# Power Optimization in Multi-Tier Heterogeneous Networks Using Genetic Algorithm
## 1 Introduction  
The blooming of emerging technologies is becoming unified through mobile communication to revolutionize our future by integrating entire global elements: transportation infrastructures, mailboxes, light switches, humans, cars, appliances, utilities, and any other entity that might take advantage of heterogeneous connectivity [1]. Presently, the utilization of existing mobile network infrastructure is reaching its limits due to massive mobile data services and a huge increase in user elements. Therefore, the preceding enhancement to achieve an ultrahigh mobile network bandwidth in the Fifth-Generation (5G) communication is pursued through the advanced utilization of the millimeter-wave (mmWave) frequency [2]. This emerging 5G deploymentmodel can be categorized into three types, including \"Enhanced mobile broadband\", with ultimate data rates well above 1 Gbps, \"Massive Machine Type\", with highly dense levels up to one-million devices/km\({}^{2}\), and \"Ultrareliable and low-latency\" communications [3].  
However, there are several limitations, especially in achieving the optimized propagation of mmWave radio signals such as scattering, fading, time delay, multipath effects, and interference [4]. Moreover, 5G communication also contains challenges in utilizing resource-constrained devices with the forecasted specifications of high capacity and low-cost spectral efficiency. The 5G communication architecture is required to accommodate thousands of devices through reliable and acceptable links [5]. Therefore, interference stands as a major challenge in such a scenario, where all the neighboring devices are simultaneously striving to establish connectivity [6]. Due to the interference issues, 5G communication has been extensively researched to incorporate efficient interference cancellation techniques [7]. The 5G network architecture contains multi-tier heterogeneous nodes and the cell architecture, including macrocells, femtocells, picocells, and device-to-device (D2D) connectivity [8]. Similarly, the user end devices have the ability to establish multiple communication paths to distinct base stations (BSs) or access points (APs) through single or multiple radio access technologies (RATs). Therefore, the 5G multi-tier architecture demands optimum coordination between all the tiers in the network to reduce interference issues among the heterogeneously connected devices. Moreover, a higher bandwidth achievement in 5G is highly dependent on interference cancellation and spectrum power management techniques [9]. Fundamentally, the interference phenomenon occurs due to the negative interaction of signals transmitted by the other devices, resulting in the reduced specification of the wireless link, such as a decreased bandwidth, higherlatency, and low QoS [10]. Interference in 5G networks can be categorized into several architectural multi-tier elements, such as inter-cell interference, intra-cell interference, and inter-system interference. Therefore, power optimization techniques are widely researched to reduce the interference effects to achieve the forecasted higher bandwidth, reliability, and enhanced quality of service (QoS). Similarly, successive interference cancellation (SIC) is a widely researched interference mitigation technique for the maximum exploitation of the mmWave spectrum [11]. Hence, we suggest power optimization in multi-tier heterogeneous networks by utilizing SIC.  
The rapid expansion of mobile data services and the surge in the number of users is putting pressure on the current communication capacities of network infrastructure [12]. The 5G network is faced with the significant challenge of delivering low-power, more spectrally efficient, high-capacity, high-performance, and cost-effective devices [13]. It also provides dependable connectivity and a suitable interface for communication among devices in close proximity. Interference has become a significant concern in multi-tier heterogeneous networks as hundreds of devices are attempting to connect in the same environment.