OE1: Two-Node LTE SISO

1) Experiment Overview

Experiment Definition: The user logs into one E-VM on the fixed (virtual) AERPAW Node (Machine #1) and one E-VM on the portable (virtual), or fixed, AERPAW Node (Machine #2). At the end of the experiment, the user can view logs and test results.

Experiment Scenarios Applicable: S1, S2, S3, S4, S7. These scenarios correspond to various different user experimentation scenarios in AERPAW. 

Experiment Goals: The main goal of this experiment is to provide a complete end-to-end LTE network, using OAIENB and srsUE.

Experiment Modes: Different modes offered in this experiment are TESTBED and EMULATION. The EMULATION mode is performed in the development environment by the experimenter. The experimenter can modify the code. In TESTBED mode performed by the operator the transmitter and receiver are connected to a USRP B205mini and the transmission and reception occur over the air. 

Most Common Configuration Parameters:

• Eutra_band (frequency band, line 32): this sets the frequency band of the transmission for 3GPP supported bands.

• Downlink_frequency (line 33): The selected frequency for the downlink transmission.

• Uplink_frequency_offset (line 34): The uplink center frequency is set based on its offset from the downlink frequency. For band 7, the standard is -120 MHz. For band 22, the standard is -100 MHz.

• N_RB_DL: (Bandwidth, line 36): LTE system bandwidth, configured as resource blocks: supported values are 6 resource blocks for 1.4 MHz system bandwidth, 15 for 3 MHz, 25 for 5 MHz, 50 for 10 MHz, 75 for 15 MHz and 100 for 20 MHz

• Att_tx (sets the tx gain reduction of variable PA in the USRP in the range of 0 to 89 for B series, 0 to 30 for X310, line 224): The default value is the maximum gain of the device. Setting this parameter will reduce the gain by this parameter. Ie. if att_tx = 30, the actual tx gain of a B205 will be ~59.

• Att_rx (sets the rx gain reduction of variable PA in the USRP in the range of 0 to 89 for B series, 0 to 30 for X310, line 225): The default value is the maximum gain of the device. Setting this parameter will reduce the gain by this parameter. Ie. if att_rx = 30, the actual rx gain of a B205 will be ~46.

2) Performing the Experiment:

2.A) Choosing the Experiment Mode

Machine #1

LTE Base Station (eNodeB or eNB) configuration

We assume the Base Station is a fixed node. Login to the E-VM corresponding to the fixed node. Navigate to the folder containing all the Radio scripts:

$ cd /root/Profiles/ProfileScripts/Radio 

Copy the OAI EPC & eNB script as startRadio.sh:

$ cp Samples/startOAI-SISO-EPCandENB.sh startRadio.sh 

Use an editor to uncomment the line  /Radio/startRadio.sh in /root/startexperiment.sh and run the following command:

$ /root/startexperiment.sh  

Machine #2:

User equipment (UE) configuration

We assume the UE is a portable node. Login to the E-VM corresponding to the portable node. Navigate to the folder containing all the Radio scripts:

$ cd /root/Profiles/ProfileScripts/Radio 

Copy the OAI EPC & eNB script as startRadio.sh:

$ cp Samples/startOAI-SISO-UE.sh startRadio.sh 

Use an editor to uncomment the line  /Radio/startRadio.sh in /root/startexperiment.sh and run the following command:

$ /root/startexperiment.sh  

3) Modifying the Experiment Configuration Parameters:

Script Parameters:

• EXEC_PATH: Path to the OAI eNB executable, lte-softmodem.

• CONFIG_PATH: Path to the OAI config file.

To modify configuration parameters, the user should navigate to /opt/openairinterface5g/ci-scripts/conf_files/ and modify the configuration file to be used. The default selected is enb.band7.tm1.100PRB.usrpb210.conf. Common configuration parameters and their approximate locations in the configuration files are listed above under "Most Common Configuration Parameters".

4) Results:

Results can be viewed by executing the following commands:

4.A) Ping Results:

The UE will search for a cell at the specific frequency. The experiment generates timestamped measurement log under the /root/Results folder. Once it finds a cell, it will initiate the attachment processes and once attached, the data sessions can be established. Example results using ping are shown in Figure 1.

4.B) IPERF Results:

The UE will search for a cell at the specific frequency. The experiment generates timestamped measurement log under the /root/Results folder. Once it finds a cell, it will initiate the attachment processes and once attached, the data sessions can be established.