Overlaid cellular system design with cell selection criteria for mobile wireless users

As the cells shrink and mobility increases in personal communication services (PCS), an increased number of handoff occurs overloading the signaling network. One major motivation to employ microcell/macrocell overlays is to increase the capacity without increasing the handoff rates. A cellular system consisting of two tiers with microcell in the lower-tier and multiple levels of (macro)cells in the upper-tier, is considered to separately serve mobiles with different speeds. The dimension of the upper-tier cell is approximately derived based on the mean velocity of mobiles the cell intends to serve. Finally, the effect of misusing the upper-tier resources is analyzed in terms of each tier call blocking rate.