Software implementation of DVB-RCT Modulator

Abstract

Digital video broadcasting-terrestrial (DVB-T), the European terrestrial digital TV system, is becoming popular in the broadcaster community around the world. Many countries have started terrestrial digital TV broadcast and are planning to switch-off analogue broadcasts in near future. A new set of services on DVB systems would be the key to sustain its successful commercial deployment. DVB-return channel terrestrial (RCT) is a complementary standard for DVB-T which defines an interactive return channel using UHF/VHF bands. Together, DVB-T/RCT system provides a bi-directional, asymmetric, broadband wireless path between broadcasters and customers, which leads to a true terrestrial wireless interactive system. A host of interactive services are possible on such a platform including IP services. This make DVB-T/RCT a cost effective solution for providing Internet access in rural areas where the telecommunication infrastructure is not fully developed but are already covered by the terrestrial broadcast networks. In this paper, software implementation of the DVB-RCT terminal (DVB-RCTT) is presented which was carried out as a master thesis work. In conjunction with two other master theses, the goal was to develop a prototype of DVB-RCTT for testing purposes at DVB-T/RCT test-bed in Sweden. The prototype consists of a PC running GNU/Linux, a PCI DVB-T card for the receiver and a PCI FPGA board for the modulator of the RCTT. The focus of the software implementation is on the medium access control (MAC) layer of the DVB-RCTT to be executed on the GNU/Linux box. First, the MAC messaging sequences between base-station and terminal at the DVB-T/RCT test-bed were studied. A DVB-RCT MAC message analyzer was developed initially for this purpose. Based on the analysis, MAC layer for a prototype of RCTT is developed under Debian GNU/Linux OS. In order to facilitate the MAC layer communication with the RCT modulator, DVB-API is extended to the support the modulator functionality. The new DVB-RCT modulator API is implemented as a hardware independent device driver under GNU/Linux. The MAC process was tested against messaging sequences obtained at DVB-T/RCT test-bed to verify correct functionality