QoS-Guaranteed Cross-Layer Transmission Algorithms with Adaptive Frequency Subchannels Allocation in the IEEE 802.16 OFDMA System

In this paper, we analyze the IEEE 802.16 OFDMA system with adaptive allocation of the frequency subchannels to the users. We perform adaptive coding and modulation, allocation of the time-frequency resource, the transmit power, and the frequency subchannels to the downlink and uplink service flows, which are scheduled for transmission in the current frame. Moreover, we consider adaptation of the frame boundary between the downlink and uplink subframes. We minimize the sum time-frequency resource, allocated in both downlink and uplink subframes, under the constraints on the maximum transmit power and the time-frequency resource available in the frame, while satisfying the QoS requirements for all downlink and uplink service flows scheduled for transmission. We propose the cross-layer optimization algorithms, which take into account the MAC and PHY layers processing during the optimization. We also present the results of the proposed algorithms evaluation by system level simulation.