Hyeong Sook Park

Bio: Hyeong Sook Park is an academic researcher from Electronics and Telecommunications Research Institute. The author has contributed to research in topics: Signal & Gray code. The author has an hindex of 5, co-authored 17 publications receiving 59 citations.

Apparatus and method of estimating signal-to-noise ratio

Abstract: The present invention relates an apparatus and method of estimating a signal-to-noise ratio (SNR) of a received signal when the received signal has a timing offset. An apparatus for estimating a signal-to-noise ratio (SNR) according to an exemplary embodiment of the present invention includes a fast Fourier transform (FFT) unit that performs a fast Fourier transform on a received signal to convert the received signal into a frequency domain signal; a preamble selector that extracts a preamble from the frequency domain signal; a correlator that correlates the preamble to a preamble reference signal generated by a receiver to calculate a correlation value; an entire power estimator that calculates entire power; a noise power estimator that applies a differential demodulation method to the correlation value to remove a timing offset and calculate noise power; and an estimating unit that uses the entire power and the noise power to estimate the signal-to-noise ratio (SNR).

Beam selection apparatus and method for selecting beam in a fixed beam terminal

Abstract: The exemplary embodiment of the present invention provides a beam selecting apparatus of a fixed beam terminal, including: a delay time measuring unit which measures delay times of a plurality of signals received through a plurality of beams; a beam selecting unit which compares a threshold value selected based on the measured delay time and a signal strength of each of the plurality of signals to select a beam; and a switching type beam former which operates the plurality of beams in accordance with the selected beam.

Method of selecting candidate vector and method of detecting transmission symbol

Abstract: The present invention relates to a method of detecting a candidate vector and a method of detecting a transmission symbol using the same. According to an embodiment of the present invention, in a multiple input multiple output (MIMO) system using spatial multiplexing (SM), a receiver selects candidate vectors corresponding to a layer located at a last row among a plurality of rearranged layers, and sequentially ranks constellation dots of a next layer for each of the selected candidate vectors. Then, a plurality of arbitrary constellation dots are selected from the ranked constellation dots, accumulated costs of the arbitrary constellation dots are calculated, and a candidate vector is selected in correspondence with a constellation dot having a minimal accumulated cost. Then, a new arbitrary constellation dot is selected in place of the constellation dot selected as the candidate vector, an accumulated cost of the selected arbitrary constellation dot is compared with accumulated costs of the other arbitrary constellation dots, and another candidate vector is selected.

Mitigating Empty Vector Set Using Enlarged QRLRL-M Soft SM-MIMO Detector

Abstract: An enlargement of the candidate vector set of QR-least reliable layer (QR-LRL) based MIMO detector for efficient soft output generation is proposed. Previous work (Bahng et al. in IEICE Trans Commun, E89---B(10):2956---2960, 2008) shows that the QR-LRL based MIMO detector approaches hard decision output ML performance, but does not match soft output ML performance due to empty candidate vector set problem. Performance degradation is more severe when modulation order is low. Some of the previous methods have provided solutions to empty vector set (EVS) problem (Kawai et al. in IEICE Trans Commun, E88---B(1):47---57, 2005; Bahng et al. in IEICE Trans Commun, E89---B(10):2956---2960, 2008; Kim et al. in IEICE Trans Commun, E92---B(11):3512---3515, 2009), but are not efficient in terms of performance or computation complexity. In this paper, we enlarge the candidate vector set of QR-LRL detector by applying every constellation point at each layer. The proposed detector thus effectively solves the EVS problem and achieves soft ML performance while keeping the computation complexity low, especially at low modulation order.

Method and apparatus for receiving uplink signal

Abstract: Disclosed herein are an apparatus and a method for receiving uplink data to determine whether to use a reception beam group in reception of the uplink data on the basis of a preamble for a random access or a CQI included in a feedback.

Maximum Likelihood Receiver for Multiple Channel Transmission Systems

Abstract: A maximum likelihood (ML) estimator for digital sequences disturbed by Gaussian noise, intersymbol interference (ISI) and interchannel interference (ICI) is derived. It is shown that the sampled outputs of the multiple matched filter (MMF) form a set of sufficient statistics for estimating the input vector sequence. Two ML vector sequence estimation algorithms are presented. One makes use of the sampled output data of the multiple whitened matched filter and is called the vector Viterbi algorithm. The other one is a modification of the vector Viterbi algorithm and uses directly the sampled output of the MMF. It appears that, under a certain condition, the error performance is asymptotically as good as if both ISI and ICI were absent.

Method and apparatus for network synchronization

Abstract: A method and an apparatus for network synchronization based on network listening are provided. The method comprises receiving signal for synchronization to other cell, performing synchronization to other cell based on a reference signal for synchronization, and receiving and/or transmitting data at a timing based on the synchronization, wherein the reference signal for synchronization is one of CRS, CSI-RS, PSS and/or SSS, DM-RS, and MBSFN-RS.

Broadcast receiver and method for optimizing a scale factor for a log-likelihood mapper

Abstract: Embodiments of a broadcast receiver and method for optimizing a scale factor in a log-likelihood ratio (LLR) mapper are generally described herein. In some embodiments, the broadcast receiver includes an LLR mapper to generate LLRs from demodulated data samples, a low-density parity-check (LDPC) decoder to generate decoded data from the LLRs, and an LLR optimizer to dynamically select a scale factor for the LLR mapper based on a number of iterations for convergence of the LDPC decoder. In some embodiments, the LLR optimizer iteratively revises the scale factor during receipt of broadcast signals until the number of iterations of the iterative decoder is either minimized for convergence or minimized for convergence failures.

Ultra-wide band positioning system

Abstract: Embodiments provided herein are directed to an ultra-wide broadband system configured to produce positioning estimates for a user device. To ensure the high quality of this positioning service, the ultra-wide broadband system is configured to prevent signal collision, and eliminate the need for inconvenient cable connections for base station deployment. Further, the one way communication nature of the ultra-wide broadband system enables low power operation of the user device.

Method and device for performing device-to-device communication by sharing uplink resource and sidelink resource in wireless communication system

Abstract: Provided are a method and a device for performing device-to-device communication by sharing an uplink resource and a sidelink resource in a wireless communication system. Particularly, a first terminal receives, from a base station, beam scanning signals and a first threshold value. The first terminal generates first reception beam information including beam information of a signal received at a signal intensity greater than or equal to the first threshold value, among the beam scanning signals. The first terminal receives second reception beam information from the base station. The second reception beam information includes beam information of a first uplink signal received by the base station from a second terminal. The first terminal transmits a sidelink signal through the sidelink resource by using a beam obtained by excluding a third reception beam from a first reception beam. The third reception beam is a beam of the first terminal for receiving a signal transmitted using a transmission beam of the base station in the same direction as a second reception beam. The sidelink resource is overlapped with the uplink resource in time and frequency domains.