Licensed receiver detection and authentication in simplex licensed networks

Cognitive radio (CR) technology enables the unlicensed user to access the spectrum holes left by the licensed user (LU), subjecting to a basic requirement of no interference on the active LUs. Nevertheless the LU protection can be misused by malicious CRs through emulating LUs. Observing that the real protection object is the licensed receiver (LR) rather than the licensed transmitter (LT), the research of licensed user emulation attack is dedicated to its genuine form, LR emulation (LRE) attack. Based on the analysis on all possible defense schemes, a digital signature based LRE defense system in the simplex licensed network (SLN) environment is proven practical. The defense mechanism is composed of signature design for LR authentication, as well as the design of public key infrastructure (PKI), used for the distribution of certificates for the LR signatures. With the aim to minimize the communication cost for maintaining the PKI, we propose a certification tree with LR ramification (CTLR) mechanism for certificate request and reply.