Lab 2: 4G LTE Network Emulation and Throughput Testing Utilizing ARA
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Before starting this lab, familiarize yourself with the basics of 4G network infrastructure by visiting *A Beginners Guide to Mobile Communication Infrastructure* and reading the section regarding 4G networks. To understand the platform that you will be using, read about the *ARA Sandbox Service*.

Objectives
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#. Successfully set up an emulated 4G network and simulate data traffic between the UE and EPC.
#. Conduct a throughput test on the emulated network and analyze performance.

Learning Objectives
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#. Gain an understanding of the key components of a 4G network and their responsibilities.
#. Define metrics that can affect the throughput of a network.
#. Get experience utilizing SDRs in a lab environment.

*This lab must be completed in a single sitting because the containers don’t save data once deleted.*

If you have signed up for ARA’s jumpbox, make sure that you have the RSA private key you use in the .ssh file of the machine you plan to use to work on the lab.

Procedure
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#. Log on to the ARA portal

   a. Using your school credentials, log in at ARA log-in portal.

   b. Search for “Iowa State University” in the search bar and press continue to be redirected to Okta.

#. Reserve two sandbox hosts.

   a. Go to ARA Sandbox Service and pick two machines. Any two machines in a cluster like those in the image below are a good choice. For future examples, Sandbox-Host 006 and Sandbox-Host 009 will be used.

   b. On the ARA portal, navigate to Reservations → Leases → Host Calendar 

   c. Ensure the hosts you chose are free to reserve. The image below shows Sandbox-Host-006 and 009 are available. Sandbox-Host-003 is currently reserved; see reservation details by hovering your mouse over the colored block.

   d. Create the first lease by clicking *Create Lease* next to host calendar. 

   e. You can choose a lease name. However, using *eNBLease* as the lease name is recommended to make things less confusing moving forward. The start and end date can be left blank.

   f. Use the *Site* dropdown menu and select **Sandbox**. Use the trailing numbers from *Sandbox-Host-xxx* for the device ID. For example, use Sandbox-Host-006.

   g. Leave the wireless section of the lease blank and click *Create Lease*.

   h. If done correctly with an available host the following messages will appear at the top right of the screen. 

   i. Do the same for the second lease using your other available host. Using the lease name *UELease* is recommended to avoid confusion later. For example, Sandbox-Host-009.

   j. Provide a screenshot of both of the successfully created hosts’ lease details in your lab report. To see lease details, click on the blue lease name. 

#. Create two containers. 

   a. Navigate to *Container → Containers → Create Container*.  

   b. For the first container, choose a name. It is recommended to use *eNBContainer* for the name to avoid confusion. Use the docker image *arawirelesshub/srsran:srsenb*.

   c. Fill in the *Spec* tab with the following specs:

      - Hostname: *eNB* (recommended, but you can choose)  
      - CPU: 6  
      - Memory: 8192  
      - Lease Name: *eNBLease* (or the name you chose for the first lease)  

   d. Click the up arrow for *ARA_Shared_Net* in the *Networks* tab, making sure that it moves to the *Allocated* section, then click **Create**.  

   e. If done correctly, a message saying *successfully created* will appear at the top right. It might take a few seconds for the container to get up and running. While waiting, create the second container.

   f. For the second container, it is recommended to use the name *UEContainer* and use the image *arawirelesshub/srsran:srsue_4g*.  
      For the *Spec* tab, use all the same specs except:  

      - Hostname: *UE*  
      - Lease Name: *UELease*  

   g. Provide screenshots of both of the successfully created containers’ *Overview* tabs.  
      Go to the container overview by clicking on the blue container name.  

#. Connect to containers using jumpbox.

   a. Select the *eNBContainer* and go to the *Console* tab.  

   b. Run the command ``passwd`` using a password you won’t forget (*root* is recommended), then start the ssh service using the command:  

      .. code-block:: bash

         service ssh start  

   c. Do this for the *UEContainer* as well.  

   d. Open two terminals or command prompt windows and ssh into ARA’s jumpbox:  

      .. code-block:: bash

         ssh username@jbox.arawireless.org  

      Make sure that the RSA private key you used to sign up for ARA’s jumpbox is in the *.ssh* folder on the machine you are using.  

   e. Go back to the *Overview* of *eNBContainer*, under specs a floating IP address is listed.  
      This is the IP address you will use to ssh from ARA’s jumpbox to the container using:  

      - Username: *root*  
      - Password: (the one you chose earlier)  

   f. Open another two terminals for *UEContainer* as well.  

#. Starting the EPC and eNB

   a. In one of the terminals for *eNBContainer*, run the following commands:  

      .. code-block:: bash

         srsepc &       # start EPC in the background
         srsenb         # start eNB

      .. figure:: /images/Picture1.png
      .. figure:: /images/Picture2.png

#. Starting the UE

   a. In one of the terminals for *UEContainer*, run:

      .. code-block:: bash

         srsue  

      .. figure:: /images/Picture3.png

   b. In the other terminal for *UEContainer*, run:

      .. code-block:: bash

         ping 172.16.0.1  

      This checks that you are connected to the core.  
      Provide a screenshot of your successful ping in your lab report.

      .. figure:: /images/Picture4.png

#. Running the throughput test

   a. In the terminals that are running *srsenb* and *srsue*, type ``t`` and hit enter to start the console trace.  

      .. figure:: /images/Picture5.png
      .. figure:: /images/Picture6.png

   b. In the unused terminal for *eNBContainer*, run:

      .. code-block:: bash

         iperf -s -u -i 1  

      .. figure:: /images/Picture7.png

   c. In the *UEContainer* terminal that was used for the ping command, run:

      .. code-block:: bash

         iperf -c 172.16.0.1 -u -i 1 -b 25M -t 10  

      .. figure:: /images/Picture8.png

   d. Provide a screenshot of both console traces in your lab report.  
      Typing ``t`` and hitting enter will stop the console trace. Type ``t`` and hit enter again to restart it.

      .. figure:: /images/Picture9.png
      .. figure:: /images/Picture10.png

   e. In the lab report, define the options for *iperf* used for the *UEContainer* and define the bitrate seen in both console traces.

   f. Run the command again but change the value for the ``-b`` flag to make a noticeable difference in the bitrate:  

      .. code-block:: bash

         iperf -c 172.16.0.1 -u -i 1 -b <NEW_VALUE> -t 10  

      Provide a screenshot of the console traces and the ``-b`` value you used.  

#. (Optional) Create a new UE

   a. To see the effects that distance between the UE and eNB can have on throughput:  

      - Find another *Sandbox-Host* that is further or closer to the eNB.  
      - Delete the lease for the current UE.  
      - Make a new one.  
      - Rerun the experiment.  

   b. Describe the changes you observed in your lab report.  

#. Deleting Leases

   a. Navigate to *Reservations → Leases* and use the box next to *Lease Name* to select both leases, then click **Delete Leases**.  

   b. Provide a screenshot of the empty *Leases* page in your lab report.