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- 저자 : Tjhung Tjeng Thiang (검색결과 2 건)
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A New Multicarrier Multicode DS-CDMA Scheme for Time and Frequency Selective Fading Channels
Cao Yewen,Tjhung Tjeng Thiang,Ko Chi Chung The Korea Institute of Information and Commucation 2005 Journal of communications and networks Vol.7 No.1
In this paper, a new multi carrier, direct sequence code division multiple access (MC-DS-CDMA) system is proposed. Our new signal construction is based on convolutional encoding of the transmitted data, serial-to-parallel (S/P) conversion of the encoded data, Walsh-Hadamard-transformation (WHT), a second S/P conversion of the WHT outputs, spread spectrum (SS) modulation with a common pseudo-noise (PN) sequence, and then multicarrier transmission. The system bit error rate (BER) performance in frequency selective fading channel in the presence of additive white Gaussian noise (AWGN) and a jamming tone is analyzed and simulated. The numerical results are compared with those from an orthogonal MC-DS-CDMA system of Sourour and Nakagawa [7]. It is shown that the two systems have almost the same BER performance, but the proposed scheme has better anti-jamming ability.
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A Unified Framework for Transmitter Power Control in Cellular Radio Systems
Chin Choy Chai,Ying Lu,Yong Huat Chew,Tjeng Thiang Tjhung 한국전자통신연구원 2004 ETRI Journal Vol.26 No.5
This paper investigates the impacts of array weight errors (AWE) in an antenna array (AA) on a parallel interference cancellation (PIC) receiver in uplink synchronous and asynchronous direct sequence code division multiple access (DS-CDMA) systems. The performance degradation due to an AWE, which is approximated by a Gaussian distributed random variable, is estimated as a function of the variance of the AWE. Theoretical analysis, confirmed by simulation, demonstrates the tradeoffs encountered between system parameters such as the number of antennas and the variance of the AWE in terms of the achievable average bit error rate and the user capacity. Numerical results show that the performance of the PIC with the AA in the DS- CDMA uplink is sensitive to the AWE. However, either a larger number of antennas or uplink synchronous transmissions have the potential of reducing the overall sensitivity, and thus improving its performance.
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