Rural Telemedicine using VoIP and DTN


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This talk presented the paper "Rural Telemedicine Networks using Store-and-forward Voice-over-IP" at Medical Informatics Europe Conference in 2009. It presents an approach for setting up voice messaging systems for rural clinics. It is low cost and does not require fixed infrastructure or support from a telecom provider.

You can find the paper here...

Rural Telemedicine using VoIP and DTN

  1. 1. Rural Telemedicine Networks using Store-and-forward Voice-over-IP Jeremiah Scholl Lambros Lambrinos Anders Lindgren
  2. 2. Agenda <ul><li>Introduction </li></ul><ul><ul><li>Why voice messaging for rural clinics is an interesting problem. </li></ul></ul><ul><li>Connectivity in low infrastructure environments. </li></ul><ul><ul><li>Delay Tolerant Networking (DTN) </li></ul></ul><ul><li>Basic technical overview for VoIP/DTN networks. </li></ul><ul><ul><li>Architecture </li></ul></ul><ul><ul><li>VoIP- DTN tunnels </li></ul></ul><ul><ul><ul><li>Sending messages </li></ul></ul></ul><ul><ul><ul><li>Receiving messages </li></ul></ul></ul><ul><ul><li>Additional Considerations </li></ul></ul>
  3. 3. Introduction <ul><li>Telemedicine has potential to improve healthcare in rural areas of the developing world. </li></ul><ul><li>Barriers include cost, poor infrastructure and lack of computer skills. </li></ul><ul><ul><li>No connectivity to the Internet and the Public Switched Telephone Network (PSTN). </li></ul></ul>
  4. 4. Voice Messaging <ul><li>Studies in South Africa suggest store-and-forward Voice-over-IP (VoIP) has potential for rural clinics. </li></ul><ul><li>VoIP can be... </li></ul><ul><ul><li>used by those that lack computer skills. </li></ul></ul><ul><ul><li>developed relatively cheaply using open source software. </li></ul></ul><ul><ul><li>deployed without fixed infrastructure (i.e. point-to-point WiFi links) or support from a telecom provider. </li></ul></ul><ul><li>Store-and-forward services… </li></ul><ul><ul><li>operate effectively during periods of disconnectivity, </li></ul></ul><ul><ul><li>allow staff at clinics to manage interruptions more easily. </li></ul></ul>
  5. 5. Connectivity <ul><li>VoIP messaging for rural areas has been supported by point-point WiFi. </li></ul><ul><li>Challenges </li></ul><ul><ul><li>Not always possible to maintain line of sight. </li></ul></ul><ul><ul><ul><li>Distance or interference. </li></ul></ul></ul><ul><ul><ul><li>Directional antennas are somewhat expensive. </li></ul></ul></ul><ul><ul><li>Large sustainable networks may prove challenging </li></ul></ul><ul><ul><ul><li>Coordination, cost and maintenance work involved with implementing each location. </li></ul></ul></ul><ul><li>What about constructing a larger network? </li></ul>
  6. 6. Delay Tolerant Networking <ul><li>One approach for rural communication networks is Delay Tolerant Networking (DTN). </li></ul><ul><li>Messages spread through network like ”epidemics” and/or are passed like a ”baton”. </li></ul><ul><ul><li>Members of the network communicate when they are close enough for local wireless communication (using WiFi, Bluetooth etc.) or when a long range link becomes available. </li></ul></ul><ul><ul><li>Store messages from each other. </li></ul></ul><ul><ul><li>Leverage mobility. </li></ul></ul><ul><ul><li>Forward them when connected to other members. </li></ul></ul><ul><ul><li>Each act of forwarding can help messages get closer to reaching their final destination. </li></ul></ul><ul><li>Allows communication of non time-critical information between participants, even if there is never a completely connected path between them. </li></ul>
  7. 7. DTN Example <ul><li>Internet services for reindeer herders in Northern Sweden. </li></ul><ul><ul><li>Email, cached web access, and basic file and data transfer. </li></ul></ul><ul><li>Messages carried by hikers, helicopters, and other vehicles. </li></ul><ul><ul><li>Semi-random encounters and a history of previous encounters used to pass messages through the network in an efficient manner. </li></ul></ul><ul><ul><li>Messages are forwarded when there is enough probability the forwarding will help the message reach its destination. </li></ul></ul>
  8. 8. DTN VoIP Basic Technical Overview
  9. 9. Architecture
  10. 10. Sending voice mail <ul><li>User enters a ”normal” phone number. </li></ul><ul><ul><li>If connectivity is not available they can leave a voice mail. </li></ul></ul><ul><ul><li>A tunneling mechanism ”bundels” the message and stores on the local server. </li></ul></ul><ul><ul><ul><li>Example with Asterisk VoIP server. </li></ul></ul></ul><ul><ul><ul><ul><li>Externnotify() command launches external application. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The application (built on open source code) “bundles” the relevant data and places it on the local server. </li></ul></ul></ul></ul><ul><ul><li>The message is transfered from the server to the DTN network at the appropriate time . </li></ul></ul>
  11. 11. Reciving voice mail <ul><li>DTN delivers a bundled message to the destination server. </li></ul><ul><ul><li>A tunneling mechanism ”debundels” the DTN packet and places the message on the local server. </li></ul></ul><ul><ul><ul><li>Example with Asterisk VoIP server. </li></ul></ul></ul><ul><ul><ul><ul><li>Message envelope file and audio file containing the message are placed in the recipient’s incoming voicemail directory. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Voicemail notification event generated. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Waiting Indicator button lights up (if available). </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Email the voicemail to the recipient (if available ). </li></ul></ul></ul></ul></ul>
  12. 12. Additional considerations <ul><li>Calls to and from the PSTN </li></ul><ul><ul><li>Use gateway VoIP server with DTN and PSTN connectivity. </li></ul></ul><ul><ul><li>Incoming messages: Handled similarly to regular voice messaging. </li></ul></ul><ul><ul><li>Outgoing messages: Server places call and plays back the recorded voice message after someone answers the phone. </li></ul></ul><ul><li>Support for time-critical information </li></ul><ul><ul><li>Supplement with a satellite link, additional data mules etc. </li></ul></ul><ul><ul><li>Significant additional cost. </li></ul></ul><ul><li>Socio-technical considerations key for sustainability. </li></ul><ul><ul><li>Different approachs to network maintaince needed </li></ul></ul>
  13. 13. thanks [email_address]