• Title/Summary/Keyword: multicarrier code-division multiple-access (MC-CDMA)

Search Result 18, Processing Time 0.126 seconds

Approximate Expression of Bit Error Rate in Uplink MC-CDMA Systems with Equal Gain Combining

  • Develi, Ibrahim;Akdagli, Ali
    • Journal of Communications and Networks
    • /
    • v.15 no.1
    • /
    • pp.25-30
    • /
    • 2013
  • Uplink multicarrier code-division multiple-access (MC-CDMA) with equal gain combining (EGC) over Nakagami fading channels is considered. An improved expression which is a feasible alternative for the bit error rate (BER) performance evaluation of MC-CDMA signals is proposed. Simulated annealing algorithm is employed to obtain the optimum value of the coefficients belonging to the proposed expression. Numerical examples show that the performance curves computed by the improved expression are in good agreement with the results obtained by the exact expression. Thus, the proposed expression can improve the accuracy of BER performance evaluation that has been realized by the approximate expression.

Adaptive Resource Allocation for MC-CDMA and OFDMA in Reconfigurable Radio Systems

  • Choi, Yonghoon
    • ETRI Journal
    • /
    • v.36 no.6
    • /
    • pp.953-959
    • /
    • 2014
  • This paper studies the uplink resource allocation for multiple radio access (MRA) in reconfigurable radio systems, where multiple-input and multiple-output (MIMO) multicarrier-code division multiple access (MC-CDMA) and MIMO orthogonal frequency-division multiple access (OFDMA) networks coexist. By assuming multi-radio user equipment with network-guided operation, the optimal resource allocation for MRA is analyzed as a cross-layer optimization framework with and without fairness consideration to maximize the uplink sum-rate capacity. Numerical results reveal that parallel MRA, which uses MC-CDMA and OFDMA networks concurrently, outperforms the performance of each MC-CDMA and OFDMA network by exploiting the multiuser selection diversity.

Blind Adaptive Multiuser Detection for the MC-CDMA Systems Using Orthogonalized Subspace Tracking

  • Ali, Imran;Kim, Doug-Nyun;Lim, Jong-Soo
    • ETRI Journal
    • /
    • v.31 no.2
    • /
    • pp.193-200
    • /
    • 2009
  • In this paper, we study the performance of subspace-based multiuser detection techniques for multicarrier code-division multiple access (MC-CDMA) systems. We propose an improvement in the PASTd algorithm by cascading it with the classical Gram-Schmidt procedure to orthonormalize the eigenvectors after their sequential extraction. The tracking of signal subspace using this algorithm, which we call OPASTd, has a faster convergence as the eigenvectors are orthonormalized at each discrete time sample. This improved PASTd algorithm is then used to implement the subspace blind adaptive multiuser detection for MC-CDMA. We also show that, for multiuser detection, the complexity of the proposed scheme is lower than that of many other orthogonalization schemes found in the literature. Extensive simulation results are presented and discussed to demonstrate the performance of the proposed scheme.

  • PDF

Effect Analysis of Timing Offsets for Asynchronous MC-CDMA Uplink Systems (비동기 MC-CDMA 상향 링크 시스템에서의 시간 옵셋 영향 분석)

  • Ko, Kyun-Byoung;Woo, Choong-Chae
    • Journal of the Institute of Electronics Engineers of Korea TC
    • /
    • v.47 no.8
    • /
    • pp.1-8
    • /
    • 2010
  • This paper models a symbol timing offset (STO) with respect to the guard period and the maximum access delay time for asynchronous multicarrier code division multiple access (MC-CDMA) uplink systems over frequency-selective multipath fading channels. Analytical derivation shows that STO causes desired signal power degradation and generates self-interferences. This effect of the STO on the average bit error rate (BER) and the effective signal-to-noise ratio (SNR) is evaluated. The approximated BER and the SNR loss caused by STO are then obtained as closed-form expressions. The tightness between the analytical result and the simulated one is verified for the different STOs and SNRs. Furthermore, the derived analytical results are verified via Monte Carlo simulations.

Effect Investigation of a GP for Asynchronous MC-CDMA Systems (비동기 MC-CDMA 시스템에 대한 보호구간의 영향 분석)

  • Ko, Kyun-Byoung;Hong, Dae-Sik
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.33 no.11C
    • /
    • pp.851-859
    • /
    • 2008
  • This paper investigates the effect a guard period (GP) in the form of a cyclic prefix for asynchronous multicarrier-code division multiple access (MC-CDMA) systems. At first, we analyze the performance of asynchronous MC-CDMA systems with a GP, which results in closed-form bit error rate (BER) performance. Furthermore, it confirms that the frequency diversity of MC-CDMA systems is identical to the path diversity. The analytical approach proposed here is extended to the case without a GP. The derived analytical results show that a GP is required for MC-CDMA systems in order to mitigate not only the effect of intersymbol interference (ISI) and intercarrier interference (ICI) but also the desired signal power degradation. In addition, the accuracy of the proposed analysis is verified by simulations.

A Study on the MRC and EGC in Nakagami-m Fading Channel (나까카미-m 페이딩 채널에서 최대비합성과 동이득합성에 관한 연구)

  • Lee, Kwan-Houng;Lee, Myung-Ho
    • Journal of the Korea Society of Computer and Information
    • /
    • v.11 no.5 s.43
    • /
    • pp.195-201
    • /
    • 2006
  • In multicarrier code division multiple access(MC-CDMA), the total system bandwidth is divided into a number of sub-bands, where each subband may use direct-sequence(DS) spreading and each subband signal is transmitted using a subcarrier frequency. In this paper, the system performance analysis of MC-CDMA using to gain combining(EGC) and maximal ratio combining(MRC) method over frequency selective Nakagami-m fading channel is analyzed. In the proposed system, a data sequence is serial-to-parallel converted, and MC-CDMA is used on each of the parallel data streams. The data streams are spread at both the symbol fraction level and at the chip level by the transmitter. In this paper, the compare to analysis,two standard diversity combining techniques, EGC and MRC, The good performance of system using to MRC more than EGC

  • PDF

A Study on Dual-rate MC-CDMA Systems (이중전송률 다중반송파 CDMA 시스템)

  • Kim Nam-Sun
    • Journal of the Korea Industrial Information Systems Research
    • /
    • v.10 no.1
    • /
    • pp.1-8
    • /
    • 2005
  • Multicarrier code division multiple access(MC-CDMA) Is a scheme that combines multicarrier modulation with CDMA. It offers robustness to frequency selective fading and can support higher rate data transmission with higher spectral efficiency. The objective of this article to proposed a new asynchronous ME-CDMA system to implement multiple data rate communications. It can be accomplished by changing the number of parallel branch(.p). For the analysis of average BER performance, numerical method and computer simulation were used. After MAI power of received signal calculated, the average BER can be acriuired using Gaussian approximation to MAI. We also compare the system performance with that of a single rate MC-CDMA system.

  • PDF

Simple Blind Channel Estimation Scheme for Downlink MC-CDMA Systems (하향링크 MC-CMDMA 시스템을 위한 간단한 미상 채널 추정 방법)

  • Seo, Bang-Won
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.37 no.6A
    • /
    • pp.480-487
    • /
    • 2012
  • In multicarrier code-division multiple access (MC-CDMA) systems, conventional blind channel estimation schemes require the inverse matrix calculation or eigenvalue decomposition of the received signal covariance matrix. Therefore, computational complexity of the conventional schemes is too high and they cannot be employed in downlink systems. In this paper, we propose a simple blind channel estimation scheme with very low computational complexity. Simulation results show that the proposed scheme has better channel estimation and bit error rate (BER) performance than the conventional schemes.

Multi-User Receiver of an MC-CDMA System Using a RBF Network (RBF Network를 이용한 다중반송파 코드분할 다중접속 시스템에서의 다중사용자 수신기)

  • 고균병;최수용;강창언;홍대식
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.25 no.6A
    • /
    • pp.885-892
    • /
    • 2000
  • A multi-used detector(MUD) using a radial basis function(RBF) network is proposed in a multicarrier-code division multiple access (MC-CDMA) system. In the proposed scheme, a RBF network is connected to the frequency domain in order to effectively utilize the frequency diversity. Simulations have been performed over the frequency selective and multipath fading channel. From these simulations, the proposed receiver is verified to be used for making the performance improvement in combating near-far effects and increasing the number of active users. The system capacity is increaed about 1.8 times at a BER of $10^{-3}$ under a single cell when the proposed scheme is compared with MUD using a parallel interference canceller(PIC).

  • PDF

Performance of MIMO MC-CDMA systems combining multi-beamforming algorithm with space-time coding (적응 다중 빔형성 기법과 시공간 부호가 결합된 MIMO MC-CDMA시스템의 성능)

  • Kim, Chan Kyu
    • Journal of the Institute of Electronics and Information Engineers
    • /
    • v.50 no.8
    • /
    • pp.53-60
    • /
    • 2013
  • In this paper, the new multi-beamforming is proposed for Multiple-input multiple-output (MIMO) Multicarrier-Code division multiple access(MC-CDMA) systems to overcome the decrease of performance due to multiuser interference and multiple-antenna interference. Installing the number of multi-beamformer which is equal to the number of multi-transmitter antennas and exploiting the proposed approach at the receiver of MIMO MC-CDMA, the multi-beams are formed toward each multi-antenna of desired user and null beam are formed to other interference. Therefore, the performance of MIMO MC-CDMA system is improved as removing the interference signal. BER performance improvement is investigated through computer simulation by the proposed approach to MIMO MC-CDMA system.