On the Optimal Chip Rate of Adaptive Power and Rate DS/CDMA Communication Systems in Nakagami Fading Channels

Ye Hoon LEE
Dong Ho KIM
Hong Jik KIM

IEICE TRANSACTIONS on Communications   Vol.E88-B    No.9    pp.3798-3801
Publication Date: 2005/09/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.9.3798
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Wireless Communication Technologies
optimal chip rate,  adaptive power and rate,  DS/CDMA,  Nakagami fading,  

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We investigate the optimal chip rate of power or rate adapted direct-sequence code division multiple access (DS/CDMA) communication systems in Nakagami fading channels. We find that the optimal chip rate that maximizes the spectral efficiency depends upon both the channel parameters, such as multipath intensity profile (MIP) and line-of-sight (LOS) component, and the adaptation scheme itself. With the rate adaptation, the optimal chip rate is less than 1/Tm irrespective of the channel parameters, where Tm is multipath delay spread. This indicates that with the rate adaptation, correlation receiver achieves higher spectral efficiency than RAKE receiver. With the power adaptation, however, the optimal chip rate and the corresponding number of tabs in RAKE receiver are sensitive to MIP and LOS component.