Flexible OFDM Schemes for Bursty Transmissions

In this paper, alpha-OFDM, a generalization of the OFDM modulation, is proposed to enhance the outage capacity of bursty transmissions. This new flexible modulation scheme is easily implemented and only requires a symbol rotation of angle alpha after the IDFT stage. The induced rotation slides the DFT window and provides frequency diversity in block fading channels. Interestingly, the results show a substantial gain in terms of outage capacity and BER in comparison with classical OFDM modulation schemes. The framework is extended to multiuser/multi-antenna OFDM based standards. Simulations, in the context of 3GPP LTE, called hereafter alpha-LTE, sustain our theoretical claims.