rried out by sending a MOB_MSHO-IND message to the serving BS. The MS context is terminated at the BS after a Resource_Retain_Time interval during which the MS may cancel the handover. The MS continues with the new serving BS by completing the network re-entry process. After the MS is in the Connected State, the data delivery is resumed. Figure 6-11 illustrates an example MS initiated hard handover with association level 0 [9]. 2. Fast Base Station Switching (FBSS): the MS and BS both maintain a list of the base stations (i.e., Diversity Set) that are involved in FBSS operation. An Anchor BS, with which the MS communicates, is defined in the set. However, the MS may add or drop a BS from the list using MOB_MSHO-REQ, to which the Anchor BS responds with MOB_BSHO-RSP. The Anchor BS may be changed by using handover messages or by using fast anchor selection feedback. Figure 6-12 illustrates the exchange of management messages during the FBSS operation. If association is used, the ranging procedure is performed before adding the BS to the Diversity Set. The measurements are based on Carrier to Interference-plus-Noise Ratio (CINR) calculations conducted on the pilot subcarriers in DL and UL subframes. Normal operation when MS is registered with a single BS is a particular case of FBSS with Diversity Set consisting of a single BS, which in this case is the Anchor BS. When operating in FBSS, the MS only communicates with the Anchor BS for UL and DL messages including management and traffic connections. Transition from one Anchor BS to another (i.e., switching) is performed without invocation of handover procedure. The BS supporting FBSS broadcasts the neighbor advertisement message that includes thresholds that may be used by the FBSS capable MS to determine whether the MOB_MSHO-REQ message should be sent to request changing the Diversity Set. When mean CINR of an active BS in the current Diversity Set is less than a certain threshold, the MS may send a MOB_MSHO-REQ message to request dropping this BS from the Diversity