# The Challenges and Compatibility of Mobility Management Solutions for Future Networks
## 4 Suitability of Legacy Techniques and Standards for 5G and Upcoming Networks
### LTE MM Mechanisms (3 GPP)  
The LTE MM mechanisms (concerning functionality) can further be segregated into the following subcategories: (i) offload traffic in 3 GPP, (ii) LTE-Wi-Fi accumulation, (iii) twofold connectivity, and (iv) LTE handoff. The discussion and applicability of these MM mechanisms regarding the concerned parameters are as follows.  
1. Offload traffic flow in 3 GPP The aim of traffic offloading is to support the operators so that the traffic burden may be lessened on the core network [53, 54].  
**Advantages of Offloading traffic flow in 3 GPP**  
* By this technique, the processing burden is managed on the nodes gracefully.  
**Drawbacks of offloading traffic flow in 3 GPP**  
* In the scenario of communication with a non-3 GPP network, it is a bit difficult to deploy IFOM for such coordination with a non-3 GPP network.
* An extra gateway is required by local IP access (LIPA) for its implementation.
* LIPA cannot support service continuity at the time of handoff.
* Radio resources congestion cannot be moderated with the help of SIPTO [36].
* LTE Wi-Fi Accumulation and Twofold Connectivity This user equipment (UE) can receive packets from LTE and Wifi interfaces concurrently [29, 55].  
**Advantages:**  
* This approach has the option to use multiple physical paths, as well as the characteristics to tolerate the faults [56].
* This approach also has the option for making connections with RAT of non3 GPPP as well as with 3 GPP [57].
**Drawbacks:**  
* LTE WI aggregation (LWA) is only suitable for downlink.
* LTE Handoff  
According to the context of the draft, we attained the following advantages, drawbacks, and discussion from the LTE handoff mechanism [58].  
**Advantages**  
* The handoff provision is available at the core and access network due to S1 and LTE-X2 methods.
* The CN signaling can be evaded with the help of LTE-X2 handoff metho.
* The capability of LTE-X2 allows it to decide handoff at the access network level; therefore, it provides fast handoff and reduces the processing load on the corresponding nodes.
**Drawbacks**  
* The SPOFs are introduced along with the increase in processing load on the CN.  
Owing to the mentioned discussion, the LTE MM mechanisms provide improved support concerning the extensibility criterion for 5G and future networks. They also fulfill parameters EL1 to EL4 by the features of decentralization, simplicity of incorporation, traffic offloading features, and multi-level handoff methods, i.e., S1, and X2 handover [59]. Similarly, it is evident that duplication in data routes (through DC and LWA), decentralization (through X2 and traffic offloading), and seamless handover (through X2 and S1 handover) also fulfill the criteria of dependability in parameters DL2, DL3, and DL4, respectively, as mentioned in Table 2 of Section 3. Next, for the adaptability criteria, LTE MM mechanisms provide an option of joining multiple access points simultaneously, hence satisfying parameters DL3 and FL4 for adaptability as mentioned in Table 2 of Section 3. Lastly, it also provides improved support concerning the power-saving criterion for 5G and future MM mechanisms by fulfilling parameters PL1 and PL3 mentioned in Table 2 of Section 3.