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Abstract-In this paper, we investigate scheduling in multiuser OFDMA systems. The objective is to maximize the resource utilization in a network, while a required Quality of Service (QoS) per user is satisfied. A notion of revenue maximization is used to determine the optimal OFDMA subcarrier allocation to different users based on their required QoS. The optimal solution for the problem is presented and its performance and complexity are studied. An iterative low complexity algorithm is also proposed to achieve near optimal performance.

Abstract-The performance of a multiuser wireless network using orthogonal frequency-division modulation (OFDM), combined with power control and adaptive beamforming for uplink transmission is presented here. A network-wide adaptive power control algorithm is used to achieve the desired signal-to-interference-and-noise-ratio at each OFDM subcarrier and increase the power efficiency of the network. As a result, we can achieve a better overall error probability for a fixed total transmit power. With the assumption of fixed-modulation for all subcarriers, transmit powers and beamforming weight vectors at each subcarrier are updated jointly, using an iterative algorithm that converges to the optimal solution for the entire network. Unlike most of the loading algorithms, this approach considers fixed bit allocation and optimizes the power allocation and reduces the interference for the entire network, rather than a single transmitter. We also propose joint time-domain beamforming and power control to reduce the complexity resulting from the number of beamformers and fast Fourier tranformed blocks. The proposed algorithm is also extended to COFDM and we show that it improves the performance of those systems.Index Terms-Antenna array, coded orthogonal frequency-division modulation (COFDM), minimum mean-squared error (MMSE), minimum variance distortionless response (MVDR), OFDM, power control.

Abstract-The objective of scheduling algorithms in wireless networks is to provide Quality of Service (QoS) for mobile users in a shared environment and at the same time utilize the system resources efficiently. We have introduced a notion of income maximization to increase throughput for multimedia wireless systems and to maintain the QoS for each user above an agreed level. We have proposed greedy and dynamic programming approaches to solve the optimization problem. The simulation results reveal that our scheduling algorithms provide high network throughput, support QoS even under heavy network loads, and generate high income for service provider.