naa a22 4500 51079145X CHVBK 20180411083321.0 cr unu---uuuuu 180411e20130701xx s 000 0 eng 10.1007/s11277-012-0793-1 doi (NATIONALLICENCE)springer-10.1007/s11277-012-0793-1 Performance Analysis of Subspace Based Downlink Channel Estimation for W-CDMA Systems Using Chaotic Codes [Elektronische Daten] [M. Sangeetha, Vidhyacharan Bhaskar] This paper presents blind channel estimation for downlink W-CDMA system that employs chaotic codes and Walsh codes for spreading information bits of the multiple users. In a W-CDMA system, while transmitting over multipath channels, both intersymbol interference (ISI) as a result of Inter Chip Interference and multiple access interference (MAI) cannot be easily eliminated. Although it is possible to design multiuser detectors that suppress MAI and ISI, these detectors often require explicit knowledge of at least the desired users' signature waveform. Earlier work focused on a subspace based channel estimation algorithm for asynchronous CDMA systems to estimate the multiple users' symbols, where only AWGN channel was considered. In our work, we study a similar subspace-based signature waveform estimation algorithm for downlink W-CDMA systems, which use chaotic codes instead of pseudo random codes, that provide estimates of the multiuser channel by exploiting structural information of the data output at the base station. In particular, we show that the subspace of the (data+noise) matrix contains sufficient information for unique determination of channels, and hence, the signature waveforms and signal constellation. We consider Rayleigh and Rician fading channel model to quantify the multipath channel effects. Performance measures like bit error rate and root mean square error are plotted for both chaotic codes and Walsh codes under Rayleigh and Rician fading channels. Springer Science+Business Media, LLC., 2012 Smoothing factor nationallicence Signature waveforms nationallicence Walsh codes nationallicence Chaotic codes nationallicence Bit error rate nationallicence Root mean square error nationallicence Sangeetha M. Department of Electronics and Communication Engineering, SRM University, 603203, Kattankulathur, Kancheepuram Dt., Tamil Nadu, India aut Bhaskar Vidhyacharan Department of Electronics and Communication Engineering, SRM University, 603203, Kattankulathur, Kancheepuram Dt., Tamil Nadu, India aut Wireless Personal Communications Springer US; http://www.springer-ny.com 71/1(2013-07-01), 1-21 0929-6212 71:1<1 2013 71 11277 https://doi.org/10.1007/s11277-012-0793-1 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11277-012-0793-1 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Sangeetha M. Department of Electronics and Communication Engineering, SRM University, 603203, Kattankulathur, Kancheepuram Dt., Tamil Nadu, India aut NATIONALLICENCE 700 1- Bhaskar Vidhyacharan Department of Electronics and Communication Engineering, SRM University, 603203, Kattankulathur, Kancheepuram Dt., Tamil Nadu, India aut NATIONALLICENCE 773 0- Wireless Personal Communications Springer US; http://www.springer-ny.com 71/1(2013-07-01), 1-21 0929-6212 71:1<1 2013 71 11277 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer