Correlation between Local Sensors in Hard Cooperative Spectrum Sensing: Beneficial or Detrimental?

In hard cooperative spectrum sensing (HCSS) for cognitive radio (CR), where local secondary users (sensors) sense whether primary users exist or not and then send decisions to the center where the final decision is made, correlation between sensors has been conventionally believed and experimentally shown to have detrimental effects on performance of HCSS. In this paper, we restudy effects of correlation and demonstrate that, contrary to common belief, the correlation has beneficial effects if the fusion rule at the center is convex and has detrimental effects if the fusion rule is concave. Further, we specially analyze the effects of correlation on AND HCSS and OR HCSS, two existing HCSS rules in the literature.