Configure NI 5G NR Test UE Parameters

NI 5G NR Test UE is used for Lab research and field trials where the below parameters need to be modified from time to time according to different test or trial requirements. This article discusses how to configure the below parameters which are the ones the end-user needs to reconfigure to fulfill the test requirements:

• Absolute Radio Frequency Channel Number (ARFCN) 
• Transmitter power
• Modulation  and Coding Scheme (MCS) 
• Number of Layers

The system key specifications of the 5G NR Test UE are listed below:

• Frequency: 3 GHz to 6 GHz 
• Subcarrier spacing: 30 kHz
• Assigned bandwidth: 100 MHz
• Resource blocks: 273 RB
• MIMO layers: 1 to 4 configurable
• Modulation: QPSK to 256 QAM 

The intended audiences are NI 5G NR Test UE users who have good knowledge of RF system, 5G NR physical layer, and 3GPP 5G NR specifications, such as transmitter power, RF spectrum, MIMO, MCS, absoluteFrequencyPointA, absoluteFrequencySSB, resource block, subcarrier spacing, modulation, and coding scheme.  

Absolute Radio Frequency Channel Number

1. Define the required operation frequency of the test UE, consider starting frequency point (defined as absoluteFrequencyPointA in 3GPP specifications) at 3.3GHz as an example.
2. Refer to 3GPP TS 38.104 version 15.4.0, Table 5.4.2.1-1, FREF = absoluteFrequencyPointA, NREF = ARFCN.

3. Find absoluteFrequencySSB from system manual, which is 22RB to absoluteFrequencyPointA, calculate the difference between absoluteFrequencySSB and absoluteFrequencyPointA: 

4. Calculate ARFCN of absoluteFrequencyPointA at 3.3GHz: 3300000 kHz = 3000000 + 15 x (NREF - 600000) kHz = 5 x NREF kHz, ARFCN = NREF = 620000.
5. Calculate ARFCN of absoluteFrequencySSB.

Transmitter Power

1. Calculate the transmitter from configured SSBPwr. From the configuration file (config_user.json), find the SSBPwr which equals the transmitted energy per resource element, for example, -3100 which means SSBPwr = -31dBm/RE.
2. Calculate transmitter power in 273 RBs: TxPwr = -31 + 10 x log (273 x 12) = 4.25 dBm.
3. Calculate the SSBPwr from the required transmitter power. Consider the required transmitter power TxPwr in 273 RBs equals 3.25 dBm. Calculate transmitter power: SSBPwr = TxPwr  - 10 x log (273 x 12) = -32 dBm.

Modulation  and Coding Scheme

1. From configuration file (config_user.json), find QAMTable value which is either 0 or 1. "0" for table 1 and "1" for table 2 of 3GPP 38.214, version 15.3.0 document in related links.

2. Consider QAMTable = 1, refer to 3GPP 38.214, version 15.3.0 document in Related Links, Table 5.1.3.1-2 shown below:

3. From configuration file (config_user.json), find MCS value, consider MCS = Imcs = 27 which means modulation order Qm = 8.
4. The modulation is 28 =  256 QAM.

Number of Layers

1. From the test procedure or design document, find the slots and layers number. Consider slot 2 and 4 layers.
2. From the configuration file (config_user.json), locate slotIdx 1 which is the index of slot 2 and NumberOfLayers.       
3. Change NumberOfLayers from 4 to 2

4. Start the system which should be operating in 2x2 MIMO in the downlink, both 4x4 MIMO and 2x2 MIMO GUI is shown below, be noted that the Throughput is some 1.3Gbit/s for 4x4 MIMO and 650Mbit/s for 2x2 MIMO: