In order to maximize the production of propylene when the external supply of ethylene is limited, the C4 cut from a hydrocarbon cracking process is first subjected to autometathesis prior to any isobutylene removal and without any ethylene addition. The impeding element preferably comprises a protective strip which extends around the sparkwheel. A first lumen is configured to receive a guidewire and a second lumen is configured to receive a pressurized fluid. The WTRU then determines a performance value with respect to the MAPs based on the backhaul link information and selects one of the MAPs to associate with based on the performance value.