# US 2019/0173723 A1 · User terminal and wireless communication method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0173723 A1 - Document ID: US20190173723A1 - Status: Published application - Kind: A1 - Application number: 16/324,160 - Filed: 2017-08-07 - Published: 2019-06-06 - Earliest claimed: 2016-08-10 - Assignees: Ntt Docomo, Inc. - Applicants: Ntt Docomo, Inc. - Inventors: Keisuke Saito; Kazuaki Takeda; Kazuki Takeda; Satoshi Nagata; Chongning Na - Web page: https://patentgrep.com/patent/US20190173723A1 ## CPC - H04L 5/0051: {of dedicated pilots, i.e. pilots destined for a single user or terminal} - H04B 7/0413: MIMO systems - H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)} - H04L 5/0094: {Indication of how sub-channels of the path are allocated} - H04L 27/22: Demodulator circuits; Receiver circuits - H04L 27/26: Systems using multi-frequency codes (H04L27/32 takes precedence) - H04L 27/2607: {Cyclic extensions} - H04L 27/2613: {Structure of the reference signals} - H04L 27/2695: {with channel estimation, e.g. determination of delay spread, derivative or peak tracking (channel estimation H04L25/0202)} - H04W 16/28: using beam steering - H04W 72/04: Wireless resource allocation - H04W 72/0446: Resources in time domain, e.g. slots or frames - H04W 72/0453: Resources in frequency domain, e.g. a carrier in FDMA - H04B 7/0452: Multi-user MIMO systems - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04B: TRANSMISSION - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract This user terminal is provided with: a reception unit that receives a downlink signal including a demodulation reference signal; a signal separation unit that separates the demodulation reference signal from the downlink signal; and a channel estimation unit that calculates a channel estimation value by using the demodulation reference signal. The demodulation reference signal is mapped on a resource element set in a transmission pattern selected from a plurality of candidate patterns. The reception unit receives an index indicating the transmission pattern, and the signal separation unit separates the demodulation reference signal by using the transmission pattern specified on the basis of the index. ## Claims ### Claim 1 A user terminal, comprising: a receiver that receives a downlink signal including a demodulation reference signal; a signal separator that separates the demodulation reference signal from the downlink signal; and a channel estimator that calculates a channel estimation value, using the demodulation reference signal, wherein: the demodulation reference signal is mapped to a resource element defined in a transmission pattern selected from among a plurality of candidate patterns, the receiver receives an index indicating the transmission pattern, and the signal separator separates the demodulation reference signal, using the transmission pattern identified based on the index. ### Claim 2 (depends on 1) The user terminal according to claim 1, wherein the plurality of candidate patterns are different from each other in at least one of a mapping interval of the demodulation reference signal in a frequency direction, a mapping interval of the demodulation reference signal in a temporal direction, a layer multiplexing method, and an overhead size. ### Claim 3 (depends on 1) The user terminal according to claim 1, wherein the receiver receives the index notified by higher layer signaling or physical layer signaling. ### Claim 4 (depends on 1) The user terminal according to claim 1, wherein the demodulation reference signal is not mapped to a resource element to which a signal different from the demodulation reference signal is mapped. ### Claim 5 (depends on 1) The user terminal according to claim 1, wherein in a case where a signal different from the demodulation reference signal is mapped to at least one of the resource elements defined in the transmission pattern, the demodulation reference signal is mapped to a resource element different from at least one of the resource elements defined in the transmission pattern. ### Claim 6 (depends on 1) The user terminal according to claim 1, wherein the receiver receives signaling that indicates an antenna port number applied to the user terminal, and a method of multiplexing the demodulation reference signal, the signal separator separates the demodulation reference signal from a downlink signal corresponding to the antenna port number indicated by the signaling, using a separation method corresponding to the multiplexing method indicated by the signaling, and a multiplexing method applied when the antenna port number is identical among user terminals is different from a multiplexing method applied when the antenna port number is different among the user terminals. ### Claim 7 (depends on 6) The user terminal according to claim 6, wherein the multiplexing method applied when the antenna port number is different among the user terminals includes code division multiplexing using a sequence having a sequence length longer than a defined sequence length. ### Claim 8 A user terminal, comprising: a receiver that receives an index indicating a transmission pattern selected from among a plurality of candidate patterns; a mapper that maps a demodulation reference signal to a resource element defined in the transmission pattern indicated by the index; and a transmitter that transmits an uplink signal including the demodulation reference signal. ### Claim 9 A radio communication method comprising: receiving a downlink signal including a demodulation reference signal; separating the demodulation reference signal from the downlink signal; and calculating a channel estimation value, using the demodulation reference signal, wherein the demodulation reference signal is mapped to a resource element defined in a transmission pattern selected from among a plurality of candidate patterns, an index indicating the transmission pattern is received, and the demodulation reference signal is separated using the transmission pattern identified based on the index.