Guaranteed handover schemes for a multilayer cellular system

Two guaranteed handover schemes are designed for a multilayer cellular system in which overflow and take-back operations in addition to the geographical information are utilized to assist in guaranteeing the handover. A system model is established to illustrate these two schemes. In the system model, the cell layer with larger sized cells (CL II) overlays the cell layer with smaller sized cells (CL I). Simulation results show that overflow operation can significantly reduce the call blocking probability which is supposed to be very high for the system with Time-based Channel Reservation Algorithm (TCRA). Moreover, by taking the overflowed traffic back to the CL I, the call blocking probability in the CL I can be further significantly improved, and the overflowed traffic can be reduced remarkably. The paper shows that the take-back operation will increase the call blocking probability in the CL II, which is generally still far smaller than that in the CL I.