Performance of multidimensional multicode DS-CDMA using code diversity and error detection

TitlePerformance of multidimensional multicode DS-CDMA using code diversity and error detection
Publication TypeJournal Article
Year of Publication2001
AuthorsKim, D. I., and V. K. Bhargava
JournalCommunications, IEEE Transactions on
Pagination875 -887
Date Publishedmay.
Keywordsantenna diversity, block codes, code diversity, code division multiple access, constant amplitude signal, diversity gain, diversity reception, error detection, error detection codes, error performance, fading channels, high rate transmission, in-phase subchannels, information rate loss recovery, interference suppression, land mobile radio, linear power-inefficient amplifier, mobile radio, MOC channels, multidimensional multicode DS-CDMA, multidimensional signaling, multipath channels, multipath fading, multiple orthogonal codes, multiuser channels, nonlinear block coding, nonlinear codes, precoding, quadrature subchannels, radiofrequency interference, redundancy, self-interference cancellation, spread spectrum communication, third-generation W-CDMA standard, variable spreading factor, W-CDMA, wide-band code-division multiple-access, wireless channel

High rate transmission can be realized using multiple orthogonal codes (MOC), as proposed in the third-generation wide-band code-division multiple-access (W-CDMA) standard. However, the linear sum of MOC channels is no longer constant amplitude, and a highly linear, power-inefficient amplifier may be required for transmission. Recently, a nonlinear block coding technique called precoding is introduced to maintain a constant amplitude signal after superposition of MOC channels. This is achieved by adding redundancy. In this paper, we first describe a multidimensional signaling scheme that recovers some information rate loss by precoding. Second, we propose a self-interference (SI) cancellation scheme resulting from a code diversity between the in-phase and quadrature subchannels among MOC channels. In a typical wireless channel with multipath fading, this type of SI can be detrimental especially when the number of parallel MOC channels is large. Third, we show that the error detection capability of precoding can be combined with code diversity, resulting in a diversity gain. In addition, we show that the diversity gain can be achieved using antenna diversity to assure the degree of freedom in code diversity, and even with the large number of MOC channels, the error performance can be maintained reliably while outperforming the variable spreading factor scheme in W-CDMA


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