Electronics and Telecommunications Research Institute

University-Industry Cooperation Group of Kyung Hee University

Bangwon Seo

Jae Young Ahn

Young Jo Ko

Young-Jo Ko

Byung Jang Jeong

Heesoo Lee

Hyun Kyu Chung

Chung Gu Kang

Hyun Seok Ryu

Hyun-Kyu Chung

In-Ho Lee

Jung Jae Yu

Yun Hee Kim

Dongwoo Kim

Sung Kyo Kang

Sun Mi Park

Provided are a method of transmitting a dedicated reference signal (DRS), a method of receiving a DRS, and a feedback method of a terminal. The method of transmitting a DRS includes determining a DRS transmitting resource for at least one terminal which is a target of transmission, and transmitting the DRS using the determined transmission resource and notifying the terminal of information about layer used by the terminal. The method of receiving a DRS includes determining a DRS receiving resource, receiving information about layer used by a terminal from a serving cell base station, and receiving the DRS for the terminal using the determined reception resource and the information about layer. Accordingly, a terminal can find the position and sequence of its DRS. In particular, in the case of multi-user multiple input multiple output (MU-MIMO) or joint scheduling, it is possible to prevent or remove signal interference using the DRS of another terminal.

Method for transmitting dedicated reference signal, and method for receiving dedicated reference signal

Provided is a method of transmitting channel rank information (RI) when the number of bits for transmitting the channel RI to be transmitted through a physical uplink shared channel (PUSCH) is three or more. The method includes mapping channel RI to be transmitted to a channel RI bit string of 3 bits or more, Reed-Muller coding and rate-matching the channel RI bit string using a basis sequence having a 32-bit code length, and generating modulation symbols by applying the bit sequence that has been Reed-Muller coded and rate-matched to a modulation mapper. Accordingly, the method of transmitting downlink channel RI can be employed when five or more antennas are used for downlink transmission or several carrier bands are used by carrier aggregation as specified in Third Generation Partnership Project (3GPP) long term evolution (LTE)-advanced following 3GPP LTE release 10.

Method of transmitting downlink channel rank information through physical uplink shared channel

Disclosed is a method for cell discovery. In a network in which a macro cell overlaps at least one small cell, when the carrier frequency used by the macro cell is different from the carrier frequency used by the small cell, the small cell transmits a discovery signal using the carrier frequency used by the macro cell, or the small cell transmits a discovery signal using a carrier frequency of the small cell that is different from the carrier frequency used by the macro cell.

Method for cell discovery

Provided is a coordinated communication method in which a plurality of cells cooperate to perform multi-antenna transmission and reception in a cellular wireless communication system. A terminal wirelessly transmits channel state information (CSI) feedback to a serving cell and at least one coordinating cell. The serving cell and the coordinating cell perform multi-point coordinated communication using the CSI feedback. Even if the serving cell and the coordinating cell belong to different base stations, information exchange between the cells is minimized, so that a transmission delay and a traffic increment of a backhaul network can be prevented.

Cooperative communication method in cellular wireless communication system and terminal for performing the method

Provided is a technology that eliminates or decreases inter-cell interference through an inter-cell cooperation in a cellular mobile communication system. A terminal generates channel state information (CSI) with respect to a plurality of base station, and transmits the CSI to a serving cell. The serving cell shares the CSI with a cooperation cell, and determines a cooperation transmission mode that decreases interference from the cooperation cell.

System for controlling inter cell interference in cellular mobile system

Provided is a data transmission apparatus to transmit a reference orthogonal frequency division multiplexing (OFDM) symbol generated by frequency division multiplexing a reference symbol and a data symbol, and a data reception apparatus to estimate a channel using the reference OFDM symbol. Since the reference symbol and the data symbol are frequency division multiplexed, a Peak to Average Power Ratio (PAPR) may not increase greatly, and the transmission apparatus may transmit the reference OFDM symbol to the data reception apparatus more frequently. Accordingly, the data reception apparatus may estimate a channel accurately.

Reference symbol structure for DFT spread OFDM system

In the hybrid automatic repeat request (H-ARQ) supporting method for cooperative transmission, a receiver selects one H-ARQ repeat method from among the chase combining method and the incremental redundancy method according to the SNR when the data packet cooperatively transmitted by transmitters generates an error. Also, the method for the receiver to select a repeat transmitter includes a method for selecting a repeat transmitter in advance, a method for removing a transmitting node from a repeat transmitter group when the SNR of the transmitting node is low, and a method for estimating the SNR of each transmitter for each predetermined time frame and selecting the transmitter having the greatest SNR as the repeat transmitter.

Cooperative H-ARQ supporting method

A selective cooperative relaying method, the method including: determining, by a base station, whether a mobile station for which the base station provides a service is the mobile station necessary for direct transmission or is the mobile station necessary for cooperative relaying via a relay station; and selecting, by a base station, mobile stations using a simple relaying scheme, a cooperative transmission diversity scheme, or a cooperative receiving diversity scheme from mobile stations necessary for the cooperative relaying via the relay station.

Method and system for operating cooperative receiving diversity scheme and selective cooperative relaying

Provided is a multi-layer transmission method of multiplexing and transmitting data and a demodulation reference signal (DM-RS) sequence in an uplink digital Fourier transform-spread-orthogonal frequency division multiplexing (DFT-S-OFDM) transmission employing multiple-input multiple-output (MIMO). The method includes allocating one DM-RS sequence as a DM-RS sequence of a first transmission layer for uplink transmission; allocating a DM-RS sequence whose cyclic shift (CS) value having the same sequence as the DM-RS sequence of the first transmission layer is configured to differ from that of the DM-RS sequence as a DM-RS sequence of a second transmission layer; and multiplexing layer-specific data and the layer-specific DM-RS sequences according to each of the first and second transmission layers. Accordingly, an RS can be transmitted in more OFDM symbols of a slot or subframe without an increase in overhead. Consequently, it is possible to satisfy requirements of LTE-advanced that a high frequency spectrum and a high mobile velocity should be supported, and transmit and receive a DM-RS multiplexed with data while maintaining orthogonality.

Method of transmitting uplink DM-RS multiplexed with data in uplink MIMO transmission

Disclosed is a method for generating and transmitting a reference signal in a clustered DFT-spread OFDM transmission scheme. A method for generating and transmitting a DM-RS in a clustered DFT-spread-OFDM scheme comprises: a step of generating DM-RS sequences corresponding to the number of clusters allocated for an uplink transmission; and a step of mapping the generated DM-RS sequences to the relevant DM-RS symbol positions for each cluster. Accordingly, the method for generating and transmitting a reference signal according to the present invention, in which DM-RS sequences are allocated and transmitted on a cluster basis, uses a complete DM-RS sequence for each cluster, and therefore inter-cell interference can be weakened, and problems which might occur when applied to a multi-user MIMO (MU-MIMO) scheme can be solved.

Method for generating and transmitting a reference signal for uplink demodulation in a clustered DFT-spread OFDM transmission scheme

Provided is a communication system for a multi-cell cooperative communication. A serving base station and at least one neighboring base station may communicate with at least one terminal through mutual cooperation. Each of the serving base station and the at least one neighboring base station may shift a phase of at least one element among elements included in a precoding matrix, using a phase shift matrix, and precode at least one data symbol. A terminal may feed back preferred phase shift matrix information to the serving base station, so that the serving base station and the at least one neighboring base station may adaptively determine a phase shift matrix. The terminal may calculate the phase shift matrix with small calculation amounts. The serving base station, the at least one neighboring base station, and the terminal may pre-store a plurality of candidate matrices with respect to the phase shift matrix.

Communication system including base stations and terminal for multi-cell cooperative communication

A transmission apparatus includes a layer mapper to map a modulated symbol to a plurality of layers, a layer shifter to uniformly divide the symbol mapped to each of the plurality of layers, in a plurality of time domain streams, and a signal transmission unit to perform a DFT on each of the plurality of time domain streams to generate a plurality of frequency domain streams, and to transmit, to a receiving apparatus. The plurality of frequency domain streams are using a plurality of antennas corresponding to each of the plurality of frequency domain streams.

Growing community of inventors

Daejeon, South Korea

Bangwon Seo