Implementation of an Opportunistic Spectrum Access scheme with disruption QoS

Opportunistic Spectrum Access (OSA) is one of the models proposed for Dynamic Spectrum Access (DSA). In OSA systems, it is important to restrict the interference caused by Secondary Users (SUs) to the Primary Users (PUs). In [1], such an OSA scheme, based on residual idle time distribution of PU traffic, was proposed for a single channel system. In this paper, we suitably modify the above scheme for OFDM-based communication. We present a prototype implementation of the scheme on a GNU Radio based software defined radio (SDR) system using USRP hardware. To the best of our knowledge, this is the first prototype implementation of an OSA system which can bound the interference to PUs. We use two different Quality of Service (QoS) metrics to validate the scheme. We also show that a naive method of transmitting for a certain fraction of the mean residual idle time may lead to poor performance.