Frequency Division Multiple Access (FDMA) will be implemented such that each peer and the relay can share the channel resource. Each peer will be given a specific frequency for transmitting and receiving. The relay will also be assigned another frequency for relaying the received signal to both peers.
Peer A is transmitting on frequency f1 and receiving on frequency f2. Peer B is transmitting on frequency f2 and receiving on frequency f1. The relay receives two signals, one from each peer and is transmitting on frequency f3.
For the relay, The modulation and frequency synchronization blocks works in the same way as at the peers. When the relay receives a packet from each peer, it splits the label from the packet and decodes both the label and the packet using the same 1/2 rate code as the peers. The packets are then checked for any errors using CRC then go to the relay packet encoder. When the decoded labels and packets from both peers are received at the relay packet encoder, the packets are encoded with a convolutional code which correspond to the 1/2 rate code corresponding to the punctured part of the one used at the peers then go to the modulation block.
