\(H(H_0/H_1)\)

Hypotheses (absent/present)

\(\tau _s(\tau _s^{con}/\tau _s^{prop})\)

Sensing time slot (in the conventional nonsequential approach/ in the proposed sequential approach)

\(\tau _r(\tau _{r,SU}/\tau _{r,CH})\)

Reporting time slot (reporting time slot at the SU/CH)

\(P_{f,k}^{con(0)}\)

Probability of false alarm in the conventional nonsequential approach with no relay at the kth cluster

\(P_{f,k}^{prop(1)}\)

Probability of false alarm in the proposed sequential approach with a relay at the kth cluster

\(P_{f,k}^{prop(2)}\)

Probability of false alarm in the proposed sequential approach with no relay at the kth cluster

\(P_{d,k}^{con(0)}\)

Probability of detection in the conventional nonsequential approach with no relay at the kth cluster

\(P_{d,k}^{prop(1)}\)

Probability of detection in the proposed sequential approach with a relay at the kth cluster

\(P_{d,k}^{prop(2)}\)

Probability of detection in the proposed sequential approach with no relay at the kth cluster

\(P_{f, k}^{*}\)

The optimal probability of false alarm at the kth cluster

\(\lambda _k^{con}\)

Decision threshold in the conventional nonsequential approach with no relay at the kth cluster

\(\lambda _k^{prop}\)

Decision threshold in the proposed sequential approach with a relay at the kth cluster

\(P_{f,FC}^{m}/P_{d,FC}^{m}\)

Global decision under binary hypotheses at the FC, here m stands for (0, 1, 2)

\(P_t/\gamma _j/\gamma _k\)

Amplify power at each SU/ the signal to noise ratio at the jth SU/ the signal to noise ratio at the kth cluster

\(Q(\cdot)/Q^{1}(\cdot)\)

Gaussian/ inverse Gaussian tail function

\(\delta _d\)

The network endtoend delay in the conventional nonsequential approach with no relay/the proposed sequential approach with and without a relay
