# The Challenges and Compatibility of Mobility Management Solutions for Future Networks
## 5 Recent MM Techniques and 5G Architecture
### MM Mechanisms and 6G Network  
We provide a short analysis in this section by observing Sections 5.1 and 5.2 along with the issues of state-of-the-art MM mechanisms for incorporating a 6G network. We also highlight prospective research areas for MM in 6G networks. In a 6G network, the NFV and SDN will offer the tools to provide the programmability aspect of the meta-surfaces, which will be rigorously tested in handoff situations [110]. The current networking paradigms allow for a time interval of 1-12 milliseconds for executing any programmability job (delay limitations, as stated in current 5G networks [8], for most of the services), but 6G networks will allow making more and more surfaces to be softwarized and orchestrated. In particular, as the number of surfaces/network nodes grows, more data must be administered to make suitable programmability decisions. These decisions must then be disseminated (orchestrated) to many network nodes (including meta-surfaces) to complete the task. As a result, the network programmability concern suffers from delay constraints.  
Further, while meta-surfaces give the operator more freedom to program, that creates difficulty in handling SDN areas, NFV orchestration, and associated signaling. As a result, the current state-of-the-art SDN and NFV processes will fail in terms of effectiveness and compactness. It is also pointed out that the backhaul capacity will provide a substantial design problem because VLC technology can transfer data at a speed of more than 1 Terabyte/sec. The present backhaul systems are incapable of supporting large bandwidths [16]. Hence, it is vital to emphasize that the network will include mmWave, 4G-LTE Apps, VLC, and drone-based APs, which are the primary reasons for the additional complexity.  
Furthermore, edge clouds offer low-latency access to cached material and planned resources; hence, deployment options will need to be reconsidered [111]. Reconsideration of the substantial limitations in existing state-of-the-art mechanisms for 6G networks and the essential publications in the field of 6G approaches [112; 113; 111; 91] will open the following research areas.  
Selection of efficient RAT and AP, especially when both (UEs and APs) are mobile
2. Selection of efficient RAT and AP, especially in a programmable situation
3. Construction of a solid heterogeneous RAT approach, similar to the 4G/5G idea, given mmWave and Terahertz technology and their associated coverage issues
4. Approaches for handling the massive increase in the number of messages during the handoff process, especially, at the time of handoff
5. The consideration of dependability and handling of VLC links for MM mechanisms
6. The impact of handoff on VLC, drone-based communication, and programmable scenarios
7. The configurable setting permits the selection of optimum AP and RAT choices.
8. The depiction of the computational complexity of optimizing methodology for user association.  
It should be noted that the above-mentioned (Section 5.3) discussion is not complete in respect of 6G but is indicative of what portion of the MM mechanism in 6G networks needs to be explored for further research potential. Therefore, through the provided qualitative analysis, we uncover the hidden challenges (gaps) and solutions by researchers in the design aspects of 5G and future MM mechanisms, especially in the 6G network, in the following text (Section 5.4).