• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.7 no.2
• /
• pp.117-127
• /
• 1996

In this paper, we present the bit error performances of 4PSK and 8PSK signal transmission schemes using Maximal Ratio Combining diversity reception for m-distribution and Rician fading channels. The suitability of modeling a Rician fading environment by a properly chosen m-distribution model is examined. Using the error performance of the derived equation has been evaluated and shown in figures as a function of fading index (m), Rician factor (K), diversity branches number (L) and E($E_b/N_o$). It is found that MRC (Maximal Ratio Combining) diversity technique is very efficient for reducing the effects of fading, And then, diversity benifit much large as depth of fading becomes deeper but more decreases as many diversity branchs. Also the results show that the error performance corresponds as much as fading becomes weak and increases with the number diversty branches.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.11A
• /
• pp.1027-1034
• /
• 2005

IEEE802.15.4a, which is started to realize the PHY layer including high precision ranging/positioning and low data rate communication functions, requires a simple and low power consumable transceiver architecture. To satisfy this requirements, the simple noncoherent on-off keying (OOK) UWB transceiver with the parallel energy window banks (PEWB) giving high precision signal processing interface is proposed. The flexibility of the proposed system in multipath fading channel environments is acquired with the pulse and bit repetition method. To analyze the bit error rate (BER) performance of this proposed system, a noise model in receiver is derived with commonly used random variable distribution, chi-square. BER of $10^{-5}$ under the line-of-sight (LOS) residential channel is achieved with the integration time of 32 ns and signal to noise ratio (SNR) of 15.3 dB. For the non-line-of-sight (NLOS) outdoor channel, the integration time of 72 ns and SNR of 16.2 dB are needed. The integrated energy to total received energy (IRR) for the best BER performance is about $86\%$.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.10A
• /
• pp.952-959
• /
• 2006

In this paper, 2-D RAKE receiver simulator is made which beamforming technique is applied to in WCI)MA uplink basestation, and the performance is compared with that of 1-D RAKE receiver with varying the number of array elements, RAKE fingers and users. To model angular component of received signal and interfering signals due to multiple access, it is assumed that multiple users are located in the arbitrary direction of the same distance far from the basestation within a sector of the cell, and the channel simulator is made by using Geometry Based Single Bounce Elliptical Model(GBSBEM) suggested by Rappaport. BER performance is compared and analyzed with the various choise of the number of array elements, the number of RAKE fingers, the number of users and Eb/No. These results indicate that increasing the number of array elements eliminates efficiently multiple access interfering signals and improves dramatically BER performance.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2012.07a
• /
• pp.373-376
• /
• 2012

Multiple-Input Multiple-Output (MIMO) 시스템의 복잡도를 감소시키는 방식은 실생활에서 MIMO 시스템을 활용하는 데에 있어 중요한 부분이다. 널리 사용되는 Maximum Likelihood (ML) 복호기의 경우 낮은 에러오율 (BER) 을 보여주지만 복잡도가 높다. 실생활에 활용하기 위하여 ML 복호기의 복잡도를 감소시킬 필요가 있고 이에 Sphere Decoding Algorithm (SDA) 이 제안되었다. 이를 발전시킨 List Sphere Decoding(LSD) 은 여러 종류가 있다. 그 중에 넓이 우선 탐색 방식인 K-Best LSD 알고리즘은 각 레이어에서 리스트의 크기가 복잡도와 밀접한 연관이 있다. 본 논문에서는 기존의 K-Best LSD 알고리즘에 기반하여 초기 반지름 설정 및 선형적으로 리스트 크기를 감소시키는 방식으로 K-Best LSD 알고리즘의 복잡도를 기존 알고리즘에 비해 크게 낮추면서도 비트 오율 성능 열화가 적은 알고리즘을 제안하고 전산 실험을 통해 이를 검증한다.

• Journal of Broadcast Engineering
• /
• v.15 no.2
• /
• pp.224-231
• /
• 2010

In this paper, we analyze the performance of the cooperative relay communication system which uses orthogonal frequency division multiplexing(OFDM) with hierarchical subcarrier modulation. In the cooperative relay communication system, data transmission is accomplished in two time slots. In the first time slot, the source broadcasts the signal to the relay and to the destination. The relay demodulates the received signal, remodulates and forwards it to the destination in the second time slot. The source uses hierarchical modulation for subcarriers to deal with the signal-to-noise power ratio (SNR) difference in the source-relay and source-destination links. The bit error rate (BER) of the relay transmission system with hierarchical modulation depends on the hierarchical modulation parameter. First, we derive the relationship between BER and the parameter, and find the optimal parameter giving the minimum BER through computer simulations. Then, we analyze the performance of the proposed cooperative relay communication system according to the relay location. From this results, we find optimal relay location to maximize the BER performance.

• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 2006.07a
• /
• pp.529-529
• /
• 2006

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.30A no.8
• /
• pp.19-26
• /
• 1993

The bit error probability of Reed-Solomon/convolutional concatenated codes can be more exactly calculated by using a more approximate bound of the symbol error probability of the convolutional codes. This paper obtains the unequal symbol error bound of the convolutional codes, and applies to the calculation of the bit error probability of the concatenated codes. Our results are tighter than the earlier studied other bounds.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.26 no.6B
• /
• pp.717-726
• /
• 2001

감쇄를 겪는 무선 채널 환경에서 전력과 대역폭을 효율적으로 조절하여 데이터를 전송하는 적응 부호 변조 방식에 적합한 제어 기법을 제안한다. 먼저 부호화 시스템에 맞도록 평균 대역폭 효율을 다시 정의하였고, 이것에 기초하여 전력 및 대역폭 효율을 최대화하도록 변조 레벨 구간을 얻었다. 이 제어 기법은 부호 이득을 최대로 이용할 수 있고, 변조 형태에 관계없이 대역폭 효율을 최대화 할 수 있다. 모의 실험 결과 제안한 방식은 요구된 비트 오율 성능을 만족하면서 기존의 방식보다 전력 할당을 효과적으로 하기 때문에 대역폭 효율이 향상되었다. 본 논문에서 제안한 제어 기법은 감쇄 특성을 가진 무선 채널에서 고속 데이터 전송에 사용될 수 있다.

• Proceedings of the KIEE Conference
• /
• 1988.07a
• /
• pp.186-189
• /
• 1988

In transmission of DPCM signals, it is desired to protect the more significant digits from more errors than the less significant digits. The SNR of DPCM is examined in the case that bit error rates of individual digits consisting of the information word are different each other. The examination shows a better DPCM coding.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.26 no.7A
• /
• pp.1227-1233
• /
• 2001

본 논문에서는 유전자 알고리즘을 기반으로 한 새로운 다중사용자 복조기를 제안하고, 최적(optimum) 다중사용자 복조기의 Hopfield 신경망 다중사용자 복조기를 비교 대상으로 하여 원근문제가 존재하는 환경에서 컴퓨터 시뮬레이션을 통해서 비트오율 성능을 비교하였다. 시뮬레이션 결과, 원근문제에 존재하는 채널환경에서는 본 논문에서 제안한 구조는 상당히 적은 계산량으로 최적의 다중사용자 복조기와 Hopfield 다중사용자 복조기와 근접한 성능을 기대할 수 있었고, 원근문제가 존재하지 않는 경우에서는 Hopfield 신경망구조보다 우월한 성능향상을 얻을 수 있었다.