Seong Chul Cho

Adaptive clipping technique for reducing PAPR on OFDM systems

This paper is concerned about peak-to-average power ratio (PAPR) reduction technique on orthogonal frequency division multiplexing (OFDM) systems. First, we analyze PAPR statistical characteristics with fast Fourier transform (FFT) size and modulation order on OFDM systems. The result is that PAPR statistical characteristic is almost same for any sufficiently large size of FFT (>64) and types of modulation schemes. Next, the bit error rate (BER) performance and the power spectral density (PSD) of OFDM systems over clipping ratio (CR) are studied and simulated. The result is that BER performance goes a little bad but PAPR reduction effect is very large. Finally, we propose adaptive clipping technique for PAPR reduction on OFDM systems by modulation order.

Convolutional turbo coded OFDM/TDD mobile communication system for high speed multimedia services

A novel mobile Internet access system based on the OFDM transmission technique is proposed and its performance is analyzed via computer simulations. Especially, OFDM is considered in combination with the TDMA/TDD scheme for a cellular mobile communication system. We present simulation results for the performance of a convolutional turbo coded OFDM/TDD system with QPSK, 16QAM, and 64QAM over ITU-R channel models. The performance of the proposed system employing pilot tone assisted channel estimation is compared to the ideal case with perfect channel estimation.

Performance evaluation of convolutional turbo codes in AWGN and ITU-R channels

In this paper, the performance of a non-binary convolutional turbo codes is evaluated through computer simulations. Especially, The influence of the various frame sizes and code rate are discussed. Also, in this paper the symbol-by-symbol MAX-Log-MAP algorithm is derived for this coding scheme. We present simulation results for the performance of the non-binary convolutional turbo coded system with QPSK, 16QAM, and 64QAM over an AWGN and the ITU-R channel models.

TD-CDMA systems using turbo code for mobile multimedia services

In this paper, the performance of a wireless communication system based on the TD-CDMA transmission technique is analyzed. In this paper, we present simulation results for the performance of a turbo coded TD-CDMA system with QPSK over Rayleigh fading channel model. And the system performance employing the simple averaging channel estimation is compared to the ideal case with the perfect channel estimation.

An improved sequential decoding algorithm in TD-CDMA system

We considered a sequential decoding algorithm which enables fast decoding and retransmission in TD-CDMA systems. In addition, we propose an improved FANO algorithm, which adopts the competition path in order to reduce the number of revisit nodes. The conventional FANO algorithm suffered from the drawback of much more revisit nodes. Furthermore, we analyze the performance of the TD-CDMA system with the proposed sequential decoding scheme over a wideband multipath channel.