Browsing by Author "Hsieh, Yu-Tao"

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Performance analysis of an adaptive two-stage partial PIC receiver
(2007)
Hsieh, Yu-Tao
;
Wu, Wen-Rong
;
電信工程研究所
;
Institute of Communications Engineering
Partial parallel-interference-cancelation (PIC) is a well-known multiuser detection technique for DS/CMDA systems. Conventionally, partial-cancelation-factors (PCFs) are optimally derived and kept constant in a designated interval. Recently, a special kind of partial PIC was proposed. In the approach, PCFs are adaptively trained (chip-by-chip) using the least-mean-square (LMS) algorithm, and PCFs are updated with a bit-by-bit fashion. It has been shown that the adaptive partial PIC detector outperforms conventional partial PIC. Despite its good performance, performance analysis of the approach has not been explored yet. This paper is aimed to fill the gap by conducting the performance analysis of an adaptive two-stage partial PIC detector. We first analyze optimal weights (i.e., PCFs), weight error means, and weight error variances. Based on these results, we derive the output mean-squared-error (MSE) and bit-error-rate (BER) for each user. Simulation results indicates that our analytical results highly agree with empirical ones.
Performance analysis of an adaptive two-stage PICCDMA receiver in AWGN channels
(2008-06-01)
Hsieh, Yu-Tao
;
Wu, Wen-Rong
;
電信工程研究所
;
Institute of Communications Engineering
Parallel interference cancellation (PIC) is considered a simple yet effective multiuser detector for direct-sequence code-division multiple-access (DS-CDMA) systems. However, its performance may deteriorate due to unreliable interference cancellation in the early stages. Thus, a partial PIC detector, in which partial cancellation factors (PCFs) are introduced to control the interference cancellation level, has been developed as a remedy. Recently, an interesting adaptive multistage PIC algorithm was proposed. In this scheme, coefficients combining the channel responses and optimal PCFs are blindly trained with the least mean square (LMS) algorithm. The algorithm is simple to implement, inherently applicable to time-varying environments, and superior to the non-adaptive type of partial PICs. Despite its various advantages, its performance has not been theoretically analyzed yet. The contribution of this paper is to fill the gap by analyzing an adaptive two-stage PIC in AWGN channels. We explicitly derive the analytical results for optimal weights, weight-error means, and weight-error variances. Based on these results, we finally derive the output bit error rate (BER) for each user. Simulation results indicate that our analytical results highly agree with empirical ones. (c) 2008 Elsevier B.V. All rights reserved.
Weight behavior analysis of adaptive two-stage partial PIC receivers
(2007)
Hsieh, Yu-Tao
;
Wu, Wen-Rong
;
電信工程研究所
;
Institute of Communications Engineering
Partial parallel-interference-cancelation (PIC) is a well-known multiuser detection technique for DS/CMDA systems. Conventionally, partial-cancelation-factors (PCFs) are optimally derived and kept constant in a designated interval. Recently, a special kind of partial PIC was proposed. In the approach, PCFs are adaptively trained (chip-by-chip) using the least-mean-square (LMS) algorithm, and PCFs are updated with a bit-by-bit fashion. It has been shown that the adaptive partial PIC detector outperforms conventional partial PIC. Despite its good performance, performance analysis of the approach has not been explored yet. This paper is aimed to fill the gap by conducting the performance analysis of an adaptive two-stage partial PIC detector. We first analyze optimal weights (i.e., PCFs), weight error means, and weight error variances. Simulation results indicates that our analytical results highly agree with empirical ones.