• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.3
• /
• pp.747-752
• /
• 1996

In this paper, we propose a new SO-MLSE(soft-output maximum likelihood sequence estimation) equalizer, which can be used in GSM digital cellular system) it uses complex correlation of training sequence to obtain the channel information and the equalization is performed by MLSE using Viterbi algorithm. In order to generate a soft-decision input to channel decoder (Viterbi decoder), the soft-output equalization algorithm is needed. The adopted algorithm doesn't require to modify the structure of HO-MLSE(hard output MLSE) equalizer, that is, SO-MLSE equalizer can be implemented by adding soft-output generation block to HO-MLSE equalizer. This algorithm uses the outputs of matched filter and HO-MLSE equalizer. It turns out that the complexity of proposed SO-MLSE equalizer is simpler than those of other SO-MLSE equalizer and its perforance is almost the same as those of others. Finally, the proposed SO-MLSE equalizer is also implemented s a prototype with ADSP-2101 16-bits fixed point digital signal processing chip.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.9 no.1
• /
• pp.111-118
• /
• 2013

This paper presents implementation of Air protocol analyzer and physical layer design algorithm. The analyzer is a measurement system providing real-time analysis of wireless signals between User Equipment (UE) and Node-B. The implemented system proposed in this paper consists of Digital Signal Processors (DSPs) and Field Programmable Gate Arrays (FPGAs). The waveform of Wideband Code Division Multiple Access (WCDMA) has been selected for verification of the proposed system. We designed the analyzer using equalizer algorithm and rake-receiver algorithm. Among various algorithms of designing the equalizer, we have chosen Linear Minimum Mean Square Error (LMMSE) equalizer that uses the inverse of channel matrix. Since the LMMSE equalizer uses the inverse channel matrix, it suffers from a large amount of computational load, while it outperforms most conventional equalizers. In this paper, we introduce an efficient procedure of reducing the computational load required by LMMSE equalizer-based receiver.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.41 no.4
• /
• pp.131-139
• /
• 2004

This paper proposes a variable-Q digital graphic equalizer with the opposite filters. A method for designing the proposed equalizer is also presented. In the proposed variable-Q equalizer, we adjust the Q-factor of the equalizer filter depending on the gain, yielding an improved equalizer performance. Also, by increasing the Q-factor of the opposite filters gracefully as the gain becomes greater, the inter-band interference can be removed effectively. We shall show that the frequency response of the proposed equalizer can reproduce the user's gain setting faithfully.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.2
• /
• pp.7-17
• /
• 2015

In this paper, we propose a single antenna SSD(simultaneous single band duplex) system using turbo equalizer. The proposed system communicates simultaneously on single band. That is the proposed system is full-duplex system. The proposed system uses balanced feed network circuit to improve isolation in single antenna structure. Also, the proposed system uses RF(radio frequency) cancellation and digital cancellation to cancel self-interference. Additionally, the proposed system uses turbo equalizer to equalize ISI(inter-symbol interference) by harsh multipath fading and to collect bit errors by residual self-interference signals. By using turbo equalizer, the proposed system guarantees QoS(quality of service). In this paper, we uses Simulink simulation program to analyze performance of the proposed system. The simulation results confirm that proposed system can communicate simultaneously by using balanced feed network, RF cancellation, digital cancellation and turbo equalizer in harsh multipath channel on single band.

• Proceedings of the Acoustical Society of Korea Conference
• /
• 1992.06a
• /
• pp.76-80
• /
• 1992

We consider the tapped-delay line (TDL) equalizer with the few calculation quantity and the simplity, the decision feedback equalizer (DFE) with the good property for interference, and lattice equalizer(LE) with high insensitivity to roundoff noise in mobile communication fading channel. The used adaptive algorithm is the LMS algorithm and RLS algorithm. In this paper, we have evaluated the performance of the TDL equalizer, the decision feedback equalizer, and lattice-structured equalizer, for the digital signal corrupted by the impulsive noise and the white gaussian noise under the fading channel environment. From the results of error performance analysis, it is confirmed that lattice-structured equalizer has better performance than DFE equalizer and TDL equalizer.

• Journal of Digital Contents Society
• /
• v.7 no.2
• /
• pp.109-115
• /
• 2006

In this paper, we design and performance evaluate the equalizer for S-DMT table modem, which supports more channels and better quality symmetric mutimedia services over HFC network. We verified that both of the designed equalizers show good convergence characteristics and that the performance of the time domain equalizer is 1 dB better than that of the frequency domain equalizer overall range of Eb/No.

• Journal of Broadcast Engineering
• /
• v.8 no.1
• /
• pp.3-10
• /
• 2003

This paper proposes a variable-Q digital graphic equalizer in which each equalizer filter has different Q-factor depending on the band as well as the gain. The proposed equalizer demonstrates the symmetric frequency response over the audible frequency range. While maintaining the similar level of hardware complexity, the proposed equalizer yields an actual response that is quite close to the desired one, as compared with the conventional equalizers. Also, we investigate how the performance is affected by the center frequencies of the filters.

• Journal of the Korea Computer Industry Society
• /
• v.3 no.1
• /
• pp.27-34
• /
• 2002

There is much interest on information communications owing to the rapid development of network and IT(Information Technology). Analog signals are converted into digital signals for information communications. However, it is very difficult to completely erase the distortion induced during the conversion of analog signals such as voices and images into digital signals. Existing audio graphic equalizer requires very complex processes to calculate the gain and coefficients of the higher-order filter which is required to generate natural sound and to satisfy the need of each person. Unfortunately it is uneconomical and very difficult to embed the existing digital audio equalizer in the system because of the complexity of the existing digital audio equalizer for high quality sound. This paper discusses the design of a new digital audio graphic equalizer(DAGEQ) which can improve system performance and the quality of audio sound, and can be embedded in the system. This new DAGEQ is designed so that the gain can be controlled automatically. The automatic control of coefficients and gain empowers real time processing and the improvement of audio quality.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39A no.1
• /
• pp.28-35
• /
• 2014

In this paper, we propose a SSD(simultaneous single band duplex) system with turbo equalizer for full-duplex over harsh ISI(inter symbol interference) channel. The proposed system uses RF(radio frequency) cancellation and digital cancellation to cancel self-interference caused by simultaneous single band duplex communication. Also, using turbo equalizer, the proposed system equalizes signal after digital cancellation. In this paper, we design SSD system with turbo equalizer. And then we evaluate BER(bit error rate) performance of the proposed system comparison with SSD system with adaptive equalizer. We use simulink program to confirm BER performance of the proposed system. The simulation results shows that the proposed system equalizes received signal effectively over harsh ISI channel and BER performance of the proposed system is better than BER performance of SSD system with adaptive equalizer.

• The Journal of the Acoustical Society of Korea
• /
• v.24 no.3E
• /
• pp.109-114
• /
• 2005

In this paper, we present a phase coherent all-digital transceiver for underwater acoustic communication, which allows the system to reduce complexity and increase robustness in time variant underwater environments. It is designed in the digital domain except for transducers and amplifiers and implemented by using a multiple digital signal processors (DSPs) system. For phase coherent reception, conventional systems employed phase-locked loop (PLL) and delay-locked loop (DLL) for synchronization, but this paper suggests a frame synchronization scheme based on the quadrature receiver structure without using phase information. We show experimental results in the underwater anechoic basin at MOERI. The results show that the adaptive equalizer compensates frame synchronization error and the correction capability is dependent on the length of equalizer.