a list of potential targets via a MOB_MSHO-REQ message. In the case of MS-initiated handover, the network performs target selection based on the list of potential targets provided by the MS. The Anchor DPF or serving DPF may start multicasting with all potential targets. The network sends to the MS the list of available targets for handover using MOB_BSHO-RSP or MOB_BSHO-REQ messages. If the list is void, the network refuses to accept MS handover. The targets provided by the network to the MS should be a subset of the ones requested by the MS or reported by the MS via MOB_SCN-REP. The MS must move to one of the targets provided by the network or reject the handover. The MS performs the handover or rejects it by sending MOB_HO-IND. any of the above conditions are not met, the handover is considered an uncontrolled or un-predictive handover and the QoS cannot be guaranteed. If the MS leaves the serving BS before receiving MOB_BSHO-RSP, but it succeeds to at least send a MOB_BSHO-IND message with an indication of the target BS, this is also considered an uncontrolled handover. In the worst case, the MS may suddenly connect to the target BS without any indication given to the target BS. This is also considered as an un-predictive handover. CHAPTER 6 The IEEE 802. 16m MAC CPS (Part I) the AAI_RNG-REQ message including a valid CMAC tuple, xi the BS responds by transmitting an encrypted AAI_RNG-RSP message including an STID for the MS. A drop is defined as a condition where an MS has stopped communication with its serving BS (either in the DL or in the UL) before the normal handover procedures with the serving BS are complete. When the MS has detected a drop during network re-entry with a target BS, it may attempt network re-entry with its preferred target BS by performing cell reselection procedures, which may include resuming communication with the serving BS. 6.4.4 Handover to and From Legacy Systems When an IEEE 802.16m system is co-deployed with a legacy system using the same RF carrier, the cells and their radio r