Trunk-resource-efficiency-controlling soft handoff based on fuzzy logic and gradient descent method

This paper proposes a strategy for controlling trunking resource efficiency (TRE) in a soft handoff area (SHA) by adapting the weights of all the assigned human-oriented rules with Sugeno´s fuzzy inference model. The inputs for the fuzzy process are the number of remaining channels of the base station (CH_rm) and the number of active sets´ pilots for each mobile station (no_BS). The outputs are the new values of soft handoff (SHO) thresholds (T_ADD, T_DROP) of the mobile station. In addition, adaptive SHO thresholds using the classic gradient descent method are also proposed. The results show that for certain values of assigned TRE in SHA with a given erlang traffic load, TRE can be controlled to be close to a certain defined value with errorsin range of 7%. The proposed algorithm is also compared with the case of SHO using the fuzzy inference system (FIS SHO) with no control, IS-95A SHO and IS-95B SHO