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In this paper, we investigate channel capacity of two kinds of uplink OFDMA (Orthogonal Frequency Division Multiple Access) schemes, i.e. ZCZ (Zero Correlation Zone) code time-spread OFDMA and sparse SC-FDMA

Key Words : SIMO, SC-FDMA, frequency diversity gain, spatial diversity gain, MMSE, ZF ABSTRACTWe investigate BER (Bit Error Ratio) performance according to the gain of spatial and frequency diversities in uplink SC-FDMA of SIMO (Single Input Multiple Output) systems. The main results of the analysis in this paper are as follows. First, we prove that performance of integrated system for considering spatial and frequency

Key Words : SIMO, SC-FDMA, frequecy diversity gain, spatial diversity gain, diversity combining order ABSTRACTWe investigate BER performance according to the order of spatial and frequency diversity combining in uplink SC-FDMA of SIMO systems. It is found that frequency diversity combining (FDC) after spatial diversity combining (SDC) is better than the reverse order combing in all SNR (Signal to Noise Ratio) range. Also, it is shown that FDC after SDC requires less computational complexity than the reverse order combining.

We investigate the channel capacity of two kinds of uplink OFDMA (Orthogonal Frequency Division Multiple Access) schemes, i.e., ZCZ (Zero Correlation Zone) code timespread OFDMA and sparse SC-FDMA (Single Carrier Frequency Division Multiple Access) which are robust to access timing offset (TO) among users. For the practical condition, we consider not only the TO among users but also the PAPR ( peak to average power ratio) which is a major issue of uplink OFDMA. In the case with TOs in arrival times among users, the amplified user's signal by power control affect the distortion of other user's signal. Meanwhile, amplified signal by simply considering distance between user and base station might be distorted due to the limit of amplifier and thus the performance might degrade. In order to achieve the maximum channel capacity, we investigate the combinations of optimized power control so called ASF (Adaptive Scaling Factor) by numerical simulations. We check that the channel capacity with optimized power control by ASF increases compared to the case without ASF i.e., ASF=1. From the simulation, in the case of high signal to noise ratio (SNR), ZCZ code time-spread OFDMA achieves higher channel capacity compared to sparse block SC-FDMA. On the other hand, in the case of low SNR, the sparse block SC-FDMA achieves better performance compared to ZCZ time-spread OFDMA.