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A Low Complexity Transmitter Structure for OFDM-FDMA Uplink Systems

The Orthogonal Frequency Division Multiplex (OFDM) transmission technique can efficiently deal with the effects of multi-path propagation in the broadband radio channel. It also has a high system inherent flexibility for designing a multiple access scheme by combining the conventional TDMA, FDMA and CDMA approaches with the OFDM modulation scheme. The FDMA multiple access schemes are especially interesting for an uplink of a communication system since it can completely avoid any Multiple Access Interferences (MAI). Moreover, the Peak-to-Average Ratio (PAR) of the uplink OFDM transmit signal can be greatly reduced if this OFDM-FDMA multiple access scheme is additionally combined with a data spreading technique based on a Discrete Fourier Transform (DFT) spreading matrix using only the user specific subcarriers.

Provided by: Hamburg University of Technology Topic: Mobility Date Added: Jan 2011 Format: PDF

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