Research on cell reselection criteria in TETRA

Terrestrial Trunked Radio (TETRA) is a wireless trunking system. In this paper, the cell reselection criterion of TETRA is analyzed based on a signal strength model. The criteria can be summarized as three cases: the neighbor cell offers the same service as the serving cell; the neighbor cell offers lower service or better service than the serving cell. In the case of same service or lower service, both the absolute and the relative signal strength are used in cell reselection decision, but the reselection threshold is smaller in the case of lower service than in the case of same service. Further, in the case of better service, only the absolute signal strength is utilized in cell reselection decision, which means that the mobile should stay in a base station w ith better service if possible. Based on these analyses, a set of key parameters of cell reselection criteria is given by simulation, which is a trade-off between the number of cell reselections and the delay in cell reselection. And the proposed method can be adopted by network designers to optimize the behavior of cell reselection.