A time and frequency synchronization scheme for multiuser OFDM
IEEE Journal on Selected Areas in Communications
Adaptive multidimensional coded modulation over flat fading channels
IEEE Journal on Selected Areas in Communications
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Orthogonal frequency division multiplexing (OFDM) is very sensitive to frequency offsets which result in considerable interference. Performance of the system will be exacerbated in the uplink of a cellular deployment with frequency reuse of one. A general mathematical model is developed to calculate the amount of interference in cellular OFDM system considering frequency offset between transmitter (Tx) and receiver (Rx), depending on different multiple access and duplexing techniques. An ideal adaptive modulation scheme is applied to compare the capacity of different cellular OFDM systems. It is found that the capacity of frequency division multiple access (FDMA) system outperforms that of time division multiple access (TDMA) system due to multiuser diversity in FDMA. Moreover, time division duplexing (TDD) system outperforms frequency division duplexing (FDD) system irrespective of the multiple access techniques by exploiting time slot (TS) opposing techniques.