• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10A
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• pp.807-815
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• 2003

MultiCode-CDMA (MC-CDMA) system of chip level MPSK incorporating with clipper (MP-CDMA)[l] shows constant envelope signal which can mitigate the performance degradation due to nonlinear transmit amplifier. In this paper, modulation is modified to carry out differential encoded MPSK rather than MPSK. The modified system is called DMP-CDMA. DMP-CDMA using differential detection has advantages on receiver complexity and pilot overhead. However, it is inferior to coherent detection by about 4.0dB due to inherent power inefficiency of noncoherent detection and the error propagation. Multiple symbol differential detection is employed in order to improve DMP-CDMA using differential detection. As the result, the performance of DMP-CDMA system is improved about 3.6dB compared to differential detection.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.410-414
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• 2006

In the present, Orthogonal Frequency Division Multiple Access (OFDMA) that wireless access scheme for high speed data transmission is noticed in mobile communication market and OFDMA/TDD scheme will be used combining Time Division Duplex (TDD) scheme based on OFDMA. The Base Station's receiver synchronizes the symbol timing to anyone user's symbol and the other user's symbols have some Symbol Timing Offset (STO). Linear phase shift is occurred by each user's STO in an OFDMA symbol and the Multiple Access Interference (MAI) caused by the summation of each user's linear phase shift degrades the performance of ranging code detection. In this paper, we analyze the ranging code detection performance for each users STO in OFDMA/TDD system. Simulation results show that the more users access and mobile speed increase, the more ranging code detection performance degrades.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.232-239
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• 2006

In this paper, we analyze the preamble model for Wireless PAN(WPAN) in proposed Ultra WideBand(UWB) Multi-Band OFDM(MB-OFDM) system of IEEE 802.15.3a standard. Besides, we propose effective Carrier Frequency Offset and Symbol Timing Offset Estimation algorithm which offers enhanced performance, and analyze its performance using Detection Probability, False Alarm Probability, Missing Probability, Mean Acquisition Time and MSE(Mean Square Error) through simulation in AWGN and UWB channel environments.

• Journal of the Semiconductor & Display Technology
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• v.8 no.2
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• pp.23-29
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• 2009

To increase the data capacity of one-dimensional symbology, 2D barcodes have been proposed a decade ago. In this paper, a new 2D barcode detection algorithm based on Local Binary Pattern is presented. To locate 2D barcode symbols, a texture analysis scheme based on the Local Binary Pattern is adopted, and a gray-scale projection with sub-pixel operation is utilized to separate the symbol precisely from the input image. Finally, the segmented symbol is normalized using the inverse perspective transformation for the decoding process. The proposed method ensures high performances under various lighting/printing conditions and strong perspective deformations. Experiments show that our method is very robust and efficient in detecting the symbol area for the various types of 2D barcodes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.6
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• pp.700-705
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• 2012

This paper suggests the detecting method in which it uses the candidate symbol obtained through PI-SDR, the little computational complexity is required. By using the candidate symbol matrices obtained through PI-SDR, ZF and MMSE method was applied and the received signal was detected. The linear detecting method using PI-SDR candidate symbol is out of the performance than ML detecting method but the complexity is low. Because of using the symbol come close to the solution of ML, the proposed method's performance is better than the existing ZF and MMSE method.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.7
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• pp.12-18
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• 2017

This paper presents a Dijkstra's-search-based sphere decoding (SD) algorithm with limited complexity for the symbol detection in MIMO communication systems. The Dijkstra search-based SD is efficient to achieve a near-optimal error rate in the MIMO symbol detection, but has a critical problem in that its complexity is variable and can correspond to that of the exhaustive search in the worst case. The proposed algorithm limits the computations while achieving a near-optimal error rate. Simulation results show that the error rate is near optimal even with the limited complexity.

• Journal of Communications and Networks
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• v.17 no.6
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• pp.609-621
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• 2015

Recently, a variety of reduced complexity soft-in soft-output detection algorithms have been introduced for iterative detection and decoding (IDD) systems. However, it is still challenging to implement soft-in soft-output detectors for MIMO systems due to heavy burden in computational complexity. In this paper, we propose a soft detection algorithm for MIMO systems which performs close to the full dimensional joint detection, yet offers significant complexity reduction over the existing detectors. The proposed algorithm, referred to as soft-input soft-output successive group (SSG) detector, detects a subset of symbols (called a symbol group) successively using a deliberately designed preprocessing to suppress the inter-group interference. In fact, the proposed preprocessor mitigates the effect of the interfering symbol groups successively using a priori information of the undetected groups and a posteriori information of the detected groups. Simulation results on realistic MIMO systems demonstrate that the proposed SSG detector achieves considerable complexity reduction over the conventional approaches with negligible performance loss.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.574-577
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• 2002

In this paper, we propose a new symbol time synchronization scheme suitable for the OFDM system with an interpolator. The proposed performs the following three steps. In the first step, the coarse symbol time synchronization is achieved by continuously measuring the average power of the received envelope signal. Based on this average power, the detection possibility for the symbol time synchronization is determined. If the signal is sufficient for synchronization, we next perform a relatively accurate symbol time synchronization by measuring the correlation a short training signal and the received envelope signal. Finally, an additional frequency synchronization is performed with a long training signal to correct symbol synchronization errors caused by the phase rotation. From the simulation results, one can see that the proposed synchronization scheme provides a good synchronization performance over frequency selective channels.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.2
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• pp.601-617
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• 2014

In digital radio broadcasting systems, long delays are incurred in service start time when tuning to a particular frequency because several synchronization steps, such as symbol timing synchronization, frame synchronization, and carrier frequency offset and sampling frequency offset compensation are necessary. Therefore, the operation of the synchronization blocks causes delays ranging from several hundred milliseconds to a few seconds until the start of the radio service after frequency tuning. Furthermore, if spectrum inversed signals are transmitted in digital radio broadcasting systems, the receivers are unable to decode them, even though most receivers can demodulate the spectral inversed signals in analog radio broadcasting systems. Accordingly, fast synchronization techniques and a method for spectral inversion detection are required in digital radio broadcasting systems that are to replace the analog radio systems. This paper presents a joint detection method of frame, integer carrier frequency offset, and spectrum inversion for DRM Plus digital broadcasting systems. The proposed scheme can detect the frame and determine whether the signal is normal or spectral inversed without any carrier frequency offset and sampling frequency offset compensation, enabling fast frame synchronization. The proposed method shows outstanding performance in environments where symbol timing offsets and sampling frequency offsets exist.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.10 s.340
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• pp.25-30
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• 2005

This paper generalizes the concept of the signal space detection to construct a fixed delay tree search (FDTS) detector which estimates a block of n channel symbols at a time. This technique is applicable to high speed implementation. Two approaches are discussed both of which are based on efficient signal space partitioning. In the first approach, symbol detection is performed based on a multi-class partitioning of the signal space. This approach is a generalization of binary symbol detection based on a two-class pattern classification. In the second approach, binary signal detection is combined with a look-ahead technique, resulting in a highly parallel detector architecture.