WiMAX Tutorial

Prerequisites

This tutorial series assumes you have an ​ORBIT account, have ​scheduled a session on the ORBIT test bed, are familiar with ​SSH'ing ​into the test bed itself, and are familiar with the basics of running ORBIT experiments. If you have not done these things yet, you may wish to do so before taking a look at this slightly more advanced experiment. If you are unfamiliar with or are entirely new to ORBIT, you may wish to start ​here.

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Getting Started

First, SSH into the test bed you plan on using for the experiment. For this experiment, we use ORBIT's Sandbox 4.

ssh <your_username>@console.sb4.orbit-lab.org

About the Base Station

WiMAX (related to and derived from WiFi) works by sending all data traffic through an ​Access Point called a Base Station. This is similar to how a cell phone connects to a cell tower. In fact, at one point WiMAX was used to provide mobile internet connectivity to cell phones! However, the WiMAX base station at WINLAB is special in that its operation settings can be changed to meet the needs of an experiment. This is good, because it permits tweaking of settings to conduct research. However, it also means that latest person to run experiments may have left the base station with settings that will make conducting experiments difficult. First, tell the base station to use default settings, and then reset it.

Interacting with the Base Station

The base station receives instructions from ​http get requests sent from the corresponding sandbox. For example, consider

wget -qO- http://cons-wm-01:5052/wimaxrf/datapath/config/load?name=defaults

"wget" is the command to send an http request; "-qO-" gives options for outputting the result of the request to the screen; "cons-wm-01" is the name of the base station; "5052" is the port number; "/wimaxrf/datapath/config/load" selects the subsetting "load" from the path; "?" demarcates instructions; "name=defaults" assigns "defaults" to the property "name".

Restoring the Base Station to Defaults

To restore the base station to defaults, run the following commands:

wget -qO- http://cons-wm-01:5052/wimaxrf/defaults
wget http://cons-wm-01:5052/wimaxrf/restart

After issuing the restart command, the base station will be unavailable for 2 minutes.

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Loading a Default Image

Much like it is recommended to reset the base station to default settings, it is also recommended to load up a "clean" disk image. This helps avoid conflicts with previous user settings. It can also save time manually setting up frequently-used properties.

omf-5.3 load -i wmx-tutorial.ndz -t node1-1.sb4.orbit-lab.org,node1-4.sb4.orbit-lab.org

This process may take a few minutes. When it is complete, confirm the installation by SSH'ing into the nodes and checking that the settings loaded correctly.

Manually Confirming Settings

ssh root@node1-1

Check that the drivers loaded correctly using the lsmod command. The WiMAX drivers on this testbed are of the i2400 family.

lsmod
lsmod | grep i2400m_usb

If they aren't loaded, put them up manually:

modprobe i2400m_usb

Connect to the WiMAX Network

Next, use the WiMAX Configuration Utility (wimaxcu) to connect to the WiMAX network:

wimaxcu ron
wimaxcu connect network 51

Assign an IP Address

By this point, the drivers are loaded, and the network is connected. However, the WiMAX card hasn't been given an IP address yet. Below is the recommended IP address for node 1 on sandbox 4. (Alternate IP addresses are allowed, but require additional configuration at other stages of an experiment.)

ifconfig
ifconfig wmx0 10.41.14.1 netmask 255.255.0.0 up
ifconfig

Note that the wmx0 network card now has an IP address.

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Testing Connection

Repeat the previous steps for other nodes. To test the connection between two nodes, use the ping utility, which sends packets at an IP address and checks for confirmation of receipt. Assuming that nodes 1 and 4 have already been connected:

ssh root@node1-1
ping 10.41.14.4