Dynamic Interference Suppression for TV White Space: the Case of Thailand

Abstract

In this work, we study the problem of co-existence between the LTE (Long Term Evolution) and the Digital Terrestrial Television Broadcasting (DTTB) channel. There are three scenarios: co-channel, upper and lower adjacent channels. We use the broadcasted signal from channel 3 called ThaiPBS, the actual case of Thailand for our study where the standard of digital terrestrial television broadcasting is DVB-T2 adopting 8 MHz bandwidth, while the 5 MHz bandwidth of LTE is considered as the interference. We propose a dynamic interference suppression method for increasing spectrum usage by optimizing TV white space utilization and minimizing interference. This method adopts the protection ratio concept to suppress the LTE interference on TV receiver. We implement our proposed algorithm as an adaptive interference controller using a Radio Frequency (RF) attenuator and a Raspberry Pi board for our testbed hardware. We illustrate the effectiveness of our proposed algorithm by doing experiment using our testbed and assessing the quality of the received TV signal by adopting the Quality of Experience (QoE) assessment. In our testbed hardware, a Log Periodic antenna is used for receiving the DTTB signal, while an RF digital transmitter is used for generating a 5MHz bandwidth of LTE signal, an ultra-high frequency (UHF) mixer is used to combine both signals, then a field strength meter is used to monitor video picture quality and to analyze the spectrum. According to the experiment, our proposed method can reduce the perceived video distortion by at least 62.5% for co-channel and 87.5% for adjacent channel, while the spectrum usage is increased by 100%.