Adaptive framework for data transmission over GSM voice channel for developing regions

Lack of data connectivity and ubiquity of voice network in several rural and remote areas of developing nation has encouraged the research community to build a mechanism for sending data on voice channel for low data rate application such as m-health, micro-financing, etc. Several attempts to send data over GSM voice channel have been explored in the past. The data rate for transmission varies from 100 bps to 3-4 kbps depending upon permissible error rate in different domains. The past techniques use only single voice channel from a sender to receiver and completely ignore the potential use of second voice channel from the receiver to sender. In this paper, we have examined the use of the second channel in data transmission that can significantly reduce the overhead of sending error codes in the forward channel during data transmission. We have also showed the use of this second channel as the feedback mechanism for adaptive data transmission that can adjust to the current error rate in transmission.