64 Green Relay Techniques in Cellular Systems
coverage area. In contrast with Layer 1 RN, a Layer 2 RN has medium access
control (MAC) layer functionality; it can decode received signals and re-encode
transmitted signals in order to achieve higher quality in the relay cell area. A
Layer 3 RN would include functionalities like mobility management, session
set-up and handover and as such acts as a full service BS. This type of relay
adds more complexity to the implementation and further increases the delay.
In 3GPP standardization [35], RNs are distinguished between Type 1 and
Type 2. Type 1 relays are RNs operating on Layer 3, i.e., protocol layer up to
Layer 3 for user data packets is available at the RN. Such Layer 3 RNs have
all the functions that ...