• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.19 no.1
• /
• pp.148-154
• /
• 2005

This paper deals with performance degradations caused by RF I/Q impairments such as amplitude mismatch and phase mismatch in W-CDMA user equipment which uses QPSK(Quadrature Phase Shift Keying) modulation. The impacts of I/Q impairments on the BER(Bit Error Rate) are analyzed by using the variations of adjacent symbol distance. The BER versus amplitude mismatch and phase mismatch with QPSK constellation is reviewed through Matlab simulation. Performance degradation produced by RF I/Q impairments is measured with the implemented RF transceiver and modulation/demodulation test equipments through EVM(Error Vector Magnitude). The minimum performance requirements of amplitude mismatch and phase mismatch in W-CDMA user equipment are presented from the point of hardware implementation and the test method of the impairments is also included.

• Proceedings of the IEEK Conference
• /
• 2000.06a
• /
• pp.25-28
• /
• 2000

In this paper, we assume various number of multipaths in one chip duration according to spreading bandwidth. And we take into account of the effects of autocorrelation and relative phases among multipath components within one chip duration, and analyze fading effects. We derive the average error probability for different number of users. Then, we compare the performance of W-CDMA systems with different bandwidths. From the simulation results for different band-widths, wideband CDMA systems show better performance than narrowband CDMA systems in vehicular and pedestrian environments.

• Proceedings of the IEEK Conference
• /
• 2001.06a
• /
• pp.97-100
• /
• 2001

The performance of mobile radio communication system is dependent on various factors such as channel environment. Especially, the number of multipath components of mobile radio channel and multipath delay property in CDMA system for different bandwidths are changed. Therefore, using multipath components, Rake receiver provides improvement of performance of W-CDMA system is evaluated by computer simulation over the types of ITU-R wideband channel model and spreading rate. The result shows that the performance of CDMA adapting RAKE receiver is Improved by the increase of multipath components in equal level of the received power.

• Proceedings of the IEEK Conference
• /
• 2000.06a
• /
• pp.197-200
• /
• 2000

This paper presents a mathematical model of the output of Rake receiver of W-CDMA signals for various outdoor channel environment and different bandwidths. This mathematical model is represented as Rayleigh and noncentral chi distribution with 3 degrees of freedom. Those are obtained from the statistics of numerically generated signals. We employ Chi-square test to show how the mathematical model fits signal statistics, and confirmed that this model is appropriate for representing W-CDMA signals.

• Proceedings of the IEEK Conference
• /
• 2000.09a
• /
• pp.87-90
• /
• 2000

Differential channel 정보를 feedback 하는 close loop Tx diversity를 제안한다. 본 Tx diversity는 기존의 channel feedback Tx diversity 보다 W-CDMA의 forward link와 reverse link channel 용량을 더 많이 늘린다. Differential channel 정보를 estimation 하는 방법을 제안한다. 부가적으로 보내는 정보 없이 W-CDMA의 forward power control 에 사용하는 dedicated pilot 심볼을 이용해 differential channel 정보를 estimation한다. 기존에 제안된 channel feedback Tx diversity들과 성능을 비교한다.

• Proceedings of the IEEK Conference
• /
• 1999.06a
• /
• pp.33-36
• /
• 1999

This paper proposes a mathematical model for the statistics of the W-CDMA signals with different bandwidth. Based on the statistics of numerically generated signals, a mathematical model is obtained such as Rayleigh, Rician, and Maxwell distribution. We employ Chi-square test to verify the fitness of the mathematical model with signal statistics. The results show obviously that the new proposed model is useful for representing W-CDMA signals.

• Proceedings of the IEEK Conference
• /
• 2003.07a
• /
• pp.541-544
• /
• 2003

In this paper, we analyzed a physical layer of W-CDMA system and a performance of a downlink of W-CDMA system by using the space-time code by computer simulation over the ITU-R realistic channel model. From the results of the simulation, we note that the increase of multi-path components affects the improvement of the system performance because of the effect of the RAKE receiver.

• Proceedings of the IEEK Conference
• /
• 2002.06a
• /
• pp.77-80
• /
• 2002

In this paper, we analyze a physical layer of W-CDMA .system and design a transmitter and receiver by using ADS (Advanced Design System). Also, we simulated a link level performance with different channel estimation algorithm in Jakes fading channel environment. For the channel estimator, we used the WMSA(Weighted Multi-Slot Averaging) algorithm, EGE(Equal Gain Estimation) algorithm and SSE(Symbol-to-Symbol Estimation) algorithm. This study will be useful in the analysis and design of W-CDMA system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 1998.05a
• /
• pp.159-162
• /
• 1998

차세대 이동통신이 음성, 데이터, 동영상등 종합적인 멀티미디어 서비스를 목표로 하며, 세계 각국은 IMT-2000의 기술개발을 진행하고 있다 이런 서비스를 위해서는 광대역의 주파수를 필요로 하며, W-CDMA방식을 표준화하고 있다. 본 논문에서는 W-CDMA방식 단말기의 RF 수신부를 요구되는 규격에 따라 제작하고 그 성능을 테스트 하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.5
• /
• pp.451-460
• /
• 2004

The pilot bit pattern of W-CDMA system is used for the channel estimation and frame synchronization confirmation. This paper proposes the binary sequences for the frame synchronization for wideband code division multiple access (W-CDMA) system. We present the circuit for the generation of ideal frame synchronization property using the binary sequences called frame synchronization word(FSW). W-CDMA system uses compressed mode where up to 7 slots per one 10 msec frame are not transmitted to make measurements from another frequency without a full dual receiver terminal. It is shown that the proposed frame synchronization words also maintain the optimal frame synchronization property in the compressed mode by using the complementary mapping relationship of preferred pair. And we discuss the realization circuit for the generation of frame synchronization words by using the concept of preferred pairs, complementary mapping relationship, and maximal length sequence.