Coexistence and interference analysis in TV white spaces

Abstract

The demand for wireless connectivity is increasing exponentially resulting in an unprecedented demand on the limited radio spectrum. Due to the current fixed spectrum licensing scheme, it is becoming increasingly arduous to find extra spectrum resulting in a paradigm shift towards efficient utilization of radio spectrum in order to address the spectrum scarcity. The transition from analogue to digital terrestrial television has freed-up some spectrum thereby creating unique opportunities for exploitation of locally underused portions of the TV bands referred to as TV white spaces (TVWS) and their exploitation offers an attractive way of making efficient use of radio spectrum as long as the secondary users do not interfere with the primary users. This is enabled by employing cognitive radio technology that allows for dynamic spectrum access. This paper investigates the aspect of interference in TV White spaces and the possibility of mutual coexistence between primary users and secondary users operating in TV White spaces. The impact of interfering signals is undertaken to show the probability of interference in both same channel and different adjacent channels scenarios. The interference analysis is carried out using the SEAMCAT simulation software. Simulation results show that in a power limited secondary network, vacation of cognitive users from active spectrum bands is crucial for ensuring coexistence. The various interference mitigation mechanisms employed by CR networks are also reviewed. In TV white spaces, mitigating interference is vital not only for primary user protection, but also for ensuring the quality of service of the secondary users.