You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: A Literature Survey on Handoff for Mobile IPv6 
Chapter Title:  IV. HIERARCHICAL MANAGEMENT SCHEME 
1. Abstract of Cited Paper (BIB001):  This paper proposed an inter-mobility handover management solution for proxy mobile IPv6(PMIPv6).Using the proxy binding update message between two PMIPv6 domains,the destination PMIPv6 domain was able to obtain the mobile node's home network prefix in advance,therefore,the mobility management and the reconfiguration the care-of-address performed by the mobile node could be avoided,resulting in the efficient saving in handover latency.Analysis and simulation results show that the proposed approach for PMIPv6 inter-mobility provides better performance in terms of low latency,low complexity and easiness of management,etc.,compared with the existing global mobility management protocol,i.e.,mobile IPv6 and fast mobile IPv6. 
2. Abstract of Cited Paper (BIB002):  The HMIPv6 protocol has been proposed as an improved technology of MIPv6 which has solved the problem of han-dover latency efficiently.But it didn't work as well as seamless handover that some special network services need.It's mainly because that the DAD checks of LCoA and RCoA occupied a majority of handover latency,which affects the handover performance badly.A policy of the link layer assists the network layer is proposed,and with the efficient address management,it can avoid DAD check during handover.It is proved in the simulation that the handover latency would be shortening,and the performance of HMIPv6 handover would be improved efficiently.

Literature Review:
Hierarchical Management is registered through the introduction of local management mechanism to amend At present, the level switch scheme (HMIPv6)  , the main idea of this scheme is to introduce address pool in the access router and Mobile Anchor Point(MAP), the address used in this network is stored in the address pool, eliminating the need for care-of address of the DAD operation. Adaptive Active forecast neighbor unicast handoff scheme for Mobile IPv6, it uses adaptive and active prediction algorithm, and full account of special circumstances such as ping-pang effect, it combines hierarchical mobility management approach, while uses predictive neighbor unicast, in order to reduce the network load, and reach fast smooth handoff. Hierarchical management of MAP discovery protocol BIB001 , this agreement improves MAP protocol of the HMIPv6, achieves the function that the MN chooses the MAP agency intelligently and selects the MAP discovery protocol on the router to make transparent, which is easy to promote. Switch based on PMIPv6 domain management method BIB002 , this method updates message by sending messages in PMIPv6 interdomain binding PBU, which makes switching objectives PMIPv6 domain ahead of time that the home network prefix of MN, and avoids the participation of the MN mobility management and re-configured care-of address, which is effective to reduce the handover latency. Switching HMIPv6 of improved DAD policy BIB003 , this scheme uses link layer to assist network layer switching, and adopts distribution of effective management of care-of address new strategies, in order to avoid the DAD operation during switching process. HMIPV6 is mainly disscussed and layer management MAP discovery protocol is presented simply. HMIPv6 handover process is as follows: (1)If moving locally, the MN only needs to register a new care-of address to MAP, MAP as a local home agent at this time, it accepts all the packets which are sent to the home agent , and sends to the MN's current address. (2)When the MN moves to a new MAP management area, MAP discovery operation will be conducted, and gets two care-of addresses through the access router uses stateless way: regional care-of address and link care-of address. It can be seen from the above process: In aspect of switching delay, HMIPv6 over MIPv6 switch within the domain of small, but inter-domain handover latency than MIPv6 increased slightly. In terms of data loss, HMIPv6 increased slightly more than the basic mobile IPv6. In the signaling load, HMIPv6 mechanism by introducing a locally incorporated, reducing the distance of the mobile node to home agent and the registered number of communication nodes, effectively reducing the mobile node and the MAP signaling interaction between the extra-territorial network. In the implementation complexity, HMIPv6 introduces the MAP agency, not only increase the implementation complexity, but also introduce new problems, first of all, all packets sent to the mobile node to be forwarded through the MAP agency, when the MAP agency services much more mobile nodes, it is easy to form network bottlenecks; Secondly, HMIPv6 MAP discovery protocol is not perfect, can not achieve the intelligent choice MAP agents, but also all of the routers can handle MAP option, not easy to promote. In a word, HMIPv6 in signal load increased significantly and in the switching delay and data loss slightly higher than the MIPv6. In the implementation complexity aspects, HMIPv6 introduced the MAP agency, an increase of implementation complexity and easily form a network bottleneck when there are too many Mobile Nodes and MAP protocol in HMIPv6 is not perfect. Layer management MAP discovery protocol improves the MAP discovery protocol in HMIPv6 not requiring that all access routers can identify and deal with MAP option, while increasing the scope of its adaptation, and the MN can intelligently select the MAP agency. The MAP discovery protocol maintain topology table of MAP agent found through the exchanged information between the MAP agents: the MN request a pre-configured MAP agent the MAP agent topology table, and then according the MAP proxy topology table, uses Vornoi diagram algorithm to find the nearest MAP agents, then it request to the most recent MAO for the MAP topology tables. The MN can intelligently select the MAP agency, MAP discovery the purpose that protocol is transparent to the router. The MAP discovery protocol's advantages over MAP discovery protocol in HMIPv6 is the mobile node can intelligently choose the MAP agency and make MAP discovery protocol transparent to the router, so the protocol is easy to promote; its disadvantage is that the mutual exchanging information between MAP agents is needed to maintain MAP pology table. The mobile node needs to use the new algorithm to find the nearest MAP agent. it increases the design complexity of MAP agent and mobile node and interaction load of the region signaling. The classification management programs of MAP discovery protocol is the same with HMIPv6 in terms of handover delay and data loss, more complex than MIPv6 in design. In the signaling load, it reduced less MAP signaling interaction with the load of extraterritorial than the MIPv6, and increases more MAP domain signaling exchange load.