QoS-driven cross-layer adaptive transmission for downlink OFDM

Cross-layer design is becoming a popular design methodology for the next-generation mobile systems. In this paper, we try to exploit a cross-layer adaptive transmission algorithm for downlink OFDM system. This algorithm takes into consideration not only the channel state information and power limitation in the physical layer, but also traffic scheduling and user fairness constraint at the data link layer. Based on proportional fairness principle and water-pouring theorem, we present a complete description of this cross-layer adaptive downlink transmission six-step algorithm. Simulation results show that the proposed cross-layer scheme outperforms the mere physical layer adaptive markedly. The novel algorithm is able to improve performance of the packet success rate (PSR) per TC and average packet delay, support added active users.