JP6483181B2 - Base station equipment - Google Patents

Description

  The present invention relates to a base station apparatus of a mobile communication system.

  2. Description of the Related Art Conventionally, in a mobile communication system, a downlink data signal transmitted from a base station is demodulated by a user apparatus (also referred to as “user apparatus” or “mobile station”), so that it is known in advance transmitted from the base station. It is known that transmission channel (channel) estimation is performed on the user apparatus side using a demodulation reference signal (hereinafter also referred to as “DMRS”) which is a training reference signal. In the LTE wireless communication system, a DMRS having an arrangement pattern fixed on wireless resources is used.

  In addition, in order to support the fifth generation mobile communication system (Non-Patent Document 1) that supports large-capacity communication, multiple connections, low delay, and the like, a plurality of information notified in advance to the user apparatus by DCI (downlink control information). Switching DMRS arrangement patterns of a plurality of DMRSs, and switching and performing notification and switching of the plurality of DMRS arrangement patterns in two stages by RRC (Radio Resource Control) signaling and DCI (non-patent document). 2 and 3).

G. Romano, “3GPP RAN progress on“ 5G ””, 3GPP, 2016. 3GPP, R1-1700117, ZTE, “Aspects of DL MIMO Transmission”. 3GPP, R1-1700135, ZTE, "Discussion on downlink DMRS design".

  However, when DMRS having a fixed arrangement pattern in the LTE wireless communication system is used, the accuracy of channel estimation may be reduced depending on the environment such as the moving speed of user equipment and the distribution of delay spread, and downlink throughput may be reduced. There is. In addition, when performing notification and switching of the plurality of DMRS arrangement patterns, it is necessary to notify the user apparatus of information on a large number of candidate DMRS arrangement patterns with a control signal (control message). Overhead may increase.

  In order to solve the above-described problem, a base station apparatus according to an aspect of the present invention is a base station apparatus of a mobile communication system, and a demodulation reference signal in a radio resource usable in a radio communication area of the base station apparatus A storage means for storing information on a plurality of arrangement pattern candidates, and at least one of a moving speed and a delay spread of a user apparatus residing in the wireless communication area of the base station apparatus, and based on the counting result Deciding means for narrowing down and deciding one or a plurality of arrangement pattern candidates that can be assigned to a user apparatus located in the wireless communication area from the plurality of arrangement pattern candidates, and information on the decided one or more arrangement pattern candidates Notification means for notifying the user apparatus.

In the base station apparatus, the storage unit stores information on a plurality of arrangement pattern candidates having different arrangement densities on the time axis of the demodulation reference signal, and the determination unit has a high moving speed of the user apparatus The arrangement pattern having a high arrangement density on the time axis of the demodulation reference signal may be selected and narrowed down.
Further, the storage means stores information on a plurality of arrangement pattern candidates having different arrangement densities on the frequency axis of the demodulation reference signal, and the determination means increases the delay spread as the delay reference signal increases. The arrangement pattern having a high arrangement density on the frequency axis may be selected and narrowed down.
In addition, the determination unit is configured to reduce the plurality of demodulation reference signal arrangement pattern candidates corresponding to a predetermined range of a cumulative distribution function of at least one of a moving speed and a delay spread of the user apparatus in the wireless communication area. One or a plurality of arrangement pattern candidates that can be assigned to the user apparatuses located in the wireless communication area may be narrowed down and determined from the arrangement pattern candidates.

Further, in the base station apparatus, the determination means can assign one or more user equipments located in the divided area from the plurality of arrangement pattern candidates for each of the plurality of divided areas into which the wireless communication area is divided. A plurality of arrangement pattern candidates are narrowed down and determined, and the first notification means notifies the information of the plurality of arrangement pattern candidates corresponding to the divided area where the user apparatus is located based on the position information of the user apparatus. May be.
Here, for each of the plurality of divided areas, the determining unit totals at least one of a moving speed and a delay spread of the user apparatus in the divided area, and based on the totaled result, the plurality of arrangement pattern candidates One or a plurality of arrangement pattern candidates that can be assigned to user apparatuses located in the divided area may be narrowed down and determined.
In addition, for each of the plurality of divided areas, the determination unit totals delay spreads of user devices in the divided areas, and based on the totaled result, users who are in the divided area from the plurality of arrangement pattern candidates A plurality of placement pattern candidates having a placement density on the frequency axis that can be assigned to a device are narrowed down and determined, and the user device can be assigned from the narrowed down placement pattern candidates based on the moving speed of the user device. Alternatively, one or a plurality of arrangement pattern candidates having an arrangement density on the time axis may be narrowed down and determined.

  In the base station apparatus, the determining unit may set an arrangement density of demodulation reference signals on the time axis in an arrangement pattern candidate to be notified to the user apparatus based on a moving speed of the user apparatus. . Here, the higher the moving speed of the user apparatus, the higher the arrangement density of demodulation reference signals on the time axis in the arrangement pattern candidates.

  Further, in the base station apparatus, the notification means switches a signal or a communication method used when notifying the user apparatus of information on the determined one or a plurality of arrangement pattern candidates based on a moving speed of the user apparatus. May be. For example, when the moving speed of the user apparatus is higher than a predetermined speed, notification is made using DCI (downlink control information), and when the moving speed of the user apparatus is lower than the predetermined speed, the upper layer Notification may be performed using RRC signaling.

  ADVANTAGE OF THE INVENTION According to this invention, the arrangement pattern of the reference signal for demodulation in a radio | wireless resource is suppressed according to the moving speed of a user apparatus, or the environment of distribution of delay spread, suppressing the increase in the overhead of the control signal transmitted to a user apparatus from a base station. Can be set.

1 is a schematic configuration diagram showing an example of the overall configuration of a mobile communication system according to an embodiment of the present invention. The block diagram which shows one structural example of the principal part of the base station in the mobile communication system of this embodiment. The figure which shows an example of the arrangement | positioning pattern of the demodulation reference signal (DMRS) transmitted to a user apparatus from a base station. (A) The figure which shows the example of the fluctuation characteristic on the time-axis of the received signal of a downlink by fading in each of a low-speed movement environment and a high-speed movement environment. (B) The figure which shows the example of the fluctuation characteristic on the frequency axis of the received signal of the downlink by the frequency selective fading in each user apparatus when delay spread is small and large in a multipath environment. The graph which shows an example of the cumulative distribution function of the moving speed of the several user apparatus located in the cell of a base station. The figure which shows an example of the some DMRS arrangement | positioning pattern candidate determined so that it might correspond to the cell which has the moving speed distribution of FIG. The graph which shows the other example of the cumulative distribution function of the moving speed of the several user apparatus located in the cell of a base station. The figure which shows an example of the some DMRS arrangement | positioning pattern candidate determined so that it might correspond to the cell which has the moving speed distribution of FIG. The figure which shows the example of the some DMRS arrangement | positioning pattern candidate determined so that it might respond | correspond to each when the fluctuation | variation on the frequency axis of the received signal by the delay spread of the user apparatus which exists in the cell of a base station differs mutually. The figure which shows an example of the some division area (grid) which divided | segmented the cell. The figure which shows the example of a DMRS arrangement | positioning pattern candidate when the moving speed of a user apparatus is low speed. The figure which shows the example of a DMRS arrangement | positioning pattern candidate when the moving speed of a user apparatus is high speed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, the embodiment of the present invention will be described on the assumption that it is applied to LTE (Long Term Evolution) / LTE-Advanced or the fifth generation mobile communication system. However, any system using a similar cell configuration or physical channel configuration may be used. For example, the concept of the present invention can be applied to any system. In addition, the reference signal sequence used for channel estimation and the coding method used for error correction are not limited to those defined in LTE / LTE-Advanced or the fifth generation mobile communication system. Any type may be used as long as it suits the application.

  FIG. 1 is a schematic configuration diagram showing an example of the overall configuration of a mobile communication system according to an embodiment of the present invention. In FIG. 1, the mobile communication system according to the present embodiment is capable of wireless communication with a base station 10 such as a macro cell base station or a small cell base station connected to a core network of a mobile communication network through a predetermined interface. User devices (also referred to as “UE”, “terminal”, “terminal device”, “mobile station”, etc.) 20, 21. In the illustrated example, the case where two user apparatuses are present in the cell 10A of the base station 10 is illustrated, but three or more user apparatuses may be present.

  FIG. 2 is a block diagram illustrating a configuration example of a main part of the base station 10 in the mobile communication system of the present embodiment. The base station 10 includes a base station device 100 and an antenna 110. The base station apparatus 100 includes a radio unit 120, a baseband processing unit 130, an external interface unit 140, a control unit 150, and the like. The wireless unit 120 may be provided on the antenna side as a device different from the main body side (BBU) of the base station apparatus 100 and connected to the main body side (BBU) of the base station apparatus 100 via an optical cable or the like. The antenna 110 may be an omnidirectional antenna, or may be an antenna composed of a plurality of elements that can form one beam or a beam in a predetermined direction (for example, a Massive MIMO antenna). The radio unit 120 includes, for example, an amplification unit, a frequency conversion unit, a transmission / reception switching unit (DUP), an orthogonal modulation / demodulation unit, and the like.

  The baseband processing unit 130 performs conversion (modulation / demodulation) of control information to be transmitted / received and user data (IP packet) and an OFDM signal (baseband signal) placed on the wireless transmission path. As a modulation method, for example, QPSK, 16QAM, 64QAM, or the like can be used. Baseband signals are transmitted to and received from the radio unit 120.

  The external interface unit 140 is connected to the core network of the mobile communication network via a line terminating device and a broadband public communication line such as an ADSL (Asymmetric Digital Subscriber Line) line or an optical line, and is connected to various nodes on the core network. The communication is performed by a predetermined communication interface and protocol.

  The control unit 150 is configured by, for example, a CPU and a memory, and can control each unit by executing a preinstalled program.

  The user devices 20 and 21 are, for example, an antenna, a transmission / reception switching unit (DUP), a reception unit, a CP removal unit, an FFT unit, a signal separation unit, a propagation path compensation unit, a demodulation unit, a composite unit, a DMRS propagation channel (channel) estimation. Unit, a signal multiplexing unit, an IFFT unit, a CP insertion unit, a transmission unit, and a control unit. The DMRS propagation channel (channel) estimation unit estimates a wireless propagation channel (equivalent propagation channel) based on the reception result of a known demodulation reference signal (DMRS) transmitted from the base station 10. The demodulation unit demodulates and decodes the data signal included in the transmission signal based on the estimation result of the wireless propagation path (equivalent propagation path). Since the constituent parts of the other parts have the same functions as those in the prior art, their description is omitted.

  Here, when the arrangement pattern of DMRS 301 arranged with a resource element in radio resource 300 as one unit is fixed as in the case of conventional LTE (see, for example, FIG. 3), it is located in cell 10A of base station 10. When the wireless communication environment of the user devices 20 and 21 changes, the received signal may change (decrease).

  FIG. 4A is a diagram illustrating an example of fluctuation characteristics on a time axis of a downlink reception signal due to fading in user apparatuses in a low-speed moving environment and a high-speed moving environment. A characteristic 401 in the figure is an example of a fluctuation characteristic of a received signal of a user apparatus in a low-speed moving environment, and a characteristic 402 in the figure is an example of a fluctuation characteristic of a received signal of a user apparatus in a high-speed moving environment. FIG. 4B is a diagram illustrating an example of fluctuation characteristics on the frequency axis of a downlink received signal due to frequency selective fading in each user apparatus when the delay spread is small and large in a multipath environment. Characteristic 411 in the figure is an example of fluctuation characteristics of the received signal of the user apparatus when the delay spread is small in the multipath environment, and character 412 in the figure is the user when the delay spread is large in the multipath environment. It is an example of the fluctuation | variation characteristic of the received signal of an apparatus. Here, the multipath environment is an environment in which a radio signal is transmitted / received via a plurality of transmission paths (paths) between the base station 10 and the same user apparatus 21 due to reflection at a mountain or a building.

  For example, in the user device 20 in a high-speed moving environment such as in a high-speed train in FIG. 1, the received signal greatly fluctuates (decreases) on the time axis as indicated by an arrow A in FIG. Further, in the user apparatus 21 in the multipath environment in FIG. 1, the received signal largely fluctuates (decreases) on the frequency axis as the delay spread increases in the multipath as indicated by the arrow B in FIG. To do. When the received signal fluctuates and decreases depending on the environment as described above, the reception quality of DMRS decreases, the estimation accuracy of the radio channel (equivalent channel) decreases, and the throughput decreases.

  In addition, when notifying the user apparatuses 20 and 21 in advance with a control signal (control message) of information on a large number of DMRS arrangement pattern candidates that may be used in the cell 10A of the base station 10, the control signal (control message) Overhead may increase.

  Therefore, in the present embodiment, while suppressing an increase in the overhead of the control signal transmitted to the user apparatuses 20 and 21, the radio resources are used for demodulation in accordance with the environment such as the moving speed of the user apparatuses 20 and 21 and the distribution of delay spread. The base station apparatus 100 performs the two-stage notification control of the DMRS arrangement pattern as described below so that the arrangement pattern of the reference signal can be set.

In the present embodiment, the control unit 150 of the base station apparatus 100 can function as the following units (1) to (4) by cooperating with each unit.
(1) Storage means for storing information on a plurality of DMRS arrangement pattern candidates (hereinafter also referred to as “DMRS arrangement pattern candidates”) in radio resources that can be used in the cell 10A as the radio communication area of the base station apparatus 100. (2) ) One or a plurality of arrangement pattern candidates that can be assigned to the user apparatuses 20 and 21 from the plurality of DMRS arrangement pattern candidates based on the environment information of the user apparatuses 20 and 21 located in the cell 10A of the base station apparatus 100 Determination means for narrowing down and determining (3) First notification means for notifying the user devices 20 and 21 of information on the determined one or more DMRS arrangement pattern candidates (4), the determined one or more DMRS arrangements Notifying the user devices 20 and 21 of designation information for designating any one DMRS arrangement pattern selected from the pattern candidates Second notification means that

  Here, the information of the determined one or more DMRS arrangement pattern candidates is, for example, for each of the one or more DMRS arrangement pattern candidates, in the DMRS arrangement pattern candidate identification information, the time axis and the frequency axis of the radio resource This is associated with the DMRS position information.

  In addition, the information of the one or more determined DMRS arrangement pattern candidates is transmitted to the user apparatuses 20 and 21 by, for example, RRC (Radio Resource Control) signaling of an upper layer (third layer).

  Also, among the determined one or more DMRS arrangement pattern candidates, DMRS arrangement pattern designation information that designates a DMRS arrangement pattern that is actually used for estimation of a radio transmission path in the user apparatus 20 is, for example, physical downlink control It is transmitted to the user apparatuses 20 and 21 by channel (PDCCH) control information (DCI).

  The control units of the user apparatuses 20 and 21 store information on one or more DMRS arrangement pattern candidates notified in advance from the base station apparatus 100. Then, the DMRS propagation channel (channel) estimation unit actually performs radio transmission from one or a plurality of DMRS arrangement pattern candidates notified in advance from the base station apparatus 100 using DMRS arrangement pattern designation information notified by the DCI of PDCCH. A DMRS arrangement pattern used for path estimation is specified. The DMRS propagation path (channel) estimation unit estimates a wireless propagation path (equivalent propagation path) based on a reception result of a known DMRS transmitted with the DMRS arrangement pattern specified by the DMRS arrangement pattern designation information.

  In this embodiment, since the tendency of the radio | wireless communication environment (for example, the moving speed of a user apparatus, delay spread) of a user apparatus for every cell differs, the DMRS arrangement pattern candidate optimal for each cell differs. Therefore, in the present embodiment, when performing the two-stage notification control of the DMRS arrangement pattern candidate, it is possible to assign from a large number of DMRS arrangement pattern candidates usable in the cell 10A to the user apparatus according to the radio communication environment of the user apparatus. DMRS arrangement pattern candidates to be notified are selected and determined. For example, the optimal DMRS arrangement pattern candidate corresponding to the tendency of the wireless communication environment of the cell 10A where the user apparatus is located is selected and determined.

  The tendency of the wireless communication environment of the cell 10A is determined from, for example, the moving speed and delay spread distribution (for example, cumulative distribution function: CDF) of all user apparatuses located in the cell 10A. For example, based on the distribution (CDF) of the moving speed, the moving speed corresponding to a predetermined range (for example, 5 to 95%) centered on 50% of the CDF of the moving speed of the user device in the cell 10A. DMRS arrangement pattern candidates may be narrowed down and determined based on the range. Further, based on a delay spread distribution (CDF), based on a delay spread range corresponding to a predetermined range (for example, 5 to 95%) centered on 50% of the CDF of the delay spread of the user equipment in the cell 10A. The DMRS arrangement pattern candidates may be narrowed down and determined.

  Here, the base station 10 may detect and acquire the moving speed and delay spread of each user apparatus from the uplink signals transmitted from each of the plurality of user apparatuses residing in the cell 10A, for example, and accumulate them. it can. When each of the plurality of user devices has a GPS reception function, the moving speed and delay spread of each user device may be detected and accumulated in association with the current position information fed back from each user device. In this case, it is possible to detect and accumulate the moving speed and delay spread of each user apparatus for each of a plurality of divided areas (grids) obtained by dividing the cell 10A, which will be described later, to create a CDF of the moving speed and delay spread. .

  FIG. 5 is a graph showing an example of a cumulative distribution function (CDF) of moving speeds of a plurality of user apparatuses residing in the cell 10A of the base station 10, and FIG. 6 is a cell having the moving speed distribution of FIG. It is a figure which shows an example of the some DMRS arrangement | positioning pattern candidate 601 and 602 determined so that it might respond | correspond to 10A. As shown in the example of FIG. 5, for example, when there are many low-speed user terminals with a moving speed of 50 [km / h] or less, the time variation of the received signal due to fading is small. DMRS arrangement pattern candidates 601 and 602 having a low density of DMRS 301 on the time axis are selected and determined. Information on the determined DMRS arrangement pattern candidates 601 and 602 is notified to user terminals located in the cell 10A.

  FIG. 7 is a graph showing another example of the cumulative distribution function of the moving speeds of a plurality of user apparatuses residing in the cell 10A of the base station 10, and FIG. 8 shows a cell 10A having the moving speed distribution of FIG. It is a figure which shows an example of several DMRS arrangement | positioning pattern candidates 801-804 determined so that it may respond | correspond to. As shown in the example of FIG. 7, when the moving speed of the user equipment in the cell 10A is widely distributed from a low speed to a high speed, the wireless communication environment (fading of fading due to the moving speed) of each user equipment in the cell 10A. In order to deal widely with the influence), DMRS arrangement pattern candidates are increased, and four types of DMRS arrangement pattern candidates 801 to 804 having different densities of DMRS 301 on the time axis are selected and determined as illustrated in FIG. Information on the determined DMRS arrangement pattern candidates 801 to 804 is notified to the user terminals located in the cell 10A.

  FIG. 9 shows an example of a plurality of DMRS arrangement pattern candidates determined to correspond to cases where variations on the frequency axis of received signals due to delay spreads of user apparatuses residing in the cell 10A of the base station 10 are different from each other. FIG. For example, when there are many user terminals with a large delay spread and a large fluctuation on the frequency axis of the received signal, DMRS arrangement pattern candidates 901 and 902 having a high density of DMRS 301 on the frequency axis as shown on the left side in FIG. 9 are selected. And decide. Information on the determined DMRS arrangement pattern candidates 901 and 902 is notified to the user terminals located in the cell 10A.

  On the other hand, when there are many user terminals with small delay spread and small fluctuations on the frequency axis of the received signal, select DMRS arrangement pattern candidates 903 and 904 with a low density of DMRS 301 on the frequency axis as shown on the right side in FIG. And decide. Information on the determined DMRS arrangement pattern candidates 903 and 904 is notified to the user terminals located in the cell 10A.

  Further, when the delay spread of the user equipment in the cell 10A is widely distributed, the frequency axis of FIG. 9 is used in order to widely cope with the radio communication environment (the influence of fading due to the moving speed) of each user equipment in the cell 10A. All four types of DMRS arrangement pattern candidates 901 to 904 having different densities of the above DMRS 301 are selected and determined. Information on the determined DMRS arrangement pattern candidates 901 to 904 is notified to the user terminals located in the cell 10A.

  In addition, the tendency of the radio | wireless communication environment (for example, the moving speed of a user apparatus, delay spread) of a user apparatus differs in each of several places in the same cell, and the optimal DMRS arrangement pattern candidate may differ. In this case, as shown in FIG. 10, the same cell 1000 is divided into a plurality of divided areas (grids) 1001, 1002,... The distribution may be obtained and DMRS arrangement pattern candidates may be selected based on the distribution. In this case, the DMRS arrangement pattern candidates can be narrowed down and determined at each location in the cell more precisely and accurately than when the optimum DMRS arrangement pattern candidates are determined for the entire cell.

  Here, the density of DMRS on the frequency axis of the DMRS arrangement pattern candidate to be selected to be notified to the user apparatus may be determined by a grid in which the user apparatus is located. For example, the density of the DMRS on the frequency axis of the DMRS arrangement pattern candidate to be selected may be determined based on the total result of the delay spread distribution in the grid where the user apparatus is located.

  Moreover, the density of DMRS on the time axis of the DMRS arrangement pattern candidate to be notified to be notified to the user apparatus may be determined based on the moving speed of the user apparatus. For example, the density of DMRS on the time axis of the DMRS arrangement pattern candidate to be selected is determined by a matching table showing the relationship between the movement speed created in advance and the density of DMRS on the time axis according to the moving speed of the user apparatus. May be.

  Further, in this embodiment, when the user apparatus moves at a high speed, the value of the delay spread largely fluctuates, so it may be difficult to follow the DMRS density in the frequency axis direction of the DMRS arrangement pattern candidate. In this case, the DMRS density in the DMRS arrangement pattern candidate to be notified may be determined according to the moving speed of the user apparatus so as to optimize the DMRS density in the time axis direction of the DMRS arrangement pattern candidate. Also in this case, in order to reduce the overhead of the control signal to the user apparatus, only the necessary DMRS arrangement pattern candidate pattern may be notified as illustrated below.

  FIG. 11 is a diagram illustrating an example of DMRS arrangement pattern candidates when the moving speed of the user apparatus is low. When the moving speed of the user apparatus is lower than the predetermined speed, high-density DMRS is not necessary on the time axis. For example, as shown in FIG. 11, one or two DMRSs 301 are present on the time axis. The selected DMRS arrangement pattern candidates 1101 and 1102 are selected and determined.

  FIG. 12 is a diagram illustrating an example of DMRS arrangement pattern candidates when the moving speed of the user apparatus is high. When the moving speed of the user apparatus is higher than a predetermined speed, high-density DMRS is required on the time axis. For example, as shown in FIG. 12, there are three or four DMRSs 301 on the time axis. The selected DMRS arrangement pattern candidates 1201 and 1202 are selected and determined.

  In the above-described embodiment, the signal and communication method used when notifying the user apparatus of information on one or more DMRS arrangement pattern candidates may be switched based on the moving speed of the user apparatus. For example, when the moving speed of the user device is a high speed that is equal to or higher than a predetermined speed, it is assumed that the situation changes instantaneously. Therefore, the DCI suitable for instantaneous change with a short signal interval (update interval). DMRS arrangement pattern candidates may be notified to the user apparatus using (downlink control information). On the other hand, when the moving speed of the user apparatus is lower than the predetermined speed, DMRS arrangement pattern candidates are notified to the user apparatus using RRC signaling of a higher layer with a relatively long signal interval (update interval). Also good.

  In the notification control of the above embodiment, when the base station apparatus 100 notifies the user apparatuses 20 and 21 of one DMRS arrangement pattern candidate, the DMRS arrangement pattern designation information described above may not be notified. In this case, the user apparatuses 20 and 21 actually use one DMRS arrangement pattern candidate notified from the base station apparatus 100 as it is for the estimation of the radio transmission path. That is, the user apparatuses 20 and 21 estimate a radio propagation path (equivalent propagation path) based on a reception result of a known DMRS transmitted with one DMRS arrangement pattern candidate notified from the base station apparatus 100. As described above, even in the one-step notification control that does not notify the DMRS arrangement pattern designation information, the signal and communication method used when notifying the user apparatus of DMRS arrangement pattern candidate information may be switched based on the moving speed of the user apparatus. For example, when the moving speed of the user apparatus is a high speed that is equal to or higher than a predetermined speed, it is assumed that the DMRS arrangement pattern necessary for channel estimation with a predetermined accuracy changes instantaneously, and therefore the signal interval (update interval) is short. The user equipment may be notified of DMRS arrangement pattern candidates used for radio transmission path estimation using DCI (downlink control information) suitable for instantaneously changing the DMRS arrangement pattern. On the other hand, when the moving speed of the user apparatus is a low speed lower than a predetermined speed, DMRS arrangement pattern candidates used for radio transmission path estimation using RRC signaling of an upper layer having a relatively long signal interval (update interval) May be notified to the user device.

  As described above, according to the present embodiment, rather than notifying the user devices 20 and 21 of DMRS arrangement pattern candidates that can be used in the cell 10A in which the user devices 20 and 21 are located, a large number of wireless environments (for example, user devices) DMRS arrangement pattern candidates narrowed down and selected according to the movement speed or delay spread) are notified to the user devices 20 and 21. Accordingly, the movement speed and delay spread distribution of the user apparatuses 20 and 21 are suppressed while suppressing an increase in overhead of a control signal (for example, a signal transmitted by RRC signaling) transmitted from the base station apparatus 100 to the user apparatuses 20 and 21. The arrangement pattern of the demodulation reference signal (DMRS) in the radio resource can be set according to the environment such as.

  Further, the processing steps described in this specification and the constituent elements of the mobile communication system, the base station device, and the user device (terminal, terminal device, mobile station, mobile device) can be implemented by various means. For example, these steps and components may be implemented in hardware, firmware, software, or a combination thereof.

  For hardware implementation, means such as a processing unit used to realize the above steps and components in an entity (for example, various wireless communication devices, Node B, terminal, hard disk drive device, or optical disk drive device) One or more application specific IC (ASIC), digital signal processor (DSP), digital signal processor (DSPD), programmable logic device (PLD), field programmable gate array (FPGA), processor , A controller, a microcontroller, a microprocessor, an electronic device, other electronic units designed to perform the functions described herein, a computer, or a combination thereof.

  Also, for firmware and / or software implementation, means such as processing units used to implement the above components may be programs (eg, procedures, functions, modules, instructions) that perform the functions described herein. , Etc.). In general, any computer / processor readable medium that specifically embodies firmware and / or software code is means such as a processing unit used to implement the steps and components described herein. May be used to implement For example, the firmware and / or software code may be stored in a memory, for example, in a control device, and executed by a computer or processor. The memory may be implemented inside the computer or processor, or may be implemented outside the processor. The firmware and / or software code may be, for example, random access memory (RAM), read only memory (ROM), nonvolatile random access memory (NVRAM), programmable read only memory (PROM), electrically erasable PROM (EEPROM) ), FLASH memory, floppy disk, compact disk (CD), digital versatile disk (DVD), magnetic or optical data storage, etc. Good. The code may be executed by one or more computers or processors, and may cause the computers or processors to execute the functional aspects described herein.

  Also, descriptions of embodiments disclosed herein are provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. The present disclosure is therefore not limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

DESCRIPTION OF SYMBOLS 10: Base station 10A: Cell 20: User apparatus 21: User apparatus 100: Base station apparatus 110: Antenna 120: Radio | wireless part 130: Baseband process part 140: External interface part 150: Control part 300: Radio | wireless resource 301: For demodulation Reference signal (DMRS)
601 and 602: DMRS arrangement pattern candidates 801 to 804: DMRS arrangement pattern candidates 901 to 904: DMRS arrangement pattern candidates 1000: Division target cell (radio communication area of base station)
1001, 1002: Grid (divided area)
1101, 1102: DMRS arrangement pattern candidates 1201, 1202: DMRS arrangement pattern candidates

Claims (7)

A base station apparatus for a mobile communication system,
Storage means for storing information on a plurality of arrangement pattern candidates of demodulation reference signals in radio resources usable in the radio communication area of the base station device;
At least one of the moving speed and the delay spread of the user equipment located in the radio communication area of the base station apparatus is totaled, and based on the total result, the plurality of arrangement pattern candidates are located in the radio communication area. Determining means for narrowing down and determining one or a plurality of arrangement pattern candidates that can be assigned to the user device;
Notification means for notifying the user device of information on the determined one or more arrangement pattern candidates ,
For each of a plurality of divided areas into which the wireless communication area is divided, the determining unit narrows down one or a plurality of arrangement pattern candidates that can be assigned to the user devices located in the divided area from the plurality of arrangement pattern candidates. Decide
The base station apparatus characterized in that the notification means notifies the information of the plurality of arrangement pattern candidates corresponding to the divided area where the user apparatus is located based on the position information of the user apparatus. In the base station apparatus of Claim 1,
The determining means includes the plurality of arrangement patterns so as to narrow down to reference pattern candidates for demodulation reference signals corresponding to a predetermined range of a cumulative distribution function of at least one of a moving speed and a delay spread of a user apparatus in the radio communication area. A base station apparatus that narrows down and determines one or a plurality of arrangement pattern candidates that can be allocated to user apparatuses located in the wireless communication area from candidates. In the base station apparatus according to claim 1 or 2 ,
For each of the plurality of divided areas, the determining unit totals at least one of a moving speed and a delay spread of the user apparatus in the divided area, and based on the totaled result, the plurality of arrangement pattern candidates are assigned to the divided areas. A base station apparatus characterized by narrowing down and determining one or a plurality of arrangement pattern candidates that can be allocated to a user apparatus in the area. In the base station apparatus according to any one of claims 1 to 3 ,
The determining means includes
For each of the plurality of divided areas, the delay spreads of the user devices in the divided areas are totaled, and based on the totaled result, frequency axes that can be assigned to the user devices located in the divided area from the plurality of arrangement pattern candidates Narrow down a plurality of arrangement pattern candidates having the above arrangement density,
Based on the moving speed of the user apparatus, one or more arrangement pattern candidates having an arrangement density on the time axis that can be allocated to the user apparatus are narrowed down and determined from the selected plurality of arrangement pattern candidates. Base station apparatus. In the base station apparatus according to any one of claims 1 to 4,
The base station apparatus characterized in that the determining means sets an arrangement density of demodulation reference signals on a time axis in arrangement pattern candidates to be notified to the user apparatus based on a moving speed of the user apparatus.   A base station apparatus for a mobile communication system,
  Storage means for storing information on a plurality of arrangement pattern candidates of demodulation reference signals in radio resources usable in the radio communication area of the base station device;
  User devices that are located in the wireless communication area from the plurality of arrangement pattern candidates based on the delay spread summation results based on the delay spread of the user devices located in the wireless communication area of the base station device Determining means for narrowing down and determining one or a plurality of arrangement pattern candidates that can be assigned to
  A base station apparatus comprising: a notification unit configured to notify the user apparatus of information on the determined one or a plurality of arrangement pattern candidates.   In the base station apparatus of Claim 6,
  The determining means includes the plurality of arrangement pattern candidates from the plurality of arrangement pattern candidates so as to narrow down to demodulation pattern reference pattern candidates corresponding to a predetermined range of the delay spread cumulative distribution function of the user apparatus in the radio communication area. A base station apparatus characterized by narrowing down and determining one or a plurality of arrangement pattern candidates that can be assigned to user apparatuses located in the area.