Analysis on multiple access for heterogeneous network diversity

In this paper, we analyze the advantages of multi-access (MA) systems in heterogeneous networks, where a mobile station (MS) can simultaneously access different non-interfering networks with different radio access technologies (RATs). For this analysis, we consider the following problem: How many RATs should the MS connect to? First, the beneficial aspects of MA is demonstrated by a simplified example, and then, MA methods in multi-RAT systems are investigated in terms of the spectral efficiency. Through our analysis and simulations, it is shown that usage of 2-RAT MA is enough to obtain most of the advantages of MA (i.e., network diversity). Also, MA is able to achieve an increase in spectral efficiency, which is compared to the increase obtained by vertical handoff (VHO) method. As a result, 2-RAT MA can be considered as a viable solution to get more spectral efficiency in multi-RAT systems and reduce signaling overhead, as compared to other MA scheme.