Transmitting: 
  • The process is similar to that of BS. The frequency offset is pre-corrected. The Ranging and BW Request are generated at the physical layer and a code is selected according to the indication at the MAC layer. 
  • After the modulation, they are mapped to competitive slots  selected at the MAC layer. Later, they are the same as the normal data.
Receiving:  
  • The process is similar to that of BS. The frequency synchronization is added. 
  • It is not required to detect the competitive codes of Ranging and bandwidth request.