WO2016072000A1

WO2016072000A1 - Wireless communication system, base station, terminal, and processing method

Info

Publication number: WO2016072000A1
Application number: PCT/JP2014/079510
Authority: WO
Inventors: 剛史下村; 須田　健二
Original assignee: 富士通株式会社
Priority date: 2014-11-06
Filing date: 2014-11-06
Publication date: 2016-05-12

Abstract

A wireless communication system (100) is capable of using a first band that is shared with another wireless communication system and a second band that is different from the first band. When the other wireless communication system is not transmitting a wireless signal in the first band, a base station (110) transmits at least one of a reference signal and a synchronization signal in the first band. Furthermore, the base station (110) uses the second band to transmit control information for specifying the timing by which at least one of the reference signal and the synchronization signal is transmitted. A terminal (120) receives at least one of the reference signal and the synchronization signal transmitted from the base station (110) via the first band on the basis of the control information transmitted from the base station (110) via the second band.

Description

Wireless communication system, base station, terminal, and processing method

The present invention relates to a wireless communication system, a base station, a terminal, and a processing method.

Conventionally, mobile communication such as LTE (Long Term Evolution) and LTE-advanced is known. In addition, there is a technology in which an eNB such as LTE (evolved Node B) performs carrier sense (CS: Carrier Sense) in order to transmit PDSCH (Physical Downlink Shared Physical Channel) using the U band (unlicensed band). It is known (for example, see Patent Document 1 below).

In addition, for example, a technique for performing wireless communication using a shared band such as an unlicensed band in addition to a band allocated to an operator such as a licensed band is being studied.

US Patent Application Publication No. 2014/0036853

However, in the above-described conventional technology, when the base station transmits a signal such as a reference signal or a synchronization signal in the shared band, the signal is transmitted after detecting a free space in the shared band using carrier sense or the like. . For this reason, it may be difficult for the terminal to accurately specify the signal transmission timing by the base station in the shared band.

In one aspect, an object of the present invention is to provide a radio communication system, a base station, a terminal, and a processing method that allow a terminal to accurately specify a signal transmission timing by a base station in a shared band.

In order to solve the above-described problems and achieve the object, according to one aspect of the present invention, a first band shared with another wireless communication system and a second band different from the first band are provided. In a usable radio communication system, a base station transmits at least one of a reference signal and a synchronization signal in the first band during a period in which the radio signal of the first band is not transmitted in the other radio communication system, and the reference Control information for specifying timing for transmitting at least one of a signal and a synchronization signal is transmitted in the second band, and a terminal is based on the control information transmitted in the second band from the base station, A wireless communication system, a base station, a terminal, and a processing method for receiving at least one of the reference signal and the synchronization signal transmitted from the base station in the first band are proposed.

According to one aspect of the present invention, there is an effect that the terminal can accurately specify the transmission timing of the signal by the base station in the shared band.

FIG. 1A is a diagram illustrating an example of a wireless communication system according to an embodiment. 1B is a diagram illustrating an example of a signal flow in the wireless communication system illustrated in FIG. 1A. FIG. 2 is a sequence diagram illustrating an example of processing in the wireless communication system. FIG. 3 is a diagram illustrating an example of a U-band frequency channel used by the base station. FIG. 4 is a diagram illustrating an example of correspondence information transmitted by the base station. FIG. 5 is a diagram illustrating Example 1 of RS transmission information. FIG. 6 is a diagram illustrating an example of a transmission method of RS transmission information. FIG. 7 is a diagram illustrating another example of the RS transmission information transmission method. FIG. 8A is a diagram illustrating a first example of a case in which the presence / absence of RS transmission can be determined when RS transmission information is transmitted. FIG. 8B is a diagram illustrating a second example of a case in which the presence / absence of RS transmission can be determined when RS transmission information is transmitted. FIG. 8C is a diagram illustrating a third example of a case in which the presence / absence of RS transmission can be determined when RS transmission information is transmitted. FIG. 8D is a diagram illustrating a fourth example of a case in which the presence / absence of RS transmission can be determined when RS transmission information is transmitted. FIG. 9 is a diagram illustrating an example of the timing of each signal transmitted by the base station. FIG. 10 is a diagram illustrating another example of the timing of each signal transmitted by the base station. FIG. 11 is a flowchart illustrating an example of processing by the base station in Example 1 of RS transmission information. FIG. 12 is a flowchart illustrating an example of processing performed by the terminal in Example 1 of RS transmission information. FIG. 13 is a diagram illustrating Example 2 of RS transmission information. FIG. 14A is a diagram illustrating a first example of a case where it is not possible to determine whether or not RS transmission is performed when transmitting RS transmission information. FIG. 14B is a diagram illustrating a second example of a case where it is not possible to determine whether or not RS transmission is performed when transmitting RS transmission information. FIG. 15 is a flowchart illustrating an example of processing performed by the base station in RS transmission information example 2. FIG. 16 is a flowchart illustrating an example of processing by the terminal in the RS transmission information example 2. FIG. 17 is a diagram illustrating Example 3 of RS transmission information. FIG. 18 is a flowchart illustrating an example of processing by the base station in Example 3 of RS transmission information. FIG. 19 is a flowchart illustrating an example of processing performed by the terminal in the third example of RS transmission information. FIG. 20 is a flowchart illustrating another example of processing performed by the terminal in the third example of RS transmission information. FIG. 21 is a diagram illustrating Example 4 of RS transmission information. FIG. 22 is a diagram illustrating an example of transmission data in three formats. FIG. 23 is a diagram illustrating a first modification of the fourth example of RS transmission information. FIG. 24 is a diagram illustrating an example of transmission data in two formats. FIG. 25 is a diagram illustrating a second modification of the fourth example of RS transmission information. FIG. 26 is a flowchart illustrating an example of processing by the base station in the fourth example of RS transmission information. FIG. 27 is a flowchart illustrating an example of processing performed by a terminal in the fourth example of RS transmission information. FIG. 28 is a flowchart illustrating another example of processing performed by the terminal in the fourth example of RS transmission information. FIG. 29 is a diagram illustrating an example of the synchronization signal transmission information. FIG. 30 is a flowchart illustrating an example of processing performed by the base station when the synchronization signal transmission information is used. FIG. 31 is a flowchart illustrating an example of processing performed by the terminal when the synchronization signal transmission information is used. FIG. 32 is a diagram illustrating Example 5 of RS transmission information. FIG. 33 is a diagram illustrating an example of a head subframe in continuous transmission. FIG. 34 is a flowchart illustrating an example of processing by the base station in Example 5 of RS transmission information. FIG. 35 is a flowchart illustrating an example of a process performed by a terminal in RS transmission information example 5. FIG. 36 is a flowchart illustrating another example of processing performed by the terminal in the fifth example of RS transmission information. FIG. 37 is a diagram illustrating Example 6 of RS transmission information. FIG. 38A is a diagram illustrating an example of a base station according to the embodiment. FIG. 38B is a diagram illustrating an example of signal flow in the base station depicted in FIG. 38A. FIG. 38C is a diagram illustrating an example of the hardware configuration of the base station. FIG. 39A is a diagram illustrating an example of a terminal according to the embodiment. FIG. 39B is a diagram showing an example of a signal flow in the terminal shown in FIG. 39A. FIG. 39C is a diagram illustrating an example of a hardware configuration of the terminal. FIG. 40A is a diagram illustrating a first example of a transmission channel for U-band resource allocation information. FIG. 40B is a diagram illustrating a second example of the transmission channel for U-band resource allocation information. FIG. 40C is a diagram illustrating a third example of the transmission channel for the U-band resource allocation information. FIG. 40D is a diagram illustrating a fourth example of the transmission channel for the U-band resource allocation information.

Hereinafter, embodiments of a radio communication system, a base station, a terminal, and a processing method according to the present invention will be described in detail with reference to the drawings.

(Embodiment)
(Radio communication system according to embodiment)
FIG. 1A is a diagram illustrating an example of a wireless communication system according to an embodiment. 1B is a diagram illustrating an example of a signal flow in the wireless communication system illustrated in FIG. 1A. As illustrated in FIGS. 1A and 1B, the wireless communication system 100 according to the embodiment includes a base station 110 and a terminal 120. The wireless communication system 100 is a wireless communication system that can use the first band and the second band for wireless communication between the base station 110 and the terminal 120.

The first band is a band shared with other wireless communication systems. The second band is a band different from the first band. For example, the second band is a band occupied by the wireless communication system 100 (own system).

The base station 110 includes a first transmission unit 111 and a second transmission unit 112. The first transmission unit 111 transmits at least one of the reference signal and the synchronization signal using the first band during a period in which the wireless signal of the first band is not transmitted in another wireless communication system. Further, the first transmission unit 111 outputs control information for specifying the timing of transmitting at least one of the reference signal and the synchronization signal to the second transmission unit 112 using the first band.

The second transmission unit 112 transmits the control information output from the first transmission unit 111 using the second band. As an example, the control information can be information indicating whether or not at least one of the reference signal and the synchronization signal is transmitted or is scheduled to be transmitted for each periodic period (for example, subframe).

The terminal 120 includes a first receiving unit 121 and a second receiving unit 122. The first receiving unit 121 receives control information transmitted from the base station 110 using the second band, and outputs the received control information to the second receiving unit 122. Based on the control information output from the first receiver 121, the second receiver 122 receives at least one of the reference signal and the synchronization signal transmitted from the base station 110 using the first band. The terminal 120 performs processing based on at least one of the reference signal and the synchronization signal received by the second receiving unit 122.

According to the wireless communication system 100 shown in FIG. 1A and FIG. 1B, the control information for specifying the timing at which the base station 110 transmits at least one of the reference signal and the synchronization signal using the shared first band is provided. The second band different from the first band can be used for transmission.

Accordingly, the terminal 120 receives the control information transmitted from the base station 110 using the second band, so that the base station 110 transmits at least one of the reference signal and the synchronization signal using the first band. The timing to perform can be specified accurately. Therefore, the terminal 120 can efficiently receive at least one of the reference signal and the synchronization signal by the base station 110 using the first band, and perform processing based on the received signal.

<Detection of a period during which no radio signal is transmitted in another radio communication system>
The base station 110 can detect a period in which the wireless signal in the first band is not transmitted in another wireless communication system, for example, based on the detection result of the wireless signal in the first band. The detection of the radio signal in the first band is, for example, CCA (Clear Channel Assessment) that detects a vacant carrier in the first band, for example, carrier sense.

For example, detection of a radio signal in the first band is a process of detecting a radio signal by detecting received power (received energy) of radio waves in the first band and comparing the detected received power with a predetermined power. Alternatively, the detection of the radio signal in the first band may be a process of detecting the radio signal by detecting a predetermined pattern (for example, a preamble) of the radio signal based on the radio wave in the first band.

Further, the base station 110 detects a period in which the first band radio signal is not transmitted in another radio communication system based on, for example, whether or not the radio signal is transmitted from the base station. As an example, when the base station 110 is transmitting a radio signal in the first band in the first period (for example, subframe), the base station 110 performs other in the second period immediately after the first period. In this wireless communication system, it can be determined that the wireless signal of the first band is not transmitted.

<Examples of the first band and the second band>
For example, the first band can be an unlicensed band (unlicensed band) that is not assigned to a specific operator. The second band may be a licensed band that is assigned to an operator of the wireless communication system 100 and is occupied by the wireless communication system 100, for example. Hereinafter, a case where the first band is an unlicensed band (hereinafter referred to as “U band”) and the second band is a licensed band (hereinafter referred to as “L band”) will be described.

(Processing in wireless communication system)
FIG. 2 is a sequence diagram illustrating an example of processing in the wireless communication system. In the wireless communication system 100, for example, each step shown in FIG. 2 is executed. First, the base station 110 and the terminal 120 perform connection processing in the L band with each other (step S201). This enables wireless communication in the L band between the base station 110 and the terminal 120.

Next, the terminal 120 notifies the base station 110 of the capability regarding the U band (Capability) (step S202). For example, the terminal 120 notifies the base station 110 that it supports wireless communication using the U band together with the L band for which connection processing has been performed in step S201.

Next, correspondence information between the U-band carrier (frequency channel) used by the base station 110 in wireless communication with each terminal and the channel number assigned to the U-band carrier by the base station 110 is transmitted to the terminal 120. Transmit (step S203).

For example, in step S203, the base station 110 individually transmits correspondence information to each terminal (including the terminal 120) using an individual channel such as RRC (Radio Resource Control). Alternatively, the base station 110 may broadcast the correspondence information to each terminal (including the terminal 120) using a broadcast channel such as a PBCH (Physical Broadcast Channel). The correspondence information transmitted by the base station 110 will be described later (for example, FIG. 4).

Also, the base station 110 starts transmission of RS transmission information indicating the transmission timing of RS (Reference Signal) in the U band in the L band. The RS transmission information is information indicating the presence or absence of RS transmission by designating the U band carrier using the channel number associated with the U band carrier (frequency channel) in the correspondence information transmitted in step S203, for example. Moreover, RS transmission information is information which shows the transmission timing of RS for every sub-frame, for example. The RS may be transmitted together with the data or may be transmitted alone.

Also, the base station 110 transmits an RRM measurement request for requesting RRM (Radio Resource Management) measurement related to the U-band carrier to the terminal 120 (step S204). Next, the terminal 120 performs RRM measurement regarding the U band in response to the RRM measurement request transmitted in step S204, and transmits the result of the RRM measurement to the base station 110 (step S205). The RRM measurement is, for example, a quality measurement for selecting a frequency channel to be used from a plurality of frequency channels.

For example, the terminal 120 specifies the RS transmission timing from the base station 110 in the U band based on the correspondence information received in step S203 and the RS transmission information from the base station 110. Then, the terminal 120 receives the RS from the base station 110 in the U band at the specified transmission timing, and performs RRM measurement based on the received RS.

Further, the terminal 120 may perform RRM measurement based on the result of timing tracking or frequency tracking based on the received RS. Timing tracking is, for example, processing for tracking the transmission timing of a radio signal by the base station 110. Frequency tracking is a process for compensating for, for example, a frequency offset of a radio signal transmitted from the base station 110 and a frequency offset in a frequency generator in the terminal 120.

Next, the base station 110 transmits information on the U-band carrier used for communication with the terminal 120 to the terminal 120 based on the result of the RRM measurement transmitted at step S205 (step S206). For example, base station 110 determines the frequency channel of the U-band carrier to be used for communication with terminal 120 based on the result of RRM measurement. Then, the base station 110 transmits information indicating the determined frequency channel in step S206. For example, the base station 110 transmits information on the U-band carrier used for communication with the terminal 120 to the terminal 120 using a dedicated channel such as RRC.

Next, the base station 110 and the terminal 120 start communication using the L band carrier and the U band carrier (step S207). Further, in the communication using the U-band carrier started in step S207, the terminal 120 performs various processes based on the RS transmitted by the base station 110 using the U-band.

Various processes based on RS include, for example, timing tracking, frequency tracking, RRM measurement, CQI (Channel Quality Indicator) measurement, CSI (Channel State Information) measurement, and the like.

Timing tracking and frequency tracking are performed for RRM measurement, CQI measurement, CSI measurement, data reception processing, and the like. The CQI measurement is, for example, channel quality measurement for selecting a modulation scheme, a transmission rate, and the like. The CSI measurement is, for example, channel quality measurement for selecting parameters such as MIMO (Multiple Input Multiple Output) and beam forming.

(U-band frequency channel used by the base station)
FIG. 3 is a diagram illustrating an example of a U-band frequency channel used by the base station. In FIG. 3, numbers on the horizontal axis (“0” to “6”) indicate common numbers in the radio communication system 100 for frequency channels in the U band. It is assumed that the base station 110 can use the frequency channels “0” to “6” included in the U band for wireless communication with the terminal 120.

The base station 110 selects a frequency channel to be used for wireless communication with the terminal 120 from the frequency channels “0” to “6” and performs numbering. In the example illustrated in FIG. 3, the base station 110 selects the frequency channels “3”, “4”, and “1”, and assigns the channel numbers # 1 and # 1 to the frequency channels “3”, “4”, and “1”, respectively. Assume that numbering is performed to add 2 and # 3.

(Corresponding information transmitted by the base station)
FIG. 4 is a diagram illustrating an example of correspondence information transmitted by the base station. In step S203 illustrated in FIG. 2, the base station 110 transmits, for example, correspondence information 400 illustrated in FIG. 4 to the terminal 120 as correspondence information between the U-band carrier (frequency channel) and the channel number. The correspondence information 400 includes frequency channels “3”, “4”, and “1” selected by the base station 110, and channel numbers # numbered by the base station 110 to the frequency channels “3”, “4”, and “1”. Information indicating 1 to # 3 in association with each other.

(Example 1 of RS transmission information)
FIG. 5 is a diagram illustrating Example 1 of RS transmission information. The RS transmission information transmitted by the base station 110 can be, for example, RS transmission information 500 shown in FIG. RS transmission information 500 shown in FIG. 5 is 1-bit information and indicates the presence / absence of RS transmission. For example, the RS transmission information 500 indicates that there is no RS transmission (no RS transmission) when the value is “0”, and that there is RS transmission (with RS transmission) when the value is “1”.

By using the RS transmission information 500 shown in FIG. 5, the terminal 120 can accurately identify the presence or absence of RS transmission, so that the RS 120 can be accurately received and each measurement based on the RS can be accurately performed. Can do. In addition, since it is not necessary to provide the terminal 120 with a circuit for detecting the RS when the RS transmission timing is unknown, the circuit scale of the terminal 120 can be reduced. Further, since the RS can be received without performing the process of detecting the RS when the RS transmission timing is unknown, the power consumption in the terminal 120 can be reduced.

(RS transmission information transmission method)
For transmission of RS transmission information, for example, a channel for transmitting L1 and L2 control signals in LTE can be used. Examples of such channels include PDCCH (Physical Downlink Control Channel: Physical Downlink Control Channel) and PHICH (Physical HARQ Indicator Channel: Physical HARQ Indicator Channel).

The PDCCH is a control channel for transmitting information and commands related to downlink resource allocation, uplink resource allocation, uplink power control, and the like on the downlink. Each PDCCH includes a 16-bit CRC (Cyclic Redundancy Check). The CRC is masked by an RNTI (Radio Network Temporary Identifier) indicating the destination and usage.

For example, the PDCCH for sending resource allocation information addressed to each terminal is masked with a C-RNTI (Cell-Radio Network Temporary Identifier: cell radio network temporary identifier) indicating the ID (identifier) of each terminal. The CRC of the PDCCH that collectively sends power control commands addressed to a plurality of terminals is masked with the common RNTI. PHICH is a control channel for returning a response signal (ACK / NACK) related to an uplink data signal transmitted from a terminal.

FIG. 6 is a diagram illustrating an example of a method for transmitting RS transmission information. For example, as illustrated in FIG. 6, the base station 110 includes the RS transmission information 610 in the PDCCH 600 and transmits the RS transmission information to each terminal (including the terminal 120). The RS transmission information 610 is 5-bit information (“10001” in the example shown in FIG. 6), and indicates whether or not RSs are transmitted in a maximum of five frequency channels.

For example, bit 611 (“1”) of the first bit of RS transmission information 610 indicates that there is RS transmission in the frequency channel corresponding to channel number # 1. The second bit 612 (“0”) of the RS transmission information 610 indicates that there is no RS transmission in the frequency channel corresponding to the channel number # 2. Also, the third bit 613 (“0”) of the RS transmission information 610 indicates that there is no RS transmission in the frequency channel corresponding to channel number # 3.

The terminal 120, based on the correspondence information 400 received from the base station 110 and the RS transmission information 610, the RS of the RS from the base station 110 in the frequency channel used by the terminal 120 for wireless communication with the base station 110. The presence or absence of transmission can be determined.

For example, when the frequency channel used between the base station 110 and the terminal 120 is the frequency channel “1”, the terminal 120 acquires the channel number # 3 corresponding to the frequency channel “1” from the correspondence information 400. To do. Then, the terminal 120 acquires the bit 613 of the third bit of the RS transmission information 610 based on the channel number # 3, and transmits the RS from the base station 110 in the frequency channel “1” based on the acquired bit 613. The presence or absence of is determined. In the example illustrated in FIG. 6, base station 110 can determine that there is no RS transmission on frequency channel “1” in the subframe corresponding to PDCCH 600.

According to the example shown in FIG. 6, the presence or absence of RS transmission in a plurality of U-band frequency channels can be collectively reported to each terminal using one PDCCH. In this case, the number of bits of the RS transmission information 610 can be reduced by associating the channel number assigned by the base station 110 with the bit position in the RS transmission information 610 using the correspondence information 400.

In addition, when the base station 110 uses less than 5 U-band frequency channels and one or more bits out of 5 bits of the RS transmission information 610 are left, the base station 110, for example, A process (for example, zero padding) is performed to set a constant value.

In this way, the base station 110 transmits the RS transmission information 610 (first control information) for each of the plurality of U-band frequency channels in the L-band PDCCH 600 (control channel). In addition, the base station 110 transmits correspondence information 400 (second control information) for specifying the arrangement of the RS transmission information 610 in the PDCCH 600 for each of a plurality of frequency channels in the U band using the L band.

As a result, based on the correspondence information 400 transmitted by the L band from the base station 110, the terminal 120 transmits the RS transmission information 610 on the frequency channel used by the terminal of the plurality of frequency channels in the U band from the PDCCH. Can be received. Thereby, the bit number of RS transmission information 610 can be reduced.

(Another example of RS transmission information transmission method)
FIG. 7 is a diagram illustrating another example of the RS transmission information transmission method. The base station 110 may transmit, for example, dedicated control channels 701 to 703 shown in FIG. 7 as RS transmission information. The individual control channels 701 to 703 are RS transmission information indicating the presence or absence of RS transmission in the frequency channels corresponding to the channel numbers # 1 to # 3, respectively.

As the dedicated control channels 701 to 703, for example, a newly defined downlink dedicated control channel (PUTICH: Physical Unified Band Transmission Indicator Channel) can be used. Alternatively, a part of PHICH may be used for the individual control channels 701 to 703.

According to the example shown in FIG. 7, the RS transmission information to each terminal can be individually transmitted. In this case, by associating the channel number assigned by the base station 110 with the arrangement order of the dedicated control channels 701 to 703 using the correspondence information 400, the terminal 120 can identify the RS transmission information addressed to the terminal 120 itself. .

Thus, the base station 110 transmits the RS transmission information 610 (first control information) for each of a plurality of U-band frequency channels through the L-band individual control channels 701 to 703. In addition, the base station 110 transmits correspondence information 400 (second control information) for specifying correspondence between a plurality of U-band frequency channels and dedicated control channels 701 to 703 using the L band.

As a result, the terminal 120 transmits the RS transmission information about the frequency channel used by the terminal among the plurality of U-band frequency channels based on the correspondence information 400 transmitted by the L band from the base station 110 to the dedicated control channel. 701 to 703 can be received. Thereby, the bit number of RS transmission information 610 can be reduced.

As shown in FIGS. 6 and 7, the base station 110 transmits RS transmission information corresponding to each of the U-band frequency channels using the downlink L1 link and L2 link control channels in the L band. . Also, the correspondence between the channel number and the arrangement order of PDCCH 600 or dedicated control channels 701 to 703 is defined in advance in radio communication system 100 using, for example, mathematical formulas and tables, and stored in the memory of base station 110 and terminal 120. The In the example shown in FIGS. 6 and 7, for example, a mathematical expression “arrangement order of PDCCH 600 or dedicated control channels 701 to 703 = channel number” is defined in radio communication system 100.

(Case where the presence or absence of RS transmission can be determined at the time of transmission of RS transmission information)
FIG. 8A is a diagram illustrating a first example of a case in which the presence / absence of RS transmission can be determined when RS transmission information is transmitted. In FIG. 8A, the horizontal axis (t) indicates time. The frequency channel pl1 indicates an L-band frequency channel used between the base station 110 and the terminal 120. The frequency channel su1 indicates a U-band frequency channel used between the base station 110 and the terminal 120. For example, when the base station 110 performs carrier sense in the subframe sb1 and detects the vacancy of the frequency channel su1, the base station 110 transmits the dummy signal 801 through the frequency channel su1 in the subframe sb1.

Thereby, the frequency channel su1 in the next subframe sb2 can be secured (occupied). For this reason, when there is transmission data, the base station 110 can determine to transmit the RS in the next subframe sb2. Moreover, even if there is no transmission data, the base station 110 can determine to transmit the RS in the next subframe sb2 when transmitting the RS alone.

If it is determined that the RS is to be transmitted in the next subframe sb2, the base station 110 transmits the RS transmission information 802 indicating “RS transmission is present” on the frequency channel pl1 in the subframe sb2, and transmits a signal 803 including the RS. It transmits on the frequency channel su1.

As described above, the base station 110 may determine that the RS is transmitted in the subframe sb2 in the subsequent subframes by transmitting the dummy signal 801 through the frequency channel su1 when the vacancy of the frequency channel su1 is detected. it can. Here, the case where the dummy signal 801 is transmitted when a vacant band is detected will be described, but a preamble signal having a predetermined pattern may be transmitted instead of the dummy signal 801.

FIG. 8B is a diagram illustrating a second example of a case where it is possible to determine whether or not RS transmission is performed when RS transmission information is transmitted. In FIG. 8B, the same parts as those shown in FIG. 8A are denoted by the same reference numerals and description thereof is omitted. For example, in the subframe sb1, it is assumed that the base station 110 transmits a signal 821 including RS on the frequency channel su1.

In this case, the frequency channel su1 in the next subframe sb2 can be secured (occupied). For this reason, when there is data to be transmitted continuously, the base station 110 can determine to transmit the RS in the next subframe sb2. In this case, in the subframe sb2, the base station 110 transmits the RS transmission information 802 indicating “RS transmission is present” using the frequency channel pl1, and transmits the signal 803 including the RS using the frequency channel su1.

As described above, when the base station 110 continuously transmits a signal in the frequency channel su1, it can determine that the RS is transmitted in the subframe sb2 after two subframes.

FIG. 8C is a diagram illustrating an example 3 of a case in which the presence or absence of RS transmission can be determined when RS transmission information is transmitted. In FIG. 8C, the same parts as those shown in FIG. 8A are denoted by the same reference numerals and description thereof is omitted. For example, when the base station 110 transmits the signal 805 including the RS in the subframe sb2, the base station 110 transmits the RS transmission information 806 indicating “RS transmission is present” on the frequency channel pl1 in the subframe sb2. In the example illustrated in FIG. 8C, the base station 110 transmits the RS transmission information 806 in the end portion of the subframe sb2.

On the other hand, the terminal 120 buffers the signal 805 including the RS transmitted in the subframe sb2, and based on the RS transmission information 806 received late, the signal 805 including the RS that has been buffered. Receive processing. In this way, by configuring the terminal 120 to buffer the signal from the base station 110, the base station 110 actually transmits the signal 805 including the RS and then transmits the RS transmission information 806. Can do. On the other hand, the terminal 120 can receive the RS efficiently by performing the reception process of the buffered signal only when the RS transmission information 806 indicating “RS transmission is present” is received. it can.

FIG. 8D is a diagram illustrating an example 4 of a case where it is possible to determine whether or not RS transmission is performed when transmitting RS transmission information. In FIG. 8D, the same parts as those shown in FIG. 8A are denoted by the same reference numerals and description thereof is omitted. For example, when the base station 110 transmits the signal 807 including the RS in the subframe sb1, the base station 110 transmits the RS transmission information 808 indicating “with RS transmission” on the frequency channel pl1 in the next subframe sb2. In the example illustrated in FIG. 8D, the base station 110 transmits the RS transmission information 808 at the head portion of the subframe sb2.

On the other hand, the terminal 120 buffers the signal 807 including the RS transmitted in the subframe sb1, and based on the RS transmission information 808 received late, the signal 807 including the RS that has been buffered. Receive processing. In this way, by configuring the terminal 120 to buffer the signal from the base station 110, the base station 110 transmits the RS transmission information 808 after actually transmitting the signal 807 including the RS. Can do. On the other hand, the terminal 120 can receive the RS efficiently by performing reception processing of the buffered signal only when the RS transmission information 808 indicating “RS transmission is present” is received. it can.

According to the cases of FIGS. 8C and 8D, in the configuration in which the frequency channel su1 is not secured by the dummy signal or the preamble signal, the RS transmission is transmitted at the time of transmission of the RS transmission information about the head of the signal transmission (for example, signals 805 and 807). The presence or absence can be determined.

(Timing of each signal transmitted by the base station)
FIG. 9 is a diagram illustrating an example of the timing of each signal transmitted by the base station. In FIG. 9, the horizontal axis (t) indicates time. The frequency channel pl1 represents an L-band frequency channel. Frequency channels su1 to su3 indicate frequency channels of U-band channel numbers # 1 to # 3. Further, “B” indicates a busy state (no bandwidth is available) as a result of carrier sense, and “I” indicates an idle state (a bandwidth is available) as a result of carrier sense.

A case will be described in which the base station 110 transmits RS transmission information using a common PDCCH using, for example, U-RNTI (UTRAN-Radio Network Temporary Identifier: UTRAN wireless network temporary identifier). In this case, the base station 110 transmits each signal as shown in FIG. 9, for example.

9, subframe 901 indicates a subframe (1 [ms]) in the licensed band, and subframe 902 indicates a subframe (1 [ms]) in the unlicensed band. The

subframes

901 and 902 may have the same timing, or may have different timings as in the example illustrated in FIG.

First, it is assumed that the base station 110 transmits PDCCH 911 (“100”) based on the result of carrier sense using the frequency channel pl1 in the first subframe 901 shown in FIG. In the PDCCH 911, channel number # 1 indicates RS transmission, and channel numbers # 2 and # 3 indicate no RS transmission. In this case, in the first subframe 902 shown in FIG. 9, the base station 110 transmits a signal 912 including RS using the frequency channel su1.

Further, in the first subframe 902, as a result of the base station 110 performing carrier sense on the frequency channel su2, it becomes idle (I) for a predetermined number of times (for example, four times) or more continuously after busy (B), It is assumed that a vacant frequency channel su2 is detected. In addition, in the first subframe 902, it is assumed that the base station 110 performs the carrier sense on the frequency channel su3, and is continuously busy (B), and the vacancy of the frequency channel su3 is not detected.

Since the base station 110 transmits a signal using the frequency channel su1 in the first subframe 902 shown in FIG. 9, the base station 110 uses the frequency channel su1 in the second subframe 902 shown in FIG. It is determined that RS can be transmitted. Further, since the vacancy of the frequency channel su2 is detected in the first subframe 902 shown in FIG. 9, the base station 110 uses the frequency channel su2 in the second subframe 902 shown in FIG. Judge that transmission is possible. Further, since the vacancy of the frequency channel su3 is not detected in the first subframe 902 shown in FIG. 9, the base station 110 uses the frequency channel su3 in the second subframe 902 shown in FIG. Is determined not to be sent.

Therefore, the base station 110 uses the frequency channel pl1 in the second subframe 901 shown in FIG. 9, and channel numbers # 1 and # 2 indicate RS transmission, and channel number # 3 indicates no RS transmission. PDCCH 921 (“110”) is transmitted. In this case, in the second subframe 902 illustrated in FIG. 9, the base station 110 transmits a signal 922 including RS using su1. Also, in the second subframe 902 shown in FIG. 9, the base station 110 transmits a signal 923 including RS using su2. Further, in the second subframe 902, as a result of the base station 110 performing carrier sense for the frequency channel su3, it becomes idle (I) for a predetermined number of times (for example, four times) continuously after busy (B), It is assumed that a vacant frequency channel su3 is detected.

Since the base station 110 transmits a signal using the frequency channel su1 in the second subframe 902 shown in FIG. 9, the base station 110 uses the frequency channel su1 in the third subframe 902 shown in FIG. It is determined that RS can be transmitted. Further, it is assumed that the base station 110 determines that the RS is not transmitted using the frequency channel su2 in the third subframe 902 illustrated in FIG. 9 because there is no data to be transmitted using the frequency channel su2. Also, since the vacancy of the frequency channel su3 is detected in the second subframe 902 shown in FIG. 9, the base station 110 uses the frequency channel su3 in the third subframe 902 shown in FIG. Judge that transmission is possible.

Therefore, the base station 110 uses the L-band frequency channel pl1 in the third subframe 901 shown in FIG. 9, channel numbers # 1 and # 3 are RS transmissions, and channel number # 2 is RS transmissions. PDCCH 931 (“101”) indicating none is transmitted. In this case, in the third subframe 902 shown in FIG. 9, the base station 110 transmits a signal 932 including RS using su1. In addition, in the third subframe 902 illustrated in FIG. 9, the base station 110 transmits a signal 933 including an RS using su3.

FIG. 10 is a diagram illustrating another example of the timing of each signal transmitted by the base station. In FIG. 10, the same parts as those shown in FIG. For example, when the base station 110 transmits RS transmission information using the dedicated control channel, the base station 110 transmits each signal as shown in FIG. 10, for example.

First, base station 110 indicates presence / absence of RS transmission in channel numbers # 1 to # 3 based on the result of carrier sense using frequency channel pl1 in first subframe 901 shown in FIG. The individual control channels 1011 to 1013 are transmitted. The dedicated control channel 1011 indicates that channel number # 1 is RS transmission (“1”). The dedicated control channel 1012 indicates that channel number # 2 is not RS transmission (“0”). The dedicated control channel 1013 indicates that channel number # 3 is not RS transmission (“0”). In this case, the operation of the base station 110 in the first subframe 902 shown in FIG. 10 is the same as the operation shown in FIG.

In the second subframe 901 shown in FIG. 10, the base station 110 transmits dedicated control channels 1021 to 1023 indicating the presence / absence of RS transmission in channel numbers # 1 to # 3, respectively, using the frequency channel pl1. The dedicated control channel 1021 indicates that the channel number # 1 is RS transmission (“1”). The dedicated control channel 1022 indicates that channel number # 2 is RS transmission ("1"). The dedicated control channel 1023 indicates that the channel number # 3 is not RS transmission (“0”). In this case, the operation of the base station 110 in the second subframe 902 shown in FIG. 10 is the same as the operation shown in FIG.

In the third subframe 901 shown in FIG. 10, the base station 110 transmits individual control channels 1031 to 1033 indicating the presence / absence of RS transmission in the channel numbers # 1 to # 3, respectively, using the frequency channel pl1. The dedicated control channel 1031 indicates that channel number # 1 is RS transmission (“1”). The dedicated control channel 1032 indicates that channel number # 2 is not RS transmission (“0”). The dedicated control channel 1033 indicates that channel number # 3 is RS transmission ("1"). In this case, the operation of the base station 110 in the third subframe 902 shown in FIG. 10 is the same as the operation shown in FIG.

(Processing by base station in example 1 of RS transmission information)
FIG. 11 is a flowchart illustrating an example of processing by the base station in Example 1 of RS transmission information. When the RS transmission information 500 shown in FIG. 5 is used as the RS transmission information, the base station 110 executes, for example, each step shown in FIG. 11 for each subframe. Moreover, when transmitting multiple types of RS in U band, the base station 110 performs each step shown in FIG. 11 about each RS to transmit.

The multiple types of RS include, for example, CRS (Cell-Specific Reference Signal: Cell Specific Reference Signal), CSI-RS (Channel State Information-Reference Signal: Channel State Information Reference Signal), and DRS (Discovery Reference Signal). . The CRS is a common RS in the cell, and is used for frequency correction, CQI measurement, demodulation, RRM measurement, etc. in the terminal 120, for example. CSI-RS is used, for example, for channel estimation for precoding in terminal 120 and estimation of other cells for CoMP (Coordinated Multiple-Point transmission and reception).

As the arrangement of the CRS in the radio resource, for example, an arrangement example defined in 3GPP (3rd Generation Partnership Project) TS36.211 can be used. As an arrangement of CSI-RS in radio resources, for example, an arrangement example defined in 3GPP TS36.211 can be used.

First, the base station 110 determines whether or not RS can be transmitted in the U band in the next subframe (step S1101). For example, when the base station 110 is continuously transmitting a radio signal, or when a transmission opportunity is secured by detecting a vacant band by carrier sense and transmitting a dummy signal, a preamble signal, etc., It is determined that RS can be transmitted in the subframe. In addition, the base station 110 determines that the RS cannot be transmitted in the next subframe when the radio signal is not continuously transmitted and the transmission opportunity is not secured by a dummy signal or a preamble signal.

In step S1101, if the RS can be transmitted in the U band in the subframe (step S1101: Yes), the base station 110 determines whether or not the RS transmission timer satisfies a specified value (step S1102). The RS transmission timer is a timer for measuring the transmission timing (transmission subframe) of the target RS, and is set according to the transmission cycle of the target RS. That is, in step S1101, the base station 110 determines whether or not the next subframe is a subframe in which the target RS is to be transmitted.

In step S1102, if the RS transmission timer satisfies the specified value (step S1102: Yes), the base station 110 sets the RS transmission information to be transmitted to “1” (with RS transmission) (step S1103). In this case, the base station 110 transmits the RS in the U band in the next subframe. In addition, the base station 110 resets the RS transmission timer (step S1104), and ends a series of processes.

In step S1101, when the RS cannot be transmitted in the U band in the subframe (step S1101: No), the base station 110 sets the RS transmission information to be transmitted to “0” (no RS transmission) (step S1105). . Further, the base station 110 advances the RS transmission timer by one subframe (step S1106). And the base station 110 complete | finishes a series of processes.

In step S1102, if the RS transmission timer does not satisfy the specified value (step S1102: No), the base station 110 determines whether there is transmission data to the terminal 120 and whether simultaneous RS transmission is required (step S1102). S1107). The transmission data to the terminal 120 is user data to be transmitted to the terminal 120. The case where RS simultaneous transmission is required is a case where the terminal 120 receiving transmission data requires simultaneous transmission of transmission data and RS for demodulation or the like.

In step S1107, if there is transmission data to the terminal 120 and RS simultaneous transmission is required (step S1107: Yes), the base station 110 moves to step S1103. If there is no transmission data to the terminal 120 or RS simultaneous transmission is not required (step S1107: No), the base station 110 proceeds to step S1105.

Note that step S1107 is processing when the target is CRS. If the target is CSI-RS or DRS, step S1107 may be omitted. In this case, when the RS transmission timer does not satisfy the specified value in step S1102 (step S1102: No), the base station 110 proceeds to step S1105.

(Processing by terminal in example 1 of RS transmission information)
FIG. 12 is a flowchart illustrating an example of processing performed by the terminal in Example 1 of RS transmission information. When the RS transmission information 500 shown in FIG. 5 is used as the RS transmission information and the CQI is measured based on the RS transmitted from the base station 110 in the U band, the terminal 120, for example, for each subframe Each step shown in FIG. 12 is executed.

First, the terminal 120 receives RS transmission information transmitted in the L band by the base station 110 (step S1201). Next, based on the RS transmission information received in step S1201, the terminal 120 determines whether there is RS transmission (RS transmission information = 1) for the current subframe (step S1202).

In step S1202, when there is no RS transmission (step S1202: No), the terminal 120 ends a series of processes. If RS transmission is present (step S1202: Yes), the terminal 120 measures CQI based on the RS transmitted from the base station 110 in the U band (step S1203), and ends a series of processes.

Also, for example, when the R120 measurement is performed based on RS transmitted from the base station 110 in the U band, the terminal 120 executes the steps illustrated in FIG. 12 for each subframe. However, in this case, the terminal 120 performs RRM measurement based on the RS transmitted from the base station 110 in the U band in step S1203.

Also, for example, when performing timing tracking or frequency tracking based on RS transmitted from the base station 110 in the U band, the terminal 120 executes the steps shown in FIG. 12 for each subframe. However, in this case, in step S1203, the terminal 120 performs timing tracking and frequency tracking based on the RS transmitted from the base station 110 in the U band.

Also, the terminal 120 may perform reception processing of data transmitted from the base station 110 simultaneously with the RS, together with CQI measurement in step S1203.

(Example 2 of RS transmission information)
FIG. 13 is a diagram illustrating Example 2 of RS transmission information. The RS transmission information transmitted by the base station 110 may be, for example, RS transmission information 1300 illustrated in FIG. The RS transmission information 1300 shown in FIG. 13 is 1-bit information and indicates whether or not RS transmission is scheduled.

For example, when the value of the RS transmission information 1300 is “0”, it indicates that there is no RS transmission plan (no RS transmission plan). Further, when the value of the RS transmission information 1300 is “1”, it indicates that the RS transmission is scheduled (RS transmission is scheduled). For example, in the case where the presence or absence of RS transmission cannot be determined when RS transmission information is transmitted, RS transmission information 1300 indicating whether or not RS transmission is scheduled can be used.

By using the RS transmission information 1300 illustrated in FIG. 13, the terminal 120 can be configured not to perform the process of detecting an RS in a subframe without an RS transmission schedule, thereby reducing power consumption in the terminal 120. Can be achieved.

In addition, the terminal 120 can receive the RS if the RS is transmitted by performing the process of detecting the RS in the subframe with the RS transmission. The process of detecting the RS can be, for example, a process of calculating the correlation between the replica signal having the same pattern as the RS and the received signal, and determining that there is an RS when the calculated correlation is higher than a threshold value.

(Case where the presence or absence of RS transmission cannot be determined when transmitting RS transmission information)
FIG. 14A is a diagram illustrating a first example of a case where it is not possible to determine whether or not RS transmission is performed when transmitting RS transmission information. In FIG. 14A, the same parts as those shown in FIG. 8A are denoted by the same reference numerals and description thereof is omitted. For example, the base station 110 sets a periodic subframe as a subframe to be transmitted if an RS can be transmitted. In the example illustrated in FIG. 14A, it is assumed that the base station 110 sets the subframe sb2 as a subframe to be transmitted if the RS can be transmitted.

In this case, for example, the base station 110 transmits the RS transmission information 1401 indicating “RS transmission is scheduled” on the frequency channel pl1 in the subframe sb2. In addition, the base station 110 performs carrier sense of the frequency channel su1 in the subframe sb2, and transmits a signal 1402 including the RS on the frequency channel su1 when a free band of the frequency channel su1 is detected by the carrier sense.

FIG. 14B is a diagram illustrating Example 2 of a case where it is not possible to determine whether or not RS transmission is performed when RS transmission information is transmitted. In FIG. 14B, the same parts as those shown in FIG. 14A are denoted by the same reference numerals and description thereof is omitted. In the example illustrated in FIG. 14B, the base station 110 performs carrier sense at a predetermined timing in the subframe sb2, and transmits the signal 1402 including the RS from the time point when the free band of the frequency channel su1 is detected by the carrier sense. Send with su1.

(Processing by base station in example 2 of RS transmission information)
FIG. 15 is a flowchart illustrating an example of processing performed by the base station in RS transmission information example 2. When the RS transmission information 1300 illustrated in FIG. 13 is used as the RS transmission information, the base station 110 executes, for example, each step illustrated in FIG. 15 for each subframe. In addition, when transmitting a plurality of types of RSs (for example, CRS and DRS) in the U band, the base station 110 executes the steps shown in FIG. 15 for each RS to be transmitted.

First, the base station 110 determines whether or not the RS transmission timer satisfies a specified value (step S1501). When the RS transmission timer satisfies the specified value (step S1501: Yes), the base station 110 sets the RS transmission information to be transmitted to “1” (RS transmission scheduled) (step S1502). Next, the base station 110 performs RS transmission processing (step S1503).

For example, the base station 110 performs carrier sense in the U band, and transmits an RS when a free band is detected by carrier sense. In addition, when the radio signal is being continuously transmitted in the U band, the base station 110 transmits the RS without performing carrier sense. On the other hand, the base station 110 does not transmit the RS when the wireless signal is not continuously transmitted in the U band and the vacant band is not detected even if the carrier sense is performed.

Next, the base station 110 determines whether or not the RS has been transmitted in step S1503 (step S1504). When the RS can be transmitted (step S1504: Yes), the base station 110 resets the RS transmission timer (step S1505) and ends the series of processes. When the RS cannot be transmitted (step S1504: No), the base station 110 advances the RS transmission timer by one subframe (step S1506). And the base station 110 complete | finishes a series of processes.

In step S1501, when the RS transmission timer does not satisfy the specified value (step S1501: No), the base station 110 determines whether there is transmission data to the terminal 120 and RS simultaneous transmission is required (step S1501). S1507).

In step S1507, when it is determined that there is transmission data to the terminal 120 and RS simultaneous transmission is required (step S1507: Yes), the base station 110 proceeds to step S1502. If it is determined that there is no transmission data to the terminal 120 or that RS simultaneous transmission is not required (step S1507: No), the base station 110 proceeds to step S1508.

That is, the base station 110 sets the RS transmission information to be transmitted to “0” (no RS transmission) (step S1508). Also, the base station 110 advances the RS transmission timer by one subframe (step S1509). And the base station 110 complete | finishes a series of processes.

Note that step S1507 is processing when the processing target is CRS. When the processing target is DRS, step S1507 may be omitted. In this case, when the RS transmission timer does not satisfy the specified value in step S1501 (step S1501: No), the base station 110 proceeds to step S1508.

(Processing by terminal in RS transmission information example 2)
FIG. 16 is a flowchart illustrating an example of processing by the terminal in the RS transmission information example 2. When RS transmission information 1300 shown in FIG. 13 is used as the RS transmission information, and CQI measurement is performed based on RS transmitted from the base station 110 in the U band, the terminal 120 may Each step shown in FIG. 16 is executed.

First, the terminal 120 receives RS transmission information transmitted in the L band by the base station 110 (step S1601). Next, the terminal 120 determines whether or not there is an RS transmission plan for the current subframe (RS transmission information = 1) based on the RS transmission information received in step S1601 (step S1602).

In step S1602, if the RS transmission is not scheduled (step S1602: No), the terminal 120 ends the series of processes. When there is an RS transmission plan (step S1602: Yes), the terminal 120 performs an RS detection process for detecting an RS from the base station 110 in the U band (step S1603). For example, the terminal 120 calculates the correlation between the RS replica signal and the received signal, and performs RS detection processing for determining that RS transmission has occurred when the calculated correlation is higher than a threshold.

Next, the terminal 120 determines whether or not there is an RS transmission from the base station 110 in the U band based on the result of the RS detection process in step S1603 (step S1604). When there is no RS transmission (step S1604: No), the terminal 120 ends a series of processes. When there is RS transmission (step S1604: Yes), the terminal 120 performs CQI measurement based on the RS transmitted from the base station 110 in the U band (step S1605), and ends a series of processes.

Further, for example, also when the terminal 120 performs RRM measurement based on the RS transmitted from the base station 110 in the U band, the terminal 120 performs the steps illustrated in FIG. 16 for each subframe. However, in this case, in step S1605, the terminal 120 performs RRM measurement based on the RS transmitted by the base station 110.

Also, for example, when performing timing tracking and frequency tracking based on RS transmitted from the base station 110 in the U band, the terminal 120 performs the steps shown in FIG. 16 for each subframe. However, in this case, in step S1605, the terminal 120 performs timing tracking and frequency tracking based on the RS transmitted by the base station 110.

Further, the terminal 120 may perform reception processing of data transmitted from the base station 110 simultaneously with the RS, together with CQI measurement in step S1605.

(Example 3 of RS transmission information)
FIG. 17 is a diagram illustrating Example 3 of RS transmission information. The RS transmission information transmitted by the base station 110 may be, for example, RS transmission information 1700 illustrated in FIG. The RS transmission information 1700 shown in FIG. 17 is 2-bit information, and indicates the type of RS to be transmitted when there is RS transmission in addition to the presence or absence of RS transmission. In the example illustrated in FIG. 17, the case where the base station 110 transmits CRS and CSI-RS as RS will be described.

For example, the RS transmission information 1700 indicates that there is no RS transmission (no RS transmission) when the value is “00”. In addition, when the value is “01”, the RS transmission information 1700 indicates that there is CRS transmission and no CSI-RS transmission (with CRS transmission). Further, when the value is “10”, the RS transmission information 1700 indicates that there is CSI-RS transmission and no CRS transmission (with CSI-RS transmission). Further, when the value of the RS transmission information 1700 is “11”, it indicates that both CRS and CSI-RS transmissions are present (with CRS and CSI-RS transmissions).

(Processing by base station in example 3 of RS transmission information)
FIG. 18 is a flowchart illustrating an example of processing by the base station in Example 3 of RS transmission information. When the RS transmission information 1700 illustrated in FIG. 17 is used as the RS transmission information, the base station 110 executes, for example, each step illustrated in FIG. 18 for each subframe. First, the base station 110 determines whether or not RS can be transmitted in the U band in the next subframe (step S1801).

For example, when the base station 110 is continuously transmitting a radio signal, or when a transmission opportunity is secured by detecting a vacant band by carrier sense and transmitting a dummy signal, a preamble signal, etc., It is determined that RS can be transmitted in the subframe. In addition, the base station 110 determines that the RS cannot be transmitted in the next subframe when the radio signal is not continuously transmitted and the transmission opportunity is not secured by a dummy signal or a preamble signal.

In step S1801, when the RS can be transmitted in the U band in the subframe (step S1801: Yes), the base station 110 determines whether or not the CRS transmission timer satisfies the specified value (step S1802). The CRS transmission timer is a timer for measuring the transmission timing (transmission subframe) of the target CRS, and is set according to the transmission cycle of the target CRS. That is, the base station 110 determines whether or not the next subframe is a subframe in which CRS is to be transmitted.

In step S1802, when the CRS transmission timer satisfies the specified value (step S1802: Yes), the base station 110 resets the CRS transmission timer (step S1803). Further, the base station 110 determines whether or not the CSI-RS transmission timer satisfies a specified value (step S1804). The CSI-RS transmission timer is a timer for measuring the transmission timing (transmission subframe) of the target CSI-RS, and is set according to the transmission cycle of the target CSI-RS. That is, base station 110 determines whether or not the next subframe is a subframe in which CSI-RS is to be transmitted.

In step S1804, when the CSI-RS transmission timer satisfies the specified value (step S1804: Yes), the base station 110 sets the RS transmission information to be transmitted to “11” (with CRS and CSI-RS transmission) ( Step S1805). Further, the base station 110 resets the CSI-RS transmission timer (step S1806), and ends a series of processing.

In step S1804, if the CSI-RS transmission timer does not satisfy the specified value (step S1804: No), the base station 110 sets the RS transmission information to be transmitted to “01” (with CRS transmission) (step S1807). . In addition, the base station 110 advances the CSI-RS transmission timer by one subframe (step S1808). And the base station 110 complete | finishes a series of processes.

In step S1802, when the CRS transmission timer does not satisfy the specified value (step S1802: No), the base station 110 determines whether there is transmission data to the terminal 120 and whether CRS simultaneous transmission is required (step S1802). S1809). The case where CRS simultaneous transmission is required is a case where the terminal 120 that receives transmission data requires simultaneous transmission of transmission data and CRS for demodulation or the like.

If it is determined in step S1809 that there is transmission data and CRS simultaneous transmission is required (step S1809: Yes), the base station 110 proceeds to step S1803. If it is determined that there is no transmission data or that CRS simultaneous transmission is not required (step S1809: No), the base station 110 proceeds to step S1810. That is, the base station 110 advances the CRS transmission timer by one subframe (step S1810).

Next, the base station 110 determines whether or not the CSI-RS transmission timer satisfies a specified value (step S1811). That is, base station 110 determines whether or not the next subframe is a subframe in which CSI-RS is to be transmitted. When the CSI-RS transmission timer satisfies the specified value (step S1811: Yes), the base station 110 sets the RS transmission information to be transmitted to “10” (with CSI-RS transmission) (step S1812). Further, the base station 110 resets the CSI-RS transmission timer (step S1813), and ends a series of processes.

In step S1811, if the CSI-RS transmission timer does not satisfy the specified value (step S1811: No), the base station 110 sets the RS transmission information to be transmitted to “00” (no RS transmission) (step S1814). . Further, the base station 110 advances the CSI-RS transmission timer by one subframe (step S1815). And the base station 110 complete | finishes a series of processes.

In step S1801, if the RS cannot be transmitted in the U band in the next subframe (step S1801: No), the base station 110 proceeds to step S1814.

(Processing by terminal in RS transmission information example 3)
FIG. 19 is a flowchart illustrating an example of processing performed by the terminal in the third example of RS transmission information. When RS transmission information 1700 shown in FIG. 17 is used as the RS transmission information, and CQI measurement is performed based on CRS transmitted from the base station 110 in the U band, the terminal 120, for example, Each step shown in FIG. 19 is executed every time.

First, the terminal 120 receives RS transmission information transmitted in the L band by the base station 110 (step S1901). Next, the terminal 120 determines whether there is CRS transmission for the current subframe based on the RS transmission information received in step S1901 (step S1902). The case of CRS transmission is a case where the value of RS transmission information is “01” or “11” (see, for example, FIG. 17).

In step S1902, when there is no CRS transmission (step S1902: No), the terminal 120 returns to step S1901. When there is CRS transmission (step S1902: Yes), the terminal 120 measures CQI based on the CRS transmitted from the base station 110 in the U band (step S1903), and ends a series of processes.

Also, for example, when the R120 measurement is performed based on the CRS transmitted from the base station 110 in the U band, the terminal 120 performs the steps illustrated in FIG. 19 for each subframe. However, in this case, in step S1903, the terminal 120 performs RRM measurement based on the CRS transmitted by the base station 110.

Also, for example, when performing timing tracking and frequency tracking based on CRS transmitted from the base station 110 in the U band, the terminal 120 executes the steps shown in FIG. 19 for each subframe. However, in this case, in step S1903, the terminal 120 performs timing tracking and frequency tracking based on the CRS transmitted by the base station 110.

FIG. 20 is a flowchart showing another example of processing by the terminal in Example 3 of RS transmission information. When RS transmission information 1700 shown in FIG. 17 is used as the RS transmission information, and CSI is measured based on CSI-RS transmitted from base station 110 in the U band, terminal 120, for example, Each step shown in FIG. 20 is executed for each frame.

First, the terminal 120 receives RS transmission information transmitted in the L band by the base station 110 (step S2001). Next, the terminal 120 determines whether there is CSI-RS transmission for the current subframe based on the RS transmission information received in step S2001 (step S2002). The case of CSI-RS transmission is a case where the value of RS transmission information is “10” or “11” (see, for example, FIG. 17).

In step S2002, when there is no CSI-RS transmission (step S2002: No), the terminal 120 returns to step S2001. When there is CSI-RS transmission (step S2002: Yes), the terminal 120 measures CSI based on the CSI-RS transmitted from the base station 110 in the U band (step S2003), and ends a series of processes. To do.

(Example 4 of RS transmission information)
FIG. 21 is a diagram illustrating Example 4 of RS transmission information. The RS transmission information transmitted by the base station 110 may be, for example, RS transmission information 2100 illustrated in FIG. The RS transmission information 2100 shown in FIG. 21 is 2-bit information, and indicates the transmission data format when there is RS transmission in addition to the presence or absence of RS transmission.

For example, the RS transmission information 2100 indicates that there is no RS transmission (no RS transmission) when the value is “00”. Further, in the RS transmission information 2100, when the value is “01”, there is RS transmission, and the transmission data format is “format 1”. Further, in the RS transmission information 2100, when the value is “10”, there is RS transmission, and the transmission data format is “format 2”. The RS transmission information 2100 indicates that there is RS transmission when the value is “11”, and the transmission data format is “format 3”.

The transmission data format is, for example, a format related to the start position and end position of the data signal in the subframe. The start position and the end position of the data signal are represented by OFDM (Orthogonal Frequency Division Multiplexing) symbols, respectively.

As an example, “format 1” is a format in which the start position of the data signal is the second OFDM symbol and the end position of the data signal is the 14th OFDM symbol. “Format 2” is a format in which the start position of the data signal is the first OFDM symbol and the end position of the data signal is the 14th OFDM symbol. “Format 3” is a format in which the start position of the data signal is the first OFDM symbol and the end position of the data signal is the thirteenth OFDM symbol.

Thus, the control information can be reduced by adopting a configuration in which the transmission data format is notified using the RS transmission information.

(Transmission data in three formats)
FIG. 22 is a diagram illustrating an example of transmission data in three formats. In FIG. 22, the horizontal axis (t) indicates time. For example, as shown in FIG. 22, base station 110 performs data transmissions 2201 to 2204 in subframes sb1 to sb4, respectively. Data transmissions 2201 to 2204 are data transmissions of “format 1”, “format 2”, “format 2”, and “format 3”, respectively.

In this way, the base station 110 transmits data using one of three formats for each subframe. Then, the base station 110 notifies the terminal 120 of the transmission data format in addition to the RS transmission by the RS transmission information 2100.

(Modification 1 in Example 4 of RS transmission information)
FIG. 23 is a diagram illustrating a first modification of the fourth example of RS transmission information. When there are two transmission data formats used by the base station 110, the RS transmission information transmitted by the base station 110 may be, for example, the RS transmission information 2300 illustrated in FIG. The RS transmission information 2300 shown in FIG. 23 is 2-bit information, and indicates the transmission data format when there is RS transmission in addition to the presence or absence of RS transmission.

For example, the RS transmission information 2300 indicates that there is no RS transmission (no RS transmission) when the value is “00”. Further, in the RS transmission information 2300, when the value is “01”, there is RS transmission, and the transmission data format is “format 1”. Further, in the RS transmission information 2300, when the value is “10”, there is RS transmission, and the transmission data format is “format 2”.

(Transmission data in two formats)
FIG. 24 is a diagram illustrating an example of transmission data in two formats. In FIG. 24, the same parts as those shown in FIG. For example, as shown in FIG. 24, the base station 110 performs data transmission 2401 to 2403 in subframes sb1 to sb3, respectively. Data transmissions 2401 to 2403 are data transmissions of “format 1”, “format 2”, and “format 2”, respectively.

Thus, the base station 110 may perform data transmission using one of two formats for each subframe. Then, the base station 110 notifies the terminal 120 of the transmission data format in addition to the RS transmission by the RS transmission information 2100.

(Modification 2 in example 4 of RS transmission information)
FIG. 25 is a diagram illustrating a second modification of the fourth example of RS transmission information. When there are two transmission data formats used by the base station 110, the RS transmission information transmitted by the base station 110 may be, for example, the RS transmission information 2500 illustrated in FIG. The RS transmission information 2500 shown in FIG. 25 is 2-bit information, and indicates the transmission data format and the presence / absence of data transmission when there is RS transmission in addition to the presence / absence of RS transmission.

For example, the RS transmission information 2500 indicates that there is no RS transmission (no RS transmission) when the value is “00”. Further, in the RS transmission information 2500, when the value is “01”, it indicates that there is RS transmission and the transmission data format is “format 1”. In addition, when the value is “10”, the RS transmission information 2500 indicates that there is RS transmission and the transmission data format is “format 2”. Further, in the RS transmission information 2500, when the value is “11”, it indicates that there is RS transmission and no data transmission.

23 to 25, the modification example of the RS transmission information example 4 has been described. Hereinafter, the case of using the RS transmission information 2100 illustrated in FIG. 21 will be described.

(Processing by base station in RS transmission information example 4)
FIG. 26 is a flowchart illustrating an example of processing by the base station in the fourth example of RS transmission information. When the RS transmission information 2100 illustrated in FIG. 21 is used as the RS transmission information, the base station 110 executes, for example, each step illustrated in FIG. 26 for each subframe.

First, the base station 110 determines whether or not the RS transmission timer satisfies a specified value (step S2601). When the RS transmission timer satisfies the specified value (step S2601: Yes), the base station 110 determines whether or not RS can be transmitted in the next subframe (step S2602). For example, when the base station 110 is continuously transmitting a radio signal, or when a transmission opportunity is secured by detecting a vacant band by carrier sense and transmitting a dummy signal, a preamble signal, etc., It is determined that RS can be transmitted in the subframe. In addition, the base station 110 determines that the RS cannot be transmitted in the next subframe when the radio signal is not continuously transmitted and the transmission opportunity is not secured by a dummy signal or a preamble signal.

In step S2602, when the RS can be transmitted in the next subframe (step S2602: Yes), the base station 110 sets the RS transmission information based on the data transmission format (step S2603). For example, in the example shown in FIG. 21, base station 110 sets RS transmission information to “01” when “format 1” is used for data transmission of the next subframe. Also, the base station 110 sets the RS transmission information to “10” when “format 2” is used for data transmission of the next subframe. Further, the base station 110 sets the RS transmission information to “11” when “format 3” is used for data transmission of the next subframe.

In addition, the base station 110 resets the RS transmission timer (step S2604), and ends a series of processes.

In step S2602, if the RS cannot be transmitted in the next subframe (step S2602: No), the base station 110 sets the RS transmission information to be transmitted to “00” (no RS transmission) (step S2605). Further, the base station 110 advances the RS transmission timer by one subframe (step S2606). Then, the base station 110 ends a series of processes.

In step S2601, when the RS transmission timer does not satisfy the specified value (step S2601: No), the base station 110 determines whether there is transmission data to the terminal 120 and whether RS simultaneous transmission is required (step S2601: No). Step S2607). When it is determined that there is transmission data to terminal 120 and RS simultaneous transmission is required (step S2607: Yes), base station 110 determines whether or not RS can be transmitted in the next subframe (step S2607). S2608). The determination in step S2608 is the same as the determination in step S2602.

In step S2608, when the RS can be transmitted in the next subframe (step S2608: Yes), the base station 110 sets the RS transmission information based on the data transmission format (step S2609). The setting in step S2609 is the same as the setting in step S2603, for example. In addition, the base station 110 resets the RS transmission timer (step S2610), and ends a series of processes.

If it is determined in step S2607 that there is no transmission data to the terminal 120 or that RS simultaneous transmission is not required (step S2607: No), the base station 110 sets the RS transmission information to be transmitted to “00” (RS transmission). (None) (step S2611). Further, the base station 110 advances the RS transmission timer by one subframe (step S2612). And the base station 110 complete | finishes a series of processes.

In step S2608, when the RS cannot be transmitted in the next subframe (step S2608: No), the base station 110 proceeds to step S2611.

(Processing by terminal in RS transmission information example 4)
FIG. 27 is a flowchart illustrating an example of processing performed by a terminal in the fourth example of RS transmission information. When RS transmission information 2100 shown in FIG. 21 is used as RS transmission information and terminal 120 does not receive data in the current subframe, terminal 120 executes, for example, each step shown in FIG. 27 for each subframe. . The case where the terminal 120 does not receive data in the current subframe is, for example, the case where the terminal 120 does not receive the PDCCH for resource allocation in the current subframe from the base station 110.

First, the terminal 120 receives RS transmission information transmitted in the L band by the base station 110 (step S2701). Next, the terminal 120 determines whether or not there is RS transmission for the current subframe based on the RS transmission information received in step S2701 (step S2702). The case of RS transmission is a case where the value of RS transmission information is “01”, “10”, or “11” (see, for example, FIG. 21).

In step S2702, when there is no RS transmission (step S2702: No), the terminal 120 returns to step S2701. When there is RS transmission (step S2702: Yes), the terminal 120 measures CQI based on the RS transmitted from the base station 110 in the U band (step S2703), and ends a series of processes.

In addition, for example, when the terminal 120 performs RRM measurement based on the RS transmitted from the base station 110 in the U band, the terminal 120 performs the steps illustrated in FIG. 27 for each subframe. However, in this case, in step S2703, the terminal 120 performs RRM measurement based on the RS transmitted by the base station 110.

Also, for example, when performing timing tracking and frequency tracking based on RS transmitted from the base station 110 in the U band, the terminal 120 executes the steps shown in FIG. 27 for each subframe. However, in this case, in step S2703, the terminal 120 performs timing tracking and frequency tracking based on the RS transmitted by the base station 110.

FIG. 28 is a flowchart illustrating another example of processing by the terminal in the fourth example of RS transmission information. When RS transmission information 2100 shown in FIG. 21 is used as RS transmission information and terminal 120 receives data in the current subframe, terminal 120 executes each step shown in FIG. 28 for each subframe, for example. The case where the terminal 120 receives data in the current subframe is, for example, a case where the terminal 120 receives the PDCCH for resource allocation in the current subframe from the base station 110.

First, the terminal 120 receives RS transmission information transmitted in the L band by the base station 110 (step S2801). Next, the terminal 120 determines whether or not there is RS transmission for the current subframe based on the RS transmission information received in step S2801 (step S2802). The case of RS transmission is a case where the value of RS transmission information is “01”, “10”, or “11” (see, for example, FIG. 21).

In step S2802, if there is no RS transmission (step S2802: No), the terminal 120 returns to step S2801. If RS transmission is present (step S2802: YES), the terminal 120 extracts data from a radio signal transmitted in the U band from the base station 110, performs reception processing (step S2803), and ends a series of processing. . The data extraction and reception processing in step S2803 can be performed based on the transmission data format indicated by the RS transmission information received in step S2801.

(Synchronous signal transmission information)
FIG. 29 is a diagram illustrating an example of the synchronization signal transmission information. The base station 110 may transmit, for example, the synchronization signal transmission information 2900 illustrated in FIG. 29 to the terminal 120 together with the RS transmission information described above or instead of the RS transmission information described above. The synchronization signal transmission information 2900 is 1-bit information and indicates whether or not a synchronization signal is scheduled to be transmitted. The synchronization signal is, for example, a PSS (Primary Synchronization Signal) or SSS (Secondary Synchronization Signal) transmitted by the base station 110. As the arrangement of the PSS and the SSS in the radio resource, for example, an arrangement example defined in 3GPP TS36.211 can be used.

For example, when the value is “0”, the synchronization signal transmission information 2900 indicates that the synchronization signal transmission is not scheduled (no synchronization signal transmission is scheduled), and when the value is “1”, the synchronization signal transmission is scheduled. (Synchronization signal is scheduled to be transmitted). For example, in the case where it is not possible to determine the presence or absence of synchronization signal transmission, the synchronization signal transmission information 2900 indicating whether or not the synchronization signal transmission is scheduled can be used. The case where the presence / absence of synchronization signal transmission cannot be determined is the same as the case where the presence / absence of RS transmission cannot be determined at the time of transmission of the RS transmission information shown in FIGS. 14A and 14B, for example.

(Processing by base station when using synchronous signal transmission information)
FIG. 30 is a flowchart illustrating an example of processing performed by the base station when the synchronization signal transmission information is used. When using the synchronization signal transmission information 2900 shown in FIG. 29 as the synchronization signal transmission information, the base station 110 executes, for example, each step shown in FIG. 30 for each subframe. In addition, when transmitting a plurality of types of synchronization signals (for example, PSS and SSS) in the U band, base station 110 may execute the steps shown in FIG. 30 for each of the synchronization signals to be transmitted.

First, the base station 110 determines whether or not the synchronization signal transmission timer satisfies a specified value (step S3001). The synchronization signal transmission timer is a timer for measuring the transmission timing (transmission subframe) of the target synchronization signal, and is set according to the transmission interval of the synchronization signal required in, for example, timing tracking or frequency tracking. In step S3001, when the synchronization signal transmission timer satisfies the specified value (step S3001: Yes), the base station 110 sets the synchronization signal transmission information to be transmitted to “1” (synchronization signal transmission scheduled) (step S3002). ).

Next, the base station 110 performs a synchronization signal transmission process (step S3003). For example, the base station 110 performs carrier sense in the U band, and transmits a synchronization signal when a free band is detected by carrier sense. In addition, when the radio signal is being continuously transmitted in the U band, the base station 110 transmits a synchronization signal without performing carrier sense. On the other hand, the base station 110 does not transmit a synchronization signal when a wireless signal is not continuously transmitted in the U band and a vacant band is not detected even after performing carrier sense.

Next, the base station 110 determines whether or not the synchronization signal has been transmitted in step S3003 (step S3004). When the synchronization signal can be transmitted (step S3004: Yes), the base station 110 resets the synchronization signal transmission timer (step S3005) and ends the series of processes. When the synchronization signal cannot be transmitted (step S3004: No), the base station 110 advances the synchronization signal transmission timer by one subframe (step S3006). And the base station 110 complete | finishes a series of processes.

In step S3001, when the synchronization signal transmission timer does not satisfy the specified value (step S3001: No), the base station 110 determines whether there is transmission data to the terminal 120 and whether synchronization signal simultaneous transmission is required. (Step S3007). When it is determined that there is transmission data to the terminal 120 and synchronization signal simultaneous transmission is required (step S3007: Yes), the base station 110 proceeds to step S3002. If it is determined that there is no transmission data to the terminal 120 or that synchronous signal simultaneous transmission is not required (step S3007: No), the base station 110 proceeds to step S3008.

That is, the base station 110 sets the synchronization signal transmission information to be transmitted to “0” (no synchronization signal transmission) (step S3008). Also, the base station 110 advances the synchronization signal transmission timer by one subframe (step S3009). And the base station 110 complete | finishes a series of processes.

(Processing by terminal when using synchronous signal transmission information)
FIG. 31 is a flowchart illustrating an example of processing performed by the terminal when the synchronization signal transmission information is used. When using the synchronization signal transmission information 2900 shown in FIG. 29 and performing timing tracking and frequency tracking based on the synchronization signal transmitted in the U band from the base station 110, the terminal 120 is shown in FIG. 31 for each subframe. Perform each step.

First, the terminal 120 receives synchronization signal transmission information transmitted in the L band by the base station 110 (step S3101). Next, the terminal 120 determines whether or not there is a synchronization signal transmission schedule (synchronization signal transmission information = 1) for the current subframe based on the synchronization signal transmission information received in step S3101 (step S3102).

In step S3102, if the synchronization signal transmission is not scheduled (step S3102: No), the terminal 120 ends the series of processes. If the synchronization signal is scheduled to be transmitted (step S3102: Yes), the terminal 120 performs a synchronization signal detection process for detecting a synchronization signal from the base station 110 in the U band (step S3103). For example, the terminal 120 calculates a correlation between the replica signal of the synchronization signal and the received signal, and performs a synchronization signal detection process that determines that there is a synchronization signal transmission when the calculated correlation is higher than a threshold value.

Next, the terminal 120 determines whether or not there is a synchronization signal transmission from the base station 110 in the U band based on the result of the synchronization signal detection process in step S3103 (step S3104). When there is no synchronization signal transmission (step S3104: No), the terminal 120 ends a series of processes. When there is a synchronization signal transmission (step S3104: Yes), the terminal 120 performs at least one of timing tracking and frequency tracking based on the synchronization signal transmitted from the base station 110 in the U band (step S3105), Terminate the process.

Also, for example, when the synchronization processing is performed based on the synchronization signal transmitted from the base station 110 in the U band, the terminal 120 performs the steps illustrated in FIG. 31 for each subframe. However, in this case, in step S3105, the terminal 120 performs synchronization processing based on the synchronization signal transmitted by the base station 110.

Also, for example, when performing timing tracking and frequency tracking based on a synchronization signal transmitted from the base station 110 in the U band, the terminal 120 executes each step shown in FIG. 31 for each subframe. However, in this case, in step S3105, the terminal 120 performs timing tracking and frequency tracking based on the synchronization signal transmitted by the base station 110.

Further, the terminal 120 may perform reception processing of data transmitted from the base station 110 simultaneously with the synchronization signal, together with timing tracking and frequency tracking in step S3105.

29 to 31, the case where the synchronization signal transmission information 2900 indicating whether or not the synchronization signal is scheduled to be transmitted has been described. On the other hand, for example, in the case where the presence / absence of synchronization signal transmission can be determined at the time of transmission of the synchronization signal transmission information, a synchronization signal indicating the presence / absence of transmission of the synchronization signal as in the RS transmission information 500 shown in FIG. Transmission information may be used.

(Example 5 of RS transmission information)
FIG. 32 is a diagram illustrating Example 5 of RS transmission information. The RS transmission information transmitted by the base station 110 may be, for example, RS transmission information 3200 illustrated in FIG. The RS transmission information 3200 shown in FIG. 32 is an extension of the RS transmission information 2100 shown in FIG. That is, RS transmission information 3200 is 2-bit information, and whether RS and PSS / SSS are transmitted and whether transmission is scheduled in the first subframe in continuous transmission or transmission is performed in a subframe other than the first. Indicates whether there is. In the example illustrated in FIG. 32, a case where the base station 110 transmits a CRS as an RS will be described.

For example, if the value of the RS transmission information 3200 is “00”, it indicates that CRS and PSS / SSS are not transmitted (no transmission). In addition, when the value is “01”, the RS transmission information 3200 indicates that CRS and PSS / SSS are scheduled to be transmitted in the first subframe (including PSS / SSS / CRS). Further, when the value of the RS transmission information 3200 is “10”, it indicates that there is CRS transmission in a subframe other than the head, and that there is no PSS / SSS transmission (with CRS without PSS / SSS). Further, when the value is “11”, the RS transmission information 3200 indicates that there is transmission in a subframe other than the head, but there is no transmission of CRS and PSS / SSS (no CRS without PSS / SSS).

PSS and SSS have the following characteristics because they use more elements in one subframe than CRS. That is, by using PSS and SSS in addition to CRS, timing tracking and frequency tracking that can be executed in one subframe are improved, and the RS transmission cycle for synchronization can be extended. In addition, the detection accuracy when the terminal 120 detects blindly becomes higher by using PSS and SSS in addition to CRS as compared with the case where only CRS is used. For this reason, the efficiency of blind detection and synchronization in terminal 120 can be improved by including PSS and SSS in the first subframe of continuous transmission.

(First subframe in continuous transmission)
FIG. 33 is a diagram illustrating an example of a head subframe in continuous transmission. In FIG. 33, the horizontal axis (t) indicates time. For example, as shown in FIG. 33, base station 110 performs data transmissions 3301 to 3303 continuously over subframes sb2 to sb4. In this case, the base station 110 transmits a radio signal including at least one of PSS and SSS in the data transmission 3301 in the first subframe sb2.

(Processing by base station in example 5 of RS transmission information)
FIG. 34 is a flowchart illustrating an example of processing by the base station in Example 5 of RS transmission information. When the RS transmission information 3200 shown in FIG. 32 is used as the RS transmission information, the base station 110 executes, for example, each step shown in FIG. 34 for each subframe. In addition, when transmitting a plurality of types of synchronization signals (for example, PSS and SSS) in the U band, base station 110 may execute the steps shown in FIG. 34 for each of the synchronization signals to be transmitted.

First, the base station 110 determines whether or not the synchronization signal transmission timer satisfies a specified value (step S3401). In step S3401, when the synchronization signal transmission timer satisfies the specified value (step S3401: YES), the base station 110 sets the RS transmission information to be transmitted to “01” (step S3402).

Next, the base station 110 performs a synchronization signal transmission process (step S3403). For example, the base station 110 performs carrier sense in the U band, and transmits a synchronization signal when a free band is detected by carrier sense. In addition, when the radio signal is being continuously transmitted in the U band, the base station 110 transmits a synchronization signal without performing carrier sense. In addition, the base station 110 does not transmit a synchronization signal when a wireless signal is not continuously transmitted in the U band and no vacant band is detected even after performing carrier sense. Moreover, the base station 110 also transmits CRS, when a synchronization signal can be transmitted in step S3403.

Next, the base station 110 determines whether or not the synchronization signal has been transmitted in step S3403 (step S3404). If the synchronization signal can be transmitted (step S3404: YES), the base station 110 resets the synchronization signal transmission timer (step S3405) and ends the series of processes. If the synchronization signal cannot be transmitted (step S3404: NO), the base station 110 advances the synchronization signal transmission timer and the CRS transmission timer by one subframe (step S3406). And the base station 110 complete | finishes a series of processes.

In step S3401, if the synchronization signal transmission timer does not satisfy the specified value (step S3401: NO), the base station 110 proceeds to step S3407. That is, the base station 110 determines whether there is transmission data to the terminal 120 and whether the target subframe is the first subframe in continuous transmission (step S3407). The case where the target subframe is the first subframe in continuous transmission is, for example, the case where a signal is not transmitted in a subframe before the target subframe.

In step S3407, if it is determined that there is transmission data to the terminal 120 and that it is the first subframe (step S3407: Yes), the base station 110 moves to step S3402. If it is determined that there is no transmission data to the terminal 120 or that it is not the first subframe (step S3407: No), the base station 110 proceeds to step S3408.

That is, the base station 110 determines whether or not the first subframe in the continuous transmission has been transmitted and the CRS transmission timer satisfies the specified value (step S3408). When the first subframe has been transmitted and the CRS transmission timer satisfies the specified value (step S3408: Yes), the base station 110 determines whether the current subframe is an intermediate subframe (step S3409). .

In step S3409, if it is an intermediate subframe (step S3409: Yes), the base station 110 sets the RS transmission information to be transmitted to “10” (step S3410). In addition, the base station 110 resets the CRS transmission timer (step S3411), and ends a series of processes.

In step S3409, if it is not an intermediate subframe (step S3409: No), the base station 110 sets the RS transmission information to be transmitted to “11” (step S3412). In addition, the base station 110 resets the CRS transmission timer (step S3413) and ends the series of processes.

In step S3408, if the first subframe has not been transmitted or the CRS transmission timer does not satisfy the specified value (step S3408: No), the base station 110 sets the RS transmission information to be transmitted to “00” ( Step S3414). In addition, the base station 110 advances the CRS transmission timer by one subframe (step S3415). And the base station 110 complete | finishes a series of processes.

(Processing by terminal in RS transmission information example 5)
FIG. 35 is a flowchart illustrating an example of a process performed by a terminal in RS transmission information example 5. When RS transmission information 3200 shown in FIG. 32 is used as RS transmission information and timing tracking and frequency tracking are performed based on PSS / SSS from base station 110, terminal 120 shows, for example, for each subframe shown in FIG. Perform each step.

First, the terminal 120 receives RS transmission information transmitted in the L band by the base station 110 (step S3501). Next, based on the RS transmission information received in step S3501, the terminal 120 determines whether or not there is a PSS / SSS transmission schedule (RS transmission information = 01) for the current subframe (step S3502). When there is no PSS / SSS transmission plan (step S3502: No), the terminal 120 ends a series of processes.

In step S3502, when there is a PSS / SSS transmission plan (step S3502: Yes), the terminal 120 detects PSS / SSS transmitted from the base station 110 in the U band. If the terminal 120 succeeds in detecting the PSS / SSS, the terminal 120 performs at least one of timing tracking and frequency tracking based on the detected PSS / SSS (step S3503), and ends the series of processes.

FIG. 36 is a flowchart showing another example of processing by the terminal in Example 5 of RS transmission information. When RS transmission information 3200 shown in FIG. 32 is used as RS transmission information and CQI measurement is performed based on CRS from base station 110, terminal 120 executes each step shown in FIG. 36 for each subframe, for example. To do.

First, the terminal 120 receives RS transmission information transmitted in the L band by the base station 110 (step S3601). Next, based on the RS transmission information received in step S3601, the terminal 120 determines whether there is CRS transmission (RS transmission information = 01 or 10) for the current subframe (step S3602).

If there is CRS transmission in step S3602 (step S3602: Yes), terminal 120 measures CQI based on CRS transmitted from base station 110 in the U band (step S3603), and ends a series of processing. To do.

In step S3602, if there is no CRS transmission (step S3602: No), the terminal 120 proceeds to step S3604. That is, terminal 120 determines whether or not there is a PSS / SSS transmission plan for the current subframe (RS transmission information = 01) based on the RS transmission information received in step S3601 (step S3604). If the PSS / SSS transmission is not scheduled (step S3604: NO), the terminal 120 ends the series of processes.

In step S3604, when there is a PSS / SSS transmission plan (step S3604: Yes), the terminal 120 detects PSS / SSS transmitted from the base station 110 in the U band. If the terminal 120 succeeds in detecting the PSS / SSS, the terminal 120 measures the CQI based on the detected PSS / SSS (step S3605), and ends the series of processes.

(Example 6 of RS transmission information)
FIG. 37 is a diagram illustrating Example 6 of RS transmission information. The RS transmission information transmitted by the base station 110 may be, for example, RS transmission information 3700 illustrated in FIG. The RS transmission information 3700 shown in FIG. 37 is obtained by replacing CSI-RS with at least one of PSS and SSS (PSS / SSS) in the RS transmission information 1700 shown in FIG. That is, the RS transmission information 3700 shown in FIG. 37 is 2-bit information, and indicates whether or not PSS / SSS is transmitted in addition to the presence or absence of RS transmission. In the example illustrated in FIG. 37, a case where the base station 110 transmits a CRS as an RS will be described.

For example, the RS transmission information 3700 indicates that there is no RS transmission (no RS transmission) when the value is “00”. The RS transmission information 3700 indicates that there is CRS transmission and no PSS / SSS transmission (with CRS transmission) when the value is “01”. Further, the RS transmission information 3700 indicates that there is PSS / SSS transmission and no CRS transmission (with PSS / SSS transmission) when the value is “10”. Further, when the value of the RS transmission information 3700 is “11”, it indicates that both CRS and PSS / SSS are transmitted (CRS and PSS / SSS are transmitted).

When the RS transmission information 3700 shown in FIG. 37 is used as the RS transmission information, the processing by the base station 110 replaces CSI-RS with at least one of PSS and SSS (PSS / SSS), for example, in the processing shown in FIG. Processing. The processing by the terminal 120 in this case is, for example, the processing shown in FIG. 20 in which CSI-RS is replaced with at least one of PSS and SSS, and CSI measurement is replaced with at least one of timing tracking and frequency tracking. Can do.

(Base station according to the embodiment)
FIG. 38A is a diagram illustrating an example of a base station according to the embodiment. FIG. 38B is a diagram illustrating an example of signal flow in the base station depicted in FIG. 38A. As illustrated in FIGS. 38A and 38B, the base station 110 includes an antenna 3801, an L-band RF unit 3802, and an uplink baseband signal processing unit 3803. Further, the base station 110 includes a downlink control unit 3804, a downlink control channel processing unit 3805, a downlink data channel processing unit 3806, and a downlink L band baseband signal generation unit 3807. In addition, the base station 110 includes an antenna 3808, a U-band RF unit 3809, a carrier sense unit 3810, and a downlink U-band baseband signal generation unit 3811.

Antenna 3801 receives a signal wirelessly transmitted from terminal 120 and outputs the signal to L-band RF unit 3802. Antenna 3801 wirelessly transmits the signal output from L-band RF section 3802 to terminal 120.

The L-band RF unit 3802 extracts an L-band signal from the uplink signal output from the antenna 3801, and performs an RF reception process on the extracted signal. The RF reception processing by the L-band RF unit 3802 includes, for example, amplification, frequency conversion from an L-band RF (Radio Frequency) band to a baseband band, conversion from an analog signal to a digital signal, and the like. The L-band RF unit 3802 outputs the signal subjected to the RF reception processing to the uplink baseband signal processing unit 3803.

Also, the L-band RF unit 3802 performs RF transmission processing of the downlink signal output from the downlink L-band baseband signal generation unit 3807. The RF transmission processing by the L band RF unit 3802 includes, for example, conversion from a digital signal to an analog signal, frequency conversion from a baseband band to an L band RF band, amplification, and the like. L-band RF unit 3802 outputs the signal subjected to the RF transmission process to antenna 3801.

The uplink baseband signal processing unit 3803 performs baseband signal processing on the uplink signals output from the L-band RF unit 3802 and the U-band RF unit 3809. Then, uplink baseband signal processing section 3803 outputs control information included in the data obtained by the baseband signal processing to downlink control section 3804.

The downlink control unit 3804 controls downlink communication from the base station 110 to the terminal 120 based on the control information output from the uplink baseband signal processing unit 3803. For example, the downlink control unit 3804 notifies the downlink U-band baseband signal generation unit 3811 of a transmission mode indicating a radio signal transmission scheme by the base station 110.

Also, the downlink control unit 3804 controls the generation of control information by the downlink control channel processing unit 3805. For example, the downlink control unit 3804 notifies the downlink control channel processing unit 3805 of the number of the U-band frequency channel to be used. Also, the downlink control unit 3804 controls transmission data generation by the downlink data channel processing unit 3806.

The downlink control channel processing unit 3805 generates control information for L band to be transmitted through the downlink control channel under the control of the downlink control unit 3804. The control information generated by the downlink control channel processing unit 3805 includes RS transmission information indicating the RS transmission timing notified from the downlink U band baseband signal generation unit 3811. The downlink control channel processing unit 3805 outputs the generated control information to the downlink L band baseband signal generation unit 3807.

The downlink data channel processing unit 3806 generates transmission data to be transmitted through the downlink data channel under the control of the downlink control unit 3804. Then, the downlink data channel processing unit 3806 transmits the transmission data (L-band transmission data) to be transmitted in the L band of the generated transmission data under the control of the downlink control unit 3804 to the downlink L-band baseband. The signal is output to the signal generation unit 3807. Also, the downlink data channel processing unit 3806 outputs transmission data (U-band transmission data) to be transmitted in the U band among the generated transmission data to the downlink U band baseband signal generation unit 3811.

The downlink L band baseband signal generation unit 3807 generates a baseband signal in the downlink L band from the base station 110 to the terminal 120. The signal generated by the downlink L-band baseband signal generation unit 3807 includes control information output from the downlink control channel processing unit 3805, transmission data for L band output from the downlink data channel processing unit 3806, and Is included. The downlink L band baseband signal generation unit 3807 outputs the generated signal to the L band RF unit 3802.

The antenna 3808 receives a signal wirelessly transmitted from the terminal 120 and outputs the signal to the U-band RF unit 3809. Further, antenna 3808 wirelessly transmits the signal output from U-band RF section 3809 to terminal 120.

The U-band RF unit 3809 extracts a U-band signal from uplink signals output from the antenna 3808, and performs RF reception processing on the extracted signal. The RF reception processing by the U-band RF unit 3809 includes, for example, amplification, frequency conversion from the U-band RF band to the baseband, conversion from an analog signal to a digital signal, and the like. U-band RF section 3809 outputs the signal subjected to the RF reception process to uplink baseband signal processing section 3803 and carrier sense section 3810.

Also, the U-band RF unit 3809 performs RF transmission processing of the downlink signal output from the downlink U-band baseband signal generation unit 3811. The RF transmission processing by the U-band RF unit 3809 includes, for example, conversion from a digital signal to an analog signal, frequency conversion from a baseband band to a U-band RF band, amplification, and the like. U-band RF section 3809 outputs the signal subjected to the RF transmission processing to antenna 3808.

The carrier sense unit 3810 performs carrier sense based on the signal output from the U-band RF unit 3809. Then, the carrier sense unit 3810 notifies the result of the carrier sense to the downlink U band baseband signal generation unit 3811. For example, when the carrier sense unit 3810 detects a free band as a result of the carrier sense, the carrier sense unit 3810 notifies the downlink U band baseband signal generation unit 3811 that the free band has been detected.

The downlink U band baseband signal generation unit 3811 generates a baseband signal in the downlink U band from the base station 110 to the terminal 120 under the control of the downlink control unit 3804. Then, the downlink U band baseband signal generation unit 3811 outputs the baseband signal to the U band RF unit 3809 at the timing when the carrier sense unit 3810 is notified that a free band has been detected.

The signal generated by the downlink U-band baseband signal generation unit 3811 is transmitted as an L-band transmission data output from the downlink data channel processing unit 3806 and an RS transmitted together with the L-band transmission data or independently. RS.

Also, the downlink U band baseband signal generation unit 3811 notifies the downlink control channel processing unit 3805 of the RS transmission timing. Thereby, RS transmission information indicating RS transmission timing in the U band is multiplexed with data, for example, and transmitted to the terminal 120 through the L band.

1A and 1B can be realized, for example, by an antenna 3808, a U-band RF unit 3809, a carrier sense unit 3810, and a downlink U-band baseband signal generation unit 3811. 1A and 1B can be implemented by, for example, antenna 3801, L-band RF unit 3802, downlink control channel processing unit 3805, and downlink L-band baseband signal generation unit 3807. .

FIG. 38C is a diagram illustrating an example of a hardware configuration of the base station. The base station 110 shown in FIGS. 38A and 38B can be realized by the communication device 3830 shown in FIG. 38C, for example. The communication device 3830 includes a processor 3831, a main storage device 3832, an auxiliary storage device 3833, a network interface 3834, a radio device 3835, and an antenna 3836. The processor 3831, the main storage device 3832, the auxiliary storage device 3833, the network interface 3834, and the wireless device 3835 are connected by a bus 3839.

The processor 3831 governs overall control of the communication device 3830. The processor 3831 can be realized by, for example, a CPU (Central Processing Unit). The main storage device 3832 is used as a work area of the processor 3831, for example. The main memory 3832 can be realized by, for example, a RAM (Random Access Memory).

The auxiliary storage device 3833 is a non-volatile memory such as a magnetic disk, an optical disk, or a flash memory. The auxiliary storage device 3833 stores various programs for operating the communication device 3830. The program stored in the auxiliary storage device 3833 is loaded into the main storage device 3832 and executed by the processor 3831.

The network interface 3834 is a communication interface that communicates with the outside of the communication device 3830 (for example, a host device of the base station 110 or a core network) by, for example, wireless or wired. The network interface 3834 is controlled by the processor 3831.

The wireless device 3835 is a communication interface that performs communication with another communication device (for example, the terminal 120) wirelessly using the antenna 3836. The wireless device 3835 is controlled by the processor 3831.

The

antennas

3801 and 3808 shown in FIGS. 38A and 38B can be realized by the antenna 3836, for example. The L-band RF unit 3802 and the U-band RF unit 3809 shown in FIGS. 38A and 38B can be realized by, for example, the wireless device 3835.

The uplink baseband signal processing unit 3803, the downlink control unit 3804, the downlink control channel processing unit 3805, and the downlink data channel processing unit 3806 shown in FIGS. 38A and 38B can be realized by the processor 3831, for example. The downlink L-band baseband signal generation unit 3807, the carrier sense unit 3810, and the downlink U-band baseband signal generation unit 3811 illustrated in FIGS. 38A and 38B can be realized by the processor 3831, for example.

(Terminal according to the embodiment)
FIG. 39A is a diagram illustrating an example of a terminal according to the embodiment. FIG. 39B is a diagram showing an example of a signal flow in the terminal shown in FIG. 39A. As illustrated in FIGS. 39A and 39B, the terminal 120 includes an antenna 3901, an L-band RF unit 3902, a downlink baseband signal processing unit 3903, an uplink control channel processing unit 3904, and an uplink baseband signal. A generation unit 3905. In addition, the terminal 120 includes an antenna 3906, a U-band RF unit 3907, and a downlink U-band baseband signal processing unit 3908.

Antenna 3901 receives a signal wirelessly transmitted from base station 110 and outputs the signal to L-band RF unit 3902. The antenna 3901 wirelessly transmits the signal output from the L-band RF unit 3902 to the base station 110.

The L-band RF unit 3902 extracts an L-band signal from the uplink signal output from the antenna 3901 and performs RF reception processing on the extracted signal. The RF reception processing by the L band RF unit 3902 includes, for example, amplification, frequency conversion from the L band RF band to the base band, conversion from an analog signal to a digital signal, and the like. L-band RF section 3902 outputs the signal subjected to the RF reception process to downlink baseband signal processing section 3903.

Also, the L-band RF unit 3902 performs RF transmission processing on the uplink signal output from the uplink baseband signal generation unit 3905. The RF transmission processing by the L band RF unit 3902 includes, for example, conversion from a digital signal to an analog signal, frequency conversion from a baseband band to an L band RF band, amplification, and the like. L-band RF section 3902 outputs a signal subjected to RF transmission processing to antenna 3901.

The downlink baseband signal processing unit 3903 performs baseband signal processing on the downlink signal output from the L-band RF unit 3902. The baseband signal processing by the downlink baseband signal processing unit 3903 includes, for example, measurement of CQI in the downlink L band.

The downlink baseband signal processing unit 3903 outputs control information related to the L band based on the baseband signal processing to the uplink control channel processing unit 3904. The control information output by the downlink baseband signal processing unit 3903 to the uplink control channel processing unit 3904 includes, for example, a measurement result of CQI in the downlink L band.

Also, the downlink baseband signal processing unit 3903 outputs control information related to the U band based on the baseband signal processing to the downlink U band baseband signal processing unit 3908. The control information output from the downlink baseband signal processing unit 3903 to the downlink U band baseband signal processing unit 3908 includes, for example, RS transmission information indicating RS transmission timing in the U band. The control information output from the downlink baseband signal processing unit 3903 to the downlink U band baseband signal processing unit 3908 includes, for example, synchronization signal transmission information indicating the transmission timing of the synchronization signal (PSS / SSS) in the U band. May be included.

The uplink control channel processing unit 3904 generates L-band control information to be transmitted through the uplink control channel. The control information generated by the uplink control channel processing unit 3904 includes control information output from the downlink baseband signal processing unit 3903 (eg, CQI), control information output from the antenna 3906 (eg, CQI measurement results, and RRM measurement results). The uplink control channel processing unit 3904 outputs the generated control information to the uplink baseband signal generation unit 3905.

The uplink baseband signal generation unit 3905 generates a baseband signal in the uplink L band. The signal generated by the uplink baseband signal generation unit 3905 includes, for example, control information output from the uplink control channel processing unit 3904. The signal generated by the uplink baseband signal generation unit 3905 may include uplink L-band transmission data. Uplink baseband signal generation section 3905 outputs the generated signal to L-band RF section 3902.

The antenna 3906 receives a signal wirelessly transmitted from the base station 110 and outputs the signal to the U-band RF unit 3907. The antenna 3906 wirelessly transmits the signal output from the U-band RF unit 3907 to the base station 110.

The U-band RF unit 3907 extracts a U-band signal from uplink signals output from the antenna 3906, and performs an RF reception process on the extracted signal. The RF reception processing by the U-band RF unit 3907 includes, for example, amplification, frequency conversion from the U band RF band to the base band, conversion from an analog signal to a digital signal, and the like. The U-band RF unit 3907 outputs the signal subjected to the RF reception processing to the downlink baseband signal processing unit 3903 and the downlink U-band baseband signal processing unit 3908.

Also, the U-band RF unit 3907 may perform an RF transmission process on an uplink signal to be transmitted by the U band. The RF transmission processing by the U-band RF unit 3907 includes, for example, conversion from a digital signal to an analog signal, frequency conversion from a baseband band to a U-band RF band, amplification, and the like. The U-band RF unit 3907 outputs the signal subjected to the RF transmission process to the antenna 3906.

The downlink U-band baseband signal processing unit 3908 performs baseband signal processing on the downlink signal output from the U-band RF unit 3907. For example, the downlink U band baseband signal processing unit 3908, based on the RS transmission information included in the control information from the downlink baseband signal processing unit 3903, the RS of the RS included in the signal from the U band RF unit 3907. Perform reception processing. Also, the downlink U band baseband signal processing unit 3908 is based on the synchronization signal transmission information included in the control information from the downlink baseband signal processing unit 3903, and the synchronization included in the signal from the U band RF unit 3907. A signal reception process may be performed.

Also, the downlink U-band baseband signal processing unit 3908 performs, for example, reception processing of a synchronization signal included in the signal output from the U-band RF unit 3907. Then, the downlink U band baseband signal processing unit 3908 performs various processes based on the RS and the synchronization signal for which the reception process has been performed. For example, the downlink U-band baseband signal processing unit 3908 includes a synchronization unit 3909, a timing / frequency tracking unit 3910, a CQI measurement unit 3911, and an RRM measurement unit 3912.

The synchronization unit 3909 performs synchronization processing with the base station 110 in the downlink U band based on the synchronization signal obtained by the baseband signal processing in the downlink U band baseband signal processing unit 3908.

Timing / frequency tracking unit 3910 performs timing tracking and frequency tracking in the downlink U band based on RS and PSS / SSS obtained by baseband signal processing. Note that the timing / frequency tracking unit 3910 may perform only one of timing tracking and frequency tracking.

The CQI measurement unit 3911 measures CQI in the downlink U band based on RS and PSS / SSS obtained by the baseband signal processing in the downlink U band baseband signal processing unit 3908.

The RRM measurement unit 3912 measures the RRM in the downlink U band based on the RS obtained by the baseband signal processing in the downlink U band baseband signal processing unit 3908.

Also, the downlink U band baseband signal processing unit 3908 outputs control information based on the baseband processing to the uplink control channel processing unit 3904. The control information output from the downlink U-band baseband signal processing unit 3908 to the uplink control channel processing unit 3904 includes, for example, the CQI measurement result by the CQI measurement unit 3911 and the RRM measurement result by the RRM measurement unit 3912. included.

1A and 1B can be realized by, for example, an antenna 3901, an L-band RF unit 3902, and a downlink baseband signal processing unit 3903. The second receiving unit 122 illustrated in FIGS. 1A and 1B can be realized by, for example, the antenna 3906, the U-band RF unit 3907, and the downlink U-band baseband signal processing unit 3908.

FIG. 39C is a diagram illustrating an example of a hardware configuration of the terminal. The terminal 120 shown in FIGS. 39A and 39B can be realized by, for example, the communication device 3930 shown in FIG. 39C. The communication device 3930 includes a processor 3931, a main storage device 3932, an auxiliary storage device 3933, a user interface 3934, a wireless device 3935, and an antenna 3936. The processor 3931, the main storage device 3932, the auxiliary storage device 3933, the user interface 3934 and the wireless device 3935 are connected by a bus 3939.

The processor 3931 manages the overall control of the communication device 3930. The processor 3931 can be realized by a CPU, for example. The main storage device 3932 is used as a work area of the processor 3931, for example. The main storage device 3932 can be realized by a RAM, for example.

The auxiliary storage device 3933 is a non-volatile memory such as a magnetic disk, an optical disk, or a flash memory. The auxiliary storage device 3933 stores various programs for operating the communication device 3930. The program stored in the auxiliary storage device 3933 is loaded into the main storage device 3932 and executed by the processor 3931.

The user interface 3934 includes, for example, an input device that receives an operation input from the user, an output device that outputs information to the user, and the like. The input device can be realized by a key (for example, a keyboard) or a remote controller, for example. The output device can be realized by, for example, a display or a speaker. Further, an input device and an output device may be realized by a touch panel or the like. The user interface 3934 is controlled by the processor 3931.

The wireless device 3935 is a communication interface that performs communication with another communication device (for example, the base station 110) wirelessly using the antenna 3936. The radio 3935 is controlled by the processor 3931.

The

antennas

3901 and 3906 shown in FIGS. 39A and 39B can be realized by the antenna 3936, for example. The L-band RF unit 3902 and the U-band RF unit 3907 shown in FIGS. 39A and 39B can be realized by, for example, the wireless device 3935.

The downlink baseband signal processing unit 3903, the uplink control channel processing unit 3904, and the downlink U band baseband signal processing unit 3908 shown in FIGS. 39A and 39B can be realized by the processor 3931, for example.

(Example of U-band resource allocation information transmission channel)
FIG. 40A is a diagram illustrating a first example of a transmission channel for U-band resource allocation information. In FIG. 40A, the same parts as those shown in FIG. 8A are denoted by the same reference numerals and description thereof is omitted. As illustrated in FIG. 40A, the base station 110 transmits resource allocation information 4001 related to the U band, for example, using the PDCCH of the frequency channel su1 of the U band. In the example shown in FIG. 40A, the base station 110 includes the resource allocation information 4001 in the head part of the signal 803 including the RS transmitted by the frequency channel su1.

Resource allocation information 4001 is information indicating an allocation resource, a modulation scheme, and the like for each terminal including the terminal 120, for example. For example, when resource allocation changes for each subframe, resource allocation information 4001 may be transmitted for each subframe.

FIG. 40B is a diagram illustrating Example 2 of a transmission channel of U-band resource allocation information. In FIG. 40B, the same portions as those shown in FIG. 40A are denoted by the same reference numerals, and description thereof is omitted. As shown in FIG. 40B, the base station 110 may transmit the resource allocation information 4001 related to the U band by the E-PDCCH (Enhanced-Physical Downlink Control Channel) of the U-band frequency channel su1. Good.

As shown in FIGS. 40A and 40B, the base station 110 can transmit, for example, resource allocation information related to the U band using the frequency channel su1 of the U band.

FIG. 40C is a diagram illustrating a third example of a transmission channel for U-band resource allocation information. In FIG. 40C, portions similar to those illustrated in FIG. 40A are denoted by the same reference numerals and description thereof is omitted. As illustrated in FIG. 40C, the base station 110 may transmit the resource allocation information 4001 related to the U band using the PDCCH of the frequency channel pl1 of the L band. In the example shown in FIG. 40C, the base station 110 transmits the resource allocation information 4001 in the head part of the subframe of the frequency channel pl1.

FIG. 40D is a diagram illustrating a fourth example of a transmission channel for U-band resource allocation information. In FIG. 40D, the same parts as those shown in FIG. 40C are denoted by the same reference numerals and description thereof is omitted. As illustrated in FIG. 40D, the base station 110 may transmit the resource allocation information 4001 related to the U band from the E-PDCCH of the L-band frequency channel pl1.

As shown in FIGS. 40C and 40D, the base station 110 may transmit resource allocation information related to the U band, for example, using the L-band frequency channel pl1.

As described above, according to the embodiment, the base station 110 transmits control information for specifying the timing of transmitting at least one of the reference signal and the synchronization signal using the U band using the L band. can do.

Thereby, the terminal 120 receives the control information transmitted from the base station 110 using the L band, whereby the base station 110 transmits at least one of the reference signal and the synchronization signal using the U band. Can be accurately identified. For this reason, the terminal 120 can efficiently receive at least one of the reference signal and the synchronization signal using the U band by the base station 110 and perform processing based on the received signal.

As described above, according to the wireless communication system, the base station, the terminal, and the processing method, the terminal can accurately specify the signal transmission timing of the base station in the shared band.

For example, conventionally, in LTE, LTE-advanced, and the like, a terminal performs timing tracking, frequency tracking, CQI measurement, RRM measurement, CSI measurement, and the like based on a reference signal and a synchronization signal transmitted from a base station. For example, in the L band, the RS is periodically transmitted from the base station. In the L band, CRS is transmitted for each subframe, and CSI-RS is periodically transmitted.

On the other hand, LTE-u using LTE in the U band has been proposed to cope with the increase in traffic. For example, a system that uses the U band for data transmission while connecting in the L band is expected to contribute to an improvement in throughput.

Here, when performing transmission by LTE in the U band, in order to realize coexistence with other systems such as between LTE-u and WLAN (Wireless Local Area Network), LBT (Listen-Before-Talk) ). When performing LBT, in order for each radio station such as a base station to perform transmission, carrier sense is performed first and it is confirmed that the radio frequency channel is not used (Idle). When a radio frequency channel is used (Busy), a radio signal cannot be transmitted. Therefore, a signal including an RS and a synchronization signal is not always transmitted from the base station for each subframe (or periodically).

For this reason, it is difficult for the terminal to specify the timing at which the RS and the synchronization signal are transmitted from the base station in the U band, and the terminal can efficiently receive the RS and the synchronization signal transmitted from the base station in the U band. Can not. For example, if a terminal detects an RS or a synchronization signal at an unknown timing whether or not an RS or a synchronization signal is transmitted, a false detection such as detecting a signal that is not an RS or a synchronization signal as an RS or a synchronization signal occurs. However, the RS and the synchronization signal cannot be received with high accuracy. In addition, a dedicated detection circuit is provided to detect the RS and the synchronization signal by pattern comparison, which increases the circuit scale.

On the other hand, according to each embodiment described above, the base station performs CS in the U band, and starts transmission if downlink transmission including RS and a synchronization signal is possible. Also, the base station informs the terminal whether or not downlink transmission including RS and synchronization signal is performed in the U band using the control channel in the L band.

Thereby, in the communication system using the U band, the terminal can accurately grasp the subframe in which the RS and the synchronization signal are transmitted, and can perform the frequency tracking and CQI measurement with high accuracy.

In addition, although the timing tracking, the frequency tracking, the CQI measurement, the RRM measurement, the CSI measurement, the data reception, and the like are given as the processes performed by the terminal based on the RS and the synchronization signal, the present invention is not limited thereto, and various processes can be performed. .

pl1, su1, su2, su3 Frequency channels sb1, sb2, sb3, sb4, 901, 902 Subframe 100 Wireless communication system 110 Base station 111 First transmission unit 112 Second transmission unit 120 Terminal 121 First reception unit 122 Second reception Part 400

corresponding information

500, 610, 802, 806, 808, 1300, 1401, 1700, 2100, 2300, 2500, 3200, 3700

RS transmission information

600, 911, 921, 931 PDCCH
611 to 613 bits 701 to 703, 1011 to 1013, 1021 to 1023, 1031 to 1033 Dedicated control channel 801

Dummy signal

803, 805, 807, 821, 912, 922, 923, 932, 933, 1402 Signal 2201 to 2204, 2401 2403, 3301 to 3303 Data transmission 2900 Synchronization

signal transmission information

3801, 3808, 3836, 3901, 3906, 3936 Antenna 3802, 3902 L-band RF unit 3803 Uplink baseband signal processing unit 3804 Downlink control unit 3805 Downlink control Channel processing unit 3806 Downlink data channel processing unit 3807 Downlink L-band baseband

signal generation unit

3809, 3907 U-band RF unit 3810 Carrier sense unit 811 Downlink U-band

baseband signal generator

3830, 3930

Communication device

3831, 3931

Processor

3832, 3932

Main storage device

3833, 3933 Auxiliary storage device 3835

Network interface

3835, 3935

Radio

3839, 3939 Bus 3903 Downlink baseband signal processing Unit 3904 uplink control channel processing unit 3905 uplink baseband signal generation unit 3908 downlink U band baseband signal processing unit 3909 synchronization unit 3910 timing / frequency tracking unit 3911 CQI measurement unit 3912 RRM measurement unit 3934 user interface 4001 resource allocation information

Claims

In a radio communication system capable of using a first band shared with other radio communication systems and a second band different from the first band,
A base station that transmits at least one of a reference signal and a synchronization signal in the first band during a period in which the wireless signal of the first band is not transmitted in the other wireless communication system, and at least one of the reference signal and the synchronization signal A base station for transmitting control information in the second band for specifying the timing for transmitting
Based on the control information transmitted from the base station in the second band, a terminal that receives at least one of the reference signal and the synchronization signal transmitted from the base station in the first band;
A wireless communication system comprising:
The base station detects the period based on a detection result of a radio signal in the first band, and transmits at least one of the reference signal and the synchronization signal in the detected period. The wireless communication system described.
The base station detects the period based on presence / absence of transmission of a radio signal from the own station in the first band, and transmits at least one of the reference signal and the synchronization signal in the detected period. The wireless communication system according to claim 1 or 2.
The wireless communication system according to any one of claims 1 to 3, wherein the second band is a band occupied by the own system.
5. The control information according to claim 1, wherein the control information is information indicating, for each periodic period, whether or not at least one of the reference signal and the synchronization signal is transmitted. The wireless communication system described.
The base station arranges the control information (hereinafter referred to as “first control information”) for each of a plurality of first bands shared with other wireless communication systems in a control channel of the second band. And transmitting the second control information for specifying the arrangement of the control information in the control channel for each of the plurality of first bands in the second band,
The terminal, based on the second control information transmitted from the base station in the second band, the first control information on the first band used by the terminal among the plurality of first bands. Receiving from the control channel;
The wireless communication system according to any one of claims 1 to 5, wherein:
The base station transmits the control information (hereinafter referred to as “first control information”) for each of a plurality of first bands shared with other wireless communication systems to an individual control channel of the second band. And transmitting second control information for identifying correspondence between the plurality of first bands and the individual control channel in the second band,
The terminal, based on the second control information transmitted from the base station in the second band, the first control information on the first band used by the terminal among the plurality of first bands. Receiving from said individual control channel;
The wireless communication system according to any one of claims 1 to 6, wherein:
The base station transmits the control information for specifying the timing for transmitting at least one of the reference signal and the synchronization signal and the type of at least one of the reference signal and the synchronization signal to be transmitted. The wireless communication system according to any one of claims 1 to 7.
The base station transmits the control information for specifying a timing for transmitting at least one of the reference signal and the synchronization signal and a format of a data signal transmitted by the base station in the first band. The wireless communication system according to any one of claims 1 to 8, characterized in that:
In a base station of a radio communication system capable of using a first band shared with other radio communication systems and a second band different from the first band,
A first transmitter that transmits at least one of a reference signal and a synchronization signal in the first band during a period in which the radio signal of the first band is not transmitted in the other wireless communication system;
A second transmitter that transmits control information in the second band for specifying the timing at which the first transmitter transmits at least one of the reference signal and the synchronization signal;
A base station comprising:
In a terminal of a wireless communication system capable of using a first band shared with other wireless communication systems and a second band different from the first band,
At least one of the reference signal and the synchronization signal is transmitted from a base station that transmits at least one of the reference signal and the synchronization signal in the first band during a period in which the radio signal of the first band is not transmitted in the other wireless communication system. A first receiving unit that receives control information for specifying the timing to perform in the second band;
A second receiving unit that receives at least one of the reference signal and the synchronization signal transmitted from the base station in the first band based on the control information received by the first receiving unit;
A terminal comprising:
In a processing method by a base station of a radio communication system capable of using a first band shared with other radio communication systems and a second band different from the first band,
Transmitting at least one of a reference signal and a synchronization signal in the first band during a period in which the radio signal of the first band is not transmitted in the other wireless communication system;
Transmitting control information for specifying timing for transmitting at least one of the reference signal and the synchronization signal in the second band;
A processing method characterized by the above.
In a processing method by a terminal of a radio communication system capable of using a first band shared with other radio communication systems and a second band different from the first band,
At least one of the reference signal and the synchronization signal is transmitted from a base station that transmits at least one of the reference signal and the synchronization signal in the first band during a period in which the radio signal of the first band is not transmitted in the other wireless communication system. Receiving control information for specifying the timing to perform in the second band,
Based on the received control information, receiving at least one of the reference signal and the synchronization signal transmitted from the base station in the first band,
A processing method characterized by the above.