| Popis: |
Spectrum sensing is a key function of cognitive radio (CR) to prevent harmful interference with licensed users and identify the available spectrum for improving the spectrum’s utilization. However, detection performance in practice is often compromised with multipath fading, shadowing and receiver uncertainty issues. To mitigate these effects, cooperative or multiuser sensing techniques are used in [1]–[2]. CR can detect signals in a single/narrow frequency band or multiple/wide frequency bands. In the recent past, most studies have focused on cooperative/distributive detection approaches. However, they are confined to the detection of signals in a narrow band [3]. In order to develop the opportunistic throughput of the cognitive network, a CR user must sense the signals in multiple frequency bands to decrease the sensing delay. In this paper, we propose wideband cooperative spectrum sensing schemes with multi-bit hard decision, which lead to energy efficiency and time-saving using two-stages in the spectrum sensing process. |
