A Review on Vertical Handover Techniques applied in Heterogeneous Cellular Networks

Global mobile data traffic reached 11.5 exabyte per month at the end of 2017, up from 6.7 exabyte per month at the end of 2016. Therefore to keep-up with this ever-increasing data demand, Heterogeneous network seams to be the most appropriate resolution. A Heterogeneous network consists of a combination of different types of nodes (small-cells and macrocells) that share coverage regions and may use different radio access technologies. Whenever a user in active connection moves from one cell to the other, the network must transfer the connection to a new cell to maintain the communication service in a process called handover. However this handover process must be seamless. Some key handover challenges and design issues for the next generation of wireless networks was discussed in this review.