A macro-microcellular system with mobile user speed estimation

Future cellular systems are expected to use differently sized and shaped cells, depending on the area to be covered (urban or rural) and the user density. This paper proposes a cellular system that uses a two-tier cellular scheme, with macrocells and microcells. Mobile users are grouped into two classes, "slow" and "fast" users: to estimate user speed, a procedure is implemented, based on the evaluation of the amount of time a mobile station resides in a microcell. A channel assignment strategy, which tries to allocate "slow" users to the low tier (microcells) and "fast" users to the high tier (macrocells), is proposed: in this way, low mobility users undergo handovers at microcell boundaries, and high mobility users undergo handovers at macrocell boundaries. A simulation study is carried out to show that the handover rate, as well as the system signaling load, are kept at an acceptable level.