• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.11
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• pp.2147-2159
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• 1994

In this parper, the performance of trellis coded DS/SSMA system using feedforward trellis encoder with sasymmetric signal constellation are evaluated over AW(In channel. The numerical results of trellis coded 4 PSK(code rate 1/2)and 8-PSK(code rate2/3) are calculated for 2-state and 4-state cases and compared with those of the Boudreau's system using feedback trellis encoder without optimizing the signal constellation. The method of moments is employed to evaluate the multiple access interference, in conjunction with the generalized transfer function techniques for trellis code. The numerical results show that the proposed system in this paper is always better than the Boudreau's system over AWGN channel; particularly at $P_b:10$, $0.2dB\sim2.4dB$ improvement over AWGN channel are obtained.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.549-551
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• 2002

A Wireless Local Area Network (WLAN) is a flexible data communication system implemented as an extension to, or as an alternative for, a wired LAN with in a building or campus. However, communications in an indoor environment present problems not encountered in outdoor wireless communication systems. Since cellular type systems are interference limited, the indoor environment is more hostile than the outdoor environment due to the lower propagation constant. In this paper, the equation for the signal to interference ratio in a multistory building will be derived. Knowing the S/I ratio, the floor frequency reuse can be determined. Finally, the simulation in this research is designed to study the performance (BER) of WLAN system in the multistory environment by applying the 8-PSK Trellis Coded modulation technique. The procedure allows a quick evaluation of BER in Wireless LAN system due to the co-channel interference.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.12
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• pp.1256-1263
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• 2003

In this paper, we analyzed the channel coding scheme of DVB and ISDB standard for high-speed satellite broadcasting. Also, this paper proposed optimal parameters of decoder with variable coding rate for implementation. According to the optimal parameters, the pragmatic TCM of rate 213, 5/6, 819 was modeled by VHDL. The results designed by VHDL can be verified.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.2071-2074
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• 2002

This paper introduces an encoder design method of Turbo TCM (Trellis Coded Modulation) with symbol puncturing. TTCM consists of two simple trellis codes in parallel and modulator. To obtain an good encoder, we calculate the free distance by the assumption that the punctured symbol is transmitted from the subset that consist of signals with the same systematic bit at random. We develop a search program to find the component encoder which maximize the free distance. Especially, for 8-PSK with code rate 2/3, we search for the component codes. We find a new encoder which has better BER performance than that of Robertson′s encoder. We verify the results through the simulation."

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.6
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• pp.1-8
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• 1994

In this paper, in order to apply the idea MDPSK to TCM, we use signal set expansion and set partition by phase differences. Through this we propose the trellis-coded MDPSK. And the Viterbi decoder containing branch metrics of the squared Euclidean distance of the Lth order phase difference as well as the first order phase difference is introduced in order to improve the bit error rate(BER) in the differential detection of the trellis-coded MDPSK. The proposed Viterbi decoder is conceptually same to the sliding multiple symbol dection method which uses the branch metric with the first and Lth order phase differences. We investigate the performance of the uncoded DQPSK and the trallis-coded D8PSK in additive white Gaussian noise (AWGN) through the Monte Carlo simulation under the two cases of using and not using the Lth order phase difference metric. The study shows that trellis-coded 8DPSK is an attractive scheme for power and bandlimited systems while also improving the BER performance when the Viterbi decoder is employed to the Lth order phase order difference metric. This performance improvement has been obtained without sacrificing the bandwidth or the power efficiency.