tation does not transmit on the air interface (while this is the case in the current version of IEEE 802.16m specifi- cation, this may have some practical implications on the implementation and operation of femto base stations, constraining and prolonging network discovery and association of the mobile stations). An unavailable interval may be used for synchronization with the overlay macro BS or for measuring the interference from neighboring cells. The femto BS may enter low duty mode if there are no attached terminals and there are no terminals in the process of network entry. Figure 4-24 provides an example of normal and low duty mode operation where the femto BS transmits overhead channels such as preambles and the system information during low-duty mode to allow terminals to discover this femto BS and perform network entry or re-entry, if necessary and authorized. A sequence of availability and unavailability intervals forms a low duty mode (LDM) pattern. The default LDM pattern is the periodic repetition of one available interval and one unavailable interval. An available interval for the default LDM pattern begins with the frame including the primary preamble. The default LDM pattern parameters include available interval (in units of superframes), unavailable interval (in units of superframes), and the start superframe offset. There may be one or more LDM patterns in a femto BS deployment. The parameters of the default LDM pattern can be pre- provisioned or directly sent to the MS during initial network entry with the femto BS using the registration response message [2]. 4.6 3GPP LTE USER EQUIPMENT STATES AND STATE TRANSITIONS The Radio Resource Control (RRC) sub-layer in 3GPP LTE performs control-plane functions such as broadcast of system information related to access stratum and non-access stratum, paging, estab- lishment, maintenance and release of an RRC connection between the User Equipment (UE) and E-UTRAN, signaling radio bearer management, security handling, mobility management including UE measu