2500 MHz FR2: 17300 MHz – 30000 MHz NetSim supports both FR1 and FR2. This is a non-editable parameter shown by NetSim based on the CA configuration chosen by the user.
DL/UL Ratio	Local	a:b	Represents the ratio in which slots are assigned to downlink and uplink transmissions. The value is in the form of a:b::DL:UL. Note that the ratio 1:0 or 0:1 might lead to NIL data transmissions since the initial attachment procedures require both UL and DL control packet transmissions.
Operating Band	Fixed	n254 n255, n256, n510, n511, n512	The operating band whose numbering is defined by 3GPP. This is a non-editable parameter (except for custom band) that is shown by NetSim based on the CA configuration chosen by the user.
F Low (MHz)	Fixed	1525-28350 MHz	The lowest frequency of the Uplink/Downlink operating band. This is a non-editable parameter (except for custom band) shown by NetSim based on the CA configuration chosen by the user
F High (MHz)	Fixed	1559-30000 MHz	The highest frequency of the Uplink/Downlink operating band. This is a non-editable parameter shown by NetSim based on the CA configuration chosen by the user
Numerology	Local	µ = 0, 1, 2, 3	Sub carrier spacing is derived from numerology per the expression \(\mathrm{\Delta}f = 2^{\mu} \times 15kHz\). Thus, Numerology = 0 means subcarrier spacing 15 kHz Numerology = 1 means subcarrier spacing 30 kHz Numerology = 2 means subcarrier spacing 60 kHz Numerology = 3 means subcarrier spacing 120 kHz
Channel Bandwidth (MHz)	Local	5-400 MHz	The bandwidth can vary from 5 MHz to 30 MHz for bands in FR1 frequency range and 50 MHz to 400 MHz for bands in FR2 frequency range. Unit is MHz
PRB Count	Local		PRB stands for physical resource block. The PRB count is dependent on Channel Bandwidth and automatically determined by NetSim. It cannot be edited in the GUI.
Guard Band (KHz)	Local	0, Standard Table (242.5-9860 kHz)	Guard band is the unused part of the radio spectrum between radio bands, for the purpose of preventing interference. The minimum guard bands are calculated using the following equation: (\(BWChannel\ x\ 1000\ (kHz)\ - \ NRB\ \ x\ SCS\ x\ 12)\ /\ 2\ - \ SCS/2.\ Unit\ is\ kHz.\)
Subcarrier Spacing	Local	15 - 120 kHz	In 5G NR, subcarrier spacing of 15, 30, 60, 120 KHz are supported. Subcarrier spacing \(= 15kHz\ (µ\ = \ 0)\) Subcarrier spacing \(= 30kHz\ (µ\ = \ 1)\) Subcarrier spacing \(= 60kHz\ (µ\ = \ 2)\) Subcarrier spacing \(= 120kHz\ (µ = 3)\ \)
Bandwidth PRB	Local	180 - 1440 kHz	The PRB bandwidth is dependent on numerology (μ) as shown below. \(Unit\ = \ kHz.\) Bandwidth\(= 180\ kHz\ (\mu = 0)\) Bandwidth\(= 360\ kHz\ (\mu = 1)\) Bandwidth\(= 720\ kHz\ (\mu = 2)\) Bandwidth\(= 1440\ kHz\ (\mu = \ 3)\)
Slot per Frame	Local	10, 20, 40, 80	This represents the number of slots in a frame and is a non-editable parameter. NetSim determines the slots per frame, based on the selected numerology, in the following way When μ= 0, a subframe has only one slot, and frame has 10 slots. When μ= 1, a subframe has 2 slots, and a radio frame has 20 slots. When μ= 2, In this configuration, a subframe has 4 slots in it, it means a radio frame contains 40 slots in it. When μ= 3, In this configuration, a subframe has 8 slots in it, it means a radio frame contains 80 slots in it.
Slot per Subframe	Local	1, 2, 4, 8	This represents the number of slots in a sub-frame and is a non-editable parameter. NetSim determines the slots per sub-frame, based on the selected numerology, in the following way When μ= 0, a subframe has only one slot When μ= 1, a subframe has 2 slots. When μ= 2, In this configuration, a subframe has 4 slots in it. When μ= 3, In this configuration, a subframe has 8 slots in it.
Slot Duration (:math:`mathbf{mu s}`)	Local	1000, 500, 250, 125μs	Slot duration is a non-editable parameter that depends on numerology selected. μ= 0, Slot Duration = 1000 μs μ= 1, Slot Duration = 500 μs μ= 2, Slot Duration = 250 μs μ= 3, Slot Duration = 125 μs
Cyclic Prefix	Local	Normal	If the cyclic prefix is set to "normal" then the number of symbols per slot is 14, if it is set to "extended" then the number of symbols per slot is 12. All carriers have the "normal" option while only certain carriers have the "extended" option.
NOTE: Cyclic Prefix is Extended only for few CA types.
Overhead (%) per DL slot	Local	0.01-0.99	This represents the fraction of symbols in a slot used for control signalling. The remaining fraction is used for data transmission. In NetSim calculations are done over aggregated PRBs per the formula given below: Data PRB available = Total PRB available - Ceil(Total PRB available×Overhead Fraction) DL Fraction range 0.01 to 0.99 Default: 0.14 for FR1, 0.18 for FR2
Overhead (%) per UL slot	Local	0.01-0.99	This represents the fraction of symbols in a slot used for control signalling. The remaining fraction is used for data transmission. In NetSim calculations are done over aggregated PRBs per the formula given below: Data PRB available = Total PRB available - Ceil(Total PRB available * Overhead Fraction) UL Fraction range 0.01 to 0.99 Default: 0.08 for FR1, 0.10 for FR2 In 4G Network the default value is 0.25 for both FR1 and FR2.
Symbol Duration (:math:`mathbf{mu s}`)	Local	71.43, 35.71, 17.86, 8.93	Symbol duration is a non editable paramater that depends the numerology selected When \(\mu\ = \ 0\), symbol duration = \(71.43\ \mu s\ \) When \(\mu\ = \ 1\), symbol duration \(= \ 35.71\ \mu s\ \) When \(\mu\ = \ 2,\) symbol duration \(= \ 17.86\ \mu s\ \) When \(\mu\ = \ 3\), symbol duration \(= \ 8.93\ \mu s\ \)
Antenna
TX Antenna Count	Local	1	The number of transmit antennas
RX Antenna Count	Local	1	The number of receive antennas
PDSCH CONFIG
MCS Table	Local	QAM64, QAM256, QAM64LOWSE	MCS Table stands for modulation and coding scheme Table. The selection options are QAM64, QAM 256, and QAM64LOWSE. We recommend users set the same MCS table for PDSCH and PUSCH. The appropriate CQI table setting would be as follows: For QAM64 - Table1 For QAM256 - Table 2 For QAM64LOWSE - Table 3
X Overhead	Local	XOH0, XOH6, XOH12, XOH18	Accounts for overhead from CSI-RS, CORESET, etc. If the xOverhead in PDSCH-ServingCellconfig is not configured (a value from 0, 6, 12, or 18), \(N_{oh}^{PRB}\) the is set to 0.
PUSCH CONFIG
MCS Table	Local	QAM64, QAM256, QAM64LOWSE	MCS Table stands for modulation and coding scheme Table. The selection options are QAM64, QAM 256, and QAM64LOWSE. We recommend users set the same MCS table for PDSCH and PUSCH. The appropriate CQI table setting would be as follows: For QAM64 - Table1 For QAM256 - Table 2 For QAM64LOWSE - Table 3
Transform Precoding	Local	Enable/Disable	Transform Precoding is the first step to create DFT-s-OFDM waveform. Transform Precoding is to spread UL data in a special way to reduce PAPR (Peak-to-Average Power Ratio) of the waveform. In terms of mathematics, Transform Precoding is just a form of DFT(Digital Fourier Transform).
CSI REPORT CONFIG
CQI Table	Local	Table1, Table2, Table3	The CQI indices and their interpretations are chosen from Table 1 or Table 3 for reporting CQI based on QPSK, 16QAM, and 64QAM. The CQI indices and their interpretations are chosen from Table 2 for reporting CQI based on QPSK, 16QAM, 64QAM and 256QAM. This is based on 3GPP Table 5.2.2.1-2, Table 1, Table 2 and Table 3. Users must set the MCS and CQI tables in the following combination QAM64: CQI Table 1 QAM 256: CQI Table 2 QAM 64 LOWSE: CQI Table 3
CHANNEL MODEL
Pathloss Model	Local	None	In the current NTN implementation, only None is available. This is because the satellite-to-gNB link is a perfect link. It is assumed that the signal reaches the gNB without experiencing any degradation due to pathloss.
ERROR MODEL AND MCS SELECTION
MCS Selection Model	Global	IDEAL_SHANNON_THEOREM_BASED_RATE, SHANNON_RATE_WITH_ATTENUATION_FACTOR	NetSim determines the modulation and coding scheme in 5G and LTE, based on received SINR, per the following models: Ideal Shannon Theorem-Based Rate: Spectral Efficiency is computed as \[Spectral\ Efficiency\ = \ log(1 + SINR)\] Shannon Rate with Attenuation Factor \((\alpha)\): Spectral Efficiency is computed as \[Spectral\ Efficiency\ = \ \alpha\ x\ log(1 + SINR)\] Then the 3GPP standards Spectral Efficiency vs MCS Table is looked up to select the MCS. This could be the 64QAM table, 256 QAM table, or the 64QAMLOWSE table depending on what was chosen by the user.
Attenuation Factor	Global	0.5-1	Attenuation factor \((\alpha)\) takes value between 0.5 and 1 with the default value of 0.75.
BLER Model	Global	ZERO_BLER BLER_ENABLE	Block Error Rate Model (BLER) is used to decide code block and transport block error in 5G and LTE. If set to true then NetSim looks up the SINR-CBS-MCS vs. BLER tables to decide on the code block errors rate for the chosen MCS. Here MCS will be chosen as explained in the MCS selection section. If OLLA is enabled then MCS bump up/down will be based on HARQ ACKs/NACKs.
Outer loop link adaption	Global	TRUE FALSE	The Outer Loop Link Adaptation (OLLA) technique, if enabled can improve the channel quality estimation by adjusting the value of SINR by an offset dependent on whether previous transmissions were decoded successfully or not, as captured by Hybrid Automatic Repeat Request (HARQ) feedback
Target BLER	Global	0-1	The OLLA algorithm in NetSim is designed to converge the transport BLER to the set value of the target BLER. Range: 0 to 1
Propagation Model: Refer mmWave Propagation Models (Per 3GPPTR38.900 Channel Model) for technical information.
UE Properties
Interface (Service link ) – Physical Layer
Parameter	Type	Range	Description
TX Antenna Count	Local	1	The number of transmit antennas.
RX Antenna Count	Local	1	The number of receive antennas.
NTN Logs
Parameter	Type	Range	Description
NTN UE Beam Association Log	Global	Enable or Disable	The NTN UE Beam Association log file records Time, UE Pos, Elevation Angle, Slant height, Theta, EIRP, PathLoss, ShadowLoss, Additional Loss, Clutter Loss, Angular Antenna Gain, Rx Power, Interference Power, SNR, SINR, CQI, MCS Index, Associated Beam flag, measurements are logged at association and at UE mobility.
NTN Radio Measurements Log	Global	Enable or Disable	The NTN Radio measurements csv log file records Timestamp, Slant height, Elevation Angle, EIRP, PathLoss, ShadowFadingLoss, AdditionalLoss, ClutterLoss, TotalLoss, BeamFormingGain, Angular Antenna Gain, UE Rx Antenna Gain, Rx Power, SNR, SINR, and more, for each carrier on the PDSCH, and are logged every sub-frame.
NTN Resource Allocation Log	Global	Enable or Disable	The NTN Radio Resource Allocation csv log file records information related to physical resource block (PRB) allocation such as the Total PRBs, Slot Start Time(ms), Slot End, BitsPerPRB, BufferFill, Allocated PRBs, Rank (scheduling metric) and more, in the DL and in the UL. All these parameters are written in every slot.
NTN Code Block Log	Global	Enable or Disable	Records parameters associated with Code Block segmentation such as Process ID, TB size, Modulation, Code Rate, CBS, BLER, CBG ID, etc. along with remarks on events associated with HARQ and PRB allocation. This will be useful to understand BLER model and Code Block segmentation in 5G.
Satellite Properties ->Service link
CHANNEL MODEL
EIRP Density (dBW/ MHz)	Local	Editable based on the band and satellite height.	Editable based on the frequency band and satellite altitude. This parameter defines the effective isotropic radiated power per unit bandwidth.
Antenna Aperture Radius(m)	Local	Editable based on the frequency band and satellite altitude	Editable based on the band and the scenario. For the standard scenarios, a pre-calculated value is provided. The aperture radius determines the beamwidth and, in turn, the beam radius on the Earth’s surface.
Noise Figure (dB) Factor	Local	0.1 to 12 dB	Represents the receiver’s internal noise contribution. A lower noise figure indicates a more sensitive receiver capable of detecting weaker signals.
Frequency Reuse	Local	FR1, FR3	Represents the number of channels allocated per beam configuration. FR1 indicates full frequency reuse across all beams, while FR3 reduces inter-beam interference by using three distinct frequency groups.
Beam Radius (km)	Local	Editable based on the band and the scenario	The beam radius is calculated based on the frequency band, satellite altitude, and aperture radius for the selected scenario, and is defined at the point where the beam power drops to half of its maximum value (i.e., 3 dB beamwidth).
Beam Count	Local	1, 7, 19	Refers to the number of beams formed in the coverage area. A single central beam corresponds to 1. The 7-beam configuration includes one central beam surrounded by a single hexagonal ring, while the 19-beam configuration includes the central beam with two hexagonal layers of surrounding beams.
Pathloss Model	Local	Free Space	NetSim computes signal attenuation per the mean pathloss model. The option available is Free space.
Outdoor Scenario	Local	Rural Urban Dense Urban	There are three types of outdoor scenarios possible namely: Rural, Urban, and Dense Urban, as defined in the 3GPPTR38.811 standard section 6.1.2. The propagation characteristics of these scenarios are provided in the NTN Technology library manual.
LOS/NLOS Selection	Fixed	3GPPTR38.811 USER DEFINED	3GPPTR38.811-Table 6.6.1-1 The LOS mode, either Line-of-sight or Non-Line-of-sight is based on LOS probability calculated per the TR 38_811_Standard Table 6.6.1-1 User Defined LOS probability is not per standard but is based on user input. NetSim will determine whether a device is in line-of-sight or non-line-of-sight based on the LOS probability value set by the user.
LOS Probability	Local	0 to 1	LOS Probability defines the LOS mode. If LOS Probability=1, the LOS mode is set to Line-of-Sight explicitly and if the LOS Probability=0, the LOS mode is set to Non-Line-of-Sight explicitly. For, any value between 0-1 LOS mode is set per the given probability, by tossing a biased coin.
Fading and Beamforming	Local	NO FADING MIMO UNIT GAIN, RAYLEIGH WITH EIGEN BEAMFORMING	RAYLEIGH WITH EIGEN BEAMFORMING: When fading and beamforming is enabled, NetSim uses the rich scattering in the channel to form spatial channels. The number of spatial channels is equal to the number of layers (in turn equal to Min (\(Nt,\ Nr\))). The beamforming gains in the spatial channel is equal to the eigen values of the channel covariance (Wishart) matrix. When running in SISO (\(N_{t} = N_{r} = 1)\) this simply simulates Rayleigh fading. NO FADING MIMO UNIT GAIN: No fading with gain equal to unity (0 dB)
Additional Loss Model	Local	0 to 10 dB	Additional loss can be set from 0 to 10 dB to account for atmospheric and scintillation losses as per the configured scenario.
Shadowing Model	Local	None, Log Normal	Constant: A shadowing model is used to represent the signal attenuation caused by obstructions along the propagation path. The constant shadowing model is suitable for the scenarios without mobility where the obstructions along the propagation paths remain unchanged. Log Normal: The lognormal shadowing model is suitable for a scenario with mobility and obstructions within the propagation environment. In this model, the shadowing value follows a log-normal distribution with a user specified standard deviation.
Standard Deviation Selection (dB)	Local	User Defined (5 to 12 dB) 3GPPTR38.811	Shadowing is caused mainly by terrain features of the radio propagation environment. The mathematical model for shadowing is a log-normal distribution. The standard deviation can be selected from the 3GPPTR38.811 Table 6.6.2, based on the elevation angle and the chosen outdoor scenario. User Defined: users can specify the standard deviation values in the range of 5 to 12 dB.
INTERFERENCE MODEL
Downlink Interference Model	Global	None, CIR Based, Exact geometric model	DL interference options are No interference, CIR Based, and Exact geometric model. If no interference is chosen then in the SINR calculations, the value of I is set to -1000. CIR Based, the User enters Carrier-to-Interference ratio, that value is used to calculate the interference. (CIR Ratio: -20 to 20 dB) Geometric models compute the exact interference.

Table-6: GUI configuration parameters