Transferring data: choosing networks
This page looks at various options for data transfer, to help you decide what is feasible for your project.
In many remote areas there is no network coverage of any kind. Data can still be collected using mobile technology, and can then be transferred to a central computer using a cable conenction or USB memory stick. The disadvantages are that the mobile devices or USBs need to be brought to the central computer frequently, and there is a risk that data could be lost before this can be achieved.
For example, a community-based monitoring initiative in Ethiopia, in the UNESCO Kafa Biosphere Reserve, used smartphones and Open Data Kit forms to collect 755 observations of forest change, as well as photographs. If the monitors could connect remotely, they transferred their data using GPRS (General Packet Radio Service - typically very slow), but could also transfer data using local wi-fi or USB if necessary.
A local network, such as is used in offices to connect to printers, does not require mobile or internet networks. Instead it requires a local computer network which smartphones can connect to. Once the data is stored on the local network, it can then be externally transferred, once the computer connects to an internet network. The disadvantages of this approach, as with no network connection, are the need for all monitors tobring data to a central laptop, or for this laptop to go around the entire project site frequently; there is a risk of data being lost before it can be transferred.
For example, this solution was used in the Chico Mendes Extractive Reserve. Every month the project manager travelled around the Reserve (1,000,000 ha) with a laptop and met the 42 monitors at designated sites and times to transfer the smartphone data using the local network. The project manager then went back to the main office, where there was internet access, to share this data externally.
Using short wave radio takes advantage of the fact that this is often an important communication tool in many forest communities. While this is much cheaper than internet networks, there are lower data bandwidth limits that reduce the complexity of data that can be sent.
For example, the Suruí Forest Carbon project in the Brazilian Amazon is currently trialling short-wave radio as a method for sharing new data collection forms and collected data. There is no mobile or internet coverage in the Indigenous Territory, so most data so far has had to be physically taken to the nearest town to be uploaded.
Mobile networks can be used to send data either by SMS (text message) or HTTP (mobile internet). However, there is a limit to the size of data that can be efficiently transferred using mobile networks.
For example, the RuaiSMS initiative in Borneo, Indonesia, enables people in forest communities to become citizen journalists, using basic mobile phones to send SMS alerts to a local TV station. These can then be edited and sent out to subscribers to the TV station newsfeed, reaching a wide audience very quickly. The citizen journalists share news on forest incursions as well as health and social issues.
It can be very expensive to install internet, particularly where reliant on satellite internet. This can also be subject to the vagaries of tropical weather. Ongoing upload and download data costs can also be significant.
For example, the Ashaninka in Brazil are using the Sapelli app to collect data, which they then transfer using an existing community internet connection. This is part of a new initiative under development to monitor illegal incursions into their Indigenous Territory. The internet connection is unstable but has proved sufficient so far. In addition, ExCiteS is developing an automated transmission system to transmit information via encrypted SMS.
Flexible systems take account of the fact that network connectivity in many remote areas can be unstable, slow or expensive.
For example, the Sapelli platform has a data transmission system especially for these circumstances: it can submit data via binary, compressed SMS messages, or by HTTP via mobile or wi-fi networks. This flexibility supports data submission in remote areas in tropical forests where mobile or wi-fi networks are not available. The Sapelli Data Sender App automatically checks for connectivity and, based on the available networks and bandwidth, the data is transmitted by SMS or HTTP. Data sent by SMS is compressed and sent to another smartphone with Sapelli installed. Received data can be exported from the smartphone or transferred to the cloud.
The ExCiteS team developed Sapelli and use it in various projects, including Congo and Brazil.