Adaptive TDMA/OFDMA for Wide-Area Coverage and Vehicular Velocities

adaptive transmission is investigated as a key technology for boosting the spectral efficiency of a new radio interface for 4G systems. Adaptive allocation of time-frequency chunks in an OFDM-based system offers a significant potential, but also poses challenges. Within work package two of WINNER, we study critical issues such as the feasibility of adaptive transmission over fading downlink/uplink channels to/from vehicular terminals, the corresponding required channel prediction accuracy, and the required feedback control bandwidth. This paper summarizes recent results obtained within WINNER, and related results obtained within the Swedish Wireless IP project. Index Terms—4G mobile wireless systems, adaptive transmission and multiple access, Orthogonal Frequency Division Multiplexing (OFDM), spectral efficiency. A I