Modem

XO+Modem Adviser: Michail Bletsas, Development: Ankur Verma see more templates or propose new

Internet Connectivity using Mobile Technologies (3G, GPRS, CDMA)

Motivation

These different technologies use the infrastructure of mobile telephone networks. Recently there has been a boom in the development of these technologies as exemplified by the following facts:

• Tanzania: The deployment of the 3G network by Vodacom, deployment of CDMA 800 networks by TTCL and Zantel, deployment of CDMA 450 network by BOL. Excerpted from [1]

• India: This is the only option for users in rural areas where no other means of broadband Internet are available. GPRS Enabled Cell Phone costs around $10 p.m., Some vendors charge about $0.025 per megabyte. Excerpted from [2]

• Beijing: 6-month plan costs RMB650 and an annual plan that includes a high-end GPRS modem costs RMB2400, which can work anywhere in China. Excerpted from [3]

• Finland: GPRS will be suitable option in the rural areas for offering the Internet connectivity in the near future. Excerpted from [4]

XO Internet Connectivity using Franklin CDU-680DOrA Mobile Broadband USB Modem

The following steps are needed to have this modem working with XO:

1. Insert the modem into any USB slot on XO. The device will be shown as a removable storage.

2. Copy [5] to /home/olpc/ folder on XO using

cp -r cdmamodem.zip /home/olpc

Please See: If you are copying these files in different path (other than /home/olpc ), you need to change DPATH variable in modemXO script.

3. Unzip it using

unzip cdmamodem.zip

4. Run modemXO script using

bash modemXO or ./modemXO or bash /home/olpc/cdmamodem/modemXO

Please Note: Necessary Packages will be installed by the script modemXO automatically

• Wvdial : wvdial-1.54.0-5.2.2.1.i386.rpm
• PPP: ppp-2.4.4-2.i386.rpm
• Libwvstreams: libwvstreams-4.2.2-3.fc7.i386.rpm

5. Using command

route -n

You can test that ppp0 is added as an interface. If it is there, you can start using Internet on XO!

Working setup

XO Internet Connectivity using AT&T USBConnect 881 Sierra Wireless USB Modem

This modem does not work with 2.6.22 (and earlier) Kernel release versions. You can check it by typing uname --r at the console.

If you are running 2.6.22 or earlier versions, you have to go through following steps to update your kernel:

1. Download the kernel rpm from [6]

2. Install the rpm using following command

rpm -ivh kernel-2.6.25-20080619.1.olpc.0.i586.rpm
cp -a /boot/* /versions/boot/current/boot/

3. Reboot your XO which will automatically install the new kernel.

4. Load usbserial and sierra module using

modprobe usbserial
modprobe sierra

5. Now copy this [7] configuration file for the modem on your XO and run following command:

wvdial --config sierraconfig.txt

Troubleshooting

• In case if you receive output "Cannot open /dev/ttyUSB0: Device or resource busy", you should run kill -9 -1 on XO to kill all pre-existing services utilizing modem.

• In case you were initially connected to other network, you might need to add the DNS address manually to /etc/resolv.conf file as nameserver <DNS address> to connect to internet.

• You need to have wvdial installed on XO. As its not provided by default, you have to download and install it using yum -y install wvdial

How to share internet among other XOs

If one XO is setup as Mesh Portal Point (MPP), other XOs can access internet with its help.

Following steps are needed to make XO with a modem work as MPP. (These commands need to run on the XO connected to modem to be setup as MPP)

1. Follow either of the above mentioned steps so that XO with modem is able to connect to Internet.

2. Type these commands at the terminal.

ifconfig msh0 up

3. Copy [8] this file to your XO and run this command:

sudo python mpp.py msh0 meshready ppp0

4. Check the channel to which this XO is connected using either command:

olpc-netstatus or looking into Sugar UI as Mesh Network #Channel_Number

The following commands need to be run on the XO that should access the internet through MPP setup above:

1. Connect to the above channel using Neighborhood view on XO.

2. Start using internet!

Please See: You can check by running command olpc-netstatus and checking the DNS server which will be the same as IP address of the XO with modem.

Work in progress here

Working on finding a generic way of interfacing most modems with XO

Acknowledgments

• Michail Bletsas - (my adviser) providing valuable guidance and support.
• Thanks to Yanni for his valuable inputs during the development.

Contact

Contact Ankur Verma through -

Email : ankur at laptop org

IRC : ankur on #olpc #sugar