Dynamic hysteresis value for position assisted soft handover

For a wideband CDMA UMTS system, we propose a soft handover algorithm with a dynamic hysteresis value, based on the user´s position within the cell. The soft handover algorithm for UTRA is an E_c/I₀ based algorithm with fixed hysteresis values, e.g. adding/dropping/replace. We propose assigning dynamic hysteresis values to individual mobiles, depending on the geo-location of the mobile terminal (MT). The performance of the proposed algorithm is compared with those of the UTRA algorithm, by carrying out simulations in an UTRA vehicular environment with different propagation conditions (shadowing) and user mobility behaviours (velocity, probability of changing direction). The simulation results show significant improvement, in terms of call outage probability, call blocking probability, mean active set number and active set update rate, over the UTRA soft handover algorithm.