The optimum rate of inter-frequency scan in inter-frequency HetNets

Inter-frequency scan (IFS) is a process performed by the user equipment (UE) to discover small cells in heterogeneous networks (HetNets) for high data rate and boosting the spectral efficiency. It is anticipated that the role of IFS will have a significant impact on the quality of service (QoS) and the energy efficiency in the future cellular systems. In this paper, a framework is presented to model and evaluate the impact of IFS on the system performance by using stochastic geometry. The energy efficiency is derived as performance metric to obtain the optimum value of the IFS rate (optimum number of scans per unit time) by taking into consideration the tradeoff between the power consumption and exploiting the abundant frequency resources at the small cells efficiently. Considering the energy consumption for performing IFSs along with the energy consumption for maintaining the uplink (UL) transmission will help to find the optimum value of IFS rate that achieves the best energy efficiency. The analysis and results show that the optimum IFS rate depends on different system parameters such as the small cells' density, UE's speed and the transmit power of the small cells (small cells coverage).