Handover ping-pongs: Even though handovers are carried out successfully, handover algorithms in the involved cells lead to a sequence of several handovers between a small set of cells, e.g. between two cells, in a relatively short period of time.
It is mainly based on the two notions of handover management: lazy handover for avoiding ping-pong effect and early handover for supporting real-time services.
It is mainly based on the two notions of handover management: lazy handover for avoiding ping-pong effect and early handover for handling real-time services.
Two types of unnecessary handover are defined in MRO: ping-pong handover and continuous handover.
where N1, N2, N3, N4, and N5 denote the numbers of ping-pong handover, continuous handover, too late handover, too early handover and wrong handover, respectively, and α i denotes the weight factor of N i.
Although they have outperformed in terms of number of handovers and rate of ping-pong handover, a simple knowledge database is required to overcome the unnecessary handover issues, thereby increases the complex of operations and extra cost.
Unnecessary handover ratio is defined as the proportion of ping-pong handover and continuous handover in the total handover attempts.
Some popular problems include the handover delay [13 16], the ping-pong effect, the handover procedure in heterogeneous networks [17 20], and the handover failure rate [21 24].
In [43], it is shown that by using MRNs on high-speed trains, the number of ping-pong handovers and handover failures can be significantly reduced.
