Communication device and communication method

Abstract

The present invention is provided with a transmission / reception unit for receiving an uplink reference signal and transmitting multi-layer signals, and a channel estimation unit for estimating the estimated channel value of a downlink channel from the uplink reference signal. The uplink reference signal is transmitted from a communication partner using a plurality of antennas, and the phases and amplitudes of the multi-layer signals are controlled using the estimated channel value, each of the multi-layer signals being transmitted in association with each of the plurality of antennas.

Description

Technical Field

[0001] The present invention relates to a communication device and a communication method. This application claims priority to Japanese Patent Application No. 2020-006001, filed in Japan on January 17, 2020, the content of which is incorporated herein by reference.

Background Art

[0002] Research and development activities related to the fifth-generation mobile wireless communication system (5G system) have been actively carried out aiming at the start of commercial services around 2020. Recently, the International Telecommunication Union Radio communications Sector (ITU-R), an international standardization organization, reported a vision recommendation regarding the standard format of the 5G system (International mobile telecommunication - 2020 and beyond: IMT-2020) (see Non-Patent Document 1).

[0003] Wireless communication will become even more important in the future, and the number of communication devices is also expected to further increase. At this time, security may become a problem. Security is one of the most important technologies in a communication system. Generally, security is often achieved by encryption at a layer higher than the physical layer for secure communication. However, since wireless communication is transmitted over a wide area, eavesdroppers may be able to receive unencrypted control information and the like. As such a technology for secure communication at the physical layer, there is physical layer security. As a physical layer security technology, for example, there is a technology of adding artificial noise set to null to a transmission signal and transmitting it to a legitimate user. Artificial noise is a technology that enables secure communication using the wireless channel between the transmitter and the legitimate user as a key. The physical layer security technology using artificial noise is described in Non-Patent Document 2.

Prior Art Documents

Non-Patent Documents

[0004] [Non-Patent Document 1] “IMT Vision - Framework and overall objectives of the future development of IMT for 2020 and beyond,” Recommendation ITU-R M.2083-0, Sept. 2015. [Non-Patent Document 2] S. Goel and R. Negi, “Guaranteeing secrecy using artificial noise,” IEEE trans. Wireless Commun. Vol. 7, No. 6, pp. 2180-2189, Jun. 2008. [Summary of the Invention] [Problems to be Solved by the Invention]

[0005] In the method described in Non-Patent Document 2, since the wireless channel is used as a key, a downlink channel estimation value is required on the transmission side. When an error occurs in the channel estimation value, if transmission control is performed using the channel estimation value including the error, there is a possibility that a legitimate user cannot correctly receive the desired signal.

[0006] One aspect of the present invention has been made in view of such circumstances, and an object thereof is to provide a communication device and a communication method capable of securely communicating even when the channel estimation value includes an error. [Means for Solving the Problems]

[0007] In order to solve the above-described problems, the configurations of a communication device and a communication method according to one aspect of the present invention are as follows.

[0008] A communication device according to an aspect of the present invention includes a transceiver that receives an uplink reference signal and transmits signals of a plurality of layers, and a channel estimation unit that estimates a channel estimation value of a downlink channel from the uplink reference signal. The uplink reference signal is transmitted from a communication partner using a plurality of antennas, the signals of the plurality of layers are phase-controlled and amplitude-controlled using the channel estimation value, and each of the signals of the plurality of layers is transmitted in association with each of the plurality of antennas.

[0009] Further, in a communication device according to an aspect of the present invention, the transceiver transmits a reference signal (CSI-RS) for channel state information (CSI) measurement, the number of resources of the CSI-RS is plural, and each of the plurality of CSI-RS resources is for measuring CSI for different ranks. Each of the plurality of CSI-RS resources has a mapping to one resource element set, and the resource element is one orthogonal frequency division multiplexing (OFDM) symbol in a slot and one subcarrier in a resource block.

[0010] Further, in a communication device according to an aspect of the present invention, a channel quality indicator (CQI) in each of the plurality of CSI-RS resources is received.

[0011] Further, in a communication device according to an aspect of the present invention, a CSI-RS resource index indicating one of the plurality of CSI-RS resources and a channel quality indicator (CQI) measured with the CSI-RS resource are received.

[0012] A communication device according to an aspect of the present invention includes a transceiver that transmits an uplink reference signal and receives signals of a plurality of layers using a plurality of antennas, and a signal detection unit that detects a desired signal from the received signals of the plurality of layers. Each of the plurality of layers and each of the plurality of antennas are associated with each other.

[0013] Also, in the communication device according to one aspect of the present invention, each of the signals of the plurality of layers is obtained based on one of the plurality of antennas.

[0014] Also, in the communication device according to one aspect of the present invention, the transceiver receives a reference signal (CSI-RS) for channel state information (CSI) measurement, the number of resources of the CSI-RS is plural, each of the plurality of CSI-RS resources is for measuring CSI for different ranks, each of the plurality of CSI-RS resources has a mapping to one resource element set, and the resource element is one orthogonal frequency division multiplexing (OFDM) symbol in a slot and one subcarrier in a resource block.

[0015] Also, in the communication device according to one aspect of the present invention, measure the channel quality indicator (CQI) in each of the plurality of CSI-RS resources, and report associating the CSI-RS resource with the CQI.

[0016] Also, in the communication device according to one aspect of the present invention, select one from the plurality of CSI-RS resources, and report the selected CSI-RS resource index and the channel quality indicator (CQI) measured by the CSI-RS resource.

[0017] Also, a communication method according to one aspect of the present invention includes steps of receiving an uplink reference signal and transmitting signals of a plurality of layers, and estimating a channel estimation value of a downlink channel from the uplink reference signal, the uplink reference signal is transmitted from a communication partner using a plurality of antennas, the signals of the plurality of layers are phase-controlled and amplitude-controlled using the channel estimation value, and each of the signals of the plurality of layers is transmitted in association with each of the plurality of antennas.

Advantages of the Invention

[0018] According to one aspect of the present invention, secure communication is possible even when there is an error in the channel estimation value in order to perform diversity combining on the receiving side.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0020] The communication system in this embodiment includes a base station apparatus (transmission apparatus, cell, transmission point, transmission antenna group, transmission antenna port group, component carrier, eNodeB, gNodeB, transmission point, transmission and reception point, transmission panel, access point, subarray, communication apparatus) and a terminal device (terminal, mobile terminal, reception point, reception terminal, reception apparatus, reception antenna group, reception antenna port group, UE, reception point, reception panel, station, subarray, communication apparatus). Further, the base station apparatus connected to (establishing a wireless link with) the terminal device is called a serving cell. In the following embodiments, when referring to a communication apparatus, it represents a base station apparatus or a terminal device.

[0021] The base station apparatus and terminal device in this embodiment can communicate in a frequency band that requires a license (licensed band) and / or a frequency band that does not require a license (unlicensed band).

[0022] In this embodiment, “X / Y” includes the meaning of “X or Y”. In this embodiment, “X / Y” includes the meaning of “X and Y”. In this embodiment, “X / Y” includes the meaning of “X and / or Y”.

[0023] FIG. 1 is a diagram showing an example of a communication system according to the present embodiment. As shown in FIG. 1, the communication system in the present embodiment includes a base station device 1A and a terminal device 2A. Also, coverage 1-1 is a range (communication area) in which the base station device 1A can be connected to the terminal device. The base station device 1A is also simply referred to as a base station device. The terminal device 2A is also simply referred to as a terminal device.

[0024] In FIG. 1, in the uplink wireless communication from the terminal device 2A to the base station device 1A, the following uplink physical channels are used. The uplink physical channel is used to transmit information output from the upper layer. · PUCCH (Physical Uplink Control Channel) · PUSCH (Physical Uplink Shared Channel) · PRACH (Physical Random Access Channel)

[0025] The PUCCH is used to transmit uplink control information (UCI). Here, the uplink control information includes an ACK (a positive acknowledgement) or NACK (a negative acknowledgement) (ACK / NACK) for downlink data (downlink transport block, Downlink-Shared Channel: DL-SCH). The ACK / NACK for downlink data is also referred to as HARQ-ACK and HARQ feedback.

[0026] Also, the uplink control information includes channel state information (CSI) for the downlink. Also, the uplink control information includes a scheduling request (SR) used to request resources for the uplink shared channel (UL-SCH). The channel state information includes a rank indicator (RI) that specifies a suitable spatial multiplexing number, a precoding matrix indicator (PMI) that specifies a suitable precoder, a channel quality indicator (CQI) that specifies a suitable transmission rate, a CSI-RS (Reference Signal) resource indicator (CRI) that indicates a suitable CSI-RS resource, and an RSRP (Reference Signal Received Power) measured by CSI-RS or SS (Synchronization Signal).

[0027] The channel quality indicator CQI (hereinafter referred to as the CQI value) can be a suitable modulation method (e.g., QPSK, 16QAM, 64QAM, 256QAM, etc.) and a coding rate in a predetermined band (details will be described later). The CQI value can be an index (CQI Index) determined by the modulation method and the coding rate. The CQI value can be determined in advance in the system.

[0028] The CRI indicates a CSI-RS resource with suitable received power / received quality from a plurality of CSI-RS resources.

[0029] Note that the rank indicator and the pre-coding quality indicator can be determined in advance by the system. The rank indicator and the pre-coding matrix indicator can be indexes determined by the spatial multiplexing number and the pre-coding matrix information. Note that a part or all of the CQI value, PMI value, RI value, and CRI value are also collectively referred to as the CSI value.

[0030] PUSCH is used to transmit uplink data (uplink transport block, UL-SCH). Also, PUSCH may be used to transmit ACK / NACK and / or channel state information together with the uplink data. Also, PUSCH may be used to transmit only uplink control information.

[0031] Also, PUSCH is used to transmit RRC messages. RRC messages are information / signals processed in the Radio Resource Control (RRC) layer. Also, PUSCH is used to transmit MAC CE (Control Element). Here, MAC CE is information / signals processed (transmitted) in the Medium Access Control (MAC) layer.

[0032] For example, the power headroom may be included in the MAC CE and reported via the PUSCH. That is, the field of the MAC CE may be used to indicate the level of the power headroom.

[0033] PRACH is used to transmit a random access preamble.

[0034] In the uplink wireless communication, an uplink reference signal (UL RS) is used as an uplink physical signal. The uplink physical signal is not used to transmit information output from the upper layer, but is used by the physical layer. Here, the uplink reference signal includes DMRS (Demodulation Reference Signal), SRS (Sounding Reference Signal), and PT-RS (Phase-Tracking reference signal).

[0035] DMRS is related to the transmission of PUSCH or PUCCH. For example, the base station device 1A uses DMRS to perform channel correction of PUSCH or PUCCH. For example, the base station device 1A uses SRS to measure the uplink channel state. Also, SRS is used for uplink sounding. Further, PT-RS is used to compensate for phase noise. Note that the uplink DMRS is also referred to as uplink DMRS.

[0036] In FIG. 1, in the downlink wireless communication from the base station device 1A to the terminal device 2A, the following downlink physical channels are used. The downlink physical channels are used to transmit information output from the upper layer. ·PBCH (Physical Broadcast Channel; Notification Channel) ·PCFICH (Physical Control Format Indicator Channel; Control Format Indication Channel) ·PHICH (Physical Hybrid automatic repeat request Indicator Channel; HARQ Indication Channel) ·PDCCH (Physical Downlink Control Channel; Downlink Control Channel) ·EPDCCH (Enhanced Physical Downlink Control Channel; Extended Downlink Control Channel) ·PDSCH (Physical Downlink Shared Channel; Downlink Shared Channel)

[0037] PBCH is used to notify the master information block (Master Information Block: MIB, Broadcast Channel: BCH) that is commonly used in the terminal device. PCFICH is used to transmit information indicating the area used for the transmission of PDCCH (for example, the number of OFDM (Orthogonal Frequency Division Multiplexing) symbols). Note that MIB is also called the minimum system information.

[0038] PHICH is used to transmit ACK / NACK for the uplink data (transport block, codeword) received by the base station device 1A. That is, PHICH is used to transmit a HARQ indicator (HARQ feedback) indicating ACK / NACK for the uplink data. Also, ACK / NACK is also referred to as HARQ-ACK. The terminal device 2A notifies the received ACK / NACK to the upper layer. ACK / NACK is ACK indicating correct reception, NACK indicating incorrect reception, and DTX indicating that there is no corresponding data. Also, when there is no PHICH for the uplink data, the terminal device 2A notifies ACK to the upper layer.

[0039] PDCCH and EPDCCH are used to transmit downlink control information (Downlink Control Information: DCI). Here, a plurality of DCI formats are defined for the transmission of downlink control information. That is, the fields for the downlink control information are defined in the DCI format and mapped to information bits.

[0040] For example, as a DCI format for the downlink, DCI format 1A used for scheduling one PDSCH (transmission of one downlink transport block) in one cell is defined.

[0041] For example, the DCI format for the downlink includes downlink control information such as information regarding resource allocation of the PDSCH, information regarding the MCS (Modulation and Coding Scheme) for the PDSCH, and the TPC command for the PUCCH. Here, the DCI format for the downlink is also referred to as a downlink grant (or downlink assignment).

[0042] Also, for example, as a DCI format for the uplink, DCI format 0 used for scheduling one PUSCH (transmission of one uplink transport block) in one cell is defined.

[0043] For example, the DCI format for the uplink includes uplink control information such as information regarding resource allocation of the PUSCH, information regarding the MCS for the PUSCH, and the TPC command for the PUSCH. The DCI format for the uplink is also referred to as an uplink grant (or uplink assignment).

[0044] Also, the DCI format for the uplink can be used to request the downlink channel state information (CSI; Channel State Information, also referred to as reception quality information).

[0045] In addition, the DCI format for the uplink can be used for settings indicating uplink resources that map the channel state information report (CSI feedback report) that the terminal device feeds back to the base station device. For example, the channel state information report can be used for settings indicating uplink resources that periodically report channel state information (Periodic CSI). The channel state information report can be used for the mode setting (CSI report mode) that periodically reports channel state information.

[0046] For example, the channel state information report can be used for settings indicating uplink resources that report aperiodic channel state information (Aperiodic CSI). The channel state information report can be used for the mode setting (CSI report mode) that reports channel state information aperiodically.

[0047] For example, the channel state information report can be used for settings indicating uplink resources that report semi-persistent channel state information (semi-persistent CSI). The channel state information report can be used for the mode setting (CSI report mode) that reports channel state information semi-persistently. Note that the semi-persistent CSI report is to periodically report CSI during the period from being activated by a higher layer signal or downlink control information to being deactivated.

[0048] In addition, the DCI format for the uplink can be used for settings indicating the type of channel state information report that the terminal device feeds back to the base station device. The types of channel state information reports include wideband CSI (e.g., Wideband CQI) and narrowband CSI (e.g., Subband CQI).

[0049] When the resources of the PDSCH are scheduled using a downlink assignment, the terminal device receives downlink data on the scheduled PDSCH. Also, when the resources of the PUSCH are scheduled using an uplink grant, the terminal device transmits uplink data and / or uplink control information on the scheduled PUSCH.

[0050] The PDSCH is used to transmit downlink data (downlink transport block, DL-SCH). Also, the PDSCH is used to transmit a system information block type 1 message. The system information block type 1 message is cell-specific (cell-specific) information.

[0051] Also, the PDSCH is used to transmit a system information message. The system information message includes a system information block X other than the system information block type 1. The system information message is cell-specific (cell-specific) information.

[0052] Also, the PDSCH is used to transmit an RRC message. Here, the RRC message transmitted from the base station device may be common to a plurality of terminal devices in the cell. Also, the RRC message transmitted from the base station device 1A may be a dedicated message (also referred to as dedicated signaling) for a certain terminal device 2A. That is, user equipment-specific (user equipment-specific) information is transmitted using a dedicated message for a certain terminal device. Also, the PDSCH is used to transmit a MAC CE.

[0053] Here, the RRC message and / or the MAC CE are also referred to as higher layer signaling.

[0054] In addition, the PDSCH can be used to request downlink channel state information. Also, the PDSCH can be used to transmit uplink resources that map channel state information reports (CSI feedback reports) that the terminal device feeds back to the base station device. For example, the channel state information report can be used for settings indicating uplink resources that periodically report channel state information (Periodic CSI). The channel state information report can be used for mode settings (CSI report mode) that periodically report channel state information.

[0055] The types of downlink channel state information reports include wideband CSI (e.g., Wideband CSI) and narrowband CSI (e.g., Subband CSI). Wideband CSI calculates one channel state information for the system band of the cell. Narrowband CSI divides the system band into predetermined units and calculates one channel state information for each of those divisions.

[0056] In addition, in downlink wireless communication, a synchronization signal (SS) and a downlink reference signal (DL RS) are used as downlink physical signals. Downlink physical signals are not used to transmit information output from the upper layer but are used by the physical layer. Note that the synchronization signal includes a primary synchronization signal (PSS) and a secondary synchronization signal (SSS).

[0057] The synchronization signal is used by the terminal device to achieve synchronization in the frequency domain and time domain of the downlink. Also, the synchronization signal is used to measure the received power, received quality, or Signal-to-Interference and Noise power Ratio (SINR). Note that the received power measured by the synchronization signal is also called SS-RSRP (Synchronization Signal - Reference Signal Received Power), the received quality measured by the synchronization signal is called SS-RSRQ (Reference Signal Received Quality), and the SINR measured by the synchronization signal is called SS-SINR. Note that SS-RSRQ is the ratio of SS-RSRP to RSSI. RSSI (Received Signal Strength Indicator) is the total average received power during a certain observation period. Also, the synchronization signal / downlink reference signal is used by the terminal device to perform channel compensation for the downlink physical channel. For example, the synchronization signal / downlink reference signal is used by the terminal device to calculate the channel state information of the downlink.

[0058] Here, the downlink reference signal includes DMRS (Demodulation Reference Signal), NZP CSI-RS (Non-Zero Power Channel State Information - Reference Signal), ZP CSI-RS (Zero Power Channel State Information - Reference Signal), PT-RS, and TRS (Tracking Reference Signal). Note that the downlink DMRS is also called the downlink DMRS. Note that in the following embodiments, when simply referring to CSI-RS, it includes NZP CSI-RS and / or ZP CSI-RS.

[0059] The DMRS is transmitted in the subframe and bandwidth used for the transmission of the PDSCH / PBCH / PDCCH / EPDCCH to which the DMRS is related, and is used for demodulating the PDSCH / PBCH / PDCCH / EPDCCH to which the DMRS is related.

[0060] Here, the downlink physical channels and downlink physical signals are collectively referred to as downlink signals. Also, the uplink physical channels and uplink physical signals are collectively referred to as uplink signals. Also, the downlink physical channels and uplink physical channels are collectively referred to as physical channels. Also, the downlink physical signals and uplink physical signals are collectively referred to as physical signals.

[0061] Also, the BCH, UL-SCH, and DL-SCH are transport channels. The channels used in the MAC layer are referred to as transport channels. Also, the unit of the transport channel used in the MAC layer is also referred to as a transport block (TB) or a MAC PDU (Protocol Data Unit). A transport block is the unit of data that the MAC layer delivers to the physical layer. In the physical layer, the transport block is mapped to codewords, and encoding processing and the like are performed for each codeword.

[0062] Also, for a terminal device supporting carrier aggregation (CA), the base station device can integrate a plurality of component carriers (CCs) for wider bandwidth transmission and communicate. In carrier aggregation, one primary cell (PCell) and one or more secondary cells (SCells) are set as a set of serving cells.

[0063] In addition, in dual connectivity (DC), as a group of serving cells, a master cell group (MCG) and a secondary cell group (SCG) are configured. The MCG is composed of a PCell and optionally one or more SCells. The SCG is composed of a primary SCell (PSCell) and optionally one or more SCells.

[0064] The base station device can communicate using a radio frame. The radio frame is composed of a plurality of subframes (subintervals). When expressing the frame length in terms of time, for example, the radio frame length can be 10 milliseconds (ms), and the subframe length can be 1 ms. In this example, the radio frame is composed of 10 subframes.

[0065] A slot is composed of 14 OFDM symbols. Since the OFDM symbol length can vary depending on the subcarrier spacing, the slot length can also vary depending on the subcarrier spacing. A mini-slot is composed of fewer OFDM symbols than a slot. A slot / mini-slot can be a scheduling unit. Note that the terminal device can know slot-based scheduling / mini-slot-based scheduling based on the position (arrangement) of the first downlink DMRS. In slot-based scheduling, the first downlink DMRS is arranged in the third or fourth symbol of the slot. In mini-slot-based scheduling, the first downlink DMRS is arranged in the first symbol of the scheduled data (resource, PDSCH).

[0066] Also, a resource block is defined by 12 consecutive subcarriers. Also, a resource element is defined by an index in the frequency domain (e.g., subcarrier index) and an index in the time domain (e.g., OFDM symbol index). Resource elements are classified as uplink resource elements, downlink elements, flexible resource elements, and reserved resource elements. In the reserved resource elements, the terminal device does not transmit uplink signals or receive downlink signals.

[0067] Also, multiple subcarrier spacings (SCS) are supported. For example, SCS is 15 / 30 / 60 / 120 / 240 / 480 kHz.

[0068] FIG. 2 is a schematic block diagram showing the configuration of the base station apparatus in the present embodiment. As shown in FIG. 2, the base station apparatus includes a transceiver unit (transceiving step) 100, a higher layer processing unit (higher layer processing step) 101, a control unit (control step) 102, and a transceiver antenna 105. The transceiver unit 100 includes a transmitter unit (transmission step) 103, a receiver unit (reception step) 104, and a measurement unit (measurement step) 106. Also, the higher layer processing unit 101 includes a radio resource control unit (radio resource control step) 1011 and a scheduling unit (scheduling step) 1012. Also, the transmitter unit 103 includes an encoding unit (encoding step) 1031, a modulation unit (modulation step) 1032, a downlink reference signal generation unit (downlink reference signal generation step) 1033, a multiplexing unit (multiplexing step) 1034, and a radio transmitter unit (radio transmission step) 1035. Also, the receiver unit 104 includes a radio receiver unit (radio reception step) 1041, a demultiplexing unit (demultiplexing step) 1042, a demodulation unit (demodulation step) 1043, and a decoding unit (decoding step) 1044.

[0069] The upper layer processing unit 101 performs processing of the Medium Access Control (MAC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, and Radio Resource Control (RRC) layer. Also, the upper layer processing unit 101 generates information necessary for controlling the transmission unit 103 and the reception unit 104, and outputs it to the control unit 102.

[0070] The upper layer processing unit 101 receives information regarding the terminal device, such as the UE capability of the terminal device, from the terminal device. In other words, the terminal device transmits its own capabilities to the base station device by means of an upper layer signal.

[0071] In the following description, the information regarding the terminal device includes information indicating whether the terminal device supports a predetermined function, or information indicating the completion of the introduction and test of the predetermined function by the terminal device. In the following description, whether the terminal device supports a predetermined function includes whether the introduction and test of the predetermined function have been completed.

[0072] For example, when the terminal device supports a predetermined function, the terminal device transmits information (parameter) indicating whether it supports the predetermined function. When the terminal device does not support the predetermined function, the terminal device does not transmit information (parameter) indicating whether it supports the predetermined function. That is, whether the terminal device supports the predetermined function is notified by whether it transmits information (parameter) indicating whether it supports the predetermined function. Note that the information (parameter) indicating whether the terminal device supports the predetermined function may be notified using 1 bit of 1 or 0.

[0073] The radio resource control unit 1011 generates, or obtains from a higher node, downlink data (transport block), system information, RRC messages, MAC CE, etc., which are arranged in the downlink PDSCH. The radio resource control unit 1011 outputs the downlink data to the transmission unit 103 and outputs other information to the control unit 102. Also, the radio resource control unit 1011 manages various setting information of the terminal device.

[0074] The scheduling unit 1012 determines the frequency and slot for allocating physical channels (PDSCH and PUSCH), the coding rate and modulation scheme (or MCS) of the physical channels (PDSCH and PUSCH), and the transmission power, etc. The scheduling unit 1012 outputs the determined information to the control unit 102.

[0075] Based on the scheduling result, the scheduling unit 1012 generates information used for scheduling physical channels (PDSCH and PUSCH). The scheduling unit 1012 outputs the generated information to the control unit 102.

[0076] Based on the information input from the upper layer processing unit 101, the control unit 102 generates a control signal for controlling the transmission unit 103 and the reception unit 104. Based on the information input from the upper layer processing unit 101, the control unit 102 generates downlink control information and outputs it to the transmission unit 103.

[0077] According to the control signal input from the control unit 102, the transmission unit 103 generates a downlink reference signal, encodes and modulates the HARQ indicator, downlink control information, and downlink data input from the upper layer processing unit 101, multiplexes the PHICH, PDCCH, EPDCCH, PDSCH, and downlink reference signal, and transmits a signal to the terminal device 2A via the transceiver antenna 105.

[0078] The symbolization unit 1031 encodes the HARQ indicator, downlink control information, and downlink data input from the upper layer processing unit 101 using a predetermined encoding method such as block encoding, convolutional encoding, turbo encoding, LDPC (Low density parity check) encoding, Polar encoding, or using the encoding method determined by the radio resource control unit 1011. The modulation unit 1032 modulates the encoded bits input from the symbolization unit 1031 using a predetermined modulation method such as BPSK (Binary Phase Shift Keying), QPSK (quadrature Phase Shift Keying), 16QAM (quadrature amplitude modulation), 64QAM, 256QAM, or using the modulation method determined by the radio resource control unit 1011.

[0079] The downlink reference signal generation unit 1033 generates, as a downlink reference signal, a known sequence for the terminal device 2A obtained according to a predetermined rule based on a physical cell identifier (PCI, cell ID) for identifying the base station device 1A.

[0080] The multiplexing unit 1034 multiplexes the modulation symbols of each modulated channel, the generated downlink reference signal, and the downlink control information. That is, the multiplexing unit 1034 arranges the modulation symbols of each modulated channel, the generated downlink reference signal, and the downlink control information in resource elements.

[0081] The wireless transmission unit 1035 performs an inverse fast Fourier transform (IFFT) on the multiplexed modulation symbols and the like to generate OFDM symbols, adds a cyclic prefix (CP) to the OFDM symbols to generate a baseband digital signal, converts the baseband digital signal into an analog signal, removes extra frequency components by filtering, up-converts to a carrier frequency, amplifies the power, and outputs the signal to the transceiver antenna 105 for transmission.

[0082] According to the control signal input from the control unit 102, the receiving unit 104 separates, demodulates, and decodes the received signal received from the terminal device 2A via the transceiver antenna 105, and outputs the decoded information to the upper layer processing unit 101.

[0083] The wireless receiving unit 1041 converts the uplink signal received via the transceiver antenna 105 into a baseband signal by down-conversion, removes unnecessary frequency components, controls the amplification level so that the signal level is appropriately maintained, and performs quadrature demodulation based on the in-phase component and the quadrature component of the received signal, and converts the quadrature-demodulated analog signal into a digital signal.

[0084] The wireless receiving unit 1041 removes the portion corresponding to the CP from the converted digital signal. The wireless receiving unit 1041 performs a fast Fourier transform (FFT) on the signal with the CP removed, extracts the signal in the frequency domain, and outputs it to the multiplexing separation unit 1042.

[0085] The multiplexing separation unit 1042 separates the signal input from the wireless receiving unit 1041 into signals such as PUCCH, PUSCH, and uplink reference signals. This separation is performed based on the radio resource allocation information included in the uplink grant determined by the base station apparatus 1A in the radio resource control unit 1011 in advance and notified to each terminal device 2A.

[0086] In addition, the multiplexing separation unit 1042 performs propagation path compensation for PUCCH and PUSCH. The multiplexing separation unit 1042 also separates the uplink reference signal.

[0087] The demodulation unit 1043 performs an Inverse Discrete Fourier Transform (IDFT) on the PUSCH to obtain modulation symbols, and demodulates the received signal using a predetermined modulation scheme such as BPSK, QPSK, 16QAM, 64QAM, 256QAM, etc., or a modulation scheme that the device itself has notified in advance to the terminal device 2A in the uplink grant.

[0088] The decoding unit 1044 decodes the encoded bits of the demodulated PUCCH and PUSCH at a predetermined coding rate of a predetermined coding scheme, or a coding rate that the device itself has notified in advance to the terminal device 2A in the uplink grant, and outputs the decoded uplink data and uplink control information to the upper layer processing unit 101. When the PUSCH is retransmitted, the decoding unit 1044 decodes using the encoded bits held in the HARQ buffer input from the upper layer processing unit 101 and the demodulated encoded bits.

[0089] The measurement unit 106 observes the received signal and obtains various measurement values such as RSRP / RSRQ / RSSI. The measurement unit 106 also obtains the received power, received quality, and suitable SRS resource index from the SRS transmitted from the terminal device.

[0090] Figure 3 is a schematic block diagram showing the configuration of the terminal device in this embodiment. As shown in Figure 3, the terminal device includes a transmission / reception unit (transmission / reception step) 200, an upper layer processing unit (upper layer processing step) 201, a control unit (control step) 202, and a transmission / reception antenna 206. Further, the transmission / reception unit 200 includes a transmission unit (transmission step) 203, a reception unit (reception step) 204, and a measurement unit (measurement step) 205. Further, the upper layer processing unit 201 includes a radio resource control unit (radio resource control step) 2011 and a scheduling information interpretation unit (scheduling information interpretation step) 2012. Further, the transmission unit 203 includes an encoding unit (encoding step) 2031, a modulation unit (modulation step) 2032, an uplink reference signal generation unit (uplink reference signal generation step) 2033, a multiplexing unit (multiplexing step) 2034, and a radio transmission unit (radio transmission step) 2035. Further, the reception unit 204 includes a radio reception unit (radio reception step) 2041, a demultiplexing unit (demultiplexing step) 2042, and a signal detection unit (signal detection step) 2043.

[0091] The upper layer processing unit 201 outputs the uplink data (transport block) generated by a user operation or the like to the transmission unit 203. Further, the upper layer processing unit 201 performs processing of the Medium Access Control (MAC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, and Radio Resource Control (RRC) layer.

[0092] The upper layer processing unit 201 outputs information indicating the functions of the terminal device supported by the own terminal device to the transmission unit 203.

[0093] The radio resource control unit 2011 manages various setting information of the own terminal device. Further, the radio resource control unit 2011 generates information to be arranged on each channel of the uplink and outputs it to the transmission unit 203.

[0094] The radio resource control unit 2011 acquires the setting information transmitted from the base station apparatus and outputs it to the control unit 202.

[0095] The scheduling information interpretation unit 2012 interprets the downlink control information received via the receiving unit 204 and determines the scheduling information. Further, the scheduling information interpretation unit 2012 generates control information for controlling the receiving unit 204 and the transmitting unit 203 based on the scheduling information, and outputs it to the control unit 202.

[0096] The control unit 202 generates a control signal for controlling the receiving unit 204, the measuring unit 205, and the transmitting unit 203 based on the information input from the upper layer processing unit 201. The control unit 202 outputs the generated control signal to the receiving unit 204, the measuring unit 205, and the transmitting unit 203 to control the receiving unit 204 and the transmitting unit 203.

[0097] The control unit 202 controls the transmitting unit 203 to transmit the CSI / RSRP / RSRQ / RSSI generated by the measuring unit 205 to the base station apparatus.

[0098] The receiving unit 204 separates, demodulates, and decodes the received signal received from the base station apparatus via the transmitting and receiving antenna 206 according to the control signal input from the control unit 202, and outputs the decoded information to the upper layer processing unit 201.

[0099] The radio receiving unit 2041 converts the downlink signal received via the transmitting and receiving antenna 206 into a baseband signal by down-conversion, removes unnecessary frequency components, controls the amplification level so that the signal level is appropriately maintained, and performs quadrature demodulation based on the in-phase component and the quadrature component of the received signal, and converts the quadrature-demodulated analog signal into a digital signal.

[0100] Further, the radio receiving unit 2041 removes the portion corresponding to the CP from the converted digital signal, performs a fast Fourier transform on the signal from which the CP has been removed, and extracts the signal in the frequency domain.

[0101] The multiplexing separation unit 2042 separates the extracted signal into PHICH, PDCCH, EPDCCH, PDSCH, and downlink reference signals respectively. Also, based on the estimated value of the channel of the desired signal obtained from channel measurement, the multiplexing separation unit 2042 compensates for the channels of PHICH, PDCCH, and EPDCCH, detects the downlink control information, and outputs it to the control unit 202. Further, the control unit 202 outputs the PDSCH and the channel estimated value of the desired signal to the signal detection unit 2043.

[0102] The signal detection unit 2043 uses the PDSCH and the channel estimated value to perform demodulation, decoding, and outputs to the upper layer processing unit 201.

[0103] The measurement unit 205 performs various measurements such as CSI measurement, RRM (Radio Resource Management) measurement, RLM (Radio Link Monitoring) measurement, and obtains CSI / RSRP / RSRQ / RSSI, etc.

[0104] The transmission unit 203 generates an uplink reference signal according to the control signal input from the control unit 202, encodes and modulates the uplink data (transport block) input from the upper layer processing unit 201, multiplexes the PUCCH, PUSCH, and the generated uplink reference signal, and transmits it to the base station apparatus via the transceiver antenna 206.

[0105] The encoding unit 2031 performs encoding such as convolutional encoding, block encoding, turbo encoding, LDPC encoding, Polar encoding, etc. on the uplink control information or uplink data input from the upper layer processing unit 201.

[0106] The modulation unit 2032 modulates the encoded bits input from the encoding unit 2031 with the modulation method notified by the downlink control information such as BPSK, QPSK, 16QAM, 64QAM, etc., or with the modulation method predetermined for each channel.

[0107] The uplink reference signal generation unit 2033 generates a sequence obtained by a predetermined rule (formula) based on a physical cell identifier (referred to as physical cell identity: PCI, Cell ID, etc.) for identifying a base station apparatus, a bandwidth in which the uplink reference signal is arranged, a cyclic shift notified by an uplink grant, a value of a parameter for generating a DMRS sequence, and the like.

[0108] The multiplexing unit 2034 multiplexes the signals of PUCCH and PUSCH and the generated uplink reference signal for each transmission antenna port. That is, the multiplexing unit 2034 arranges the signals of PUCCH and PUSCH and the generated uplink reference signal in resource elements for each transmission antenna port.

[0109] The wireless transmission unit 2035 performs inverse fast Fourier transform (IFFT) on the multiplexed signal, performs modulation in the OFDM system, generates an OFDMA symbol, adds a CP to the generated OFDMA symbol, generates a baseband digital signal, converts the baseband digital signal into an analog signal, removes unnecessary frequency components, converts it to a carrier frequency by upconversion, amplifies the power, and outputs it to the transceiver antenna 206 for transmission.

[0110] Note that the terminal device is not limited to the OFDMA system, and can perform modulation in the SC-FDMA (DFT-spread-OFDM) system.

[0111] In particular, in a wireless communication system, it is one of the most important things to communicate with a communication partner safely without leaking information other than a regular user (regular terminal device). In order to maintain secure communication, encryption by a higher layer is common. In order to further enhance security, it is desirable to take security measures also at the physical layer.

[0112] In wireless communication, since the transmitted signal reaches a wide area, it is possible for eavesdroppers (unauthorized users, unauthorized terminal devices) to receive the wireless signal. If unencrypted control information or the like leaks, the probability that the eavesdropper can demodulate and decrypt it increases. Therefore, at the physical layer, secure communication is possible by making it difficult for the eavesdropper to demodulate and decrypt.

[0113] In addition, the base station device can transmit the desired signal with random phases and amplitudes from each of the plurality of transmitting antennas so that authorized users can correctly receive the desired signal and unauthorized users cannot correctly receive the desired signal (also called the random phase method). Also, if the amplitude is determined so that the transmission power becomes small, secure communication is possible while suppressing the transmission power. The random phase method requires that the channel between the transmitting side and the authorized user be known. In this embodiment, secure communication from the base station device to the authorized terminal device will be described, but one aspect of the present invention is not limited to this. For example, one aspect of the present invention also includes the case of secure communication from the authorized terminal device to the base station device.

[0114] In the above-described random phase method, channel estimation is performed at the base station device to know the channel. Since the channel estimation value includes an error, there is a possibility that the authorized terminal device cannot accurately receive the desired signal. Therefore, on the receiving side, the desired signal is extracted by diversity combining using a plurality of receiving antennas. To enhance security, the authorized terminal device estimates by blind estimation without using a training signal.

[0115] In addition, since the authorized terminal device is equipped with a plurality of receiving antennas, if transmission is performed by the MIMO (Multiple Input Multiple Output) method in which the transmission side spatially multiplexes signals of a plurality of layers (streams), high-speed transmission with high security is possible.

[0116] The details of the random phase method will be described. The modulation signal b k (n) of the k-th subcarrier of the t-th transmitting antenna can be expressed as in Equation (1).

[0117] [Number] However, θ t,k represents the phase randomly set by the base station device. Also, a t (k) is the amplitude of the modulation signal of the t-th transmission antenna and the k-th subcarrier. Also, a t (k) is required to correctly receive the desired signal and suppress the transmission power. Note that a t (k) is a real number and can take negative values. Also, the desired signal d r (k) of the r-th layer and the k-th subcarrier that should be correctly received by the legitimate terminal device is preferably as shown in Equation (2).

[0118] [Number] However, N T is the number of transmission antennas, and H q,t (k) is the channel between the q-th receiving antenna and the t-th transmission antenna. That is, the desired signal of the r-th layer is transmitted to be received by the q-th receiving antenna. At this time, a t (k) is obtained as shown in Equation (3).

[0119] [Number] However, H^ q,t (k) represents the channel estimation value of H q,t (k). Also, the superscript T represents the transposed matrix, Re(x) represents the real part of the complex number x, and Im(x) represents the imaginary part of the complex number x.

[0120] When the channel estimation value includes an error, there is a possibility that the legitimate terminal device cannot correctly receive the desired signal. Therefore, the legitimate terminal device obtains the desired signal by diversity combining. The diversity combining weight can be obtained from the training signal or the reference signal, but is obtained by a blind algorithm that does not use the training signal or the reference signal in order to enhance security. The received signal of the k-th subcarrier and the i-th OFDM symbol at the legitimate terminal device is Y kWhen (i) is satisfied, the desired signal d^ r ^(k) of the r-th layer and the k-th subcarrier requested by the legitimate terminal device is expressed by Equation (8) using the diversity combining weight W r of the r-th layer.

[0121] [Number] Here, H with a superscript represents a complex conjugate transpose matrix, λ is a forgetting factor, and δ is a very small positive number. Also, C r is an N R -dimensional vector, and the elements are different for each layer to be obtained. For example, when the desired signal of the r-th layer is received by the q-th receiving antenna, C r has the q-th element as 1 and the other elements as 0.

[0122] The base station device needs to know the downlink channel. In this embodiment, assuming the channel reciprocity of TDD (Time Division Duplex), the downlink channel is estimated using uplink signals (e.g., SRS, uplink DMRS). In the case of multi-layer transmission, it is transmitted from a plurality of transmitting antennas. For example, as shown in FIG. 4, the base station device 401 has N T antennas 402-1 to 402-N T and the legitimate terminal device 403 has N R antennas 404-1 to 404-N R . For example, the legitimate terminal device 403 transmits SRS from the N R antenna ports, and the base station device 401 receives SRS with N T antennas and estimates the downlink channel. At this time, the base station device 401 can estimate the downlink channel with a maximum of N RThe signals of the layers can be transmitted through spatial multiplexing. As described above, the base station apparatus 401 transmits a desired signal by using the channel estimation value so that the signals of each layer are received by the receiving antennas of the normal terminal apparatus 403. In order for the normal terminal apparatus 403 to correctly receive the desired signal, the channel should not change significantly. Therefore, it is desirable that the normal terminal apparatus 403 receive the desired signal by using the antenna (or the antenna at the same position) used for transmitting the SRS. Also, since the normal terminal apparatus 403 obtains the diversity combining weights for each receiving antenna and obtains the desired signal of the corresponding layer, it is necessary to associate each layer transmitted by the base station apparatus 401 with the receiving antennas of the normal terminal apparatus 403. Here, let the antenna port numbers of the SRS (or DMRS) used by the normal terminal apparatus 403 be 1 to N R Let it be. For example, layer 1 is associated with SRS antenna port 1, layer 2 is associated with SRS antenna port 2, and so on, associating the layer index and the SRS antenna port number one-to-one. At this time, the normal terminal apparatus receives the signal of layer 1 with the same antenna as SRS antenna port 1, and receives the signal of layer 2 with SRS antenna port 2. Also, when the base station apparatus 401 transmits signals of L (<N R ) layers, it is also possible to select a receiving antenna with a good channel state. At this time, the base station apparatus 401 instructs the normal terminal apparatus 403 of the correspondence between the layer index and the SRS antenna port number by control information. Also, the base station apparatus 401 can indicate the antenna for receiving each layer as QCL (Quasi Colocation) information. For example, for layer 1, when the SRS antenna port number 1 is set as the QCL information, it means that the normal terminal apparatus 403 must receive the signal of layer 1 with an antenna that becomes the same channel as when it is received with SRS antenna port number 1.

[0123] In this embodiment, in order for the base station apparatus to estimate the downlink channel, precoding, rank (number of layers), and MCS suitable for a normal terminal apparatus can be determined using the estimated value of the downlink channel. On the other hand, when there are degradation factors that cannot be estimated by the base station apparatus, such as inter-cell interference, it is desirable to have the normal terminal apparatus report CSI. The base station apparatus transmits CSI-RS, and the normal terminal apparatus obtains and reports a suitable rank indicator and channel quality indicator from the CSI-RS. In this embodiment, since the normal terminal apparatus estimates the diversity combining weight using a blind algorithm, channel estimation using CSI-RS is not performed. Therefore, CSI-RS can measure CSI with 1 resource element regardless of the number of ranks. In this case, even if a plurality of CSI-RS antenna ports are set, the normal terminal apparatus may refer to the resource element of 1 port for the CSI-RS resource. For example, when the number of ranks is 1, the normal terminal apparatus refers to the resource element of CSI-RS antenna port 1, and when the number of ranks is 2, the normal terminal apparatus refers to the resource element of CSI-RS antenna port 2. For rank adaptation, resource elements of the maximum number of ranks are required. For example, in the case of a maximum of 4 ranks, 4 resource elements, i.e., the resource element for the number of ranks 1, the resource element for the number of ranks 2, the resource element for the number of ranks 3, and the resource element for the number of ranks 4, are required. In the resource element for the number of ranks r, r CSI-RS are transmitted. The r CSI-RS are associated with r CSI-RS antenna port numbers. For example, the r CSI-RS are the same as the CSI-RS transmitted with CSI-RS antenna port numbers 1 to r. The normal receiving terminal measures CSI using the quality of the blindly estimated CSI-RS. At this time, the normal terminal apparatus can measure CSI for each resource element and report a suitable number of ranks, CQI, or RSRP (Reference Signal Received Power) to the base station apparatus. The normal terminal apparatus can report a suitable resource index instead of a suitable number of ranks.Note that the normal terminal device can report CQI and RSRP for one or more rank numbers. The resource elements for each rank number can be different CSI-RS resources. The CSI-RS resource is set in association with a CSI-RS resource ID (identifier) and the resource element to which the CSI-RS is mapped. The resource element to which the CSI-RS is mapped is indicated by the OFDM symbol in the slot in which the CSI-RS is transmitted and the subcarriers in the resource block. Also, the CSI-RS resources used for rank measurement may be included in one CSI-RS resource set. For example, the maximum rank number to be reported may be the number of CSI-RS resources set in the CSI-RS resource set. Also, since the base station device transmits CSI-RS based on the downlink channel estimation value in the same way as the desired signal, it is necessary to indicate the receiving antenna of the normal terminal device corresponding to the CSI-RS antenna port. For example, in the resource element of rank number R, each of CSI-RS antenna ports 1 to R and each of SRS antenna ports 1 to R are associated with the normal terminal device. Also, the base station device can set the CSI-RS antenna port and the SRS antenna port in an associated relationship as a QCL relationship.

[0124] Note that the frequency band used by the communication device (base station device, terminal device) according to this embodiment is not limited to the licensed band or unlicensed band described so far. The frequency bands targeted by this embodiment include white bands (white spaces) that are not actually used for the purpose of preventing interference between frequencies, etc., even though permission to use them for specific services has been granted by countries or regions (for example, frequency bands allocated for television broadcasting but not used in some regions), and shared frequency bands (license sharing bands) that have been exclusively allocated to specific operators so far but are expected to be shared by multiple operators in the future.

[0125] A program that operates on an apparatus according to an aspect of the present invention may be a program that controls a Central Processing Unit (CPU) or the like to function a computer so as to realize the functions of an embodiment according to an aspect of the present invention. The program or information handled by the program is temporarily stored in a volatile memory such as a Random Access Memory (RAM), a non-volatile memory such as a flash memory, a Hard Disk Drive (HDD), or other storage device systems.

[0126] In addition, a program for realizing the functions of an embodiment according to an aspect of the present invention may be recorded on a computer-readable recording medium. It may be realized by causing a computer system to read and execute the program recorded on this recording medium. Here, the "computer system" refers to a computer system built in an apparatus and including hardware such as an operating system and peripheral devices. Further, the "computer-readable recording medium" may be a semiconductor recording medium, an optical recording medium, a magnetic recording medium, a medium that temporarily holds a program, or other recording media readable by a computer.

[0127] In addition, each functional block or various features of the apparatus used in the above-described embodiments can be implemented or executed by an electric circuit, for example, an integrated circuit or a plurality of integrated circuits. The electric circuit designed to execute the functions described in this specification may include a general-purpose use processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, discrete gates or transistor logic, discrete hardware components, or a combination thereof. The general-purpose use processor may be a microprocessor, or may be a conventional type processor, controller, microcontroller, or state machine. The above-described electric circuit may be composed of a digital circuit or an analog circuit. Further, when an integrated circuit technology that replaces the current integrated circuit appears due to the progress of semiconductor technology, one or more aspects of the present invention can also use a new integrated circuit based on such technology.

[0128] Note that the invention of the present application is not limited to the above-described embodiments. In the embodiments, an example of the apparatus has been described, but the invention of the present application is not limited thereto, and it can also be applied to stationary or non-mobile electronic devices installed indoors and outdoors, for example, terminal devices or communication devices such as AV devices, kitchen devices, cleaning / washing devices, air conditioning devices, office devices, vending machines, and other household appliances.

[0129] As described above in detail with reference to the drawings regarding the embodiments of the present invention, the specific configuration is not limited to this embodiment, and design changes and the like within the scope not departing from the gist of the present invention are also included. Further, one aspect of the present invention can be variously modified within the scope shown in the claims, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Further, a configuration in which elements described in the above embodiments and having the same effects are replaced with each other is also included.

Industrial Applicability

[0130] One aspect of the present invention is suitable for use in a communication device and a communication method.

Explanation of Signs

[0131] 1A Base station device 2A Terminal device 100 Transmission / reception unit 101 Upper layer processing unit 102 Control unit 103 Transmission unit 104 Reception unit 105 Transmission / reception antenna 106 Measurement unit 1011 Radio resource control unit 1012 Scheduling unit 1031 Encoding unit 1032 Modulation unit 1033 Downlink reference signal generation unit 1034 Multiplexing unit 1035 Radio transmission unit 1041 Radio reception unit 1042 Multiplexing separation unit 1043 Demodulation unit 1044 Decoding unit 200 Transmission / reception unit 201 Upper layer processing unit 202 Control unit 203 Transmission unit 204 Reception unit 205 Measurement unit 206 Transmission / reception antenna 2011 Radio resource control unit 2012 Scheduling information interpretation unit 2031 Encoding unit 2032 Modulation unit 2033 Uplink reference signal generation unit 2034 Multiplexing unit 2035 Radio transmission unit 2041 Radio reception unit 2042 Multiplexing separation unit 2043 Signal detection unit 401 Base station device 402-1 to 402-N TAntenna 403 Terminal device 404-1 to 404-N R Antenna

Claims

1. A transceiver that receives an uplink reference signal and transmits control information and signals of multiple layers; A channel estimator that estimates a downlink channel from the uplink reference signal; Comprising: The uplink reference signal is transmitted from a communication partner using multiple antennas; The signals of the multiple layers are phase-controlled and amplitude-controlled using the estimated value of the downlink channel; Each of the signals of the multiple layers is given a layer index; The control information includes an association between the layer index and an antenna port number of one of the multiple antennas from which the uplink reference signal of the communication partner was transmitted; Instructing the communication partner to receive with the associated antenna port number according to the layer index; A communication device.

2. The transceiver transmits a reference signal (CSI-RS) for channel state information (CSI) measurement; The number of resources (CSI-RS resources) to which the CSI-RS is allocated is multiple, and for each CSI-RS resource, a mapping to one resource element is set; The resource element is one orthogonal frequency division multiplexing (OFDM) symbol in a slot and one subcarrier in a resource block; For one of the CSI-RS resources, CSI measurement for any one of the multiple rank numbers is performed; Among the multiple CSI-RS resources, different rank numbers of CSI measurements are performed for different CSI-RS resources; The communication device according to Claim 1.

3. Receiving a channel quality indicator (CQI) for each of the multiple CSI-RS resources; The communication device according to Claim 2.

4. Receiving a CSI-RS resource index indicating one of the multiple CSI-RS resources and a channel quality indicator (CQI) measured with the CSI-RS resource; The communication device according to Claim 2.

5. A transceiver that transmits an uplink reference signal and receives control information and multiple layer signals using multiple antennas; A signal detector that detects a desired signal from the received signals of the multiple layers based on the control information; comprising: The control information includes an association between a layer index indicating one of the multiple layers and an antenna port number of one of the multiple antennas from which the uplink reference signal was transmitted; Based on the control information, a signal of a corresponding layer index is detected from the signal received with the antenna port number. Communication device.

6. The transceiver receives a reference signal (CSI-RS) for channel state information (CSI) measurement. The number of resources (CSI-RS resources) to which the CSI-RS is assigned is plural, and for each CSI-RS resource, mapping to one resource element is set. The resource element is one orthogonal frequency division multiplexing (OFDM) symbol within a slot and one subcarrier within a resource block. For one of the CSI-RS resources, CSI measurement for any one of a plurality of rank numbers is performed. Among the plurality of CSI-RS resources, CSI measurements for different rank numbers are performed for different CSI-RS resources. The communication device according to claim 5.

7. Measure the channel quality indicator (CQI) for each of the plurality of CSI-RS resources. Report the CSI-RS resource in association with the CQI. The communication device according to claim 6.

8. Select one from the plurality of CSI-RS resources, and report the selected CSI-RS resource index and the channel quality indicator (CQI) measured with the CSI-RS resource. The communication device according to claim 6.

9. Receiving an uplink reference signal, and transmitting control information and signals of a plurality of layers. Estimating a downlink channel from the uplink reference signal. Comprising The uplink reference signal is transmitted from a communication partner using a plurality of antennas. The signals of the plurality of layers are phase-controlled and amplitude-controlled using the estimated value of the downlink channel. Each of the signals of the plurality of layers is given a layer index. The control information includes an association between the layer index and an antenna port number of one of the plurality of antennas from which the uplink reference signal of the communication partner is transmitted. The layer index instructs the communication partner to receive with the associated antenna port number. Communication method.

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