Transmitter and transmission method

Abstract

The present application relates to a transmitter and a transmission method. In the transmitter, a signal allocation unit maps a phase tracking reference signal (PT-RS) to a subcarrier, and a transmission unit transmits a signal containing the phase tracking reference signal. The subcarriers to which the phase tracking reference signal is mapped are different between cells, groups or mobile stations.

Description

[0001] This application is a divisional application of the invention patent application with application date of April 16, 2018, application number 201880034016.0, and invention name “Transmitter, receiver, transmitting method and receiving method”. Technical Field

[0002] The present invention relates to a transmitter and a transmitting method. Background Art

[0003] Research is being conducted on a communication system called the fifth generation mobile communication system (5G). In 5G, research is being conducted on how to flexibly provide functions for various use cases, such as an increase in the number of communication services required, an increase in the number of terminals to be connected, high reliability, and low latency. Representative use cases include three: extended mobile broadband (eMBB: enhanced Mobile Broadband), massive communication / massive connections (mMTC: massive Machin Type Communications), and ultra-reliable and low-latency communication (URLLC: Ultra Reliable and Low Latency Communicant). In the international standardization organization 3GPP (3rd Generation Partnership Project), research is being conducted on the improvement of the communication system from two aspects: the improvement of the LTE system and the new RAT (Radio Access Technology) (for example, refer to non-patent document 1).

[0004] Prior art literature

[0005] Non-patent literature

[0006] Non-patent document 1: RP-161596, "Revision of SI: Study on New Radio Access Technology", NTT DOCOMO, September 2016

[0007] Non-patent document 2: R1-1612335, "On phase noise effects", Ericsson, November 2016 Summary of the invention

[0008] In the new RAT, compared with LTE / LTE-Advanced, for example, signals with frequencies as high as 6 GHz or higher are used as carriers. In particular, when a higher frequency band and a high-order modulation order are used, the error rate characteristics are degraded due to CPE (Common Phase Error) or ICI (Inter-carrier Interference) generated by the phase noise (Phase Noise) of the local oscillator of the transmitter (for example, refer to non-patent document 2). Therefore, in the new RAT, in addition to channel equalization, the receiver is also studied to perform CPE correction (CPE Correction) or ICI correction (ICI Correction) using a phase tracking reference signal (PT-RS: Phase Tracking Reference Signal) (hereinafter sometimes also referred to as "CPE / ICI correction").

[0009] However, methods for suppressing interference to PT-RSs transmitted from multiple base stations (sometimes also referred to as BS (Base station), gNB) or multiple mobile stations (sometimes also referred to as terminals, UE (User Equipment)) have not been fully studied.

[0010] One embodiment of the present invention contributes to providing a transmitter, a receiver, a transmission method, and a reception method that can appropriately suppress interference with PT-RSs transmitted from a plurality of base stations or mobile stations.

[0011] A transmitter of one embodiment of the present invention includes: an allocation circuit that maps a phase tracking reference signal into a subcarrier; and a transmission circuit that transmits a signal containing the phase tracking reference signal, wherein the subcarriers onto which the phase tracking reference signal is mapped are different between cells, groups or mobile stations.

[0012] A receiver of one embodiment of the present invention includes: a receiving circuit that receives a signal containing a phase tracking reference signal; and a demodulation circuit that demodulates a data signal using a phase noise estimation value calculated using the phase tracking reference signal, wherein the subcarriers mapped with the phase tracking reference signal are different between cells, groups or mobile stations.

[0013] A sending method according to one aspect of the present invention comprises the following steps: mapping a phase tracking reference signal into a subcarrier, sending a signal containing the phase tracking reference signal, wherein the subcarriers onto which the phase tracking reference signal is mapped are different between cells, groups or mobile stations.

[0014] A receiving method according to one aspect of the present invention comprises the following steps: receiving a signal containing a phase tracking reference signal, demodulating a data signal using a phase noise estimation value calculated using the phase tracking reference signal, wherein the subcarriers to which the phase tracking reference signal is mapped are different between cells, groups or mobile stations.

[0015] Furthermore, these general or specific methods may be implemented through systems, methods, integrated circuits, computer programs, or storage media, or through any combination of systems, devices, methods, integrated circuits, computer programs, and storage media.

[0016] According to one aspect of the present invention, it is possible to appropriately suppress interference with PT-RSs transmitted from a plurality of base stations or mobile stations.

[0017] It will be clear from the description and drawings that more advantages and effects of one embodiment of the present invention can be provided by several embodiments and the features described in the description and drawings, respectively, without providing all the features in order to obtain one or more of the same features. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This shows a mapping example of DMRS and PT-RS.

[0019] Figure 2 A partial structure of a transmitter according to the first embodiment is shown.

[0020] Figure 3 A partial structure of a receiver according to embodiment 1 is shown.

[0021] Figure 4 The structure of the transmitter according to the first embodiment is shown.

[0022] Figure 5 The structure of the receiver according to the first embodiment is shown.

[0023] Figure 6 The processing of the transmitter in implementation mode 1 is shown.

[0024] Figure 7 The following shows the processing of the receiver according to the first embodiment.

[0025] Figure 8 An example of mapping of PT-RS in an operation example of implementation mode 1 is shown.

[0026] Fig. 9 A mapping example of PT-RS in operation example 1 of implementation example 2 is shown.

[0027] Fig.10 A mapping example of PT-RS in action example 2 of implementation mode 2 is shown.

[0028] Fig.11 An example of mapping of PT-RS in operation example 1 of implementation example 3 is shown.

[0029] Fig.12 An example of mapping of PT-RS in action example 2 of implementation mode 3 is shown.

[0030] Fig.13 A mapping example of PT-RS in action example 3 of implementation mode 3 is shown. DETAILED DESCRIPTION

[0031] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0032] The higher the frequency band to which the signal is allocated, or the higher the modulation order used by the signal, the greater the impact of CPE / ICI on the error rate characteristics. Therefore, as described above, in the study of using a higher frequency band and a higher modulation order, in addition to channel equalization, CPE / ICI correction using PT-RS is also performed in the receiver.

[0033] In order to track the CPE / ICI that randomly changes in time, the PT-RS is compared with the reference signal (DMRS: Demodulation Reference Signal) used for channel estimation (demodulation) and mapped on the time axis with high density. Specifically, it is assumed that the configuration density in the time domain of the mapped PT-RS is set for each codeword, 1 codeword among 2 adjacent codewords, or 1 codeword among 4 adjacent codewords. In addition, due to the characteristics of CPE / ICI such as small changes between subcarriers, PT-RS is mapped with relatively low density in the frequency domain. Specifically, it is assumed that the configuration density in the frequency domain of the mapped PT-RS is set for 1 subcarrier per RB (Resource Block), 1 subcarrier among 2 adjacent RBs, or 1 subcarrier among 4 adjacent RBs.

[0034] According to the PT-RS protocol in 3GPP RAN1#88, PT-RS is used between a base station (BS, eNB, gNB) and a mobile station (terminal, UE) notified by the base station through high-layer signaling (e.g., RRC (Radio Resource Control) signaling). In addition, it is assumed that the configuration density of PT-RS in the time domain and frequency domain varies flexibly according to the modulation order or bandwidth used between the base station and the mobile station.

[0035] In addition, a method for a mobile station to determine the configuration density of PT-RS is being studied. As one method, there is a method such as notifying the configuration density of PT-RS from a base station through a PT-RS-specific control signal (explicit notification / explicit). As another method, there is a method such as predetermining the correspondence between the configuration density of PT-RS and other parameters (for example, modulation order or bandwidth, etc.), and the mobile station checks the other parameters notified by DCI (Downlink Control Information) and their correspondence during communication and determines the configuration density of PT-RS (implicit notification / implicit). Furthermore, methods other than these methods may also be used.

[0036] On the other hand, the DMRS used for channel estimation has a large change in the frequency domain of the channel characteristics, and the change in the time domain is not as large as the phase noise, so it is mapped with a high density in the frequency domain and a low density in the time domain compared to the PT-RS. In addition, in order to advance the timing of data demodulation in the new RAT, it is assumed that the front-loaded DMRS configured in the front of the time slot is introduced.

[0037] In addition, in the new RAT, it is assumed that MIMO (Multiple Input Multiple Output) is used. That is, the base station and one or more mobile stations within the cell formed by the base station can transmit and receive using multiple antenna ports corresponding to different beams (precoding) using the same time and frequency resources. Since there is a limit on the maximum transmission power in each of the base station and the mobile station, it is assumed that the limit is applied so that the total transmission power of the multiple antenna ports used in data transmission does not exceed the maximum transmission power. Therefore, compared with the case of transmitting with multiple antenna ports, the transmission power of each antenna port can be increased when transmitting with one antenna port.

[0038] In PT-RS, the same precoding as that of the antenna port (sometimes also referred to as the DMRS port) to which DMRS is transmitted is studied, and PT-RS is also considered to be defined as a part of DMRS. In this case, the DMRS used as PT-RS is mapped more densely in the time domain and less densely in the frequency domain than other DMRS. In addition, the reference signal used in the correction of CPE / ICI caused by phase noise may also be called a name different from "PT-RS".

[0039] In addition, PT-RS is sent and received between the base station and each mobile station in the cell formed by the base station. Here, in the group of antenna ports of the local oscillator of the shared transmitter (base station in the downlink and mobile station in the uplink), since the CPE / ICI value is the same, PT-RS can be sent from any antenna port in the group, and it is not necessary to send from all antenna ports in the group. Therefore, compared with the number of antenna ports for sending and receiving data, the number of antenna ports for sending and receiving PT-RS is sometimes small.

[0040] Moreover, for the PT-RS transmitted and received by a mobile station, it can be considered that the data is orthogonally multiplexed. In addition, it can be considered that FDM (Frequency Division Multiplexing) is also used between PT-RS. Therefore, when the PT-RS of one antenna port is transmitted in one RE (Resource Element), data or PT-RS of other antenna ports are not transmitted in the same RE.

[0041] Based on the above, it can be considered that the transmission power per RE of 1 antenna port of PT-RS is greater than the transmission power per RE of 1 antenna port of data. As mentioned above, PT-RS is sent from a base station (downlink) or multiple mobile stations (uplink) constituting multiple cells, so it causes interference to each other. At this time, the magnitude of the interference caused by the PT-RS sent from a certain antenna port to another cell is greater than the interference caused by the data sent from a certain antenna port to another cell.

[0042] Figure 1 This shows an example of mapping DMRS and PT-RS in MIMO. The numbers in the REs mapped with DMRS and PT-RS represent port numbers. Figure 1 The DMRS and PT-RS with the same number share precoding.

[0043] In addition, in NR (New Radio), it is assumed that the CP-OFDM (Cyclic Prefix-Orthogonal Frequency Division Multiplexing) method is used in the downlink (the direction from the base station to the mobile station, the downlink). On the other hand, in the uplink (the direction from the mobile station to the base station, the uplink), both the CP-OFDM method and the DFT-S-OFDM (Discrete Fourier Transform-Spread OFDM) method are studied, and it is assumed that the communication method is switched to match the communication environment and used.

[0044] For example, in the case of a downlink, if the PT-RS transmitted from the base station connected to the mobile station and the PT-RS transmitted from other base stations exist in the same RE, there is a conflict between the PT-RSs. At this time, when the transmission power of the PT-RS per RE of one antenna port is high compared to the transmission power of the data, the amount of interference between the PT-RSs increases compared to the case where the data and the PT-RS conflict. Similarly, in the case of an uplink, if the PT-RS transmitted from a mobile station connected to a certain base station conflicts with the PT-RS transmitted from other mobile stations connected to other base stations, the amount of interference between the PT-RSs increases compared to the case where the data and the PT-RS conflict.

[0045] In each embodiment of the present invention, a method of suppressing collision between PT-RSs and preventing the amount of interference from increasing will be described.

[0046] (Implementation Method 1)

[0047] [Overview of Communication System]

[0048] The communication system of this embodiment includes a transmitter 100 and a receiver 200. That is, in the downlink, the transmitter is a base station and the receiver is a mobile station. In addition, in the uplink, the transmitter is a mobile station and the receiver is a base station.

[0049] Figure 2 1 is a block diagram showing a part of the structure of the transmitter 100 according to the present embodiment. Figure 2 In the transmitter 100 shown, the signal allocation unit 106 (allocation circuit) maps the phase tracking reference signal (PT-RS) to the subcarrier, and the transmission unit 107 (transmission circuit) transmits a signal including the PT-RS.

[0050] Figure 3 FIG. 2 is a block diagram showing a part of the structure of the receiver 200 according to the present embodiment. Figure 3 In the receiver 200 shown, the receiving unit 202 (receiving circuit) receives a signal including a PT-RS. The data demodulation unit 207 demodulates the data signal using a phase noise estimation value (CPE / ICI estimation value) calculated using a phase tracking reference signal (PT-RS).

[0051] Here, the subcarriers to which the PT-RS is mapped differ among cells, groups, or mobile stations.

[0052] [Structure of the transmitter]

[0053] Figure 4 is a block diagram showing the structure of the transmitter 100 according to the present embodiment. Figure 4In the embodiment, the transmitter 100 includes a PT-RS generating unit 101, a frequency hopping pattern generating unit 102, a frequency hopping unit 103, an error correction coding unit 104, a modulation unit 105, a signal allocation unit 106, a transmission unit 107, and an antenna 108.

[0054] The PT-RS generating section 101 generates a PT-RS, and outputs the generated PT-RS to the frequency hopping section 103 .

[0055] The frequency hopping pattern generation unit 102 determines the frequency hopping pattern (e.g., the initial position of the PT-RS and the frequency hopping offset) using, for example, at least one of the cell ID, the group ID, the UE ID (mobile station ID), and the time slot number. The frequency hopping pattern can also be calculated according to a predetermined frequency hopping pattern generation formula. The frequency hopping pattern generation unit 102 outputs the determined frequency hopping pattern to the frequency hopping unit 103.

[0056] For example, the cell ID is a cell ID corresponding to a base station to which the mobile station is connected, the group ID is an ID of a group to which the mobile station belongs, and the UE ID is an ID of the mobile station.

[0057] The frequency hopping unit 103 frequency-hops the position of the PT-RS input from the PT-RS generating unit 101 per unit time (e.g., symbol, slot, mini-slot, subframe, or frame, etc.) according to the frequency hopping pattern input from the frequency hopping pattern generating unit 102, and outputs the PT-RS after frequency hopping to the signal allocating unit 106. In addition, the frequency hopping unit 103 may output the PT-RS to the signal allocating unit 106 without frequency hopping the PT-RS.

[0058] Error correction coding section 104 performs error correction coding on the input transmission data signal, and outputs the error correction coded signal to modulation section 105 .

[0059] Modulation section 105 performs modulation processing on the signal input from error correction coding section 104 , and outputs the modulated data signal to signal distribution section 106 .

[0060] Signal allocating section 106 maps the DMRS, the data signal input from modulation section 105 , and the PT-RS input from frequency hopping section 103 into the time domain and the frequency domain, and outputs the mapped signals to transmitting section 107 .

[0061] Transmitting section 107 performs radio transmission processing such as frequency conversion of a carrier wave on the signal input from signal distribution section 106 , and outputs the signal after the radio transmission processing to antenna 108 .

[0062] Antenna 108 transmits the signal input from transmission section 107 to receiver 200 .

[0063] [Receiver Structure]

[0064] Figure 5 2 is a block diagram showing the structure of the receiver 200 according to this embodiment. Figure 5 , the receiver 200 includes an antenna 201, a receiving unit 202, a frequency hopping pattern generating unit 203, a signal separating unit 204, a channel estimating unit 205, a CPE / ICI estimating unit 206, a data demodulating unit 207, and an error correction decoding unit 208.

[0065] Antenna 201 receives the signal from transmitter 100 (see Figure 4 ) sends a signal and outputs the received signal to the receiving unit 202.

[0066] Receiving section 202 performs wireless reception processing such as frequency conversion on the reception signal input from antenna 201 , and outputs the signal after the wireless reception processing to signal separation section 204 .

[0067] Similar to the transmitter 100 (the frequency hopping pattern generation unit 102), the frequency hopping pattern generation unit 203 determines the frequency hopping pattern used in the transmission of the PT-RS (for example, the initial position and frequency hopping offset of the PT-RS) using, for example, at least one of the cell ID, the group ID, the UE ID, and the time slot number. The frequency hopping pattern can also be calculated based on the frequency hopping pattern generation formula that is the same as the frequency hopping pattern generation formula used by the transmitter 100. The frequency hopping pattern generation unit 203 outputs the determined frequency hopping pattern to the signal separation unit 204.

[0068] The signal separation unit 204 specifies the positions in the time domain and frequency domain to which the data, DMRS, and PT-RS are respectively mapped from the signal input from the receiving unit 202, using the frequency hopping pattern input from the frequency hopping pattern generating unit 203, and separates the signals. The signal separation unit 204 outputs the data from the separated signals to the data demodulating unit 207, outputs the DMRS to the channel estimating unit 205 and the CPE / ICI estimating unit 206, and outputs the PT-RS to the CPE / ICI estimating unit 206.

[0069] Channel estimation section 205 estimates channel information using the DMRS input from signal separation section 204 , and outputs the channel estimation information (channel information) to data demodulation section 207 .

[0070] The CPE / ICI estimation unit estimates CPE / ICI using the PT-RS and DMRS input from the signal separation unit 204 , and outputs the CPE / ICI estimation value to the data demodulation unit 207 .

[0071] Data demodulation section 207 demodulates the data signal input from signal separation section 204 using the channel estimation information input from channel estimation section 205 and the CPE / ICI estimation value input from CPE / ICI estimation section 206. Data demodulation section 207 outputs the demodulated signal to error correction decoding section 208.

[0072] Error correction decoding section 208 decodes the demodulated signal input from demodulation section 207 and outputs the obtained received data signal.

[0073] [Operations of Transmitter 100 and Receiver 200]

[0074] Next, the operations of the transmitter 100 and the receiver 200 will be described in detail.

[0075] Figure 6 An example of the processing flow of the transmitter 100 is shown. Figure 7 An example of the processing flow of the receiver 200 is shown.

[0076] exist Figure 6 In the example, the transmitter 100 determines the frequency resource (subcarrier) to which the PT-RS is mapped (ST101). In addition, the transmitter 100 may perform frequency hopping on the PT-RS.

[0077] Next, transmitter 100 maps PT-RS to the frequency resource determined in ST101 (ST102). Then, transmitter 100 transmits a signal including PT-RS to receiver 200 (ST103).

[0078] On the other hand, similarly to the transmitter 100 (ST101), the receiver 200 determines the frequency resources (subcarriers, frequency hopping patterns) to which the PT-RS is mapped (ST201). Next, the receiver 200 separates the PT-RS (and DMRS, data) from the signal transmitted by the transmitter 100 based on the frequency resources determined in ST201 (ST202). Next, the receiver 200 uses the PT-RS (and DMRS) to perform CPE / ICI estimation (ST203). Then, the receiver 200 demodulates the data using the CPE / ICI estimation value (ST204).

[0079] At this time, the subcarriers to which the PT-RS is mapped and transmitted from the transmitter 100 are different between different cells, different groups or different mobile stations. As a result, the PT-RS transmitted by the transmitter 100 can be prevented from being transmitted in the same subcarrier as the PT-RS of other cells / groups / mobile stations, and the conflict between the PT-RSs can be reduced. In other words, the possibility that the PT-RS transmitted by the transmitter 100 is interfered by the PT-RS of other cells / groups / mobile stations can be reduced.

[0080] Furthermore, the subcarriers to which the PT-RS is mapped may be associated with each cell ID, group ID, or UE ID, for example, or may be notified from the base station to the mobile station through higher layer signaling.

[0081] Next, a method for determining frequency resources (subcarriers) for mapping PT-RS in the transmitter 100 and the receiver 200 is described. Figure 6 The ST101 and Figure 7 Processing of ST201 shown).

[0082] Furthermore, the following describes a case where the PT-RS is frequency-hopped in each time slot.

[0083] [Action examples]

[0084] In the operation example, in the first slot to which PT-RS is mapped in the frame, PT-RS are evenly distributed and mapped at equal intervals in the frequency domain. In the subsequent slots of the frame, the same frequency hopping offset is applied to all PT-RSs in the allocated frequency band of the mobile station.

[0085] That is, in the operation example of this embodiment, the transmitter 100 performs frequency hopping on the PT-RS so that the subcarriers mapped with the PT-RS in each time slot are evenly distributed and equally spaced. In other words, the transmitter 100 (signal allocation unit 106) maps multiple PT-RS transmitted in each time slot (at the same time) at equal intervals in the frequency domain.

[0086] For example, transmitter 100 (frequency hopping pattern generation section 102) and receiver 200 (frequency hopping pattern generation section 203) determine the initial position of the PT-RS and the frequency hopping offset according to the following method.

[0087] In the following, the size of the allocated frequency band of the mobile station is set to "N UE_BW [RB]”, the configuration density of the PT-RS mapped in the mobile station in the frequency domain is set to “N density [RB] is one”.

[0088] First, a method for determining the frequency position of the PT-RS in the time slot where the PT-RS is first arranged in the frame (that is, the initial position of the PT-RS) will be described.

[0089] The transmitter 100 receives the N allocated to the mobile station. UE_BW One subcarrier is selected as the initial position among RBs (where 1RB = 12 subcarriers), and PT-RS is mapped in the subcarrier of the selected initial position. When selecting the initial position (subcarrier), the transmitter 100 uses a pseudo-random function and at least one of "cell ID, group ID, UE ID". Thus, in different cells, different groups or different mobile stations, as different subcarriers as possible are selected.

[0090] Next, the transmitter 100 maps the PT-RS to the RB N away from the RB where the PT-RS is configured. density The transmitter 100 repeatedly performs this process until the PT-RS is mapped on the N RBs. UE_BW / N density subcarriers (ie, for all RBs to which PT-RS is mapped).

[0091] In this way, the initial position (subcarrier) of the PT-RS in the RB to which the PT-RS is mapped within the allocated frequency band is the same in each RB, so the PT-RS in the first time slot is mapped uniformly and equally spaced in the frequency domain.

[0092] Next, a method for determining the frequency hopping offset for the PT-RS in the second slot and thereafter will be described.

[0093] The transmitter 100 is in [0, 1, 2…12N density -1], select a frequency hopping offset and set the selected value to "f HOP ". Furthermore, the transmitter 100 uses a pseudo-random function, at least one of "cell ID, group ID, UE ID" and a time slot number when selecting a frequency hopping offset. Thus, as different frequency hopping offsets as possible are selected in different cells, different groups, different mobile stations, or different time slots.

[0094] The transmitter 100 maps the PT-RS in each time slot onto the PT-RS mapped N times in the time slot before the time slot. UE_BW / N density All subcarriers of the PT-RS leave f HOP Transmitter 100 repeats this process for each time slot until the frame ends.

[0095] In addition, the receiver 200 specifies the frequency hopping pattern (initial position and frequency hopping offset) and specifies the subcarrier position to which the PT-RS transmitted from the transmitter 100 is mapped, through the same processing as that of the transmitter 100 described above.

[0096] Figure 8 A mapping example of PT-RS in an operation example of this embodiment is shown.

[0097] exist Figure 8 In the frequency domain, the configuration density of PT-RS is "one in 1RB" ( Figure 8 One of the 12 subcarriers in the density =1. Therefore, Figure 8In the PT-RS, no matter which time slot, the PT-RS is mapped to one subcarrier in all RBs of the allocated frequency band of the mobile station. In addition, the PT-RS is frequency-hopped at the boundary of the time slot.

[0098] like Figure 8 As shown, the initial position of the PT-RS in time slot #0 is in each RB ( Figure 8 In the figure, the same subcarrier (the 4th subcarrier of each RB) is represented in 2RB). Figure 8 As shown, the frequency hopping offset f HOP Therefore, in time slot #1, PT-RS is mapped to the subcarriers mapped with PT-RS in each RB of time slot #0, separated by f. HOP =7 subcarriers (the 11th subcarrier in each RB).

[0099] That is, Figure 8 As shown, in each time slot including the initial time slot and the subsequent time slot, the frequency spacing of the PT-RS is uniformly the same ( Figure 8 1RB (12 subcarriers)).

[0100] The operation example of this embodiment has been described above.

[0101] Thus, in this embodiment, the subcarriers to which the PT-RS is mapped are different between cells, groups or mobile stations. For example, the transmitter 100 determines the subcarriers to which the PT-RS is mapped based on "cell ID, group ID or UE ID" or high-level signaling. Thus, for each cell / group / mobile station, the PT-RS is mapped to a different subcarrier.

[0102] This increases the possibility that a plurality of transmitters 100 corresponding to different cells, different groups, or different mobile stations transmit PT-RS using different frequency resources (subcarriers) in the same time domain (eg, the same time slot).

[0103] Thus, for example, in the downlink, it is possible to reduce the collision between the PT-RS transmitted from the base station (transmitter 100) connected to the mobile station (receiver 200) and the PT-RS transmitted from other base stations (other transmitters 100). Similarly, in the uplink, it is possible to reduce the collision between the PT-RS transmitted from the mobile station (transmitter 100) connected to the base station (receiver 200) and the PT-RS transmitted from other mobile stations (other transmitters 100) connected to other base stations.

[0104] Therefore, according to the present embodiment, collisions between PT-RSs transmitted from a plurality of base stations or mobile stations can be suppressed, and interference can be appropriately suppressed.

[0105] In addition, the transmitter 100 applies frequency hopping to the PT-RS. At this time, the frequency hopping pattern of the PT-RS is determined based on the "cell ID, group ID or UE ID" and the index of the time domain (for example, the time slot number). As a result, since the possibility of different frequency hopping patterns being used between different cells / groups / mobile stations increases, the possibility of the PT-RS transmitted by the transmitter 100 being interfered with by the PT-RS of other cells / groups / mobile stations can be reduced. That is, the interference caused by the conflict between the PT-RSs between different cells / groups / mobile stations is randomized. In addition, in addition to the "cell ID, group ID or UE ID", by making the frequency hopping pattern different according to the index of the time domain, for example, by mapping multiple PT-RSs in a certain time slot to the same subcarrier through the "cell ID, group ID or UE ID", even in the case of a conflict between PT-RSs, it is possible to prevent the PT-RSs from continuing to conflict throughout the multiple time slots.

[0106] In addition, the transmitter 100 evenly distributes the PT-RS in the frequency domain in the time slot to which the PT-RS is initially mapped in the frame, maps the PT-RS at equal intervals, and applies the same frequency hopping offset to all PT-RSs in the allocated frequency band of the mobile station in the subsequent time slots. Thus, since the subcarriers to which the PT-RSs are mapped in each time slot are evenly distributed and are equally spaced, the PT-RSs are robust to the frequency selectivity of the channel.

[0107] In addition, by setting "the configuration density of PT-RS in the frequency domain is 1 for n (integer) RBs", the subcarrier position of the PT-RS mapped in each RB in the allocated frequency band of the mobile station becomes the same between RBs. As a result, the receiver 200 does not need to specify the subcarrier position to which the PT-RS is mapped for each RB, so the amount of calculation of the receiver 200 can be reduced.

[0108] (Variation 1 of Implementation Example 1)

[0109] Furthermore, in Embodiment 1, the case where the number of antenna ports for PT-RS is one is described (for example, see Figure 8 ), but the number of antenna ports for PT-RS may be more than 2. In the case where the number of antenna ports for PT-RS is multiple, for example, the transmitter 100 may also select the initial position of PT-RS so that it is mapped to different subcarriers according to the antenna port number in addition to the "cell ID, group ID or UE ID". However, the same value is used for the frequency hopping offset of the PT-RS transmitted from multiple antenna ports respectively. This is to avoid conflicts between PT-RS ports due to frequency hopping.

[0110] (Variation 2 of Implementation Example 1)

[0111] In addition, when there is coordination between cells and information on how PT-RS is mapped in each cell is shared between cells, for these cells, PT-RS can also be uniformly mapped in the frequency domain as in Implementation 1. For example, when there is coordination between cells, the interface between base stations (for example, X2 interface) can also be used to notify each other of information on the subcarriers for sending PT-RS.

[0112] In this way, compared with the increased possibility of PT-RS conflict between cells when the information of the subcarriers for sending PT-RS between cells is not shared, when there is coordination between cells, the subcarriers for mapping PT-RS can be made reliably different between cells, thereby avoiding PT-RS conflict between cells.

[0113] In particular, in Embodiment 1, the possibility that the intervals in the frequency domain of PT-RS are the same or an integer multiple between cells increases, and when the mapping of PT-RS is determined separately in each cell, the possibility that PT-RS in each time slot collide simultaneously in multiple subcarriers increases. Therefore, by applying the actions of Embodiment 1 between coordinated cells, as described above, the possibility of PT-RS colliding simultaneously in multiple subcarriers can be suppressed, and the amount of calculation in the receiver 200 can be reduced.

[0114] (Implementation Method 2)

[0115] The basic structure of the transmitter and receiver of this embodiment is the same as that of the transmitter 100 and receiver 200 of Embodiment 1, so Figure 4 and Figure 5 illustrate.

[0116] In this embodiment, the same or different frequency hopping offsets are applied to each PT-RS mapped in the allocated frequency band of the mobile station. That is, in Embodiment 1, compared with the equal spacing of the subcarriers mapped with PT-RS in each time slot, in this embodiment, the subcarriers mapped with PT-RS in each time slot are not necessarily equal spacing (but unequal spacing).

[0117] Hereinafter, operation example 1 and operation example 2 of the present embodiment will be described respectively.

[0118] [Action Example 1]

[0119] In operation example 1 of the present embodiment, the candidate subcarrier of the frequency hopping destination of the PT-RS is the entire allocated frequency band of the mobile station. That is, in operation example 1, the transmitter 100 performs frequency hopping in the entire allocated frequency band of the mobile station, and a plurality of PT-RSs are mapped to any subcarrier in the allocated frequency band.

[0120] For example, transmitter 100 (frequency hopping pattern generation section 102) and receiver 200 (frequency hopping pattern generation section 203) determine the initial position of the PT-RS and the frequency hopping offset according to the following method.

[0121] In the following, the size of the allocated frequency band of the mobile station is set to "N UE_BW [RB]”, the configuration density in the frequency domain of the PT-RS mapped in the mobile station is set to “N density [RB] in one". In this case, in each time slot, N UE_BW / N density Here, in all N UE_BW / N density Add [0, 1, 2…N UE_BW / N density -1] at index i.

[0122] First, a method for determining the frequency position of the PT-RS in the time slot where the PT-RS is initially arranged in the frame (that is, the initial position of the PT-RS) will be described.

[0123] The transmitter 100 receives the N allocated to the mobile station. UE_BW One subcarrier is selected as the initial position among RBs (here, 1RB = 12 subcarriers), and PT-RS is mapped in the subcarrier of the selected initial position. When selecting the initial position (subcarrier), the transmitter 100 uses a pseudo-random function, at least one of "cell ID, group ID, UE ID", and the index i of PT-RS. Thus, different subcarriers are selected as much as possible in different cells, different groups, different mobile stations, and different PT-RS (index i).

[0124] Next, the transmitter 100 receives the N UE_BW In the RBs, another subcarrier is selected as the initial position based on the same method, and the PT-RS is mapped to the subcarrier at the selected initial position. The transmitter 100 repeatedly performs the same process until the PT-RS is mapped to N RBs. UE_BW / N density subcarriers.

[0125] Thus, in operation example 1 of this embodiment, the initial positions (subcarriers) of multiple PT-RSs in the allocated frequency band of the mobile station are not limited to being equally spaced, but may be irregular. In other words, there are cases where the initial positions of the mapped PT-RSs are unequally spaced.

[0126] Next, a method for determining the frequency hopping offset for the PT-RS in the second slot and thereafter will be described.

[0127] The transmitter 100 receives N UE_BW / N density PT-RS, from [0, 1, 2…12N UE_BW -1], one hopping offset is selected each time, and each PT-RS is frequency-hopped using the selected value. Furthermore, when selecting the hopping offset, the transmitter 100 uses a pseudo-random function, at least one of "cell ID, group ID, UE ID", the index i of the PT-RS, and the time slot number. Thus, in different cells, different groups, different mobile stations, different PT-RSs, or different time slots, as different hopping offsets as possible are selected.

[0128] Furthermore, through the same processing as that of the transmitter 100 described above, the receiver 200 specifies the frequency hopping pattern (initial position and frequency hopping offset) and specifies the subcarrier position to which the PT-RS transmitted from the transmitter 100 is mapped.

[0129] Fig. 9 A mapping example of PT-RS in operation example 1 of this embodiment is shown.

[0130] exist Fig. 9 In the frequency domain, the configuration density of PT-RS is "one in 1RB" (that is, N density =1) In addition, the allocated frequency band of the mobile station (=N UE_BW ) is 2RB. Therefore, in each time slot, PT-RS is mapped to 2 subcarriers. In addition, PT-RS frequency hopping is performed at the boundary of the time slot.

[0131] exist Fig. 9 In the example, the initial position of the PT-RS in time slot #0 is the same subcarrier in two RBs in the allocated frequency band (the 9th subcarrier in each RB). Furthermore, the initial position of the PT-RS is not limited to the same subcarrier position in each RB in the allocated frequency band.

[0132] In addition, if Fig. 9 As shown in FIG. 1 , the frequency hopping offset for one PT-RS is 2 subcarriers, and the frequency hopping offset for the other PT-RS is 10 subcarriers. That is, different frequency hopping offsets are set for each PT-RS. Fig. 9 In time slot #1, PT-RS is mapped to subcarriers that are 2 subcarriers and 10 subcarriers away from the subcarriers to which PT-RS is mapped in each RB of time slot #0. Fig. 9 In the time slot #1, in the allocated frequency band of the mobile station, two PT-RSs are mapped in one RB, and no PT-RS is mapped in the other RB. In this way, each PT-RS is irregularly mapped in the frequency domain.

[0133] In operation example 1, a plurality of PT-RSs ( Fig. 9 Therefore, in the operation example 1, the frequency hopping offset is set for each of the two PT-RSs. Figure 8 ), the frequency hopping offset is not limited to being the same in all PT-RS. Fig. 9 As shown, there are cases where PT-RSs are mapped in a concentrated manner in some RBs and PT-RSs are not mapped in other RBs. However, even in this case, the density of PT-RSs in the entire allocated bandwidth is still "one in 1 RB".

[0134] As described above, in Operation Example 1, since the frequency hopping pattern (initial position, frequency hopping offset) is determined for each PT-RS, the degree of freedom of frequency hopping of each PT-RS increases, and the randomness of interference increases.

[0135] Furthermore, in action example 1 ( Fig. 9 ), the case where the number of antenna ports for PT-RS is 1 is described, but the number of antenna ports for PT-RS may be more than 2. In the case where the number of antenna ports for PT-RS is multiple, for example, the transmitter 100 may also select the initial position of PT-RS so that it is mapped to different subcarriers according to the antenna port number in addition to the "cell ID, group ID or UE ID" and the index i of PT-RS. However, the same value is used for the frequency hopping offset of PT-RS respectively transmitted from multiple antenna ports. This is to avoid conflicts between PT-RS ports due to frequency hopping.

[0136] [Action Example 2]

[0137] In action example 2 of the present embodiment, the candidates for the subcarriers of the frequency hopping destination of the PT-RS are limited to a restricted frequency band. Hereinafter, the restricted frequency band is referred to as a "PT-RS subband". The bandwidth of the PT-RS subband can also be set according to the setting of the configuration density of the frequency domain of the PT-RS, so that the PT-RS is mapped to only one subcarrier in the PT-RS subband.

[0138] For example, transmitter 100 (frequency hopping pattern generation section 102) and receiver 200 (frequency hopping pattern generation section 203) determine the initial position of the PT-RS and the frequency hopping offset according to the following method.

[0139] In the following, the size of the allocated frequency band of the mobile station is set to "N UE_BW [RB]”, the configuration density in the frequency domain of the PT-RS mapped to the mobile station is set to “N density [RB] in one". In this case, in each time slot, N UE_BW / N density PT-RS.

[0140] In addition, the transmitter 100 converts N UE_BW RBs are divided into each adjacent N density A group of RBs is called a "PT-RS subband".

[0141] First, a method for determining the frequency position of the PT-RS in the time slot where the PT-RS is initially arranged in the frame (that is, the initial position of the PT-RS) will be described.

[0142] The transmitter 100 selects a subcarrier in a PT-RS subband of the initial time slot as the initial position, and maps the PT-RS in the subcarrier of the selected initial position. When selecting the initial position (subcarrier), the transmitter 100 uses a pseudo-random function, at least one of "cell ID, group ID, UE ID", and the index of the PT-RS subband. Thus, in different cells, different groups, different mobile stations, and different PT-RS subbands, subcarriers that are as different as possible are selected.

[0143] The transmitter 100 repeatedly performs the above-described initial position setting process for all PT-RS subbands.

[0144] Next, a method for determining the frequency hopping offset for the PT-RS in the second slot and thereafter will be described.

[0145] For each PT-RS subband, the transmitter 100 selects one of the subcarriers in the PT-RS subband as the subcarrier of the frequency hopping destination. For example, when selecting the subcarrier, the transmitter 100 uses a pseudo-random function, at least one of "cell ID, group ID, UE ID", the index of the PT-RS subband, and the time slot number. Thus, in different cells, different groups, different mobile stations, different PT-RS subbands, or different time slots, as different frequency hopping offsets as possible are selected. That is, in each PT-RS subband, the difference between the index of the subcarrier selected in the current time slot and the index of the subcarrier to which the PT-RS is mapped in the previous time slot is the frequency hopping offset.

[0146] The transmitter 100 repeatedly performs the same subcarrier selection process for all PT-RS subbands.

[0147] Furthermore, the receiver 200 specifies the subcarrier position to which the PT-RS is mapped in each slot for each PT-RS subband through the same processing as the above-described transmitter 100 .

[0148] Fig.10 A mapping example of PT-RS in operation example 2 of this embodiment is shown.

[0149] exist Fig.10In the frequency domain, the configuration density of PT-RS is "one in 1RB" (that is, N density =1). In addition, Fig.10 In the example, the allocated frequency band of the mobile station is divided into PT-RS subbands (including PT-RS subbands #0 and #1) for each 1 RB. In addition, the PT-RS frequency hopping is performed at the boundary of the time slot.

[0150] exist Fig.10 In the example, the initial position of the PT-RS in time slot #0 is selected in each PT-RS subband. Fig.10 In the example, as the mapping position of the PT-RS in time slot #1, any subcarrier in each PT-RS subband is selected. Fig.10 As shown, the PT-RS mapped in time slot #0 in PT-RS subband #0 is not frequency-hopped to PT-RS subband #1 in time slot #1, but is frequency-hopped to the subcarrier in PT-RS subband #0. The same is true for the PT-RS in PT-RS subband #1.

[0151] In addition, Fig.10 In the embodiment 1 ( Figure 8 ) is different, the frequency hopping offset is not limited to be the same in all PT-RS, and the frequency interval of PT-RS is uneven.

[0152] Thus, in action example 2, the transmitter 100 maps any one of the plurality of PT-RSs to each of the plurality of PT-RS subbands (partial frequency bands), and performs frequency hopping within the corresponding PT-RS subband for each PT-RS. Thus, a frequency hopping pattern (initial position, frequency hopping offset) is determined for each PT-RS, so the degree of freedom of frequency hopping of each PT-RS is increased, and the randomness of interference is increased.

[0153] In addition, in action example 2, each PT-RS is frequency-hopped in the PT-RS subband. That is, in action example 2, the frequency hopping of the PT-RS is limited to the PT-RS subband, and in any time slot, the PT-RS is mapped in each PT-RS subband. Therefore, in action example 2, all PT-RS are prevented from being mapped in close subcarriers, which is robust to frequency selectivity.

[0154] Furthermore, in action example 2 ( Fig.10), the case where the number of antenna ports for PT-RS is 1 is described, but the number of antenna ports for PT-RS may be more than 2. In the case where the number of antenna ports for PT-RS is multiple, for example, the transmitter 100 may also select the initial position of PT-RS so that in addition to the "cell ID, group ID or UE ID" and the index of the PT-RS subband, it is also mapped in different subcarriers according to the antenna port number. However, the same value is used for the frequency hopping offset of the PT-RS respectively transmitted from multiple antenna ports. This is to avoid conflicts between PT-RS ports due to frequency hopping.

[0155] In the above, the operation example 1 and the operation example 2 of the present embodiment have been described.

[0156] Thus, in this embodiment, each PT-RS is irregularly configured in the frequency domain, so the combination of multiple subcarriers of multiple PT-RSs respectively mapped at the same time (for example, the same time slot) is more likely to be different between different cells / groups / mobile stations. Therefore, the possibility of simultaneous collision of PT-RSs mapped in multiple subcarriers can be reduced between different cells / groups / mobile stations.

[0157] In addition, according to the present embodiment, for example, in a certain time slot (for example, the time slot to which the PT-RS is initially mapped in a frame), even if the PT-RS is mapped to the same subcarrier between different cells / groups / mobile stations, in other time slots, the possibility that the PT-RS is mapped to different subcarriers between different cells / groups / mobile stations increases. Therefore, the possibility of PT-RS collision in the entire multiple time slots can be reduced between different cells / groups / mobile stations.

[0158] (Variation of Implementation Example 2)

[0159] Furthermore, when there is no coordination between cells and when the cells do not share information on how the PT-RS is mapped in each cell, the PT-RS may be irregularly mapped in the frequency domain for these cells as in the second embodiment.

[0160] In this way, compared with the increased possibility of PT-RS conflict between cells when the information of the subcarriers for sending PT-RS between cells is not shared, as in implementation mode 2, by irregularly mapping PT-RS in the frequency domain, the randomness of the subcarriers mapped with PT-RS in each cell is increased, thereby reducing the possibility of PT-RS conflict simultaneously mapped in multiple subcarriers between cells.

[0161] (Variation of Embodiments 1 and 2)

[0162] In addition, when there is coordination between cells, multiple PT-RSs transmitted at the same time (e.g., time slot) may be uniformly mapped in the frequency domain as in Implementation Example 1, and when there is no coordination between cells, multiple PT-RSs transmitted at the same time may be irregularly (with unequal intervals) mapped in the frequency domain as in Implementation Example 2. In addition, depending on whether there is coordination between cells, the transmitter 100 may switch between the PT-RS mapping of Implementation Example 1 and the PT-RS mapping of Implementation Example 2.

[0163] Furthermore, in the case of coordination between cells, the interface between base stations (for example, X2 interface) may be used to mutually notify each other of the information of the subcarriers for transmitting PT-RS.

[0164] In this way, by flexibly switching the mapping method of PT-RS according to the coordination status between cells, PT-RS can be mapped in the most appropriate method for each situation. Therefore, when there is coordination between cells and the mapping method of embodiment 1 is applied, the amount of calculation of the receiver 200 can be reduced. In addition, when there is no coordination between cells and the mapping method of embodiment 2 is applied, the possibility of simultaneous collision of PT-RS of multiple subcarriers can be reduced.

[0165] (Implementation 3)

[0166] The basic structure of the transmitter and receiver of this embodiment is the same as that of the transmitter 100 and receiver 200 of Embodiment 1, so Figure 4 and Figure 5 Provide explanation.

[0167] In this embodiment, the transmitter 100 maps the PT-RS to any of the subcarriers mapped with the DMRS using the same precoding as the PT-RS. That is, the frequency hopping destination of the PT-RS is limited to the same subcarrier as the shared precoding DMRS. That is, the PT-RS exists in the subcarrier where the DMRS transmitted by the same antenna port exists.

[0168] Hereinafter, operation examples 1 to 3 of this embodiment will be described respectively. The PT-RS mapping methods of operation examples 1 to 3 of this embodiment are respectively the same as those of the operation example 1 of embodiment 1 (see Figure 8 ), Example 1 of operation of Implementation 2 (refer to Fig. 9 ), and operation example 2 of implementation example 2 (refer to Fig.10 ) corresponds to the aspect that the subcarriers mapped with PT-RS are limited to the subcarriers mapped with the same precoded DMRS.

[0169] [Action Example 1]

[0170] In action example 1, similar to action example 1 of embodiment 1, in the time slot to which the PT-RS is first mapped in the frame, the PT-RS is evenly distributed in the frequency domain and mapped at equal intervals. In addition, in the subsequent time slots of the frame, the same frequency hopping offset is applied to all PT-RSs in the allocated frequency band of the mobile station. That is, the transmitter 100 performs frequency hopping on the PT-RS so that the subcarriers to which the PT-RS is mapped in each time slot are evenly distributed and at equal intervals.

[0171] However, in Operation Example 1 of the present embodiment, the subcarrier to which the PT-RS is mapped (including the frequency hopping target subcarrier) is any subcarrier to which a DMRS to which the same precoding as that of the PT-RS is applied exists.

[0172] For example, transmitter 100 (frequency hopping pattern generation section 102) and receiver 200 (frequency hopping pattern generation section 203) determine the initial position of the PT-RS and the frequency hopping offset according to the following method.

[0173] In the following, the size of the allocated frequency band of the mobile station is set to "N UE_BW [RB]”, the configuration density in the frequency domain of the PT-RS mapped in the mobile station is set to “N density [RB] one of them”.

[0174] In addition, it is assumed that PT-RS is connected to DMRS port number 1 to N. port The same precoding is sent. That is, port PT-RS is sent through each antenna port.

[0175] First, a method of determining the frequency position of the PT-RS in the time slot where the PT-RS is initially arranged in the frame (that is, the initial position of the PT-RS) will be described.

[0176] For example, the transmitter 100 maps the PT-RS to which the same precoding as the DMRS port number 1 is applied to the subcarrier. At this time, the transmitter 100 transmits the N UE_BW One of the subcarriers of the DMRS port number 1 among the RBs (here, 1RB = 12 subcarriers) is selected as the initial position, and the PT-RS is mapped to the subcarrier of the selected initial position. When selecting the initial position (subcarrier), the transmitter 100 uses a pseudo-random function and at least one of "cell ID, group ID, UE ID". Thus, as different subcarriers as possible are selected in different cells, different groups or different mobile stations.

[0177] Next, the transmitter 100 maps the PT-RS to the RB N away from the RB where the PT-RS is configured. densityThe transmitter 100 repeatedly performs this process until the PT-RS is mapped in N RBs. UE_BW / N density subcarriers (i.e., in all RBs to which PT-RS is mapped).

[0178] In addition, if the mapping of the PT-RS corresponding to the DMRS port number 1 is completed, the transmitter 100 maps the other DMRS ports 2 to DMRS port numbers N. port The PT-RSs up to this point are similarly mapped to the subcarriers.

[0179] Next, a method for determining the frequency hopping offset for the PT-RS in the second slot and thereafter will be described.

[0180] Here, assume that for each N DMRS_Space The subcarriers are mapped to the DMRS in one DMRS port.

[0181] N for antenna port number 1 UE_BW / N density PT-RS, the transmitter 100 is from [0, N DMRS_Space , 2N DMRS_Space , ...], and uses the selected value (frequency hopping offset) to perform frequency hopping of all PT-RSs. Furthermore, when selecting the frequency hopping offset, the transmitter 100 uses a pseudo-random function, at least one of "cell ID, group ID, UE ID", and a time slot number. Thus, in different cells, different groups, different mobile stations, or different time slots, as different frequency hopping offsets as possible are selected.

[0182] Once the frequency hopping of the PT-RS corresponding to antenna port number 1 is completed, the transmitter 100 performs frequency hopping of the PT-RS corresponding to antenna port number 2 to antenna port number N. port The PT-RS up to this frequency is frequency-hopped using the frequency hopping offset used in antenna port number 1.

[0183] Furthermore, the receiver 200 specifies the frequency hopping pattern (initial position and frequency hopping offset) and specifies the subcarrier position to which the PT-RS transmitted from the transmitter 100 is mapped, through the same processing as that of the transmitter 100 described above.

[0184] Fig.11 A mapping example of PT-RS in operation example 1 of this embodiment is shown.

[0185] exist Fig.11 In the frequency domain, the configuration density of PT-RS is "one in 1RB" (that is, N density =1). Therefore, Fig.11 In which time slot is the PT-RS mapped to one subcarrier in all RBs of the allocated frequency band of the mobile station. DMRS_Space The number of subcarriers is 4. In addition, the PT-RS frequency hopping is performed at the boundary of the time slot.

[0186] In addition, Fig.11 In FIG. 1 , as an example, the mapping example of the PT-RS of the antenna port number 1 is shown, but the PT-RS may be mapped similarly to other antenna port numbers.

[0187] like Fig.11 As shown in FIG. 1 , the initial position of the PT-RS of antenna port number 1 in time slot #0 is one of the subcarriers corresponding to DMRS port number 1 (the 4th subcarrier of each RB). Fig.11 As shown, the frequency hopping offset is 4 subcarriers. Therefore, in time slot #1, the PT-RS is mapped to a subcarrier (the 8th subcarrier of each RB) that is 4 subcarriers away from the subcarrier to which the PT-RS is mapped in each RB of time slot #0. Furthermore, the frequency hopping offset is not limited to Fig.11 The 4 subcarriers shown are from N DMRS_Space You can choose an integer multiple of , that is, 0, 4, 8, ...

[0188] That is, Fig.11 As shown, in each time slot including the initial time slot and the subsequent time slot, the frequency interval of the PT-RS is uniformly the same ( Fig.11 Therefore, since the subcarriers mapped with PT-RS in each time slot are evenly distributed and equally spaced, PT-RS is robust to the frequency selectivity of the channel.

[0189] In addition, Fig.11 In the embodiment 1 ( Figure 8 ), the PT-RS of antenna port number 1 is mapped to the subcarrier where the DMRS (DMRS port number 1) of the same port exists. That is, the PT-RS of antenna port number 1 (port 1) can be configured in the RE of the subcarrier where the DMRS of antenna port number 1 exists (refer to Fig.11 ).

[0190] [Action Example 2]

[0191] In operation example 2 of this embodiment, as in operation example 1 of embodiment 2, the candidate subcarrier of the frequency hopping destination of the PT-RS is the entire allocated frequency band of the mobile station. That is, in operation example 2, the transmitter 100 performs frequency hopping in the entire allocated frequency band of the mobile station and maps the plurality of PT-RSs to any subcarrier in the allocated frequency band.

[0192] However, in Operation Example 2 of the present embodiment, the subcarrier to which the PT-RS is mapped (including the subcarrier of the frequency hopping destination) is any subcarrier to which a DMRS to which the same precoding as that of the PT-RS is applied exists.

[0193] For example, transmitter 100 (frequency hopping pattern generation section 102) and receiver 200 (frequency hopping pattern generation section 203) determine the initial position of the PT-RS and the frequency hopping offset according to the following method.

[0194] In the following, the size of the allocated frequency band of the mobile station is set to "N UE_BW [RB]”, the configuration density in the frequency domain of the PT-RS mapped to the mobile station is set to “N density [RB] in one". In this case, in each time slot, N UE_BW / N density PT-RS. Among them, in all N UE_BW / N density Add [0, 1, 2…N UE_BW / N density -1] at index i.

[0195] In addition, assuming that the DMRS port number 1 to N port The same precoding is used to send PT-RS. port PT-RS is sent through each antenna port.

[0196] First, a method for determining the frequency position of the PT-RS in the time slot where the PT-RS is initially arranged in the frame (that is, the initial position of the PT-RS) will be described.

[0197] For example, the transmitter 100 maps the PT-RS to which the same precoding as the DMRS port number 1 is applied to the subcarrier. At this time, the transmitter 100 transmits the N UE_BW One subcarrier among the subcarriers of the DMRS port number 1 among RBs (here, 1RB = 12 subcarriers) is selected as the initial position, and the PT-RS is mapped in the subcarrier of the selected initial position. When selecting the initial position (subcarrier), the transmitter 100 uses a pseudo-random function, at least one of "cell ID, group ID, UEID", and the index i of the PT-RS. Thus, in different cells, different groups, different mobile stations, and different PT-RSs, as different subcarriers as possible are selected.

[0198] Next, the transmitter 100 receives the N UE_BWIn the same way, other subcarriers are selected as the initial positions of the PT-RS of antenna port number 1 among the RBs, and the PT-RS is mapped in the selected subcarriers of the initial positions. The transmitter 100 repeatedly performs the same process until the PT-RS is mapped in N RBs. UE_BW / N density subcarriers.

[0199] Furthermore, once the mapping of the PT-RS corresponding to the DMRS port number 1 is completed, the transmitter 100 maps the other DMRS ports 2 to DMRS port numbers N to DMRS port numbers 1 to 2. port The PT-RSs up to this point are also mapped to the subcarriers.

[0200] Thus, in Operation Example 2, the initial positions (subcarriers) of a plurality of PT-RSs in the allocated band of the mobile station are not limited to being equally spaced but irregular. In other words, there are cases where the initial positions of the mapped PT-RSs are unequally spaced.

[0201] Next, a method for determining the frequency hopping offset for the PT-RS in the second slot and thereafter will be described.

[0202] Here, assume that for each N DMRS_Space The subcarriers are mapped to the DMRS in one DMRS port.

[0203] For antenna port number 1 mapped in one time slot, N UE_BW / N density PT-RS, the transmitter 100 shifts the hopping frequency from [0, N DMRS_Space , 2N DMRS_Space , ...] are selected one at a time, and each PT-RS is frequency-hopped using the selected value (frequency hopping offset). Furthermore, the frequency hopping offset selected for each PT-RS may also be a different value. In addition, when selecting the frequency hopping offset, the transmitter 100 uses a pseudo-random function, at least one of "cell ID, group ID, UE ID", the index i of the PT-RS, and the time slot number. Thus, in different cells, different groups, different mobile stations, different PT-RSs, or different time slots, frequency hopping offsets that are as different as possible are selected.

[0204] If the frequency hopping of the PT-RS corresponding to antenna port number 1 is completed, the transmitter 100 performs frequency hopping of the PT-RS corresponding to antenna port number 2 to antenna port number N. port For the PT-RS up to now, the PT-RS is frequency-hopped using the frequency hopping offset used in antenna port number 1.

[0205] Furthermore, the receiver 200 specifies the frequency hopping pattern (initial position and frequency hopping offset) and specifies the subcarrier position to which the PT-RS transmitted from the transmitter 100 is mapped, through the same processing as that of the transmitter 100 described above.

[0206] Fig.12 A mapping example of PT-RS in operation example 2 of this embodiment is shown.

[0207] exist Fig.12 In the frequency domain, the configuration density of PT-RS is "one in 1RB" (that is, N density =1) In addition, the allocated frequency band of the mobile station (=N UE_BW ) is 2RB. Therefore, in each time slot, PT-RS is mapped to 2 subcarriers. In addition, PT-RS frequency hopping is performed at the boundary of the time slot.

[0208] In addition, Fig.12 In FIG. 1 , as an example, the mapping example of the PT-RS of the antenna port number 1 is shown, but the PT-RS may be mapped similarly to other antenna port numbers.

[0209] exist Fig.12 In the example, the initial position of the PT-RS of antenna port number 1 in time slot #0 is one of the subcarriers corresponding to DMRS port number 1. That is, Fig.12 The PT-RS of antenna port number 1 (port 1) shown in FIG. 1 can be configured in the RE of the subcarrier where the DMRS of antenna port number 1 exists. Fig.12 In time slot #0, the PT-RS in the two RBs within the allocated frequency band are respectively mapped to the same subcarrier (the 8th subcarrier of each RB), but the initial position of the PT-RS is not limited to the same subcarrier position in each RB within the allocated frequency band, and can also be different.

[0210] In addition, if Fig.12 As shown, the frequency hopping offset of the PT-RS of one party is the subcarrier spacing N of DMRS port number 1 DMRS_Space The integer multiple (1 times) is 4 subcarriers, and the frequency hopping offset for other PT-RS is the subcarrier spacing N DMRS_Space In other words, a different frequency hopping offset is set for each PT-RS. Fig.12 In the time slot #1, in the allocated frequency band of the mobile station, two PT-RSs are mapped in one RB, and no PT-RS is mapped in the other RB. In this way, each PT-RS is irregularly mapped in the frequency domain.

[0211] As described above, in Operation Example 2, since the frequency hopping pattern (initial position, frequency hopping offset) is determined for each PT-RS, the degree of freedom of frequency hopping of each PT-RS increases, and the randomness of interference increases.

[0212] [Action Example 3]

[0213] In action example 3 of the present embodiment, similar to action example 2 of embodiment 2, the candidates for the subcarriers of the frequency hopping destination of the PT-RS are limited to a limited frequency band (PT-RS subband). The bandwidth of the PT-RS subband may be set according to the setting of the configuration density of the PT-RS in the frequency domain, so that the PT-RS is mapped to only one subcarrier in the PT-RS subband.

[0214] However, in operation example 3 of the present embodiment, the subcarrier to which the PT-RS is mapped (including the subcarrier of the frequency hopping destination) is any subcarrier to which a DMRS to which the same precoding as that of the PT-RS is applied exists.

[0215] For example, transmitter 100 (frequency hopping pattern generation section 102) and receiver 200 (frequency hopping pattern generation section 203) determine the initial position of the PT-RS and the frequency hopping offset according to the following method.

[0216] In the following, the size of the allocated frequency band of the mobile station is set to "N UE_BW [RB]”, the configuration density in the frequency domain of the PT-RS mapped to the mobile station is set to “N density [RB] in one". In this case, in each time slot, N UE_BW / N density PT-RS.

[0217] In addition, it is assumed that PT-RS is connected to DMRS port number 1 to N. port The same precoding is sent. That is, port In addition, assume that N DMRS_Space Each of the subcarriers is mapped to a DMRS in a DMRS port.

[0218] In addition, the transmitter 100 converts N UE_BW RBs are divided into N adjacent density A group of RBs (PT-RS subbands).

[0219] First, a method for determining the frequency position of the PT-RS in the time slot where the PT-RS is initially arranged in the frame (that is, the initial position of the PT-RS) will be described.

[0220] The transmitter 100 selects one of the subcarriers of the DMRS of the DMRS port number 1 in a certain PT-RS subband of the initial time slot as the initial position, and maps the PT-RS in the subcarrier of the selected initial position. When selecting the initial position (subcarrier), the transmitter 100 uses a pseudo-random function, at least one of "cell ID, group ID, UE ID", the index of the PT-RS subband, and the antenna port number. Thus, in different cells, different groups, different mobile stations, different PT-RS subbands, and different antenna ports, as different subcarriers as possible are selected.

[0221] The transmitter 100 repeatedly performs the above-described initial position setting process for all PT-RS subbands.

[0222] In addition, once the mapping of the PT-RS corresponding to the DMRS port number 1 is completed, the transmitter 100 maps the other DMRS ports 2 to DMRS port numbers N. port The PT-RSs up to this point are mapped to the subcarriers in the same manner.

[0223] The following is a specific calculation example of the initial position of the PT-RS. Here, it is assumed that the number of the first time slot to which the PT-RS is mapped is t0. The PT-RS of antenna port p is mapped in the s-th PT-RS subband in time slot t0. The number of subcarriers in the PT-RS subband to which the PT-RS can be mapped is 12N. density / N DMRS_Space Assume that among the indices of these subcarriers, the smallest number is k0 p，s The index F of the subcarrier to which the PT-RS is mapped init (s, p, t0) can also be obtained according to the following formula (1).

[0224]

[0225] Furthermore, the pseudo-random function c(k) may also use the function described in 3GPP standard 36.211 "7.2 Pseudo-random sequence generation". init =100N ID +p for initialization. Among them, N ID It may also be a cell ID, a group ID, a UE ID, or a value obtained by combining them.

[0226] Next, a method for determining the frequency hopping offset for the PT-RS in the second slot and thereafter will be described.

[0227] For each PT-RS subband, the transmitter 100 selects a subcarrier that transmits the DMRS of the DMRS port number 1 in the PT-RS subband as the subcarrier of the frequency hopping destination. For example, when selecting the subcarrier, the transmitter 100 uses a pseudo-random function, at least one of "cell ID, group ID, UE ID", the index of the PT-RS subband, the time slot number, and the antenna port number. Thus, in different cells, different groups, different mobile stations, different PT-RS subbands, different time slots, and different antenna ports, as different frequency hopping offsets as possible are selected. That is, in each PT-RS subband, the difference between the index of the subcarrier selected in the current time slot and the index of the subcarrier to which the PT-RS is mapped in the previous time slot is the frequency hopping offset.

[0228] Transmitter 100 repeatedly performs the same subcarrier selection process for all PT-RS subbands.

[0229] A specific calculation example of the frequency hopping offset of the PT-RS is shown below: The index F(s, p, t) of the subcarrier to which the PT-RS is mapped in the time slot t after the first time slot t0 can also be obtained according to the following formula (2).

[0230]

[0231] In addition, the pseudo-random function c(k) can also be calculated based on c init =10000N ID +100s-+p is initialized. Among them, N ID It can also be a cell ID, group ID, UE ID, or a combination of these values. Therefore, the frequency hopping offset F from time slot t-1 to time slot t is calculated according to the following formula (3): hop (s, p, t).

[0232] F hop (s, p, t) = F (s, p, t)-F (s, p, t-1) (3)

[0233] Furthermore, the receiver 200 specifies the subcarrier position to which the PT-RS is mapped in each slot for each PT-RS subband through the same processing as the above-described transmitter 100 .

[0234] Fig.13 A mapping example of PT-RS in operation example 3 of this embodiment is shown.

[0235] exist Fig.13 In the frequency domain, the configuration density of PT-RS is "one in 1RB" (that is, N density =1). In addition, Fig.13In the example, the allocated frequency band of the mobile station is divided into PT-RS subbands (including PT-RS subbands #0 and #1) for each 1 RB. In addition, the interval between DMRSs of the same antenna port number (=N DMRS_Space ) is 4 subcarriers. In addition, PT-RS frequency hopping is performed at the boundary of the time slot.

[0236] In addition, Fig.13 In FIG. 1 , as an example, the mapping example of the PT-RS of the antenna port number 1 is shown, but the PT-RS may be mapped similarly to other antenna port numbers. Fig.13 The PT-RS of the antenna port number 1 (port 1) shown can be configured in the RE of the subcarrier where the DMRS of the antenna port number 1 exists.

[0237] exist Fig.13 The initial position of the PT-RS in time slot #0 is determined by the smallest index k0 among the subcarriers that can map the PT-RS in each PT-RS subband #0, #1 (i.e., s=0, 1) and antenna port number p=1. p，s (k0 1，0 , k0 1，1 ) and formula (1). In addition, Fig.13 As the mapping position of the PT-RS in time slot #1, any subcarrier in each PT-RS subband is selected. For example, the mapping position F(s, 1, 1) of the PT-RS of antenna port number 1 (p=1) in time slot #1 (t=1) in each PT-RS subband #0, #1 (i.e., s=0, 1) can also be calculated according to formula (2).

[0238] That is, Fig.13 As shown, the PT-RS mapped in time slot #0 in PT-RS subband #0 is not frequency-hopped to PT-RS subband #1 in time slot #1 but is frequency-hopped to the subcarrier in PT-RS subband #0. The same is true for the PT-RS in PT-RS subband #1.

[0239] In addition, Fig.13 In the embodiment 1 ( Figure 8 ) is different, the frequency hopping offset is not limited to be the same in all PT-RS, and the frequency interval of PT-RS is uneven.

[0240] Thus, in action example 3, the transmitter 100 maps any one of the multiple PT-RSs to each of the multiple PT-RS subbands (partial frequency bands), and performs frequency hopping in the corresponding PT-RS subband for each PT-RS. Thus, the frequency hopping mode (initial position, frequency hopping offset) is determined for each PT-RS, so the degree of freedom of frequency hopping of each PT-RS is increased, and the randomness of interference is increased. In addition, in action example 3, each PT-RS is frequency-hopped separately in the PT-RS subband, so that all PT-RSs are avoided from being mapped in close subcarriers, and the frequency selectivity is robust.

[0241] In the above, operation examples 1 to 3 of the present embodiment have been described.

[0242] Thus, in this embodiment, the subcarriers to which the PT-RS is mapped are limited to the subcarriers to which the DMRS using the same precoding as the PT-RS exists. Thus, assuming that the spatial channels used in the DMRS and the PT-RS are the same, the accuracy of the CPE / ICI correction can be improved. In addition, by making the mappable subcarriers of the PT-RS different according to the antenna port, the PT-RSs of different antenna ports can be avoided from being mapped to the same subcarrier.

[0243] In Embodiment 3, when the subcarriers where the PT-RS may exist are different for each antenna port, since the PT-RS transmitted by different antenna ports are not mapped to the same subcarrier, it is not necessary to have the same frequency hopping offset between different antenna ports. Fig.13 As shown in the antenna ports 1 and 5, even in the case where the subcarriers to which the PT-RS can be mapped are repeated, the PT-RS ports 1 and 5 may not be multiplexed in the same subcarrier but may be mapped in different subcarriers.

[0244] In the above, each embodiment of the present invention has been described.

[0245] Furthermore, in the above-mentioned embodiment, in determining the initial position of the PT-RS in the first time slot and the frequency hopping offset, at least one of the "cell ID, group ID, UE ID" and the time slot number may be used in combination.

[0246] Furthermore, the index of the time domain used in determining the frequency hopping offset of the PT-RS may not be a symbol number but may be a slot number, a mini-slot number, a subframe number, a frame number, or a value obtained by combining them.

[0247] In addition, the temporal period (interval time) of frequency hopping can also be set to every 1 symbol, every 2 symbols, every predetermined number of symbols, every 1 time slot, every 1 small time slot, every 1 subframe, etc. For example, when the interval time of frequency hopping is short, the randomness of interference caused by the collision of PT-RS increases, and when the interval time of frequency hopping is long, the frequency of the receiver 200 specifying (calculating) the position of PT-RS can be reduced. In addition, the timing of frequency hopping is not limited to the time slot boundary.

[0248] In addition, the time period of the PT-RS frequency hopping can also be set to match the data allocation unit. If the data allocation unit is a time slot, the PT-RS frequency hopping is also set in a time slot unit, and if the data allocation unit is a small slot, the PT-RS frequency hopping can also be set in a small slot unit.

[0249] In addition, even if the data allocation unit is a small time slot, the PT-RS frequency hopping can be set in time slot units. This is because the data allocation unit is different for each cell, and in order to make the PT-RS frequency hopping period consistent between cells, the PT-RS frequency hopping unit is set regardless of the data allocation unit.

[0250] In addition, in the above-mentioned embodiment ( Figure 8 to Figure 13 ) assumes that the length of the time slot is 14 code elements, but the length of the time slot is not limited to 14 code elements. For example, the same frequency hopping can also be applied when the length of the time slot is 7 code elements. In addition, the position of the RE of the DMRS mapped in each antenna port shown in each figure is an example, but is not limited to this. In addition, the DMRS between different antenna ports can also be CDM (Code Division Multiplexing).

[0251] In addition, when control channels (PDCCH (Physical Downlink Control Channel), PUCCH (Physical Uplink Control Channel)) and data channels (PDSCH (Physical Downlink Shared Channel), PUSCH (Physical Uplink Shared Channel)) are frequency multiplexed, PT-RS can also be mapped in their codewords.

[0252] In addition, the “CPE / ICI correction” used in the above-mentioned embodiments means “correcting CPE”, “correcting ICI”, or “correcting both CPE and ICI”.

[0253] Furthermore, in the above-described embodiment, phase noise is generated not only from the local oscillator of the transmitter but also from the local generator of the receiver in some cases.

[0254] In addition, the initial position of the PT-RS, the frequency hopping offset, and the allocated frequency band N used in each operation example of the above-mentioned embodiment UE_BW [RB], the configuration density in the frequency domain "N density [RB] one”, the frequency spacing of DMRS ports is N DMRS_Space and other parameters are examples and are not limited to these values.

[0255] In addition, in each action example of the above-mentioned implementation mode, the method of setting the frequency position of the PT-RS may be not the subcarrier unit but the RB unit. For example, the initial position of the PT-RS may be expressed in RB units, and the position of the RB may be calculated and selected using a pseudo-random function and various indexes. At this time, the intervals of the RBs to which the PT-RS is mapped may also be equal intervals or unequal intervals. Moreover, the frequency hopping offset may also be set in RB units, and the value may also be calculated and selected using a pseudo-random function and various indexes. In each RB to which the PT-RS is mapped, the relative subcarrier position of the mapped PT-RS may also be a predetermined value, a value notified from a higher layer, or a value calculated using a pseudo-random function and various indexes.

[0256] In addition, the present invention can be implemented by software, hardware, or software in collaboration with hardware. Each functional block used in the description of the above-mentioned embodiment can be partially or entirely implemented as an integrated circuit, that is, LSI, and each function described in the above-mentioned embodiment can also be partially or entirely controlled by an LSI or a combination of LSIs. LSI can be composed of individual chips, or it can be composed of one chip so that it contains part or all of the functional blocks. LSI can also include data input and output. Due to different integration levels, LSI is sometimes also referred to as IC, system LSI, super LSI (Super LSI), and ultra-large LSI (UltraLSI). The method of integrated circuit is not limited to LSI, and can also be implemented with a dedicated circuit, a general-purpose processor, or a dedicated processor. In addition, an FPGA (Field Programmable Gate Array) that can be programmable after LSI manufacturing can also be used, or a reconfigurable processor (Reconfigurable Processor) that can reconfigure the connection and setting of the circuit unit inside the LSI can be used. The present invention can also be implemented as digital processing or analog processing. Furthermore, if there is an integrated circuit technology that can replace LSI as semiconductor technology advances or other technologies derived from it, it is of course possible to use this technology to integrate functional blocks. There is also the possibility of applying biotechnology, etc.

[0257] The transmitter of the present invention includes: an allocation circuit that maps a phase tracking reference signal into a subcarrier; and a transmission circuit that transmits a signal containing the phase tracking reference signal, wherein the subcarriers onto which the phase tracking reference signal is mapped are different between cells, groups or mobile stations.

[0258] In the transmitter of the present invention, the subcarrier to which the phase tracking reference signal is mapped is determined using an index for identifying the cell, group or mobile station, or higher layer signaling.

[0259] In the transmitter of the present invention, the phase tracking reference signal is frequency-hopped every unit time.

[0260] In the transmitter of the present invention, the frequency hopping offset of the phase tracking reference signal is determined using an index for identifying the cell, group or mobile station or an index in the time domain.

[0261] In the transmitter of the present invention, the index of the time domain is a symbol number, a time slot number, a mini-slot number, a subframe number or a frame number.

[0262] In the transmitter of the present invention, the frequency hopping offsets of the phase tracking reference signals transmitted from the plurality of antenna ports are the same.

[0263] In the transmitter of the present invention, the allocation circuit maps the plurality of phase tracking reference signals transmitted at the same time at equal intervals in the frequency domain.

[0264] In the transmitter of the present invention, the allocation circuit maps the plurality of phase tracking reference signals transmitted at the same time at unequal intervals in the frequency domain.

[0265] In the transmitter of the present invention, the allocation circuit performs frequency hopping in the entire frequency band allocated to the mobile station, and maps the plurality of phase tracking reference signals to any subcarrier in the frequency band.

[0266] In the transmitter of the present invention, the frequency band allocated to the mobile station is divided into a plurality of partial frequency bands, and the allocation circuit maps any one of the plurality of phase tracking reference signals in each of the plurality of partial frequency bands, and performs frequency hopping within the corresponding partial frequency band for the one phase tracking reference signal.

[0267] In the transmitter of the present invention, when there is coordination between cells, the allocation circuit maps the multiple phase tracking reference signals sent at the same time at equal intervals in the frequency domain; when there is no coordination between cells, the allocation circuit maps the multiple phase tracking reference signals at unequal intervals in the frequency domain.

[0268] In the transmitter of the present invention, the allocation circuit maps the phase tracking reference signal to any subcarrier to which a demodulation reference signal using the same precoding as that of the phase tracking reference signal is mapped.

[0269] The receiver of the present invention includes: a receiving circuit that receives a signal containing a reference signal for phase tracking; and a demodulation circuit that demodulates a data signal using a phase noise estimation value calculated using the reference signal for phase tracking, wherein the subcarriers mapped with the reference signal for phase tracking are different between cells, groups or mobile stations.

[0270] The sending method of the present invention includes the following steps: mapping a phase tracking reference signal in a subcarrier, sending a signal containing the phase tracking reference signal, and the subcarrier to which the phase tracking reference signal is mapped is different between cells, groups or mobile stations.

[0271] The receiving method of the present invention includes the following steps: receiving a signal containing a reference signal for phase tracking, demodulating a data signal using a phase noise estimation value calculated using the reference signal for phase tracking, and the subcarriers mapped with the reference signal for phase tracking are different between cells, groups or mobile stations.

[0272] One aspect of the present invention is useful for a mobile communication system.

[0273] Description of symbols

[0274] 100 Transmitter

[0275] 101 PT-RS generation unit

[0276] 102, 203 frequency hopping pattern generation unit

[0277] 103 Frequency Hopping Unit

[0278] 104 Error Correction Coding Unit

[0279] 105 Modulation Unit

[0280] 106 Signal Distribution Unit

[0281] 107 Sending Unit

[0282] 108,201 Antenna

[0283] 200 Receiver

[0284] 202 Receiving Unit

[0285] 204 signal separation unit

[0286] 205 Channel Estimation Unit

[0287] 206 CPE / ICI estimation unit

[0288] 207 Data demodulation unit

[0289] 208 Error Correction Decoding Unit

Claims

1. A transmitter, comprising: An allocating circuit maps a phase tracking reference signal to a subcarrier; and a transmitting circuit, transmitting a signal including the phase tracking reference signal, The subcarrier to which the phase tracking reference signal is mapped is determined based on an index for identifying a mobile station, and is a subcarrier to which a demodulation reference signal using the same precoding as that of the phase tracking reference signal is mapped.

2. The transmitter according to claim 1, wherein: The phase tracking reference signal is frequency-hopped per unit time.

3. The transmitter according to claim 2, wherein: The jump offset for the phase tracking reference signal is determined using an index for identifying the mobile station or an index in the time domain.

4. The transmitter according to claim 3, wherein: The index of the time domain is a symbol number, a time slot number, a mini-time slot number, a subframe number or a frame number.

5. The transmitter according to claim 3, wherein: The jump offset for the phase tracking reference signal transmitted from each of a plurality of antenna ports is the same.

6. The transmitter according to claim 1, wherein The allocation circuit maps the plurality of phase tracking reference signals transmitted at the same time into the frequency domain at equal intervals.

7. The transmitter according to claim 1, wherein: The allocation circuit maps the plurality of phase tracking reference signals transmitted at the same time into the frequency domain at unequal intervals.

8. The transmitter according to claim 7, wherein: The allocation circuit performs frequency hopping in the entire frequency band allocated to the mobile station, and maps the plurality of phase tracking reference signals to any subcarrier in the frequency band.

9. The transmitter according to claim 7, wherein: The frequency band allocated to mobile stations is divided into a number of sub-bands. The allocation circuit maps any one of the plurality of phase tracking reference signals to each of the plurality of sub-bands, and performs frequency hopping of the one phase tracking reference signal within the corresponding sub-band.

10. The transmitter according to claim 1, wherein In the case of coordination between cells, the allocation circuit maps the multiple phase tracking reference signals sent at the same time to the frequency domain at equal intervals. In the case of no coordination between cells, the allocation circuit maps the multiple phase tracking reference signals to the frequency domain at unequal intervals.

11. A sending method, comprising the following steps: Mapping a phase tracking reference signal to a subcarrier; and sending a signal including the phase tracking reference signal, The subcarrier to which the phase tracking reference signal is mapped is determined based on an index for identifying a mobile station, and is a subcarrier to which a demodulation reference signal using the same precoding as that of the phase tracking reference signal is mapped.

Images