Now-a-days, bus is a very common means of public transport. For security reasons, many buses have video surveillance cameras installed inside them. These cameras provide passengers and drivers with an added sense of security and also supply valuable evidence during criminal investigations. However, these cameras collect and store data locally in the bus, which is then transferred to the central server at the end of the day. Due to a growing need of security, there is a requirement of a system to upload the video feed data dynamically from plying buses to the station. This project exploits the TV whitespaces for transmission of video feeds from buses to the central base station on the fly. The system consists of the following components: (1) A FPGA based SDR board to be ﬁxed on buses to collect the video feed from inside the bus and transmit it to the central location, (2) An open source software (GNU-radio) to configure and control the hardware and; (3) A MAC-layer design for effective communication strategy. The entire system has been tested in one of the labs at IIT Delhi and is undergoing pilot tests for field deployment in Madison, Wisconsin, USA.
This project initially started as a joint project of IIT Delhi and University of Wisconsin-Madison (UW-Madison). I joined the project in July 2011 and initially worked on the MAC-layer design of the system. Over the first 2 months, I explored different wireless technologies (WiFi, WiMAX, GSM, CDMA), studied their communication protocols and chose the appropriate one(s) for the project. Then, I designed the entire physical layout consisting of buses, towers and central main station along with the complete MAC-Layer protocol based on two different technologies- Distributed Polling Mechanism and Time Division Multiple Access(TDMA)(refer to paper for details). This took about 3 months. The next semester went on for implementation of the designs and by the end of Spring 2012, I successfully demonstrated the novel polling and handoffs mechanisms on USRP boards in the lab. This work was later presented at COMSNETS 2013. I went on to UW-Madison as a summer intern where I worked on modifying the OFDM design of Rice University’s WARP board to disable some subcarriers and make it suitable for TV Whitespace applications. I came back and continued it as a semester project where I completed the other component of the system- the SDR board started by my seniors, who had left by then. The entire system, once tested and assembled in lab, was transferred to UW, Madison for deployment on public buses.
Figure 1: Testing custom OFDM design on WARP boards at UW Madison