Paper Info
Title
Performance analysis of a linear MMSE receiver for bandlimited random-CDMA using quadriphase spreading over multipath channels
Abstract
This paper analyzes the bit-error-rate (Pe) performance of a linear minimum mean-square error (LMMSE) receiver for bandlimited direct-sequence code-division multiple-access systems which use quadriphase spreading with aperiodic pseudonoise (PN) sequences. The analysis is based on the improved Gaussian approximation (IGA) with focus on chip pulse shaping. It shows that the IGA reduces to the standard Gaussian approximation (SGA) if 1) random quadriphase spreading is employed, 2) the spreading factor takes moderate to large values, and 3) the chip pulse excess bandwidth (BW) is zero. Hence, the SGA, known for its inaccuracy in low regions of Pe, remains an accurate approximation even when the number of active users in the system is small as long as the aforementioned conditions are met. The analysis holds for either matched or different transmit and receive filters. Consequently, closed form conditional Pe expressions are derived for the coherent selective RAKE and the LMMSE receivers and verified with Monte Carlo simulations. Numerical results are presented to illustrate the performance improvement achieved by the LMMSE receiver which, in contrast to the coherent selective RAKE receiver, not only suppresses interference when the excess BW of chip pulse is nonzero, but also harnesses the energy of all paths of the desired user. Under the examined scenarios tailored toward current narrowband system settings, the LMMSE receiver achieves 60% gain in capacity over the selective RAKE receiver. A third of the gain is due to interference suppression capability of the receiver while the rest is credited to its ability to collect the energy of the desired user diversified to many paths. Future wideband systems will yield an ever larger gain.
Year
DOI
Venue
2004
10.1109/TWC.2004.830839
IEEE Transactions on Wireless Communications
Keywords
Field
DocType
multipath channel,conditional pe expression,larger gain,lmmse receiver,coherent selective rake receiver,performance analysis,bandlimited random-cdma,improved gaussian approximation,accurate approximation,chip pulse,linear mmse receiver,coherent selective rake,chip pulse excess bandwidth,selective rake receiver,code division multiple access,fading,monte carlo methods,bit error rate,monte carlo simulation,matched filters,bandwidth,chip,radio receivers,minimum mean square error,pulse shaping,spread spectrum communication,rake receiver,gaussian processes
Rake,Wideband,Rake receiver,Narrowband,Minimum mean square error,Algorithm,Real-time computing,Code division multiple access,Statistics,Mathematics,Spread spectrum,Bit error rate
Journal
Volume
Issue
ISSN
3
4
1536-1276
Citations 
PageRank 
References 
4
0.39
20
Authors
2
Name
Order
Citations
PageRank
A. Mirbagheri1141.42
Y. C. Yoon220324.14