OpenVoice : Low-Cost Mobile WirelessCommunication Project For Rural Area

Based on OpenWRT

Presented byS. M.BrundhaEmbedded Systems

• Introduction• Regular Tele- communication• Open voice technologies• Projects undertaken by Govt.• Over view of open voice design• Results and discussion• Conclusion• Future Scope• References

Contents

• Telecommunication services in rural areas is very poor• Because of expensive Infrastructure, difficult terrain and

electrical problems.• So we go for Open Voice technique for mobile wireless

communication • This design combines VoIP technology and mesh ad-hoc

network implemented on embedded device with openWRT as main firmware.

• Also this technology useful in military communications, communication after disaster.

INTRODUCTION

General Tele -communication systems• Analog Tele -communication system called as Plain old telephone system.

The major components of Telephone system are :

1. Local Loop It is the twisted-pair cable that connects the subscriber telephone to the nearest

end office or local central office. 2. Trunks

They are the transmission media that handle the communication between offices.

3. Switching Offices A switching office consists of switches, in that each switch connects several local

loops or trunks and allows a connection between different subscribers

Digital Tele -communication

The voice signal is digitalized for RF transmission.

• It contains Base station system and Network Sub system• Base Station sub system includes: Base Transceiver system Base Station controller• Network Switching sub system: MSC with databases such as HLR,ELR,AUC,VLR IWF for data services

• We have 2.5 G ,3G and 4G providing voice as well as data services with their stipulated data rates .

• People in rural areas lack these services .

• Considering a situation where we have a village 54 kms away from internet there is no Tele- communication facility for that village ,we can establish a low cost Wifi link with a single hop and allow village people to make phone calls via internet .

• To link calls from one mobile to other we need to have a VOIP server.

The concept of Open Voice

• The regular approach is so complex it requires heavy infrastructure so instead we can go for open voice approach.

• This is not a new concept we are familiar with Skype and voice call etc.

• Technologies includeVOIPMesh Adhoc networkOLSR protocolOpen WRT

This is combination of wireless mesh network and adhoc which means device can communicate with other device in the radio range

• In mesh each node acts as a Relay for data transmission as in multihop network

• So the advantages is this network is self healing, self configurable, low cost implementation and scalable.

WIRELESS MESH ADHOC NETWORK

• This was originally developed for military application.• OLSR (Optimized Link State Routing) is a proaktif protocol

commonly used to build mesh adhoc network.• So the communication between the devices in mesh happens

by OLSR protocol• OLSR works using routing table regularly updated to keep

topology information so it can be used to determine path in data transmission

OLSR Protocol

• Open WRT is a wireless router different from other router s and its like a mini linux box

• This supports many softwares and other applications.• Open WRT combines with OLSR protocol and Asterisk (which is a

software it performs the operation of the BSC and MSC)• So instead of a heavy equipments we made it a software based one .

Open WRT

VOIP technology overallLet us see how we can link these technologies

• Devices should be provided with internet they need to have Zoiper application for SIP(session initiation protocol)

configuration and for voice call. When they make a call this transfers to asterisk server (SIP Server it does

switching) and then to the router.

Air Jaldi

Digital Gangetic plains in kanpur

Village Telco

Govt. Undertaken Projects

Open voice design overview• Mobile phone with Zoiper application we do the SIP configuration where we

provide the user credentials when call is made it gets directed to the Asterisk server which does the switching based on a software code avoiding heavy equipment

• Then provided to Router which directs to VOIP server (present in outside world)• Further the reverse process takes place.• The Asterisk server and the router are within the home network • Communication between them happens using OSLR protocol

Functional Diagram

Results and DiscussionThey have conducted experiment with 6 phones and have drawn the following Results

Testing Area

Mesh Ad-Hoc With OLSR

Network Traffic

Conclusion• So this is a low cost approach for mobile communication • This prototype can provided telecommunication access in the

rural areas or other application such as communication after disaster.

• communication at battlefield or search and rescue activity without service provider and not depend to infrastructure communication and electrical resources with good quality at packet loss and jitter value.

• So if we want to extend to longer distance we can make use of NOC (network operation center ) based on geographical locations

Future Scope

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Thank you