# Interference Management in Femtocells by the Adaptive Network Sensing Power Control Technique
## 2 Related Work  
Recently, there has been innovative research to design and develop multiple novel approaches, techniques and strategies for an adaptive and cognitive femtocell, used for reducing the ICI between the MUE and the femtocell. An algorithm presented in [11] mitigates the ICI in a two-tier macro and femtocell network. The power control modelled with unity function and every macro BS and femto BS, separately capitalizes its utility function by dynamically regulating the transmit power of its existing subchannels and chooses the appropriate power setting in the firefly algorithm (FA) iteration optimization technique. This algorithm provides a good tradeoff between the performance of the FUE and the MUE by fine-tuning the coefficient value of the utility function. The tradeoff is between the macrocell user's and femtocell user's performance, as discussed in [12]. The QoS of macrocell users is increased, while the QoS of the femtocell users is not degraded. HeNB and eNB decide to increase or decrease their transmission power, based on the estimated SINR (signal to interference plus noise ratio) of MUE and FUE. Fair allocation of resources in the distributed power adjustment algorithm [13] for the heterogeneous mobile network is when a BS relies on the signal power received from the adjacent BS and adjusts its transmission power. An established threshold SINR value or predetermined value for interference is not used for power tuning. The researcher presents a technique in [14] to alleviate the downlink interference of macro UE, received from the femto BS. The femto BS has the capability to sense the spectrum and obtain essential information, such as the usage of macrocell downlink radio resources and information about cell-edge MUE. The femto BS then allocates transmit power to each channel effectively, so the overall system throughput increases, while still satisfying the MUE outage constraint. The smart femto base station algorithm (FBSA) and downlink power-control algorithm (DPCA) in [15] are two techniques presented to lessen the interference between the femto BS and macro BS by using power control. The FBSA distributes femto users to the non-interfered femto BS, to bypass interference and enhance the achievable data rate. When the SFSA is unable to resolve this issue, DPCA is engaged, which improves the achievable data rate (ADR) of all femto users. A stochastic approximation (SA) algorithm proposed in [16] for downlink transmit power control in femto BS networks is based on the essential channel measurement feedback report in macrocell signaling. The femto BS can adjust the transmitted power by listening to the feedback report from the cell-edge MUE to macrocells, such as channel quality indicator (CQI) and ACK/NAK signals. This does not need any extra backhaul signaling from the macro BS. A power optimization algorithm in [17] optimizes the transmission power of the femtocell in a decentralized manner, to reduce the interference in an adjacent cell and user equipment. When applying particular schedulers such as maximum (max) and minimum (min), proportional fair, and resource fair, the optimum power enhances the average throughput of the system and its fairness and efficiency. To increase the system throughput of the femtocell, the distributed Dynamic Power Control Algorithm (DPCA) [18] is used, which dynamically regulates the downlink transmission power of the femtocell based on the feedback report received from its users. This technique can be effectively used on random network topology with minimum overhead. Cooperative optimal power control theory in [19] is used to manage interference in the femto BS. In the first phase, it measures the downlink transmit power by assuming all sub channels, while in the next phase, the selection of sub channels can be employed for an additional reduction in interference. In game theory [20], a sophisticated base transmits a power control technique, which generates opportunities to reuse the spectrum between mutually interfering femto BSs.