Coexistence of secondary user networks under primary user constraints in TV white space

Moving forward based on the current spectrum regulations and industrial standardization for unlicensed usage of TV white space, we postulate a potential deployment scenario and describe the management procedure of coexisting secondary user (SU) networks under the interference constraints to the primary user (PU) receivers. For the quantitative evaluation of coexistence we first introduce a new parameter named quality of coexistence (QoC), which is utilized to measure the benefits achieved by a novel coexistence scheme also proposed in this paper, namely, interference-constrained time slot splitting and allocation. Furthermore, on the basis of a system model we obtain the optimal SU networks time slot allocation ratios by maximizing the aforementioned QoC, therefore, leading to an efficient spectrum usage by SUs without incurring harmful interference to the PUs. Finally, we simulate a coexistence scenario in TV white space in order to compare the proposed scheme with other schemes that select a single SU network to operate based on simplistic criteria. It can be seen that when the SU network employs adaptive transmit power control (TPC), the medium value of QoC is doubled by using the optimal time slot allocation, resulting in significant improvement in coexistence.