• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.89-92
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• 2001

In this paper, adaptive multi-stage parallel interference cancellation (PIC) receiver is considered for a multi-rate DS-CDMA system. In each stage of the adaptive multi-stage PIC receiver, multiple access interference (MAI) estimates are obtained using the sub-bit estimates from the Previous stage and the adaptive weights for the sub-bit estimates. The adaptive weights are obtained by minimizing the mean squared error between the received signal and its estimate through a least mean square (LMS) algorithm. It is shown that the adaptive multi- stage PIC receiver achieves smaller BER than the matched filter receiver, multi-stage PIC receiver, and multi-stage partial PIC receiver for the multi-rate DS-CDMA system in a Rayleigh fading channel.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
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• pp.13-16
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• 2002

In this paper, we propose adaptive despreading receiver for multi-code PW-CDMA system with binary-level clipping. The distortion due to clipping the multi-level signal causes the performance degradation. Adaptive despreading alleviates the effect of clipping. It is shown that the proposed adaptive despreading receiver achieves smaller BER than conventional despreading receiver for multi-code PW-CDMA system with binary-level clipping.

• Journal of Communications and Networks
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• 제7권3호
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• pp.243-247
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• 2005

We propose an efficient block least-mean-square (BLMS) adaptive algorithm, in conjunction with error control coding, for direct-sequence code division multiple access (DS-CDMA) systems. The proposed adaptive receiver incorporates decision feedback detection and channel encoding in order to improve the performance of the standard LMS algorithm in convolutionally coded systems. The BLMS algorithm involves two modes of operation: (i) The training mode where an uncoded training sequence is used for initial filter tap-weights adaptation, and (ii) the decision-directed where the filter weights are adapted, using the BLMS algorithm, after decoding/encoding operation. It is shown that the proposed adaptive receiver structure is able to compensate for the signal-to­noise ratio (SNR) loss incurred due to the switching from uncoded training mode to coded decision-directed mode. Our results show that by using the proposed adaptive receiver (with decision feed­back block adaptation) one can achieve a much better performance than both the coded LMS with no decision feedback employed. The convergence behavior of the proposed BLMS receiver is simulated and compared to the standard LMS with and without channel coding. We also examine the steady-state bit-error rate (BER) performance of the proposed adaptive BLMS and standard LMS, both with convolutional coding, where we show that the former is more superior than the latter especially at large SNRs ($SNR\;\geq\;9\;dB$).

• 한국전자파학회논문지
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• 제9권6호
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• pp.746-760
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• 1998

본 논문에서는 이동 위성 채널에서 트렐리스 부호화된 CPFSK 신호를 검파하는데 있어서 최적의 수신 방식인 MLSD 대신에 복잡도를 크게 줄이면서 MLSD와 거의 같은 성능을 얻는 적응 RSSD 수신 방식을 제안 한다. 제안된 앉줬D를 시변 채널인 이동 위성 채널에 적용하기 위해서는 채널의 상태를 추정해야 하는 문제 가 발생하며l 본 논문에서는 채널의 특성을 추정하는 방법으로 steepest desc에t 알고리틈을 이용하며I 보다 효율적인 채널 추정을 위해 symbol-aided방법이 사용된다. syr뼈ol-aided 방법은 신뢰성 있는 채널 추정을 위하여 송신단에서는 주기적으로 알고 있는 섬볼을 삽입한 후에, 수신단에서는 알고 있는 섬볼이 수신되면 비터비 프로세서는 임시 데이터 결정을 하여 채널 추정기로 보내는 방법이다. 이러한 임시 데이터 결정 방법 을 사용한 채널 추정기는 긴 결정 지연 시간올 이용한 방법보다도 이동 위성 채널에서 빠르고 신뢰성 있게 채널을 추정한다. 본 논문에서 제안한 적웅 RSSD 수신 방식은 적웅 MLSD에 대한 준최적 수신 방식임에도 불구하고 복잡도를 크게 줄이면서 이통 위성 채널을 빠르고 신뢰성 있게 추적한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권6호
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• pp.1116-1132
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• 2010

In this paper, a new forward error correction (FEC) protocol is proposed for point-to-multipoint satellite links. Link-layer error control protocols in point-to-multipoint satellite links impose several problems such as unreliability and receiver-heterogeneity. To resolve the problem of heterogeneous error rates at different receivers, the proposed scheme exploits multiple multicast channels to which each receiver tunes. The more channels a receiver tunes to, the more powerful error correcting capability it achieves. Based on its own channel condition, each receiver tunes to as many channels as it needs, which prevents from receiving unwanted parities. Furthermore, each receiver saves the decoding time, processing overhead, and processing energy. Performance evaluation shows that the proposed scheme guarantees the target PER while saving energy. The proposed technique is highly adaptive to the channel variation with respect to the throughput efficiency, and provides scalable PER and throughput efficiency.

• Journal of Positioning, Navigation, and Timing
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• 제8권1호
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• pp.19-29
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• 2019

This paper analyzes the design factors for GNSS anti-jamming receiver system in which the adaptive beamforming algorithm is applied in GNSS receiver system. The design analysis factors used in this paper are divided into three: antenna, beamforming algorithm, and operation environment. This paper analyzes the above three factors and presents numerical simulation results on antenna and beamforming algorithm.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권2호
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• pp.155-167
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• 2015

An adaptive equalization scheme based on all-digital jitter measurement is proposed for a continuous time linear equalizer (CTLE) preceding a clock and data recovery (CDR) in a receiver circuit for high-speed serial interface. The optimum equalization coefficient of CTLE is determined during the initial training period based on the measured jitter. The proposed circuit finds automatically the optimum equalization coefficient for CTLE with 20", 30", 40" FR4 channel at the data rate of 5 Gbps. The chip area of the equalizer including the adaptive controller is 0.14 mm2 in a $0.13{\mu}m$ process. The equalizer consumes 12 mW at 1.2 V supply during the normal operation. The adaptive equalizer has been applied to a USB3.0 receiver.

• 한국통신학회논문지
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• 제25권10B호
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• pp.1714-1721
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• 2000

In the mobile communication using DS-CDMA systems the problem of multiple user interference which reduce the performance is generated by multiple user access. In this paper to solve this problem we proposed the direct decision blind adaptive receiver with knowledge of only the desired user's spreading sequence. Simulation result present that the total user's power has equal gain The gain of signal to interference ratio for the proposed blind DD-LMS receiver has about 6[dB] than conventional receiver at additive white Gaussian noise and large gain at multipath channels. And when interference user's power has more large gain than desired user's power the gain of SIR for the proposed receiver has large value. And simulation result of bit error rate present that DD-LMS receiver has higher performance than LCCMA receiver. Thus the proposed blind DD-LMS receiver has robustness against interference of high power user and multipath channels.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
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• pp.44-48
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• 2002

This paper describes an adaptive signal processing of digital receiver with DDC(Digital Down Convertor), DDC is implemented by using NCO(Numerically Controlled Oscillator), digital low pass filter. for the passband sampling, we present the results of digital receiver simulation with DDC. We confirm that the low IP signal is converted to zero IF by DDC. DOA(Direction Of Arrival) estimation technique using MUSIC(Multiple SIgnal Classification) algorithm with high resolution is presented. We Cow that an accurate resolution of DOA depends on the input sampling number.

• ETRI Journal
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• 제42권1호
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• pp.26-35
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• 2020

Herein, we consider uplink multiuser massive multiple-input multiple-output systems when multiple users transmit information symbols to a base station (BS) by applying simple space-time block coding (STBC). At the BS receiver, two detection filters for each user are used to detect the STBC information symbols. One of these filters is for odd-indexed symbols and the other for even-indexed symbols. Using constrained output variance metric minimization, we first derive a special relation between the closed-form optimal solutions for the two detection filters. Then, using the derived special relation, we propose a new blind adaptive algorithm for implementing the minimum output variance-based optimal filters. In the proposed adaptive algorithm, filter weight vectors are updated only in the region satisfying the special relation. Through a theoretical analysis of the convergence speed and a computer simulation, we demonstrate that the proposed scheme exhibits faster convergence speed and lower steady-state bit error rate than the conventional scheme.