uration of RS operational parameters. During this process, the relay-enabled BS determines the path (i.e., access station) for this RS, based on the RS neighbor station measurements and other information such as path loading. If the current access station is not changed, the RS continues network entry with the current access station and skips the second access station selection phase. If the current access station is changed and is located in the same cell, the relay-enabled BS sends a relay station selection request message to the RS to indicate the preamble index of the selected access station. The RS responds with a generic acknowledgement message. Subsequently, the relay-enabled BS and the RS perform network re-entry, as described earlier. The relay-enabled BS releases resources allocated to the corresponding RS. If initial network entry is required for the RS due to failure in the network re-entry with the selected access station, the original access station would be the first candidate for network entry. Figures 4-20 and 4-21 illustrate these procedures. The timers denoted by T in the figures are used for measuring the permissible time per process and upon expiration of corresponding timers, other procedures are enacted. The timers and the MAC management messages shown in these figures are defined in reference [10]. Note that the uplink relay zone configuration action frame indicates the effective action time of the uplink relay zone configuration defined by the relay control channels on the relay link. If the effective action time is defined as 0, the uplink relay configuration defined by the relay control channels is effective in the current frame; if the value is set to N, the configuration defined by the relay control channels in frame i is effective in frame i + N. Note that the IEEE 802. 16m standard has not specified a detailed state-machine for the relay station and Figures 4-20 and 4-21 are depicted based on the procedures specified in the IEEE 802.16j-2009 standard for completeness of the subject 