On Tile-and-Energy Allocation in OFDMA Broadband Wireless Networks

The Orthogonal Frequency Division Multiple Access (OFDMA) technique has been widely applied in broadband wireless networks, such as IEEE 802.16 (WiMAX) and 3GPP Long Term Evolution (LTE). Existing studies have targeted at improving network throughput by increasing the transmission rates of mobile stations (MSs). Nevertheless, this is at the cost of higher energy consumption of MSs. In the letter, we consider the tile-and-energy joint allocation problem for uplink transmissions in an OFDMA wireless network. We formulate this problem as a mixed integer programming, where the objective is to minimize MSs' energy consumption subject to satisfying their traffic demands. We show this to be NP-hard and develop a heuristic taking advantage of the water-filling technique. Simulation results show that the performance of our heuristic is close to the optimum, especially when the network is under non-saturated condition.