Author
Youn-Ok Park
Bio: Youn-Ok Park is an academic researcher from Electronics and Telecommunications Research Institute. The author has contributed to research in topics: Orthogonal frequency-division multiplexing & MIMO. The author has an hindex of 10, co-authored 61 publications receiving 452 citations.
Papers published on a yearly basis
Papers
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26 Sep 2007TL;DR: In this article, a low density parity check (LDPC) encoding method was proposed and an apparatus thereof was presented. And the present invention relates to the LDPC encoding method and the apparatus thereof.
Abstract: The present invention relates to a low density parity check (LDPC) encoding method and an apparatus thereof. In the LDPC encoding method, a matrix multiplication corresponding to ET−1 and T−1 is eliminated according to a structural characteristic in an encoding process. Accordingly, shift weights that are not −1 among shift weights corresponding to partial blocks A, B, and C of a parity check matrix are used to perform an encoding operation, and a cyclic shift operation of an information unit block is performed in parallel so that a first parity block and a second parity block may be simultaneously generated.
103 citations
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21 Nov 2003TL;DR: An encoder using LDPC (low density parity check) codes, and an encoding method is presented in this article. But the encoder does not have the ability to generate parity check matrices.
Abstract: An encoder using LDPC (low density parity check) codes, and an encoding method. The encoder comprises a parity check matrix generator for generating a parity check matrix H; and a codeword generator for processing the parity check matrix H to generate a codeword, and the codeword generator comprises: an AB analyzer for analyzing the parity check matrix H into matrixes A and B; a pivoting unit for pivoting the parity check matrix H; a bit-reversing unit for bit-reversing the pivoted matrix; an LU analyzer for analyzing the matrix A into matrixes L and U; and a codeword generator unit for performing a logical operation on the matrixes A, B, L and U. A bit-reversing method is used to effectively generate a parity check matrix having a high girth by using a regular encoder.
46 citations
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TL;DR: It is shown that the selection of the first layer impacts the error performance significantly, and based on the observation, a novel signal detection method QR-LRL is proposed, which is shown to be the best choice in terms of noise enhancement in detecting the other layers.
Abstract: The performance of the ordered successive interference cancellation (OSIC) signal detection method is well known to depend on the successful detection of the first layer. In a previous work, in an effort to mitigate the error propagation effect, all the constellation points were tried as the first layer symbol, thereby achieving a better performance. In this letter, we show that the selection of the first layer impacts the error performance significantly, and based on the observation, we propose a novel signal detection method QR-LRL. In the proposed work, the least reliable layer (LRL) is chosen to be the first layer, which is shown to be the best choice in terms of noise enhancement in detecting the other layers. Also, we discuss Log Likelihood Ratio (LLR) computation when the proposed method is used. Computer simulations confirm the efficacy of the proposed method.
31 citations
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08 Dec 2006TL;DR: In this paper, an initial ranging request signal from a subscriber station to a base station is received and the base station generates initial ranging information including delay time information to the subscriber station, and receives uplink data delayed and transmitted using a delay time from the user.
Abstract: When a base station of a time division duplex based mobile communication system receives an initial ranging request signal from a subscriber station, the base station generates initial ranging information including delay time information to the subscriber station, and receives uplink data delayed and transmitted using a delay time from the subscriber station. Also, when the subscriber station transmits an initial ranging request signal to the base station and receives initial ranging information including delay time information from the base station, the subscriber station establishes a transmission parameter value by using the transmission parameter value included in the initial ranging information and transmits uplink data by using the established delay time.
23 citations
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10 Nov 2005TL;DR: In this article, a logical index generator (142) and an intermediate index converter (144) were used to allocate a data subcarrier to a physical index, the logical index being included with only data sub-carriers and the physical index indicating a location of substantial subcarriers within a symbol.
Abstract: A subcarrier allocating apparatus allocating data to be transmitted to a plurality of orthogonal subcarriers in an orthogonal frequency division multiplexing (OFDM) system, the apparatus including: a logical index generator (142) generating a logical index for allocating a data subcarrier to a physical index, the logical index being included with only data subcarriers and the physical index indicating a location of a substantial subcarrier within a symbol; an intermediate index converter (144) converting the logical index into an intermeidate index by performing a given operation on the generated logical index and a pilot location constant; and a physical index converter (146) converting the intermediate index into a physical index based on the number of data subcarriers on the left and right sides of a null subcarrier for insertion of a guard interval formed by the null subcarrier.
22 citations
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01 Jan 2007
TL;DR: In this paper, the authors provide updates to IEEE 802.16's MIB for the MAC, PHY and asso-ciated management procedures in order to accommodate recent extensions to the standard.
Abstract: This document provides updates to IEEE Std 802.16's MIB for the MAC, PHY and asso- ciated management procedures in order to accommodate recent extensions to the standard.
1,481 citations
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TL;DR: This tutorial survey offers the most comprehensive collection to date of self-interference cancellation techniques and discusses how all of them can be implemented within the different domains of a typical transceiver.
Abstract: In-band full-duplex (IBFD) technology can enable unique system capabilities and network architectures by allowing devices to transmit and receive on the same frequency at the same time. While previously considered impossible, this ability can now be used to optimize resource sharing within the crowded frequency spectrum for various communication systems, including 5G new radio. The potential of these IBFD systems can only be realized if each device incorporates a sufficient number of self-interference cancellation techniques to ensure that its receivers do not saturate. This tutorial survey offers the most comprehensive collection to date of these techniques and discusses how all of them can be implemented within the different domains of a typical transceiver. In addition, the results of a novel IBFD system study are presented for more than 50 demonstrated communication systems with more than 80 different measurement scenarios. The various system parameters are then combined into a new figure of merit, which can be used to propel future research and accelerate the inclusion of IBFD technology within an upcoming wireless standard.
311 citations
01 Jan 1999
TL;DR: This paper compares and analyze preambles for OFDM systems based on repeated OFDM data symbols or repeated short pseudonoise sequences (PN-sequences) and finds the PN-based preamble gives better detection properties in terms of lower false detection probability and lower probability of missing the synchronization signal.
Abstract: Fast and reliable time and frequency synchronization is crucial for packet-based orthogonal frequency division multiplex (OFDM) systems. In this paper we compare and analyze preambles for OFDM systems based on repeated OFDM data symbols or repeated short pseudonoise sequences (PN-sequences). We make an analytical evaluation for AWGN channels and simulate the performance in oneand two-tap Rayleigh fading channels. The PN-based preamble gives better detection properties in terms of lower false detection probability and lower probability of missing the synchronization signal. The PN-based preamble has low peak-to-average power ratio and it makes it possible to use an ADC with one-bit quantization in stand-by mode. For frequency offset estimation both preambles give similar performance, but the PN-based preamble allows for a greater reduction in stand-by mode power consumption.
205 citations
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22 Sep 2010TL;DR: A block-request streaming system provides for improvements in the user experience and bandwidth efficiency of such systems, typically using an ingestion system that generates data in a form to be served by a conventional file server (HTTP, FTP, or the like), wherein the ingestion system intakes content and prepares it as files or data elements to be serve by the file server, which might or might not include a cache as mentioned in this paper.
Abstract: A block-request streaming system provides for improvements in the user experience and bandwidth efficiency of such systems, typically using an ingestion system that generates data in a form to be served by a conventional file server (HTTP, FTP, or the like), wherein the ingestion system intakes content and prepares it as files or data elements to be served by the file server, which might or might not include a cache. A client device can be adapted to take advantage of the ingestion process as well as including improvements that make for a better presentation independent of the ingestion process. In the block-request streaming system, the an ingestion system generates data according to erasure codes and the client device, through various selection and timing of requests for media data and redundant data, can efficiently decode media to provide for presentations.
180 citations
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20 Dec 2013TL;DR: In this article, the authors describe methods and devices that enhance the endurance of a non-volatile memory (e.g., flash memory) by obtaining, for each of the plurality of die, an endurance metric.
Abstract: The embodiments described herein methods and devices that enhance the endurance of a non-volatile memory (e.g., flash memory). The method includes obtaining, for each of the plurality of die, an endurance metric. The method also includes sorting the plurality of die into a plurality of die groups based on their corresponding endurance metrics, where each die group includes one or more die and each die group is associated with a range of endurance metrics. In response to a write command specifying a set of write data, the method further includes writing the write data to the non-volatile memory by writing in parallel subsets of the write data to the one or more die assigned to a single die group of the plurality of die groups.
179 citations