SHOW: Novel Symmetric Design for a Hybrid Handoff Scheme in Wireless Networks

Handoff of mobile users is a challenging task for heterogeneous networks. Hard handoff (HHO) and soft handoff (SHO) are two popular schemes. There hardly exists any in-depth research dedicated to a new hybrid handoff method incorporating these two basic schemes so as to retain the advantages from both of them. In this paper, we propose a novel hybrid handoff method by allocating the available frequency bands to HHO and SHO in a sophisticated approach, which is based on mathematical combinatorial or symmetric design (SD). Due to the neat mathematical property regarding the intersection numbers (indicating the particular commonly-shared bands between each pair of cells) from block design theory, the ratio of common (or commonly-shared) frequency bands (CFBs) reserved for SHO between each pair of cells can be guaranteed regardless of the users' mobility. Hence, our proposed new hybrid scheme can be widely adopted, even in high-mobility network environments. Finally, numerical and simulation results are also studied extensively to verify the proposed hybrid handoff scheme and they demonstrate that our method can reduce new call blocking probability significantly as one of the major advantages.