• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.3
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• pp.294-303
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• 2010

Radiocommunication systems is very useful method to configure the unified command communication system in case of the disasters. Currently Korea's radiocommunication network against the disasters is operating with TETRA system. This system is very powerful with multifunction to apply in the disaster situation. However, Korea's disaster radiocommunication system is so important to keep and maintain survivability. Therefore this paper study on the alternate systems to TETRA system.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1705-1708
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• 2002

Spreading codes with ZCD(zero-correlation duration) property have the MAI(multiple access interference) rejection ability in the CDMA systems. A class of multi-level spreading codes, i.e., Zero padded ternary ZCD codes are introduced in this paper. By the selected zero-padding method to the binary ZCD codes, ternary ZCD codes are generated and they have enhanced ZCD property and family size than the binary ZCD codes.

• Journal of electromagnetic engineering and science
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• v.7 no.1
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• pp.28-34
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• 2007

In this paper, we present a quasi-Jacket block matrices over binary matrices which all are belong to a class of cocyclic matrices is the same as the Hadamard case and are useful in digital signal processing, CDMA, and coded modulation. Based on circular permutation matrix(CPM) cocyclic quasi block low-density matrix is introduced in this paper which is useful in coding theory. Additionally, we show that the fast algorithm of quasi-Jacket block matrix.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.9
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• pp.27-35
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• 1999

In this paper, we propose an error detection scheme of phase offsets for binary sequences including PN (Pseudo Noise) sequences based on the number theoretical approach. It is important to know phase offsets of spreading sequences in the CDMA (Code Division Multiple Access) mobile communication systems because phase offsets of the same spreading sequence are used to achieve the acquisition and are used to distinguish each base station. When the period of the sequence is not very long, the relative phase offset between the sequence and its shifted replica can be found by comparing them, but as the period of the sequence increases it becomes difficult to find the phase offset. The error detection failure probability of the proposed method is derived, and it is confirmed by the simulation results. We also discuss the circuit realization of the proposed method and show it can be easily implemented.

• Journal of Communications and Networks
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• v.12 no.4
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• pp.330-333
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• 2010

In this paper, using binary (N, M, L, $\epsilon$) low correlation zone (LCZ) sequence sets, we construct new quaternary LCZ sequence sets with parameters (2N, 2M, L, $2{\epsilon}$). Binary LCZ sequences for the construction should have period $N\;{\equiv}\;3$ mod 4, L|N, and the balance property. The proposed method corresponds to a quaternary extension of the extended construction of binary LCZ sequence sets proposed by Kim, Jang, No, and Chung [1].

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.7
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• pp.1374-1389
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• 1994

In this paper, a novel M-ary orthogonal CDMA scheme which utilizes time hopping codes and binary orthogonal sequences is proposed for personal communication system. Its modulated output signal has the characteristics of greater bandwidth occupancy and lower spectral density level as well. So this scheme is useful for spectrum overlay with existing narrowband communication systems which occupy current radio frequency channels. This paper investigates system characteristics through the analysis of modulated output signal power spectrum, and demonstrates the possibility of spectrum overlay.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.11
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• pp.15-22
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• 2008

The cdma2000 1xEV-DO system controls the data rates of mobile terminals based on a binary overload indicator from the base station and a simple probabilistic model. However, this control scheme has difficulty in predicting the future behavior of mobile terminals due to a probabilistic uncertainty and has no reliable means of suppressing the traffic overload, which may result in performance degradation of CDMA systems that have interference-limited capacity. This Paper proposes a new traffic control scheme that controls the data rates of mobile terminals effectively by predicting the future traffic load and adjusting the forward-link control channel. The proposed scheme is analyzed by modeling it as a multi-dimensional Markov process and compared with conventional schemes. The numerical results show that the maximum cell throughput of the proposed scheme is much higher than those of the conventional schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5A
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• pp.611-617
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• 2000

Asynchronous mode W-CDMA system is kmown to be quite appropriate to the next generation mobile communication system, especially in a non-homogenious cellular architecture. In this case, however, each base station needs to use different spreading code for identification, so it is a demeanding task for a mobile terminal to find the best cell site and get an accurate code synchronization at the beginning of a communication. Since slow acquisition of a base station could mean the failure of initiation, a fast algorithm to accelerate the cell search process is essential. In this paper, a new cell search algorithm based on the binary code position modulation within the code block is proposed. Different cell sites are identified by different hopping code sequences, andeach position modulation is performed by the hopping code. The proposed algorithm is proved to make the cell search time in most places in a cell much shorter than the previous algorithms, and to make the receiver implementation simpler.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.548-548
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• 2006

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.34-34
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• 2004