cast MAC management message, based on which the serving BS may update the MS context to include the CSG femto BS list that the MS may belong to. On reception of a mobile scanning interval request message by the serving BS, the BS responds with a mobile scanning interval response message granting or refusing the MS scanning interval request or a different interval and further containing the list of recommended neighbor base stations by the serving BS. Following receipt of the mobile scanning interval response CHAPTER 4 IEEE 802. 16m System Operation and State Diagrams message granting the request, the MS scans for one or more neighbor base stations and may attempt to select the cell and associate with that cell through completion of the Access State procedures. The MS scans all the recommended neighbor base stations identified in mobile scanning interval response message and sends a report to the serving BS at the end of the scanning interval via a mobile scanning interval report management message. The OSG femto base stations operate similar to macro base stations when paging an MS. Depending on network topology, a femto-cell or a macro BS may be assigned to one or more paging groups. The overlay macro BS and the CSG femto BS may share the same paging group identifications. In addition to the normal operation mode, femto base stations may support low duty operation mode in order to reduce interference in neighbor cells. As shown in Figure 4-24, the low duty operation mode consists of available and unavailable intervals. During an available interval, the femto BS may become active on the air interface for synchronization and signaling purposes such as paging, ranging, or for data transmission opportunities for the mobile stations. During the available interval, the femto base station may become active on the air interface for activities such as paging, transmitting system information and synchronization signals (see Figure 4-24), ranging, or user data transmission. During the unavailable interval, the femto base s