A study of access methods effect on the performance of two-tier LTE femtocell networks

Femtocells are a promising solution for the provision of high indoor coverage and capacity. Furthermore, OFDMA-based femtocells have proven to be highly versatile when dealing with cross-layer co-channel interference; however, concerns still exist related to the impact of the different access methods to femtocells in an overlaid network. Femtocells based on a Closed Subscribers group, where only device owners are allowed to connect, introduce severe interference to microcells' users. On the other hand, Open Access femtocells where any user can connect, does not bring many advantages to the femtocell owner. In this paper, a study of the two types of access methods (Closed & Open Access) is proposed and a discussion of how to overcome their drawbacks by using the Hybrid access method is presented, which allows all users to connect but under restrictions. The performance of the model is evaluated throughout system level simulations and it is shown that Hybrid access contributes to seriously improve the performance of the whole network.