# A Velocity-Aware Handover Trigger in Two-Tier Heterogeneous Networks
## 1 Introduction  
For new-generation wireless systems, researchers aspire to a future with better communication infrastructure with respect to quantity and quality. A fundamental area of application for heterogeneous systems is in different real-time services requiring a high data rate in different mobility conditions with a short delay. To accomplish convergence, heterogeneous technologies are incorporated over an Internet Protocol-based (IP-based) core. Currently, Internet Protocol Version 4 (IPv4)-based centers are set up to accomplish convergence. The Internet Engineering Task Force has comprehended the disadvantages of the IPv4-based network and has proposed a switch to IPv6. The change to IPv6 cores is necessary in order to accomplish perfect convergence [1] and to assist unique Internet addresses because of the increased number of cellphones.  
These days, clients may utilize fast vehicular systems such as bullet trains. There thus exists significant enthusiasm for velocity following because of the link between velocity and handover failures (HOFs). This is because if velocity reaches a point where the time across the handover zone does not match the base handover delay, the handover procedure cannot be finished and calls will drop. On the other hand, recurrent handover is caused by the high-velocity mobility of mobile terminals [2]. The wireless access issues in rapid high-velocity mobility situations are as follows [3]: (1) Frequent handover, which generates frequent cell re-selection, communication quality degradation, and data service unavailability; (2) Doppler recurrence movement and fast fading, which causes an excruciatingly low correspondence connection rate, difficulties in handover initiation, and various handover failures; and (3) Large car body loss and multipath loss, which causes feeble intra-train signals. Usually, frequent handover brings the issue of packet loss and packet reordering.  
The consumer demands rapid data access with consistent connectivity to the best-connected network at any time, anywhere. In this way, a principal problem in high-velocity heterogeneous wireless systems is how to accomplish quick handover. Knowledge of the velocity of the user equipment (UE) represents a basic part of handover execution. Moreover, the inter-working of various wireless access technologies aims to fulfill the UE with respect to quality of service (QoS). These difficulties spur the need to utilize Media-Independent Handover (MIH). A definitive motivation behind IEEE 802.21 MIH is to provide a mobility process unattached to media by offering helpful data about the link layer and candidate networks [4]. This urges us to embrace a standout method amongst the most illustrative endeavors for mobility management. Proxy Mobile IPv6 (PMIPv6) can be used to defeat the host-based issues by supporting mobility management without host inclusion in mobile signaling.  
This paper will present consistent handover execution in view of the coordination between PMIPv6 and MIH, in light of the fact that guaranteeing consistent inter-networking of a heterogeneous network requires the flawless participation of all the layers. The rest of this paper is presented as follows: Section 2 introduces other approaches that estimate velocity and support handover performance for mobile UE. Section 3 depicts velocity observation utilizing Allan variance (AVAR) and introduces the proposed mobility management flow process. Section 4 gives a simulation configuration, scenario, and results. Discussion and concluding remarks are given in Sections 5 and 6, respectively.