2016/11/4(五) 14:20 - 陳永芳 教授 中央大學通訊系 - Adaptive Allocation in OFDMA Systems with Time-varying Channels
Topic： Adaptive Allocation in OFDMA Systems with Time-varying Channels
Date&Time：2016/11/4 (五) 14:20
Speaker：陳永芳 教授 中央大學通訊系
Location：清華大學台達館 R216
Abstract：
Previously, we propose a scheme for the subcarrier, bit, and power allocation problem to minimize the total transmit power for multiuser orthogonal frequency division multiplexing systems in downlink transmission. The data rate requirement and the bit error rate constraint of each user are satisfied in the solution of the joint assignment. However, it is a batch mode which may not be so efficient in terms of computational complexity for slowly time-varying channel environments. The solutions to the allocation problem in the neighboring time frames may be similar. By utilizing this property, we propose a scheme to obtain the solution in an adaptive fashion, which offers comparable performance with a reduced computational complexity compared to the previously proposed method.
Based on a derived expression composed of the channel gains, the numbers of assigned subcarriers, and the data rates, the proposed adaptive scheme is able to track the channel variation for the solution adjustment in a faster speed compared to the batch mode method. Simulation results reveal that the proposed adaptive scheme has the competitive performance compared with those of the optimal and the existing schemes while the computational complexity and the number of iterations are both reduced.
Date&Time：2016/11/4 (五) 14:20
Speaker：陳永芳 教授 中央大學通訊系
Location：清華大學台達館 R216
Abstract：
Previously, we propose a scheme for the subcarrier, bit, and power allocation problem to minimize the total transmit power for multiuser orthogonal frequency division multiplexing systems in downlink transmission. The data rate requirement and the bit error rate constraint of each user are satisfied in the solution of the joint assignment. However, it is a batch mode which may not be so efficient in terms of computational complexity for slowly time-varying channel environments. The solutions to the allocation problem in the neighboring time frames may be similar. By utilizing this property, we propose a scheme to obtain the solution in an adaptive fashion, which offers comparable performance with a reduced computational complexity compared to the previously proposed method.
Based on a derived expression composed of the channel gains, the numbers of assigned subcarriers, and the data rates, the proposed adaptive scheme is able to track the channel variation for the solution adjustment in a faster speed compared to the batch mode method. Simulation results reveal that the proposed adaptive scheme has the competitive performance compared with those of the optimal and the existing schemes while the computational complexity and the number of iterations are both reduced.