Power Control Algorithm with Active Link Protection for two-tier femtocell Networks

Femtocell is a promising cost-effective technology for enhancing indoor coverage with high-rate data. However, femtocell base station (FBS) is controlled by terminal users, the bursty interference caused by femtocell will greatly degrade the Quality of Service (QoS) of macrocell users (MUEs), and even cause their communication interrupt. To address this problem, this paper investigates a suite of distributed power control algorithm with active link protection in two-tier femtocell networks. First, MUE collects the pilot signal power strength of FBSs at predetermined time interval to judge the presence of nearby femtocells. Second, MUE chooses an access channel (AC), and then initializes the protection margin of the signal to interference plus noise ratio (SINR) and transmitted power for this AC according to the above judgment. Finally, MUE and femtocell users (FUEs) update their transmitted power synchronously by the modified distributed power control based on active link protection (DPC/ALP) algorithm to maintain their QoS. Numerical examples show that the proposed scheme can be effectively applied in two-tier femtocell networks, and provide an acceptable admission speed and an effective QoS protection for both MUEs and FUEs.