Software defined radio testbed of television white space for video transmission

Abstract

Recently, television white space (TVWS) has grabbed a lot of attention from researchers in the Cognitive Radio (CR) area. This underutilized spectrum is one of the possible solutions for spectrum scarcity problem in wireless communication. Thus, many research works have been carried out in order to find a suitable method to utilize this spectrum in an efficient manner. Nevertheless, the actual hardware implementation on utilizing this spectrum is still lacking. Therefore, in this research, an Orthogonal Frequency Division Multiplexing (OFDM) real-time video transmission is proposed using software defined radio (SDR) platform. Two modulation schemes are used namely Phase-shift keying (PSK) with its Binary-PSK (BPSK) and Quadrature-PSK (QPSK) and Quadrature amplitude modulation (QAM) with 16QAM and 64QAM modes. The free channel used in this work is selected under ultra high frequency (UHF) band based on the energy detection, which is either on channel 54 or channel 56. The proposed system is developed with the physical (PHY) layer design of the transmitter and receiver in GNU Radio and integration of medium access control (MAC) layer functionality. Video capture and display programs are designed based on OpenCV modules. The performance of this design is evaluated based on two types of environment, indoor and outdoor, with packet delivery ratio (PDR) and end-to-end delay (EED) as the performance metrics. Three types of video motion are used in the experimentation which are fast (mobile), medium (foreman) and slow (akiyo). Under allocated bandwidth of 1.0 MHz, optimal performances of PDR and EED for both scenarios are shown. In the indoor scenario, QPSK½ exhibits the best performance with 0.92 of PDR and 24.7 seconds of EED for akiyo. Meanwhile for foreman and mobile, BPSK¾ achieves the best performance with PDR of 0.96 and 0.95 and EED of 33.2 seconds and 35.0 seconds, respectively. In the outdoor scenario, the best performance of PDR is achieved by 16QAM½ with 0.9 and 23.5 seconds of EED for akiyo. For foreman and mobile, QPSK½ exhibits the best performance with 0.94 and 0.9 of PDR and 31.2 seconds and 32.5 seconds of EED, respectively. In conclusion, the proposed design exhibits promising solutions for the OFDM real-time video transmission over TVWS.