81 lines
4.9 KiB
Markdown
81 lines
4.9 KiB
Markdown
# 5G gNB Frequency Configuration
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Configuring the frequency settings for a 5G gNB involves specifying multiple parameters in the gNB configuration file. This guide outlines the necessary parameters and provides step-by-step instructions for configuration.
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[TOC]
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## Configuration parameters
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To configure the gNB with the required frequency and bandwidth, modify following parameters in the configuration file:
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### `gNBs` Section
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* `absoluteFrequencySSB`: ARFCN (frequency number) of the middle frequency of the SSB. This value must align with the NR frequency raster defined in TS 38.104, Section 5.4.3.1.
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* Steps to compute this value are provided below.
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* `dl_absoluteFrequencyPointA`: ARFCN (frequency number) for Point A, lowest subcarrier of the reference resource block (Common RB 0).
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* Steps to compute this value are provided below.
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* `dl_frequencyBand`: downlink NR frequency band number.
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* `dl_subcarrierSpacing`: downlink subcarrier spacing.
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* *Allowed values:* `0` = 15 kHz, `1` = 30 kHz, `2` = 60 kHz, `3` = 120 kHz
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* `dl_carrierBandwidth`: number of PRBs for downlink.
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* `initialDLBWPlocationAndBandwidth`: resource indicator value (RIV) of the initial BWP.
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* Steps to compute this value are provided below.
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* `initialDLBWPsubcarrierSpacing`: initial downlink BWP subcarrier spacing.
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* *Allowed values:* `0` = 15 kHz, `1` = 30 kHz, `2` = 60 kHz, `3` = 120 kHz
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* `initialDLBWPcontrolResourceSetZero`: CORESET0 index (valid configurations, based on SCS and frequency bandwith, are given in TS 38.213, Table 13.1 to Table 13.14).
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* `ul_frequencyBand`: uplink NR frequency band number.
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* `ul_absoluteFrequencyPointA`: ARFCN (frequency number) for Point A, lowest subcarrier of the reference resource block (Common RB 0).
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* **Set only for FDD configurations.**
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* Frequency separation between DL and UL channels for a specific 5G NR band is defined in 38.101-1 5.4.4-1 for FR1 bands and in 38.101-5 5.4.4-1 for FR1 NTN bands. `ul_absoluteFrequencyPointA` is calculated by substracting the given frequency offset from the `dl_absoluteFrequencyPointA`.
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* `ul_carrierBandwidth`: number of PRBs for uplink.
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* `initialULBWPlocationAndBandwidth`: resource indicator value (RIV) of the initial BWP.
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* Steps to compute this value are provided below.
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* `initialULBWPsubcarrierSpacing`: initial uplink BWP subcarrier spacing.
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* *Allowed values:* `0` = 15 kHz, `1` = 30 kHz, `2` = 60 kHz, `3` = 120 kHz
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* `subcarrierSpacing`: general subcarrier spacing for both DL and UL.
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* *Allowed values:* `0` = 15 kHz, `1` = 30 kHz, `2` = 60 kHz, `3` = 120 kHz
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### `RUs` Section
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* `bands`: NR frequency band number for RU(s).
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## Determining the ARFCN value for `absoluteFrequencySSB` and `dl_absoluteFrequencyPointA`
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Follow these steps to find the ARFCN values for `absoluteFrequencySSB`, `dl_absoluteFrequencyPointA`, `initialDLBWPlocationAndBandwidth`, and `initialULBWPlocationAndBandwidth`:
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1. Convert RU center frequency to ARFCN value
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* Example tool: [5G NR ARFCN Calculator](https://5g-tools.com/5g-nr-arfcn-calculator/)
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* Input the center frequency of the RU (in MHz) into the tool to calculate the ARFCN value.
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2. Enter parameters into the online tool for NR Point A computation
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* Example tool: [NR Reference Point A Tool](https://www.sqimway.com/nr_refA.php)
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* Enter the NR frequency band, ARFCN value for center frequency (use the value calculated in step 1), subcarrier spacing, CORESET0 index (`initialDLBWPcontrolResourceSetZero` in the gNB config file) and bandwidth into the tool.
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3. Obtain required values
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* From the tool's output, use the following results for your configuration:
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* Arfcn GSCN: This corresponds to `absoluteFrequencySSB` - value for `absoluteFrequencySSB` can be selected freely from the table, if `Coreset(0) check` is "ok".
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* Point A Arfcnc: This corresponds to `dl_absoluteFrequencyPointA`.
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* locationAndBandwidth full: Use this value for both `initialDLBWPlocationAndBandwidth` and `initialULBWPlocationAndBandwidth`.
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4. Set `dl_absoluteFrequencyPointA`, `absoluteFrequencySSB`, `initialDLBWPlocationAndBandwidth`, and `initialULBWPlocationAndBandwidth` in the gNB configuration file
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## Example calculation
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1. Convert RU center frequency to ARFCN value
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* Center frequency = 3450 MHz
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* Center frequency ARFCN = 630000
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2. Enter parameters into the online tool for NR Point A computation
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* Open the [NR Reference Point A Tool](https://www.sqimway.com/nr_refA.php) and input the following values:
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* Frequency band = n78
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* NR Arfcn scan (center frequency) = 630000
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* SCS = 30 kHz
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* Bandwidth = 100 MHz
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* Control ResourceSet Zero = 11
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3. Obtain required values
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* The tool provides following output values:
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* Arfcn GSCN (`absoluteFrequencySSB`) = 630048
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* Point A Arfcnc (`dl_absoluteFrequencyPointA`) = 626724
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* locationAndBandwidth full (`initialDLBWPlocationAndBandwidth`) = 1099
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* locationAndBandwidth full (`initialULBWPlocationAndBandwidth`) = 1099
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