|Version 39 (modified by 6 years ago) ( diff ),|
This tutorial series assumes you have an ORBIT account, have scheduled a session on the ORBIT testbed, are familiar with SSH'ing into the testbed 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.
The image used for this experiment is 'baseline.ndz'. In this tutorial we will use nodes equipped with Netgear AC341u LTE dongles. The basestation is Amarisoft running on Bsc03out.
During a normal experiment using OMF, the following actions are scripted and automated. This is a look at the steps involved in something as simple as starting an LTE connection behind the scenes.
You will run the following commands on node7-1, node1-7, and node19-3 in the Grid.
After connecting to the grid console:
omf load -i baseline.ndz -t node7-1.grid.orbit-lab.org
omf tell -a on -t node7-1.grid.orbit-lab.org
- It will take roughly 60 seconds to come up.
Commands on the node
Loading the driver
By Default Orbit nodes do not configure any wireless devices so the first thing, when manually configuring the device is to load the drivers; the following 2 lines will load the Sierra wireless Netgear LTE dongle:
modprobe GobiSerial modprobe GobiNet
Connecting to the device
Control of the device is done over the serial port that is created by the driver (in this case /dev/ttyUSB1) through a sequence of AT commands and you can use your favorite serial port communication program to talk to it; in this tutorial we will use Minicom. To start to program execute:
minicom -D /dev/ttyUSB1
Managing the LTE connection
Once in minicom, one can issue series of commands to the LTE modem typically consisting of:
a.) Configure modem for pass-through mode:
It should return 1 . If it does not, run the following commands:
which will reset the modem.
You should see
c.) Connect to the basestation:
You should see
OK shortly followed by
$QCRMCALL: 1, V4
d.) Check the status of the connection:
Will return a status like:
at!gstatus? !GSTATUS: Current Time: 10049 Temperature: 42 Bootup Time: 0 Mode: ONLINE System mode: LTE PS state: Attached LTE band: B25 LTE bw: 10 MHz LTE Rx chan: 8365 LTE Tx chan: 26365 EMM state: Registered Normal Service RRC state: RRC Connected IMS reg state: No Srv RSSI (dBm): -83 Tx Power: 0 RSRP (dBm): -117 TAC: 0001 (1) RSRQ (dB): -10 Cell ID: 01A2D001 (27447297) SINR (dB): 1.6
The LTE link is established. Exit Minicom by PRESSING
Ctrl+A followed by x, then
enter to select OK option.
Testing the connection
Once the modem is connected, IP address has to be assigned to the newly created Ethernet device (in this case eth2):
The node should get an address in the 192.168.3.0/24 subnet (any existing dhcpd instance on eth2 has to be killed). Use ICMP to test connectivity with the default gateway:
root@node1-7:~# ping 192.168.3.1 PING 192.168.3.1 (192.168.3.1) 56(84) bytes of data. 64 bytes from 192.168.3.1: icmp_seq=1 ttl=64 time=44.9 ms 64 bytes from 192.168.3.1: icmp_seq=2 ttl=64 time=42.8 ms
The ping can be canceled with
Ctrl+C. More elaborate link performance test can be done by using iperf between multiple nodes that are connected to the basestation.
Reconnecting the client
Use minicom (or any other serial port program) to issue a set of AT commands to reset the connection. Commands are:
(NOTE: after the AT!reset command the minicom will display the popup window that the connection was lost- one has to wait for the pop-up to go away before proceeding)
The output should look like:
root@node1-7:~# minicom -D /dev/ttyUSB1 Welcome to minicom 2.7 OPTIONS: I18n Compiled on Jan 1 2014, 17:13:19. Port /dev/ttyUSB1, 06:02:02 Press CTRL-A Z for help on special keys AT OK AT!reset OK AT!entercnd="A710" OK AT!dxcfg=wwan,connect,11 OK $QCRMCALL: 1, V4 at!gstatus? !GSTATUS: Current Time: 58 Temperature: 28 Bootup Time: 6 Mode: ONLINE System mode: LTE PS state: Attached LTE band: B25 LTE bw: 10 MHz LTE Rx chan: 8365 LTE Tx chan: 26365 EMM state: Registered Normal Service RRC state: RRC Connected IMS reg state: No Srv RSSI (dBm): -69 Tx Power: -33 RSRP (dBm): -90 TAC: 0001 (1) RSRQ (dB): -5 Cell ID: 01A2D001 (27447297) SINR (dB): 21.2 OK
Once connection is reset, dhcp lease needs to be renewed; if there is already dhcpd session it needs to be terminated:
root@node1-7:~# dhcpcd eth2 err, eth2: dhcpcd already running on pid 2071 (/var/run/dhcpcd-eth2.pid) root@node1-7:~# kill 2071 root@node1-7:~# dhcpcd eth2 root@node1-7:~# dhcpcd.sh: interface eth2 has been configured with new IP=192.168.3.2 root@node1-7:~#
Managing the basestation
Uses rest interface to manage the BS. To set the LTE connection bandwidth to 5 MHz issue the following commands on the console (not node):
wget http://bsc03out.orbit-lab.org:5054/bscontrol/bs/1/default_cell_parameters?n_rb_dl=25 wget http://bsc03out.orbit-lab.org:5054/bscontrol/bs/1/restart
Setting n_rb_dl to 50 sets it to 10 MHz while setting it to 100 sets the bandwidth to 20 MHz. After basestatin restart, most of the clients need to be also reconnected.