A closed loop control model separating resource and packet scheduling in multihop cellular networks

4G cellular systems and the IMT Advanced candidates will provide broadband wireless access with QoS. Especially in multihop configurations of these systems the base station controls resources centrally while relays can take over a part of the responsibility on the second hop. To make this work on layer two, scheduling is the most important task. However, many dimensions of the problem lead to much confusion. In this paper we approach this complexity inside the MAC layer. First, we propose that Packet and Resource Scheduling are two distinct tasks inside the medium access control layer of a wireless system. Due to the frequency selective channel and huge path loss ranges dynamic subcarrier assignment and adaptive power control are important. Proper resource scheduling also relies on accurate channel quality indication so there is a natural loop from base station to user terminal and back. Existing work and solutions see this as one single unit and end up in NP-hard problems or heuristics. Instead we propose a closed loop control approach and show how almost independent building blocks fit into that system view. We conclude with adaptive power control results.