Optimal Two-Stage Partial PIC Receivers for Aperiodic Spreading Codes

Y.-T. Hsieh and W.-R. Wu (Taiwan)


CDMA, multiuser detection, parallel interference cancellation.


The parallel interference cancellation (PIC) is considered as a simple yet effective multiuser detector in direct sequence code division multiple access (DS-CDMA) systems. However, the system performance may be deteriorated due to unreliable interference estimate in early canceling stages. Thus, partial cancellation factors (PCFs) were introduced to control the interference can cellation level and this results in the partial PIC approach. There are various types of partial PIC. Existing methods for determining optimum PCFs are not all available. In this paper, we consider a two-stage partial PIC receiver operated in asynchronous CDMA systems with aperiodic spreading codes. Using the minimum bit error rate crite rion we derive closed-form solutions for optimal PCFs. Simulation results show that our theoretical optimal PCF values highly agree with the empirical ones. Also, the two-stage partial PIC using derived optimal PCFs out performs not only a two-stage, but also a three-stage full PIC.

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