An adaptive distributed coverage optimization scheme in LTE enterprise femtocells

Providing an appropriate indoor coverage is still a fundamental challenge for mobile operators, in particular for Long Term Evolution (LTE) enterprise femtocell networks. Femtocells are envisioned to be employed in indoor environments to increase the radio coverage as well as the network capacity. Deployment of a large number of femtocells to collaboratively provide more indoor coverage in an enterprise environment imposes critical challenges in the physical layer design of such a network. Clearly, the coverage optimization of enormous femtocells in a centralized manner is a very cost effective solution. On the other hand, in LTE enterprise networks, each femtocell has a local knowledge (messages received from user equipments) of its own neighbor femtocells. For the above scenario, in this paper, we propose an Adaptive Distributed Femtocell Coverage Optimization (ADFCO) algorithm in a LTE enterprise environment consisting of N femtocells. The ADFCO algorithm updates the TX power of femtocells and balances the traffic load of each user. In addition, the proposed scheme reduces unwanted handovers and decreases the coverage gaps and overlaps, while maximizes the overall system's capacity. Numerical results, supported by the modified version of the Femtocell Power management Interference Simulator (FePIS) and the realistic parameters in the ITU-R P.1238-7 standard, show that the ADFCO algorithm displays an 1.6 times improvement in the indoor coverage and 50% enhancement in the overall capacity when compared to the fixed TX power allocation scheme.