Abstract
An adaptive parallel interference cancelation (APIC) scheme is proposed for the multicarrier direct sequence code division multiple access (MC-DS-CDMA) system. Frequency diversity inherent in the MC system is exploited through maximal ratio combining, and an adaptive least mean square algorithm is used to estimate the multiple access interference. Theoretical analysis on the bit-error rate (BER) of the APIC receiver is presented. Under a unified signal model, the conventional PIC (CPIC) is shown to be a special case of the APIC. Hence the BER derivation for the APIC is also applicable to the CPIC. The performance and the accuracy of the theoretical results are examined via simulations under dierent design parameters, which show that the APIC outperforms the CPIC receiver provided that the adaptive parameters are properly selected.
Highlights
Future generations of broadband wireless mobile communication systems are expected to support various services over a multitude of channels encountered in indoor, open rural, suburban, and urban environments, while maintaining the required quality of service (QoS) [1, 2]
An adaptive parallel interference cancelation (APIC) scheme is proposed for the MC-direct-sequence code-division multiple access (DS-CDMA) system, in which the frequency diversity inherent in the MC system is exploited through maximal ratio combining (MRC)
Under the unified signal model, we show that the theoretical result derived for the APIC is applicable to the conventional parallel IC (PIC) (CPIC), as long as the adaptive step-size is set to zero
Summary
Future generations of broadband wireless mobile communication systems are expected to support various services over a multitude of channels encountered in indoor, open rural, suburban, and urban environments, while maintaining the required quality of service (QoS) [1, 2]. A number of MC-CDMA schemes have been proposed in the literature [5,6,7,8,9]. Their performances are analyzed and compared with that of single carrier (SC) DS-CDMA systems in frequency-selective Rayleigh fading channels [9,10,11,12,13]. The underlying reason is the integration of an orthogonal frequency division multiplexing (OFDM) overlay, which can be designed such that each subcarrier undergoes flat fading and reduces the severe intersymbol interference (ISI) encountered in SC-DS-CDMA systems
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