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In this paper, we propose a fast and efficient adaptive transmission algorithm for the Mobile WiMAX system. In our algorithm, we select the position of the boundary between the downlink and uplink subframes, the positions of the service flows within the frame, the coding and modulation schemes, and the transmission power values. Our algorithm gains high spectral efficiency, satisfies quality-of-service (QoS) requirements for the service flows, and has low computational complexity. The algorithm includes a frame boundary position optimization procedure, downlink and uplink optimization procedures, as well as a procedure that selects a transmission power value that enables satisfaction of the QoS requirements. All these procedures are novel, efficient, and fast. We evaluate the adaptive transmission algorithm by performing a system-level simulation of the Mobile WiMAX system with multisector topology. We show that our algorithm has high spectral efficiency and low computational complexity, enabling QoS provisioning. Index Terms--Adaptive transmission, Mobile WiMAX, quality-of-service (QoS).

In this paper, we consider the quality-of-service (QoS)-oriented intersystem handover between the IEEE 802.11b network and the overlay network. We propose the handover scheme and algorithm that guarantee to simultaneously meet the three key QoS parameters, that is, the minimum data rate, the maximum data block delay, and the maximum bit error rate, for the arbitrary number of downlink and uplink multiservice connections. In addition to the QoS requirements, our intersystem handover scheme guarantees to keep the call-dropping probability during the handover and the sum of the average number of ping-pong events during the entry to and the exit from the IEEE 802.11b system below the predetermined values. We define the IEEE 802.11b network as the priority network for the mobile station. Thus, we maximize the time during which the mobile station is served by the IEEE 802.11b network while satisfying the QoS requirements in both networks, as well as the maximum call-dropping probability and the maximum average number of ping-pong event constraints. To solve this task, we propose a novel intersystem handover scheme that utilizes the minimum signalto-noise ratio threshold, entry hysteresis, and exit hysteresis. Index Terms--IEEE 802.11, IEEE 802.21, intersystem handover, quality-of-service (QoS) requirements.