Sensing or transmission: Causal cognitive radio strategies with censorship
Artikel i vetenskaplig tidskrift, 2013

This paper introduces a novel opportunistic transmission strategy for cognitive radios (CRs). The primary user (PU) is assumed to transmit in a time-slotted manner according to a two-state Markov model, and the CR is either sensing, that is, obtaining a causal, noisy observation of a primary user (PU) state, or transmitting, but not both at the same time. In other words, the CR observations of the PU are censored whenever the CR is transmitting. The objective of the CR transmission strategy is to maximize the utilization ratio (UR), i.e., the relative number of the PU-idle slots that are used by the CR, subject to that the interference ratio (IR), i.e., the relative number of the PU-active slots that are used by the CR, is below a certain level. We introduce an a-posteriori LLR-based CR transmission strategy, called CLAPP, and evaluate this strategy in terms of the achievable UR for different PU model parameters and received SNRs. The performance of CLAPP is compared with a simple censored energy detection scheme. Simulation results show that CLAPP has 52% gain in UR over the best censored energy detection scheme for a maximum IR level of 10% and an SNR of -2dB.

Spectrum utilization

missing observation

opportunistic spectrum access


spectrum sensing

interference ratio

hidden Markov model


cognitive radio



Kasra Haghighi

Chalmers, Signaler och system, Kommunikation, Antenner och Optiska Nätverk

IEEE Transactions on Wireless Communications

1536-1276 (ISSN)

Vol. Submitted


Informations- och kommunikationsteknik





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