values in order to report this information to the serving BS after registration, i.e., by sending a relay station neighbor measurement report during the neighbor station measurement and reporting stage. The BS indicates a request for this information through the ranging response message during initial ranging. 4.4 State transitions in relay stations Power Down Power ON/OFF Initialization Access State Operational State State Failed Operation Path/ Normal Operation Path Power Down FIGURE 4-17 State transition diagram of IEEE 802.16m relay station [3] According to the IEEE 802.16j-2009 standard specification, the BS and the RS may exchange messages to indicate support for the first stage access station selection in the multi-hop relay network [10]. An RS attempting network entry may obtain the system information transmitted by neighboring relay and base stations to select an access station. The RS then proceeds to the rest of the network entry process with the selected access station (i.e., the Access State procedures shown in Figure 4-19). The BS may request the RS to perform neighbor measurements during network entry or re-entry using the RS network entry optimization parameter in the ranging response message. The neighbor station measurement report can include the signal strength and preamble index of neighbor non-transparent stations with unique BS identifications, as well as signal strength and preamble indices of neighbor transparent or non-transparent relay stations with shared BS identifications. After registration, if the neighbor measurement is not required, the RS can skip the neighbor station measurement reporting and second stage access station selection phases and directly proceed to the next stage, as indicated by the RS network entry optimization parameter in the ranging response message. If the RS is a mobile RS and the relay-link channel descriptor ix provides the list of preamble indices reserved for mobile relay stations, the mobile RS must report the received signal strengths and the correspondi