Macrocell/microcell selection schemes based on a new velocity estimation in multitier cellular system

The International Mobile Telecommunications IMT-2000 system uses a microcell concept to provide multimedia services and to support an increasing number of users. However, in a microcell system, the number of handoffs is greatly increased. To solve this problem, a multitier cellular structure is proposed, in which high-speed mobile terminals (MTs) are serviced in macrocells and low-speed MTs are serviced in microcells to minimize the number of handoffs. It is important to estimate precisely the speed of the MT for the correct selection of the macrocell/microcell. We propose two macrocell/microcell selection schemes based on a new velocity estimation method in a multitier cellular system which uses the sojourn time in a microcell overlapping region. The proposed schemes have various advantages such as good performance when the MT's direction is varying, efficient user allocation to cells, quick velocity estimation capability, easy implementation, and low power consumption. We analyze and simulate conventional schemes and our proposed schemes in the Manhattan cell model, and show that the proposed schemes have better performance.