## 2 Background
### Mobility Management in Future Wireless Networks
Furthermore, 6G is expected to support higher speeds than 5G, catering to applications like hyper-fast downloads and next-generation transportation systems [19]. It is also expected to leverage Ultra-Dense HetNets to increase network capacity and improve coverage, especially in urban areas. The high bandwidth and low latency of 6G are expected to enable the widespread adoption of drones for various applications such as delivery services, infrastructure inspection, and public safety. Also, they could be used as movable cells to  
Figure 1: Some critical functionalities of Mobility Management in wireless networks. support unexpected gathering scenarios that put the network in an overloaded state or provide coverage to zones in which temporary coverage is needed [20]. Thus, MM requires further development to cope with the demands for more efficient handover techniques and optimized resource allocation. This will give the ability to manage the applications in real time and handle various cell types within Ultra-Dense HetNets, high mobility speed users, and unique mobility patterns of drones. While MM struggles with seamless connectivity, congestion cases in some or all cells of the network can turn the cells into an overloaded state. This significantly disturbs the network effectiveness, therefore increasing HO delays and RL failure when a UE moves from one cell to another. During an overloaded state, congested cells (close to the UE) may not be able to accommodate new connections efficiently. The UE might need to wait longer for the overloaded cell to accept the handover request, leading to disruptions in service. Moreover, if the overloaded cell consistently rejects handover requests due to insufficient resources, it can result in a higher RL failure rate, indicating an unsuccessful handover. This can force the UE to connect to a farther, less congested cell, impacting performance [21]. On the other hand, when a UE cannot connect to the closest cell because of overload, it might connect to the second closest cell if it is available and not overloaded. However, this \"second closest cell\" might also be overloaded due to increased traffic received from the UEs rejected by the first overloaded cell. This creates a cascading effect, where an overloaded state in one cell can cause an overload in neighboring cells. This also contributes to the \"closest loaded cell\" problem. UEs might prioritize connecting to the closest cell, even if it is overloaded, due to a shorter signal path and potentially lower power consumption. This further exacerbates congestion in the overloaded cell and increases the likelihood of RL failure rate. The overloaded cells struggle to handle the high volume of data traffic from numerous connected UEs. This can increase the packet loss rate due to insufficient resources in the overloaded cell, resulting in missing information and disruptions in services like video streaming or video calls [22]. Understanding the negative impacts of congested cell scenarios boosts the necessity of developing MM strategies to mitigate that impact and ensure efficient handovers, resource allocation, and overall network performance. Sharing the load partially with the neighboring cells that have the lowest load among the surrounding cells could reduce the negative impact on network performance. Therefore, this article proposes a DDLB algorithm that reacts periodically on the cell that is relatively loaded compared with its neighboring cells, taking into consideration the importance of achieving the seamless connectivity and optimal user experience promised by future wireless networks. The algorithm shows valuable enhancements in the network performance when compared with a standard network performance. It is achieved by reducing the number of failed attach attempts of UEs while establishing a connection with the network with the best available cell, minimizing the number of HOF rates, maintaining the lowest PP effect rates, and ensuring lower periods of OL states.