now Bilal has made the statement clear that HO Hys create a Hysteresis corridor around the nominal cell border to avoid the ping pong handovers, and this HO takes place when the HO margin value is achieved.
the ericsson parameter is called “HO Hysteresis”, for instance = 6dB. It means that when the difference of RxLev between serving and neighbour exceeds 6dB, a HO is detected from serving to neighbour.
the alcatel parameter is called HO Margin, and does exactly the same.