SE5: LTE Handover

This page is under active development.

1) Experiment Overview

Experiment Definition: The user logs into one E-VM on each of three fixed (virtual) AERPAW Nodes (1 core network and 2-5 base stations) and one E-VM on the portable (virtual), or fixed, AERPAW Node (1 user equipment). 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 that can perform S1 handover, using srsUE with srsENB and open5GS. The different modes offered in this experiment are EMULATION, TESTBED and applicable tests for these modes are PING, IPERF 

Mode Descriptions:

EMULATION

Base Station to Single UE Link (1 EPC + 2-5 BS PC + 1 UE PC)

Description: Two or more radio modules (on each side) send IQ samples to the channel emulator, so the channel emulator should be stated such that it can forward (selectively) IQ samples.

TESTBED 

Base Station to Single UE Link (1 EPC + 2-5 BS PC + 1 UE PC)

Description: This mode sets up an EPC, 2 eNBs, and a UE. A connection will be established. If the default configuration settings are used, the experiment runs using settings for FDD in band 22 at 20 MHz bandwidth (100 resource blocks). 

Test Descriptions:

PING

Description: Ping (latency is the technically more correct term) means the time it takes for a small data set to be transmitted from your device to a server on the Internet and back to your device again. The ping time is measured in milliseconds (ms)

IPERF

Description: Iperf has client and server functionality, and can create data streams to measure the throughput between the two ends in one or both directions.

Software version

Core Network Node: 

• Ubuntu version 22.04

• Open5GS 2.4.12

Base Station Nodes (for B205mini / B210 container): 

• Ubuntu version 22.04

• srsLTE version 23.10

• UHD 4.3.0

User Equipment (UE) Nodes (for B205mini / B210 container): 

• Ubuntu version 22.04

• srsLTE version 23.10

• UHD 4.3.0

Most Common Configuration Parameters:

• EARFCN (center frequency): this sets the center frequency of the downlink transmission for 3GPP supported bands. The uplink center frequency is automatically set, and it depends on whether the band is TDD (same uplink and downlink frequency) or FDD (uplink and downlink offset by the channel spacing)

• 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

• USRP Tx Gain (sets the gain of variable PA in the USRP in the range of 0 to 89 for B series, 0 to 30 for X310): default is 0 dBFS which has been determined for the external Tx RF front end.

• USRP Rx Gain (sets the gain of variable PA in the USRP in the range of 0 to 76 for B series, 0 to 30 for X310): default is 0 dBFS which has been determined for the external Rx RF front end and Tx/Rx isolation.

2) Modifying the Experiment Configuration Parameters:

Base Station: 

The shell scripts /root/Profiles/ProfileScripts/Radio/Samples/startSRSRAN-Handover-ENB-1.sh calls a script /root/Profiles/ProfileScripts/Radio/Helpers/startHO1ENB.sh which can be edited by the experimenter to modify the parameters of the first base station.

Similarly, the shell scripts /root/Profiles/ProfileScripts/Radio/Samples/startSRSRAN-Handover-ENB-2.sh calls a script /root/Profiles/ProfileScripts/Radio/Helpers/startHO2ENB.sh which can be edited by the experimenter to modify the parameters of the second base station. This can be repeated for extra base stations using the appropriately numbered scripts. The value of "mme_addr" in all base stations should be set to the value of IP address used to ssh into the core network container. Additionally, the value of "gtp_s1c_bind_addr" should be set to the value of IP address used to ssh into the base station container.

UE: 

The shell script /root/Profiles/ProfileScripts/Radio/Samples/startSRSRAN-Handover-UE.sh calls the script /root/Profiles/ProfileScripts/Radio/Helpers/startHOUE.sh which can be edited by the experimenter to modify the parameters of the UE.

3) Performing the Experiment:

Core Network Node: 

Open5GS Core Network configuration

We assume the core network 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 open5GS script as startRadio.sh

$ cp Samples/startOpen5GS_HO.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

Once the experiment is finished, or to make modifications, stop the experiment:

$ /root/stopexperiment.sh

Base Station Nodes: 

LTE Base Station (eNodeB or eNB) configuration

Login to the E-VM corresponding to the fixed node. Navigate to the folder containing all the Radio scripts 

$ cd /root/Profiles/ProfileScripts/Radio

Run the following commands based on the number of base station nodes being used. 

On the first base station node, copy the srsRAN SISO script as startRadio.sh

$ cp Samples/startSRSRAN-Handover-ENB-1.sh startRadio.sh

On the second base station node, copy the srsRAN SISO script as startRadio.sh

$ cp Samples/startSRSRAN-Handover-ENB-2.sh startRadio.sh 

On the third base station node, copy the srsRAN SISO script as startRadio.sh

$ cp Samples/startSRSRAN-Handover-ENB-3.sh startRadio.sh

On the fourth base station node, copy the srsRAN SISO script as startRadio.sh

$ cp Samples/startSRSRAN-Handover-ENB-4.sh startRadio.sh 

On the fifth base station node, copy the srsRAN SISO script as startRadio.sh

$ cp Samples/startSRSRAN-Handover-ENB-5.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

Once the experiment is finished, or to make modifications, stop the experiment:

$ /root/stopexperiment.sh

UE Node: 

UE configuration: 

The shell script /root/Profiles/ProfileScripts/Samples/startSRSRAN-Handover-UE.sh calls the script /root/Profiles/ProfileScripts/Radio/Helpers/startUE.sh which can be edited by the experimenter to modify the parameters of the UE.

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 srsRAN SISO script as startRadio.sh

$ cp Samples/startSRSRAN-Handover-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

Once the experiment is finished, or to make modifications, stop the experiment:

$ /root/stopexperiment.sh

4) Vehicle Movement:

In order to actually perform a handover for this experiment, some form of vehicle movement must take place. The fixed nodes in this experiment do not require any vehicle movement or planning as they cannot move. The UE is meant to be a portable node and capable of movement. Other scripts such as traffic and vehicle can be run as described here. A preplanned script that travels across all 5 Lake Wheeler Nodes (LW#) can be found here under PF4. Once configured, /root/startexperiment.sh should start all of the needed scripts.

5) Results:

Results can be viewed by executing the following commands:

5.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.