Resource allocation and power control in a TDD OFDM-based system for 4G cellular networks

Time division duplex (TDD) systems based on orthogonal frequency division multiplexing (OFDM) have recently been proposed as potential candidates for next generation (4G) cellular networks. In this paper, as a multiple access scheme we propose an adaptive frequency division multiple access (AFDMA), where resources are assigned to users exploiting channel knowledge at the transmitter. In order to reduce the system overhead, the algorithm can also work on group of sub-carriers and OFDM symbols. The proposed solution is shown, through numerical results, to be superior to conventional allocation strategies, namely time division multiple access (TDMA) and FDMA. Furthermore, we also investigate a new power control algorithm based on a single-user discrete bit loading technique. Numerical results are reported for both downlink and uplink transmissions in a multi-cell environment supporting real-time traffic