Evaluation of Outage Probability in Two-Tier Open Access Femtocell Networks

In wireless network, providing good indoor coverage has become a great challenge for operators to meet the requirement of high speed data services. These services will help the operators to maintain the customer base and increase the revenue. User deployed femtocell has provided the much needed and less expensive solution for indoor coverage. Sharing all available spectrum between femtocell and macrocell network leads to the efficient utilization of the spectrum. However, this could result in much higher interference power. Also, deployment of femtocells in an unplanned manner make the statistical analysis of two tier network difficult. In this paper, we take into account the random deployment of femtocells and derive a semi-analytical expression for the outage probability of a typical user in the network. This is analogous to the cumulative distribution function (CDF) of downlink signal to interference ratio (SIR). To limit the interference power, we consider open access femtocell deployment scenario where users associate with the base station (BS) from which they receive maximum power.