Seoul National University

Samsung Electronics Co., Ltd.

Qualcomm Incorporated

Korea University Research and Business Foundation

Quaclcomm Incorporated

Byonghyo Shim

Hyoungju Ji

Taeyoung Kim

Sunho Park

Jiyun Seol

Inyup Kang

Ji-Yun Seol

Farrokh Abrishamkar

Sungnam Hong

Insung Kang

Byungju Lee

Hyojin Lee

Sharad Deepak Sambhwani

Tae-young Kim

Tae-Young Kim

Yeohun Yun

Chanhong Kim

Chae-Man Lim

Jongbu Lim

Seunghwan Lee

Hee Jeong Seo

Youngjoon Kim

Keon-Kook Lee

Keonkook Lee

Jong-Yoon Hwang

Seung-Hwan Won

Young-Min Ki

Hyungyu Ju

Yongjun Ahn

Guyoung Lim

Sun-Ho Park

Lua Ngo

Wonjun Kim

Provided is an active user detection and channel estimation method of a base station in a wireless communication system based on grant-free uplink transmission. The method, according to one embodiment, comprises the steps of: receiving superimposed signals () from k active terminals; by using a first artificial neural network and using the received signals () as input, calculating, for all terminals in a cell of a base station, an estimated probability ({circumflex over (Ω)}) of each of the terminals being an active terminal; and estimating channels of the active terminals by using a second artificial neural network and using the received signals () and an active user detection result value as input.

Active user detection and channel estimation method and device, using deep neural network

The disclosure relates to a 5G communication system or a 6G communication system for supporting higher data rates beyond a 4G communication system such as long term evolution (LTE). The disclosure relates to a technique for controlling a base station power using an artificial intelligence based technology to improve an energy efficiency of a communication network. A method performed by a base station of a communication system according to an embodiment of the disclosure may include acquiring state information, determining an active/sleep request indicator (ASRI) based on at least a part of the state information, transmitting at least one of the state information and the ASRI to a central unit, receiving, from the central unit, power control information determined based on the at least one of the state information and the ASRI, and performing a power control based on the received power control information.

Method and apparatus for power control for network energy optimization

An operation method of a base station in a time division duplex communication system includes: a step for setting a time period in which a terminal can transmit an uplink in a downlink period; a step for generating a sparse vector signal including information about the time period; and a step for transmitting the sparse vector signal to the terminal. In addition, an operation method of the terminal in the time division duplex communication system includes: a step for receiving a part of a sparse vector signal from the base station; a step for recovering the received sparse vector signal by compressed sensing; and a step for transmitting uplink data in a time period instructed in a downlink period based on the basis of the recovered signal.

Uplink transmission method and device in time-division duplex communication system

A method by which a transmitting end operates in a wireless communication system comprises the steps of: performing sparse coding on information so as to have sparsity of which the number of non-zero symbols is K; configuring a codebook by including a code for spreading for each user; spreading the coded information by using one or more codes in the codebook; and transmitting a channel by overlapping the spread information. Therefore, even if the number of encoded symbols increases, the number of symbols actually having a value is very sparsely configured such that the complexity of a transmitter and a receiver does not increase, and thus restoration performance improves.

Method and device for transmitting information by using sparse coding

The present disclosure relates to a 5G or pre-5G communication system for supporting a higher data transmission rate than in a 4G communication system such as LTE. The present disclosure relates to uplink transmission in a wireless communication system, and an operating method of a terminal includes mapping codes that are included in at least one codebook onto data symbols. and transmitting the data symbols spread by using the at least one codebook, and the data symbols are used for a base station to detect at least one active terminal including the terminal.

Apparatus and method for uplink transmission in wireless communication system

The present prevent relates to a method of sparsifying a channel using beamforming in a wireless communication system, the method including inserting pilot symbols into resources allocated among resource elements constituting a time-frequency grid; calculating beamforming weights for sparsifying a beamformed time-domain channel; and beamforming frequency-domain channels of a plurality of antennas mapping the pilot symbols by using the beamforming weights.

Apparatus and method for sparsifying channel using beamforming

The present disclosure relates to a 5G generation or pre-5G communication system for supporting a higher data transmission rate than a 4G communication system such as LTE. The present disclosure relates to uplink transmission in a wireless communication system, and an operating method of a terminal includes: determining a second codebook for a reference signal, based on a first codebook for data; and transmitting at least one reference signal generated by using the second codebook, and at least one data signal generated by using the first codebook.

The present disclosure relates to a 5G or pre-5G communication system to be provided to support a higher data transmission rate beyond the 4G communication system, such as LTE. The present invention provides a method for estimating a downlink channel by a receiver in a wireless communication system, the method comprising: estimating the downlink channel on the basis of a reference signal to recover an information bit, and checking whether the information bit recovery has succeeded; and when the information bit recovery has not succeeded, selecting at least one of the received signals as a virtual reference signal on the basis of the accuracy of the data reconstructed at a related resource location and the correlation between the related resource location and a resource location related to the reference signal, and estimating the downlink channel on the basis of at least one virtual reference signal.

Apparatus and method for estimating downlink channel in wireless communication system

The present disclosure relates to a pre-5-generation (5G) or 5G communication system to be provided for supporting higher data rates beyond 4-generation (4G) communication system such as long term evolution (LTE). The present disclosure relates to channel information feedback in a wireless communication system, and an operation method of a receiving node includes: determining compressed channel information based on an eigenvalue decomposition of a covariance matrix regarding a channel, and transmitting, to a transmitting node, a direction index and a magnitude index representing the compressed channel information. Herein, a dimension of the compressed channel information is lower than a dimension of channel information associated with the transmitting node. Also, the disclosure includes other embodiments, different from the above described embodiment.

Apparatus and method for feeding back channel information in wireless communication system

A method of receiving a signal by a receiver in a mobile communication system is provided. The method includes: receiving a reference signal from a transmitter; determining first channel information based on the received reference signal; receiving a data signal based on the first channel information; and determining second channel information based on the received data signal and the first channel information. Iterative channel estimation is performed to reduce channel estimation errors by determining errors of signals received from a turbo decoding unit and using symbol information as pilots even in subcarriers where the pilot signals are not transmitted, and to increase the accuracy of LLR calculation through an iteration process such as a detection and decoding process in comparison with the conventional technology, thereby increasing the reception performance of the turbo decoding unit and improving communication efficiency.

Method and apparatus for estimating communication channel in mobile communication system

Disclosed are a method and an apparatus for grouping antennas in a multiple-input multiple-output antenna system. The method of the present invention comprises the steps of: measuring a channel vector for a plurality of antennas of a base station; grouping channel coefficients of the channel vector in accordance with a plurality of antenna grouping patterns and determining grouped codebook vectors corresponding to the grouped channel coefficients; selecting one of the antenna grouping patterns using the grouped codebook vectors for the antenna grouping patterns; and feeding back, to the base station, a pattern index indicating the selected antenna grouping pattern and a codebook index indicating the grouped codebook vector corresponding to the selected antenna grouping pattern.

Method and apparatus for grouping antennas in multiple-input multiple-output antenna system

An apparatus and method for symbol decoding by selecting a degree of freedom (DOF) parameter for a noise vector; selecting a delta probability value; computing a cost function for a lattice point that is one of a discrete set of nominal codeword positions in a hypersphere; selecting a sphere decoding radius based on the DOF parameter, the delta probability value and the cost function; and decoding a symbol using the sphere decoding radius. And, the apparatus and method of setting pre-defined threshold probabilities; computing threshold radii based on the pre-defined threshold probabilities; setting an initial sphere radius square to the value of a first threshold radii; finding the Lattice point based on the initial sphere radius square; computing an updated sphere radius square as the minimum of either a cost function or a second threshold radii; and finding a next lattice point based on the updated sphere radius square.

Method and apparatus for symbol decoding using tree pruning based sphere search

Techniques for recovering a desired transmission in the presence of interfering transmissions are described. For successive equalization and cancellation (SEC), equalization is performed on a received signal to obtain an equalized signal for a first set of code channels. The first set may include all code channels for one sector, a subset of all code channels for one sector, multiple code channels for multiple sectors, etc. Data detection is then performed on the equalized signal to obtain a detected signal for the first set of code channels. A signal for the first set of code channels is reconstructed based on the detected signal. The reconstructed signal for the first set of code channels is then canceled from the received signal. Equalization, data detection, reconstruction, and cancellation are performed for at least one additional set of code channels in similar manner.

Successive equalization and cancellation and successive mini multi-user detection for wireless communication

An apparatus and a method for interference cancellation in a Multiple Input Multiple Output (MIMO) wireless communication system. The method for interference cancellation includes equalizing first reception signals received through two or more reception antennas to estimate transmission signals transmitted through two or more transmission antennas, generating two or more second reception signals in which a mutual interference between the transmission signals is removed from the first reception signals by using the estimated transmission signals, independently equalizing the generated two or more second reception signals, and combining the independently equalized two or more second reception signals to estimate a transmission signal in which an interference is removed.

Apparatus and method for interference cancellation in MIMO wireless communication system

Method and apparatus for decoding code words received over a communication channel are disclosed. A radius-adaptive sphere decoding methodology reduces the number of operations in sphere-constrained search. Imposing probabilistic noise constraint on top of sphere constraint, particularly at an early stage, provides a more stringent necessary condition. Hence, many branches that are unlikely to be selected are removed in the early stage of sphere search. The trade-off between computational complexity and performance can be controlled by adjusting the pruning probability.

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Seoul, South Korea

Byonghyo Shim