• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.5 no.4
• /
• pp.18-29
• /
• 1994

In this paper, the performance of stepped serial search scheme and matched filter scheme for code acqusition in FH / CDMA are evaluated under land mobile radio communication channel environments. And delay lock loop scheme is used as code tracking system. As the results for code acquisition system, it is shown that the performance of stepped searial scheme is superior to matched filter scheme, because system complexity is reduced and system performance is improved by increasing the hopping frequency not to substitute for special hardware. Also, it is shown that its performance is improved under Rayleigh/ Rician fading environments. As the results for code tracking system, it is found that mean hold time is increased due to the increase of the number of lock state and hopping frequency, M.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.8A
• /
• pp.733-738
• /
• 2002

Zero Cross-correlation Zone (ZCZ) code has a good performance in Multi-user CDMA system to get low correlation zone and reject co-channel interference. In this paper, we do analysis of spreading code design to obtain this kind of property of correlations with a complex spreading scheme and denote their effective performance for mobile communication system. In addition, a Jacket polyphase sequence is an example to show the improved performance and regular properties effective performance for mobile communication system. In addition, a Jacket polyphase sequence is as an example to show the improved performance and regular properties.

• Proceedings of the IEEK Conference
• /
• 2003.07a
• /
• pp.101-104
• /
• 2003

In this paper, we analyze the performance of transmitter and receiver of W-CDMA system using the space-time code in downlink over JTC realistic channel model. We can get a diversity gain by using the space time code. We also apply the RAKE receiver to improve a performance in multi-path fading channel environment.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.16 no.5
• /
• pp.424-433
• /
• 1991

In the noncoherent FH/FSK system presence of the multitione jamming and noise, in the case random and 송 structures jamming model, the performance analyzed that random and struetured jamming derived error proability. It is found that error probability and performance when error corecting code used Hamming. BCH, Convolutional code under the worst case partial band jamming interference.

• Proceedings of the IEEK Conference
• /
• 2003.11c
• /
• pp.277-280
• /
• 2003

In this paper, we analyze the performance of transmitter and receiver of W-CDMA system using the channel coding and space time code in downlink over ITU-R realistic channel model. We can improve the reliability of communications and increase the data rate by channel coding, and we can get a diversity gain by using the space time code over fading channels. We also apply the RAKE receiver to improve tile performance in multi-Path fading channel environment.

• Journal of Communications and Networks
• /
• v.7 no.3
• /
• pp.258-262
• /
• 2005

An adaptive beamforming system based on code filtering and differential correlation approaches is proposed. The differential correlation method was originally proposed for time delay estimation of direct sequence code division multiple access (DS-CDMA) systems under near-far ratio conditions and the code filtering correlation algorithm, on the other hand, was proposed for array response estimation in DS-CDMA systems under perfect power control. In this paper, by combining differential correlation concept with the code filtering beamforming technology, an accurate estimate of the beam forming weights and an enhanced performance of DS-CDMA systems under sever near-far ratio conditions is achieved. The system performance in terms of beam pattern and bit-error-rate (HER) shows that the proposed adaptive beamformer outperforms the conventional code filtering correlation technique.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.3A
• /
• pp.277-285
• /
• 2008

We previously proposed an Orthogonal Code Hopping Multiplexing (OCHM) scheme for statistical multiplexing on a synchronous downlink. OCHM enables a large number of users to share a limited number of code channels through statistical multiplexing. We here improve the performance of OCHM by prioritizing encoded symbols according to their importance using both the conventional code division and the previously proposed code hopping multiplexing schemes. Prioritization is useful for channel coding schemes with different levels of importance for encoded symbols such as turbo-codes. Scheme performance is evaluated by simulation in terms of the required Eb/N0 for a 1% block error rate.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.8
• /
• pp.1613-1619
• /
• 2004

Turbo codes of long block sizes have been known to show very good performance in an AWGN channel and the turbo code has been strongly recommended as error correction code for W-CDMA in 3GPP(3rd Generation Partnership Project). Recently, turbo codes of short block sizes suitable for real time communication systems have attracted a lot of attention. Thus, in this paper we consider the turbo code of 1/3 code rate and short frame size of 192 bits in ITU-R channel model. We analyzed the performance of W-CDMA systems of 10MHz bandwidths employing RAKE receiver with not only MRC diversity but also SOVA-based turbo code.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.2
• /
• pp.119-124
• /
• 2015

In this paper, we analyze the effect of line-width of optical sources on the performance of spectral amplitude coding (SAC) optical code division multiple-access (OCDMA) systems. For a performance analysis we use a symmetric balanced incomplete block design (BIBD) code as the code sequence because we can construct a series of code families by choosing different values of q and m. The ideal BIBD code (m=2) requires narrower line-width than the nonideal BIBD codes when the effective power is large ($P_{sr}=-10dBm$). But the nonideal BIBD codes (m>2) need narrower line-width than the ideal BIBD code when $P_{sr}=-25dBm$.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38A no.11
• /
• pp.970-972
• /
• 2013

Signal acquisition performance is evaluated for the tiered polyphase code (TPC) which is proposed as a ranging signal structure for global navigation satellite systems (GNSSs). Compared to the tiered code (TC) which is adopted in European Union's GALILEO system, the TPC shows robust performance to frequency offset in acquiring signal. Therefore the TPC should have SNR gain in signal acquisition and can reduce computational complexity in the receiver. In this paper, we compare the signal detection probability of the TC and TPC under the same receiver architecture and GALILEO E5a-I signal parameters.