• Journal of Communications and Networks
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• v.4 no.2
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• pp.90-96
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• 2002

We present a family of constant-amplitude constellations of even dimensions 8 and above. These constellations allow trellis coded modulation to be implemented without the usual penalty paid for constellation expansion. The new constellations are generated by concatenating either n QPSK points or n QPSK points rotated by 45 degrees, for any n $\geq$ 4. Our constellations double the number of points available for transmission without decreasing the distance between points and without increasing the average or peak energies, introducing asymmetry, or increasing the modulation level. Effective gains of 2.65 dB with minimum complexity through 6.42 dB with moderate complexity are demonstrated using the 8D constellation.

• Journal of Communications and Networks
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• v.6 no.3
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• pp.258-268
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• 2004

We demonstrate rotationally invariant space-time (ST) trellis codes with a 4-D rectangular signal constellation for data transmission over fading channels using two transmit antennas. The rotational invariance is a good property to have that may alleviate the task of the carrier phase tracking circuit in the receiver. The transmitted data stream is segmented into eight bit blocks and quadrature amplitude modulated using a 256 point 4-D signal constellation whose 2-D constituent constellation is a 16 point square constellation doubly partitioned. The 4-D signal constellation is simply the Cartesian product of the 2-D signal constellation with it-self and has 32 subsets. The partition is performed on one side into four subsets A, B, C, and D with increased minimum-squared Euclidian distance, and on the other side into four rings, where each ring includes four points of equal energy. We propose both linear and nonlinear ST trellis codes and perform simulations using an appropriate multiple-input multiple-output (MIMO) channel model. The 4-D ST codes constructed here demonstrate about the same frame error rate (FER) performance as their 2-D counterparts, having however the added value of rotational invariance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.12
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• pp.990-1001
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• 1990

This paper compared and analyzed trellis coding with modem, discussed the basic concepts of it's structure and design. Logical observation was made on estimation method of coding gain and effect of error coefficient for trellis coding with modem. A signal space was analyzed on multidimensional coding in voiceband modem and differentially trellis coding with modem. As a result, we has obtained that 16 points constellation is more efficient than 2 dimensional.

• International Journal of Computer Science & Network Security
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• v.24 no.1
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• pp.156-162
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• 2024

Humanity has gone since a long time through several pandemics; we cite H1N1 in 2009 and also Spanish flu in 1917. In December 2019, the health authorities of China detected unexplained cases of pneumonia. The WHO (World Health Organization) has declared the apparition of Covid-19 (novel Coronavirus). In data analysis, multiple approaches and diverse techniques were used to extract useful information from multiple heterogeneous sources and to discover knowledge and new information for decision-making. In this paper, we propose a multidimensional model for analyzing the Coronavirus Covid-19 data (spread and vaccination in European countries).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.2
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• pp.299-306
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• 2017

The real number M-ary QAM system can reduce PAPR and effectively improve the transmission efficiency as it increases gradually the value of M according to the state of channel. However, only approximate performance analysis was performed due to the complexity of the analysis. In this paper, we introduce an exact performance analysis considering the change of a boundary line due to the difference in frequency of use of the signal points. Also, we propose a new constellation of 2 time dimension ($3{\times}2^m$)-ary QAM with odd m which has better performance in PAPR. In the performance analysis, we obtain the signal point error rate and the bit error rate of real number M-ary QAM for the various values of m and compare performance between the proposed QAM and the conventional $2^k-ary$ QAM with integer k.

• The Journal of Korean Institute of Information Technology
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• v.17 no.3
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• pp.31-41
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• 2019

In this paper, we design and implement the simulator for the transmitter and receiver of 4D-8PSK TCM with 2.0, 2.25, 2.5, and 2.75 bits/symbol-channel transmission efficiency recommended by the CCSDS for satellite communications, and then analyze the BER performance of 4D-8PSK TCM system in AWGN channel. The transmitter of 4D-8PSK TCM is designed in accordance with the recommendation in the CCSDS standard. Meanwhile, for the receiver design of 4D-8PSK TCM, we design the differential decoder generalizing the differential encoder/decoder scheme. The trellis decoding algorithm is designed by applying the auxiliary trellis information and the Viterbi algorithm, and an 8-dimensional constellation mapper equation given in the CCSDS standard is deconstructed to design constellation mapper. Especially, we present the optimized receiver for 4D-8PSK TCM system by investigating the BER performances for the traceback lengths in the Viterbi decoder through computer simulations..