ignaling There are several information elements that need to be exchanged between the BS and UTs and RNs and UTs. For these purposes, dedicated control channels © 2009 by Taylor & Francis Group, LLC Multihop Extensions to Cellular Networks exist. Without association, the BCH or random access channels (RACHs) must be used. Later, there are dedicated channels for which resources were provided. On each link (hop one or hop two), such channels must exist, but the informa- tion exchange is local (i.e., only meant for this hop). An exception is the arrival of a new UT at an RN, where the second hop operates just like BS-to-UT. However, the information about changed configuration and the additional ter- minal is notified from the RN to the BS so that routing and resource reserva- tion can be adapted accordingly. 8.4.9 Handover Decision Handover (HO) is the disassociation of a UT from any BS (or RN) and associa- tion to another BS or RN. In a multihop setup, the signaling for HO goes over all hops until the BS is informed and acknowledges. A mobility management entity (MME)/system architecture evolution (SAE) gateway in the network is responsible for switching the routing path if the BS is changed [8]. Here. with a focus on relay- ing; the new case is an intracell handover between two relays or between the BS and RN. Figure 8.13 shows the message sequence chart (MSC) for it. The BS is always in control of associations and directs its RNs to release (disassociate) or bind (associate) a UT to it. 8.4.10 Channel Quality Indication (CQI) In a fading channel environment, the broad OFDM channel is frequency selec- tive. The resource scheduler must know the channel state SO that it can use this information for the DSA and AMC mentioned earlier. Therefore, the UT does channel measurements (e.g., by analyzing the receive signal strength of pilot sig- nals). The measurements are packed into a compact format and sent back to the BS (or RN) for their further use on the DL. For the uplink, the BS (or RN) itself performs the measureme