An Underlay Control Channel for Dynamic Spectrum Access: Packet Design, Implementation, Analysis, and Evaluation

This paper presents the design and implementation of an underlay control channel (UCC) that has recently been proposed for application in cognitive radio networks. The UCC builds its waveform based on filter bank multicarrier spread spectrum (FB-MC-SS) signaling. The use of spread spectrum signaling allows one to transmit UCC at a level well below noise temperature and hence, minimize taxation on the primary users. Moreover, the use of filter banks allows us to avoid those portions of the spectrum that are in use by the primary nodes. Hence, the UCC interference to the primary network will be very close to none. We propose a specific packet for UCC and develop algorithms for packet detection, timing acquisition and tracking, as well as channel estimation and equalization. We also present analytical equations that quantify the probability of false detection (when background noise is picked as a UCC packet) and the probability of missed detection (when a packet exists, but the receiver fails to detect it). Moreover, we present the detail of an implementation of the proposed transceiver on a software radio platform and compare our theoretical results with those from experiments.