The Optimum Rate of Inter-Frequency Scan in Inter-Frequency HetNets

Inter-frequency scan (IFS) is a process carried out by the terminals to discover the small cells (SCs) in the interfrequency heterogeneous networks (HetNets) prior to offload them to the discovered SCs. The IFS has a great impact on the quality of service, the energy efficiency and the spectral efficiency in the cellular systems. In this paper, a framework is presented to model and evaluate the impact of IFS on the system performance by using the 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 trade-off in the offloading process between the power consumption and exploiting the system resources efficiently. Considering the energy consumption for performing IFSs along with the energy consumption for maintaining the uplink 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 SCs’ density, terminal’s speed and the transmit power of the SCs (SCs’ coverage).