WO2020170352A1

WO2020170352A1 - Base station apparatus, terminal apparatus, and communication system

Info

Publication number: WO2020170352A1
Application number: PCT/JP2019/006249
Authority: WO
Inventors: 大出高義; 河▲崎▼義博
Original assignee: 富士通株式会社
Priority date: 2019-02-20
Filing date: 2019-02-20
Publication date: 2020-08-27
Also published as: JPWO2020170352A1; JP7277818B2

Abstract

A base station apparatus that wirelessly communicates with a terminal apparatus by use of either a first uplink frequency paired with a downlink frequency or a second uplink frequency different from the first uplink frequency and by use of the downlink frequency, is provided with: a radio control unit that transmits, to the terminal apparatus, an uplink reference signal transmission request for requesting the transmissions of first and second uplink reference signals using the first and second uplink frequencies, respectively, and control information related to the first and second uplink reference signals and that also transmits, to the terminal apparatus, frequency control information related to the first or second uplink frequency; and a reception unit that receives the first and second uplink reference signals transmitted from the terminal apparatus by use of the first and second uplink frequencies, respectively.

Description

Base station device, terminal device, and communication system

The present invention relates to a base station device, a terminal device, and a communication system.

In the current network, the traffic of mobile terminals (smartphones and future phones) occupy most of the network resources. Also, the traffic used by mobile terminals tends to continue to grow.

On the other hand, along with the development of IoT (Internet of things) services (for example, monitoring systems for transportation systems, smart meters, devices, etc.), it is required to support services with various requirements. Therefore, in addition to the standard technology of 4G (4th generation mobile communication) (for example, Non-Patent Documents 1 to 11) in the communication standard of 5th generation mobile communication (5G or NR (New Radio)), There is a demand for a technology that realizes a high data rate, a large capacity, and a low delay. Regarding the 5th generation communication standard, technical studies are being carried out by a working group of 3GPP (for example, TSG-RAN WG1, TSG-RAN WG2, etc.), and the first edition of the standard was issued at the end of 2017. (Non-Patent Documents 12 to 39).

As mentioned above, in order to support a wide variety of services, 5G is classified into eMBB (Enhanced Mobile BroadBand), Massive MTC (Machine Type Communications), and URLLC (Ultra-Reliable and Low Latency Communication). It is expected to support many use cases.

In 5G, for example, we are considering communication using higher frequencies, such as 28GHz, which is higher than the frequencies of 800MHz and 5GHz used in LTE (Long Term Evolution).

ㆍIn such communication using high frequency, compared with 800MHz and 5GHz, since it is not used much, there is an advantage that it is possible to widen the bandwidth by widening the bandwidth. Therefore, in the communication using the high frequency, it is possible to improve the transmission speed and increase the line capacity as compared with the communication using the 800 MHz or the like.

On the other hand, in communications using such high frequencies, there are cases in which the straightness of radio waves is so strong that reflected waves and transmitted waves cannot be used. Further, since the propagation loss is proportional to the magnitude of the frequency, for example, in the communication using the high frequency, the propagation loss may be larger than that in the case of 800 MHz.

Therefore, 5G will introduce SUL (Supplementary UpLink). When the SUL uses, for example, an uplink frequency and a downlink frequency as a set and uses the uplink frequency and the downlink communication, respectively, the base station apparatus uses a different uplink frequency instead of the paired uplink frequency. And the terminal device to communicate. For example, when 2155 MHz is the down frequency and 1745 MHz is the up frequency, and when these are paired and communication is performed, instead of 1745 MHz, 900 MHz is used as the frequency (or SUL frequency) of the up communication, etc. Is. SUL is defined in, for example, Non-Patent Document 20 below.

Regarding this SUL, in 5G, when the measured quality of downlink communication (measured quality of DL) is lower than a threshold (broadcast threshold), the UE (User Equipment) is supposed to select the SUL frequency (SUL carrier) (for example, Non-Patent Document 20 below, “9.2.6”). Therefore, in the above example, when the measurement quality of the downlink frequency of 2155 MHz is lower than the threshold value, 900 MHz is used as the SUL frequency instead of the uplink frequency of 1745 MHz. As described above, whether to use the paired upstream frequency or the SUL frequency is selected according to the result of the measurement quality in the downstream frequency.

Explaining the advantages of introducing SUL, for example, they are as follows. That is, FIG. 26(A) is a diagram showing the coverage range of the base station 300, and FIG. 26(B) is a diagram showing examples of utilization frequencies. In the communication using the high frequency described above, for example, the high frequency radio wave transmitted from the base station 300 reaches the terminal 400, but the high frequency radio wave transmitted from the terminal 400 is smaller than the transmission power of the base station 300. However, it may not reach the base station 300. Therefore, as shown in FIG. 26A, the coverage range in which both downlink communication and uplink communication can be performed may be smaller than the coverage range in the case of downlink communication alone.

On the other hand, by introducing SUL, it becomes possible to improve the coverage range in upstream communication, for example, for communication using high frequencies. That is, as described above, the lower the frequency, the smaller the propagation loss. Therefore, for example, as shown in FIG. 26(B), a low frequency is used at the time of SUL for a combination of a high frequency upstream frequency and a downstream frequency. In this case, the frequency used in SUL (hereinafter, may be referred to as “SUL frequency”) is lower than the frequency of the set, so that the propagation loss can be reduced. For example, as shown in FIG. As shown, the coverage range when SUL is used can be made the same as the coverage range when only downlink communication is performed.

FIG. 27 is a diagram showing an example of frequencies used as SUL in a frequency range (450 MHz to 6000 MHz) in FR (Frequency Range) 1 (Table 5.2-1 of Non-Patent Document 39). As shown in FIG. 27, it is understood that, within the range of FR1, a high frequency is not used so much as the frequency used as SUL.

In 5G, it is also specified that the frequency used as SUL is transmitted (or notified) using SIB1 (System Information Block Type 1) (for example, Non-Patent Document 24 below).

On the other hand, SRS (Sounding RS) is one of RSs (Reference Signals, reference signals or pilots) used in uplink communication. As RS, in addition to SRS, there is Demodulation RS for PUSCH (Physical Uplink Shared Channel). Such an RS is transmitted together with data and control signals and cannot be transmitted without the data and control signals. However, SRS is transmitted even when, for example, a wireless line (wireless channel) is not set (for example, RRC (Radio Resource Control) is not set, RA (Random Access) is not completed) If conditions are met, the UE can transmit and can transmit without data or control signals. Note that SRS is introduced from LTE and is specified even in 5G (for example, Non-Patent Document 15).

In the 5G specification, as described above, whether to use the upstream frequency or the SUL frequency is determined by comparing the measurement quality of the downstream frequency to be paired with the threshold value.

However, the downlink frequency measurement quality and the uplink frequency measurement quality do not always match. For example, even when the measurement quality of the downlink frequency of the pair is smaller than the threshold value, the measurement quality of the SUL frequency may be deteriorated. Alternatively, for example, even when the measurement quality of the downlink frequency of the set is equal to or more than the threshold value, the measurement quality of the uplink frequency of the set may be deteriorated. Therefore, in uplink communication, transmission delay may increase and throughput may decrease.

In 5G, URLLC may be required depending on the type of service. A decrease in throughput may not be able to meet such demands.

Also, the SUL frequency is commonly set as a system as shown in FIG. The communication environment of each terminal device differs from one terminal device to another, and the radio channel quality between the terminal device and the base station device may also differ from one terminal device to another. Therefore, when a terminal device uses SUL for communication, the SUL frequency is not always optimal for that terminal device. Moreover, since the SUL frequency is predetermined as a system, the terminal device cannot individually change the SUL frequency. Therefore, the transmission delay may increase in the upstream communication and the throughput may decrease.

Therefore, one disclosure is to provide a base station device, a terminal device, and a communication system capable of improving the throughput in uplink communication.

According to one aspect, a wireless communication with a terminal device is performed by using a first uplink frequency that forms a pair with a downlink frequency, a second uplink frequency different from the first uplink frequency, and the downlink frequency. In the base station apparatus for performing the above, the uplink reference signal transmission request for requesting transmission of the first and second uplink reference signals using the first and second uplink frequencies, respectively, and the first and second uplinks. A radio control unit for transmitting control information regarding a reference signal to the terminal device, and transmitting frequency control information for the first or second upstream frequency to the terminal device; and the first and second radio control units from the terminal device. And a receiving unit that receives the first and second uplink reference signals transmitted using the respective uplink frequencies.

According to one disclosure, throughput in upstream communication can be improved.

FIG. 1 is a diagram showing a configuration example of a communication system. FIG. 2 is a diagram illustrating a configuration example of the base station device. FIG. 3A is a diagram showing a configuration example of a radio control unit of a base station device, and FIG. 3B is a diagram showing a configuration example of a radio control unit of a terminal device. FIG. 4 is a diagram illustrating a configuration example of the terminal device. 5A is a diagram showing an example of the SUL frequency in the case of FDD, and FIG. 5B is a diagram showing an example of the SUL frequency in the case of TDD. FIG. 6 is a diagram illustrating a sequence example of the operation example 1. FIG. 7 is a diagram illustrating a sequence example of the operation example 1. FIG. 8A and FIG. 8B are diagrams showing an example of SRS transmission. FIG. 9 is a diagram illustrating a sequence example of the operation example 2. FIG. 10 is a diagram showing a configuration example of a MAC payload of RAR. FIG. 11 is a diagram illustrating a sequence example of the operation example 3. FIG. 12 is a diagram illustrating a sequence example of the operation example 3. FIG. 13 is a diagram illustrating a sequence example of the operation example 4-1. FIG. 14 is a diagram illustrating a sequence example of the operation example 4-1. FIG. 15 is a diagram showing a sequence example of the operation example 4-2. FIG. 16 is a diagram illustrating a sequence example of the operation example 4-2. 17A and 17B are diagrams showing an example of GAP and SRS transmission in the case of TDD, and FIGS. 17C to 17F are diagrams showing an example of GAP and SRS transmission in the case of FDD. is there. 18A and 18B are diagrams showing an example of GAP and SRS transmission in the case of TDD, and FIGS. 18C to 18F are diagrams showing examples of GAP and SRS transmission in the case of FDD. is there. FIG. 19 is a flowchart showing an operation example in the base station device. FIG. 20 is a flowchart showing an operation example in the base station device. FIG. 21 is a flowchart showing an operation example in the base station device. FIG. 22 is a flowchart showing an operation example in the base station device. FIG. 23 is a flowchart showing an operation example in the base station device. FIG. 24 is a flowchart showing an operation example in the base station device. FIG. 25 is a diagram showing a configuration example of a communication system. FIG. 26(A) is a diagram showing an example of a coverage range, and FIG. 26(B) is a diagram showing an example of frequency allocation. FIG. 27 is a diagram showing an example of the SUL frequency.

Hereinafter, the present embodiment will be described in detail with reference to the drawings. The problems and examples in this specification are examples, and do not limit the scope of rights of the present application. In particular, even if the described expressions are different, as long as they are technically equivalent, the technology of the present application can be applied even if the expressions are different, and the scope of rights is not limited. Then, the respective embodiments can be appropriately combined within a range in which the processing content is not inconsistent.

The terms and technical contents described in the present specification may appropriately use the terms and technical contents described in specifications and contributions as a standard for communication such as 3GPP. An example of such a specification is 3GPP TS 38.211 V15.4.0 (2018-12) mentioned above.

Note that the 3GPP specifications will be updated from time to time. Therefore, the latest specification at the time of filing the present application may be used as the above-mentioned specification.

The embodiments of the base station, terminal, and communication system disclosed in the present application will be described in detail below with reference to the drawings. The following embodiments do not limit the disclosed technology.

[First Embodiment]
<Example of configuration of communication system>
FIG. 1 is a diagram illustrating a configuration example of a communication system 10 according to the first embodiment.

The communication system 10 includes a base station device (hereinafter sometimes referred to as “base station”) 100 and terminal devices (hereinafter sometimes referred to as “terminal”) 200-1 and 200-2.

The base station 100 is, for example, a communication device that wirelessly communicates with the terminals 200-1 and 200-2. The base station 100 wirelessly communicates with the terminals 200-1 and 200-2 located in the service available range (or cell range) of the base station 100 to provide various services such as a call service and a Web browsing service. .. The base station 100 may be, for example, a gNB (next generation Node B) defined by 5G or an eNB (evolved Node B) defined by 4G. Below, the base station 100 may be described as gNB.

The terminals 200-1 and 200-2 are communication devices such as feature phones, smartphones, personal computers, tablet terminals, and game devices. The terminals 200-1 and 200-2 can be provided with various services within the service available range of the base station 100.

In the example of FIG. 1, the number of terminals 200-1 and 200-2 is two, but it may be one or three or more. Hereinafter, the terminals 200-1 and 200-2 may be referred to as the terminal 200.

The communication from the base station 100 to the terminal 200 may be referred to as downlink communication or DL (Down Link), and the communication from the terminal 200 to the base station 100 may be referred to as uplink communication or UL (Up Link).

Further, for example, a frequency used in downlink communication may be referred to as a downlink frequency, and a frequency used in uplink communication may be referred to as an uplink frequency.

Further, for example, the frequency may have a certain bandwidth. In the first embodiment, with respect to the frequency, for example, the case where the frequency has such a constant bandwidth and the case where the frequency itself does not have the bandwidth may be used without distinction.

The terminal 200 according to the first embodiment can perform uplink communication with the base station 100 using SUL. The frequency used when the terminal 200 performs uplink communication using SUL may be referred to as the SUL frequency, for example.

Further, the terminal 200 according to the first embodiment can perform upstream communication and downstream communication with the base station 100 by using a combination of upstream frequency and downstream frequency. As an example of such a set, for example, there is a relationship between the downlink frequency when using as PDCCH (Physical Downlink Control Channel) and the uplink frequency when using PUSCH. In this case, the base station 100 transmits the control signal using the downlink frequency (PDCCH), and the terminal 200 receives the uplink frequency (PUSCH) indicated by the UL grant included in the control signal transmitted using the PDCCH. ) Is used to send user data, and so on.

For example, in the example of FIG. 27, the frequency in which “Duplex Mode” is used as “FDD” or “TDD” is a frequency that is a set, and the frequency used as “SUL” is the SUL frequency.

In the following, in the case where the upstream frequency and the downstream frequency are used as a group for upstream communication and downstream communication, the upstream frequency may be referred to as a group upstream frequency, and the downstream frequency may be referred to as a group downstream frequency, respectively. .. The set up frequency and the set down frequency may be collectively referred to as a set frequency.

FIG. 5(A) shows an example of the relationship between the group frequency and the SUL frequency in the case of FDD (Frequency Division Duplex), and FIG. 5(B) shows the relationship between the group frequency in the case of TDD (Time Division Duplex). It is a figure showing the example of a relationship with a SUL frequency.

As shown in FIG. 5(A) and FIG. 5(B), the upstream frequency that is a set may be all or part of the frequencies included in “UL” in the figure, and the downstream frequency that is a set may be It may be all or part of the frequencies included in "DL" in the figure. There may be a plurality of downlink frequencies for one uplink frequency, or a plurality of uplink frequencies for one downlink frequency. Alternatively, a plurality of upstream frequencies may be a set of frequencies for a plurality of downstream frequencies.

Note that, as shown in FIG. 5B, in the case of TDD, the upstream frequency and the downstream frequency forming a pair may be the same frequency. In this case, the two frequencies can be said to be exactly the same frequency. However, in the first embodiment, considering that the timings to be used are different, even if the frequencies are the same, the “uplink frequency to be a pair” and the “downlink frequency to be a pair” are different Sometimes expressed.

Also, as shown in FIG. 5(A) and FIG. 5(B), as the SUL frequency, a frequency different from the set frequency is used. In this case, the SUL frequency may be lower or higher than the set of frequencies.

Furthermore, by using SUL, for example, two ULs can be formed for one DL in the same cell. Of the two ULs, for example, one is a set of upstream frequencies and one is a SUL frequency.

When SUL is used, the “SUL frequency” may be used by the base station 100 or the terminal 200 as a “group” in relation to the “downstream frequency to be a group”. Therefore, in such a relationship, the "SUL frequency" can be included in the "set". However, in the first embodiment, since the frequencies used are different between the SUL frequency and the group of frequencies, the “SUL frequency” and the “group of frequencies” may be described separately.

<Example of base station configuration>
FIG. 2 is a diagram illustrating a configuration example of the base station 100.

The base station 100 includes an antenna 101, a reception radio unit 102, a reception baseband processing unit 103, a control information extraction unit 104, a radio quality measurement unit 105, a radio control unit 106, a memory 107, a control signal creation unit 108, and a transmission baseband. The processing unit 109 and the transmission wireless unit 110 are provided.

The base station 100 includes a receiver 120, a controller 130, and a transmitter 140. The reception unit 120 includes a reception radio unit 102, a reception baseband processing unit 103, a control information extraction unit 104, and a radio quality measurement unit 105. The control unit 130 also includes the wireless control unit 106. Further, the transmission unit 140 includes a control signal creation unit 108, a transmission baseband processing unit 109, and a transmission wireless unit 110.

For example, the control unit 130 can realize the function of the wireless control unit 106 by reading and executing the program stored in the memory 107. The control unit 130 may be, for example, a controller or a processor such as a CPU (Central Processing Unit), a DSP (Digital Signal Processor), and an FPGA (Field Programmable Gate Array).

The antenna 101 receives the wireless signal transmitted from the terminal 200 and outputs the received wireless signal to the reception wireless unit 102. In this case, uplink communication is performed. Further, the antenna 101 transmits the radio signal output from the transmission radio unit 110 to the terminal 200. In this case, downlink communication is used.

The reception wireless unit 102 performs A/D (Analogue to Digital) conversion, frequency conversion, and the like on the wireless signal output from the antenna 101, and converts the wireless signal in the wireless band into a received signal in the baseband ( Down-convert). The reception wireless unit 102 may include an A/D conversion circuit and a frequency conversion circuit. The reception radio unit 102 performs reception processing such as frequency conversion using the instructed downlink frequency so that the radio signal of the downlink frequency instructed (or set) by the radio control unit 106 can be received.

The reception baseband processing unit 103 performs demodulation processing, error correction decoding processing, and the like on the reception signal output from the reception wireless unit 102 to extract (or reproduce) user data, control signals, SRS, and the like. The reception baseband processing unit 103 outputs the extracted user data and control signals to UPF (User Plane Function) and AMF (Access and Mobility Management Function), respectively. Further, the reception baseband processing unit 103 outputs control information such as downlink radio channel quality information measured by the terminal 200 to the control information extraction unit 104. Furthermore, the reception baseband processing unit 103 outputs the reference signal (or reference signal) to the wireless quality measuring unit 105.

In the first embodiment, SRS is used as the reference signal. As described above, the SRS is a reference signal that can be transmitted/received even when the wireless line setting is not made, and is a reference signal that can be transmitted without the transmission of data or control signals. is there. However, other reference signals, for example, Demodulation RS for PUSCH, Phase-tracking RS for PUSCH, or Demodulation RS for PUCCH (Physical Uplink Control Channel) may be used.

The control information extraction unit 104 extracts control information from the signal output from the reception baseband processing unit 103. As such control information, for example, as described above, there is information about the wireless channel quality in the downlink communication measured by the terminal 200. The control information extraction unit 104 outputs the extracted control information to the wireless control unit 106.

The wireless quality measuring unit 105 uses the SRS output from the reception baseband processing unit 103 to measure the quality of the wireless line with the terminal 200. The SRSs output from the reception baseband processing unit 103 include SRSs transmitted using a pair of upstream frequencies and SRSs transmitted using a SUL frequency. In addition, there is an SRS transmitted using each of the plurality of SUL frequencies.

The wireless quality measuring unit 105 measures the wireless quality of the SUL frequency by measuring the wireless quality using the SRS transmitted using the SUL frequency. Further, the wireless quality measuring unit 105 measures the wireless quality using the SRS transmitted using the upstream frequency that is a group, and thereby measures the wireless quality of the upstream frequency that is a group. Further, the wireless quality measuring unit 105 measures the wireless quality using the SRS transmitted using each of the plurality of SUL frequencies, thereby measuring the wireless quality of each of the plurality of SUL frequencies. In this way, the radio quality measuring unit 105 can directly measure the radio frequency quality of the uplink frequency by using the SRS.

Note that the wireless quality measuring unit 105 may measure the wireless line quality by measuring RSRP (reference Signal Received Power) based on the received SRS, for example. Alternatively, the wireless quality measuring unit 105 may measure the wireless channel quality by, for example, RSRQ (Reference Signal Received Quality) obtained by comparing the SRS created by the wireless quality measuring unit 105 with the received SRS. The wireless quality measuring unit 105 outputs the measurement result to the wireless control unit 106.

The wireless control unit 106 controls the wireless line. For example, the wireless control unit 106 performs the following processing.

That is, the wireless control unit 106 exchanges control information (message) related to the wireless line setting with the terminal 200, sets the wireless line, and sets the frequency used in the set wireless line to the transmission wireless unit 110 and the receiving wireless unit. It is output to the unit 102.

Further, the radio control unit 106 uses an uplink frequency and a SUL frequency that are a pair, respectively, to request transmission of the first and second SRSs (or an uplink reference signal transmission request), and a first and a second. 2 and control information related to SRS transmission. The radio control unit 106 transmits the created information to the terminal 200 via the control signal creation unit 108 using the downlink frequency.

Further, the wireless control unit 106 transmits, to the terminal 200, an SRS transmission request for requesting transmission of each SRS using each of a plurality of SUL frequencies and control information regarding each SRS transmission.

Further, the wireless control unit 106 selects one of the upstream frequencies and the SUL frequencies that are paired, which is used for wireless communication with the terminal 200. Further, the wireless control unit 106 selects one of the SUL frequencies to be used for wireless communication with the terminal 200, from among the plurality of SUL frequencies. The radio control unit 106 outputs the selection result (or frequency control information regarding the uplink frequency) to the control signal creation unit 108 as the uplink frequency setting information. When selecting the uplink frequency, the radio control unit 106 may use the measurement result from the radio quality measurement unit 105 to make the selection. Details of selection and the like will be described in an operation example.

FIG. 3A is a diagram showing a configuration example of the wireless control unit 106.

The radio control unit 106 includes an uplink frequency control unit 1060, a system information setting management unit 1061, a radio control unit 1062, a random access control unit 1063, a HO (Hand Over) control unit 1064, and a radio resource control unit 1065.

The upstream frequency control unit 1060 controls the upstream frequency. For example, the uplink frequency control unit 1060 performs the following processing. That is, the upstream frequency control unit 1060 selects and selects an upstream frequency (either the SUL frequency or a pair of upstream frequencies, or one SUL frequency from a plurality of SUL frequencies) used for wireless communication with the terminal 200. The result is output to the control signal creation unit 108 as the uplink frequency setting information. Further, the uplink frequency control unit 1060 outputs the selected uplink frequency to the reception radio unit 102. As a result, the base station 100 can perform uplink communication with the terminal 200 at the uplink frequency selected by the uplink frequency control unit 1060.

The system information setting management unit 1061 creates and sets system information. For example, the system information setting management unit 1061 performs the following processing. That is, the system information setting management unit 1061 creates system information including information about one or more SUL frequencies used as SUL, and outputs the created system information to the control signal creation unit 108. Further, the system information setting management unit 1061 may create the SRS transmission request and the control information related to the SRS transmission, and may create the system information including these pieces of information. Details will be described in an operation example. Furthermore, the system information setting management unit 1061 creates system information including various kinds of information such as information about adjacent base stations, and outputs the system information to the control signal creation unit 108.

The wireless control unit 1062 controls wireless lines. For example, the wireless control unit 1062 performs the following processing.

That is, the wireless control unit 1062 creates an SRS transmission request and control information related to SRS transmission, and outputs the created SRS transmission request and control information related to SRS transmission to the control signal creation unit 108. The control information regarding SRS transmission includes, for example, a parameter used when the terminal 200 creates an SRS sequence and a parameter used when the terminal 200 calculates a radio resource used for SRS transmission. Radio control section 1062 outputs the created SRS transmission request and control information related to SRS transmission to control signal creation section 108. The radio control unit 1062 may create control information about SRS transmission without creating an SRS transmission request, and may output the created control information about SRS transmission to the control signal creation unit 108. Also, the wireless control unit 1062 creates a reference signal for downlink communication. Radio control section 1062 outputs the created reference signal to control signal creation section 108.

The random access control unit 1063 controls the wireless line setting. For example, the random access control unit 1063 exchanges control information (message) related to random access with the terminal 200. Such control information includes, for example, a message specified in a random access procedure (procedure) such as “Contention based Random Access” and “Non-contention based Random Access” defined in LTE and 5G. The random access control unit 1063 can set a wireless line of a specific frequency by exchanging messages according to such a random access procedure. The random access control unit 1063 outputs the set frequency to the transmission wireless unit 110 and the reception wireless unit 102 (or instructs to perform the transmission process and the reception process at the set frequency). As a result, thereafter, the base station 100 and the terminal 200 can wirelessly communicate with each other at the set frequency.

Note that in the first embodiment, SRS transmission may be performed during the random access procedure, and upstream frequency selection may be performed at the stage of the random access procedure. Details will be described in an operation example.

The HO control unit 1064 controls the terminal 200 when performing a handover. For example, the HO control unit 1064 exchanges control information (message) related to handover with the terminal 200.

The radio resource control unit 1065 allocates radio resources to the terminal 200, for example, based on the downlink radio channel quality information output from the control information extraction unit 104. Such allocation of radio resources may be referred to as scheduling. Radio resource control section 1065 outputs scheduling information indicating the scheduling result to control signal creation section 108.

Returning to FIG. 2, the memory 107 stores, for example, information used when the wireless control unit 106 performs processing. For example, the memory 107 may store control information regarding SRS transmission, and in this case, the wireless control unit 106 can read this control information from the memory 107 as appropriate.

The control signal creation unit 108 creates a control signal including information output from the wireless control unit 106, and outputs the created control signal to the transmission baseband processing unit 109. The information output from the radio control unit 106 includes, for example, an SRS transmission request, control information regarding SRS transmission, uplink frequency setting information, scheduling information, and the like.

Note that the control signal creation unit 108 does not use the system information output from the system information setting management unit 1061 or the reference signal output from the wireless control unit 1062 as the system information or the reference signal, instead of the control signal. You may output to the band process part 109.

The transmission baseband processing unit 109 performs error correction coding processing, modulation processing, and the like on the user data and control signals output from the UPF and APF, the control signals and system information output from the control signal creation unit 108, and the like. Then, these data and signals are converted into baseband signals. The transmission baseband processing unit 109 outputs the converted baseband signal to the transmission wireless unit 110.

The transmission wireless unit 110 performs D/A (Digital to Analog) conversion, frequency conversion processing, and the like on the baseband signal to convert the baseband signal in the baseband band into a wireless signal in the wireless band (upconversion). ) Do. The transmission radio unit 110 performs a transmission process such as frequency conversion so that the radio signal has the downlink frequency instructed (or set) by the radio control unit 106. The transmission radio unit 110 outputs a radio signal to the antenna 101.

<Example of terminal configuration>
FIG. 4 is a diagram illustrating a configuration example of the terminal 200.

The terminal 200 includes an antenna 201, a reception radio section 202, a reception baseband processing section 203, a control signal extraction section 204, a radio quality measurement section 205, a radio control section 206, and a memory 207. Further, the terminal 200 includes a control information creation unit 208, an SRS creation unit 209, a transmission baseband processing unit 210, and a transmission wireless unit 211.

Note that the terminal 200 includes a receiving unit 220, a control unit 230, and a transmitting unit 240. The reception unit 220 includes a reception radio unit 202, a reception baseband processing unit 203, a control signal extraction unit 204, and a radio quality measurement unit 205. The control unit 230 also includes a wireless control unit 206. Further, the transmission unit 240 includes a control information creation unit 208, an SRS creation unit 209, a transmission baseband processing unit 210, and a transmission wireless unit 211.

For example, the control unit 230 can realize the function of the wireless control unit 206 by reading and executing the program stored in the memory 207. The control unit 230 may be, for example, a controller such as a CPU, DSP, or FPGA, or a processor.

The antenna 201 receives the radio signal transmitted from the base station 100 and outputs the received radio signal to the reception radio unit 202. In this case, downlink communication is used. Further, the antenna 201 transmits the radio signal output from the transmission radio unit 211 to the base station 100. In this case, uplink communication is performed.

The reception radio unit 202 performs A/D conversion, frequency conversion, and the like on the radio signal output from the antenna 201, and converts (down-converts) the radio signal in the radio band into a reception signal in the baseband. The reception wireless unit 202 may include an A/D conversion circuit, a frequency conversion circuit, and the like. In addition, the reception wireless unit 202 is set so as to be able to receive the radio signal of the downlink frequency designated (or set) by the radio control unit 206, and the radio signal transmitted from the base station 100 is set using the set downlink frequency. On the other hand, reception processing such as frequency conversion is performed. Reception radio section 202 outputs the converted reception signal to reception baseband processing section 203.

The reception baseband processing unit 203 performs demodulation processing, error correction decoding processing, and the like on the reception signal output from the reception wireless unit 202 to extract (or reproduce) user data, control signals, reference signals, and the like. .. The reception baseband processing unit 203 outputs the extracted user data and the like to the upper layer. In addition, the reception baseband processing unit 203 outputs the extracted control signal and the like to the control signal extraction unit 204. Further, the reception baseband processing unit 203 outputs the extracted reference signal to the wireless quality measuring unit 205.

The control signal extraction unit 204 extracts, from the control signal output from the reception baseband processing unit 203, SRS transmission request, control information regarding SRS transmission, upstream frequency setting information, scheduling information, and the like. The control signal extraction unit 204 outputs the extracted information to the wireless control unit 206. Further, the control signal extraction unit 204 receives the system information output from the reception baseband processing unit 203 and outputs the system information to the wireless control unit 206.

The wireless quality measurement unit 205 measures the wireless line quality of downlink communication based on the reference signal output from the reception baseband processing unit 203. The wireless quality measuring unit 205 may measure the wireless line quality by measuring RSRP or RSRQ, for example.

The wireless control unit 206 controls the wireless line.

FIG. 3B is a diagram showing a configuration example of the wireless control unit 206.

The radio control unit 206 includes an SRS transmission control unit 2060, a system information setting management unit 2061, a radio control unit 2062, a random access control unit 2063, a HO control unit 2064, and a radio resource control unit 2065.

The SRS transmission control unit 2060 controls SRS transmission. For example, the SRS transmission control unit 2060 performs the following processing. That is, when the SRS transmission control unit 2060 receives the SRS transmission request and the control information related to the SRS transmission from the control signal extraction unit 204, the SRS transmission control unit 2060 creates the SRS according to the parameters for the SRS creation included in the control information related to the SRS transmission, The SRS creating unit 209 is instructed. At this time, the SRS transmission control unit 2060 outputs this SRS creation parameter to the SRS creation unit 209. Further, the control information regarding SRS transmission includes a parameter for calculating a radio resource used for SRS transmission. The SRS transmission control unit 2060 uses this parameter to calculate the radio resource used for SRS transmission. When transmitting the SRS, the SRS transmission control unit 2060 instructs the transmission wireless unit 211 to transmit using the calculated wireless resource.

The system information setting management unit 2061 makes settings and the like according to the system information transmitted from the base station 100. For example, when the system information setting management unit 2061 receives the information about the adjacent base station as the system information, the system information setting management unit 2061 notifies the wireless control unit 2062 of this system information. The terminal 200 may receive the SRS transmission request and the control information related to the SRS transmission included in the system information. In this case, the system information setting management unit 2061 notifies the SRS transmission control unit 2060 of this information.

The wireless control unit 2062 controls the wireless line. For example, the wireless control unit 2062 performs the following processing. That is, when the radio control unit 2062 receives the uplink frequency setting information output from the control signal extracting unit 204, the radio control unit 2062 outputs the uplink frequency included in the uplink frequency setting information to the transmission radio unit 211. As a result, the radio control unit 2062 sets the uplink frequency, and thereafter the transmission radio unit 211 performs radio communication at the set uplink frequency. The radio control unit 2062 also outputs the measurement result of the downlink radio channel quality output from the radio quality measurement unit 205 to the control information creation unit 208.

The random access control unit 2063 controls the wireless line setting. For example, the random access control unit 2063 exchanges control information (message) regarding the random access procedure with the base station 100. As described above, the random access control unit 2063 exchanges the messages specified by “Contention based Random Access” and “Non-contention based Random Access”. The random access control unit 2063 may set a wireless line of a specific frequency according to a random access procedure. In that case, the set frequency (for example, the frequency not used in the random access procedure) is notified to the reception wireless unit 202 and the transmission wireless unit 211. As a result, the terminal 200 can wirelessly communicate with the base station 100 at the frequency set in the wireless line setting.

The HO control unit 2064 controls the terminal 200 when performing a handover. For example, the HO control unit 2064 exchanges control information (message) regarding handover with the base station 100.

The radio resource control unit 2065 receives the scheduling information output from the control signal extraction unit 204. Then, the radio resource control unit 2065 controls the reception radio unit 202 and the transmission radio unit 211 so that the terminal 200 can perform transmission and reception by using the radio resources allocated to the terminal 200 included in the scheduling result. To do. For example, the wireless resource control unit 2065 outputs information regarding wireless resources to the reception wireless unit 202 and the transmission wireless unit 211. As a result, the terminal 200 can transmit and receive user data to and from the terminal 200 using the assigned wireless resource.

Returning to FIG. 4, the memory 207 stores, for example, information used when the wireless control unit 206 performs processing. The wireless control unit 206 can appropriately read these pieces of information from the memory 207 and perform processing.

The control information creation unit 208 creates control information including the information output from the wireless control unit 206, and outputs the created control information to the transmission baseband processing unit 210. The information output from the wireless control unit 206 includes, for example, wireless communication quality of downlink communication.

The SRS creating unit 209 creates an SRS based on the parameters included in the control information related to the SRS transmission according to the instruction from the wireless control unit 206. The SRS creation unit 209 outputs the created SRS to the transmission baseband processing unit 210.

The transmission baseband processing unit 210 outputs user data output from an upper layer (for example, MAC: Media Access Control, see Non-Patent Document 21), control information output from the control information creation unit 208, and output from the SRS creation unit 209. Error correction coding processing, modulation processing, and the like are performed on the generated SRS and the like, and these signals and the like are converted to baseband signals. The transmission baseband processing unit 210 outputs the converted baseband signal to the transmission wireless unit 211.

The transmission wireless unit 211 converts the baseband signal in the baseband band into a wireless signal in the wireless band by performing D/A conversion processing and frequency conversion processing on the baseband signal. At this time, the transmission wireless unit 211 performs conversion into a wireless signal so that the signal has the upstream frequency instructed by the wireless control unit 206. The transmission wireless unit 211 outputs a wireless signal to the antenna 101.

Note that the transmission wireless unit 211 transmits the SRS that has undergone processing such as modulation at the upstream frequency instructed by the SRS transmission control unit 2060, for example. The instructed upstream frequencies include a pair of upstream frequencies and a SUL frequency. Accordingly, for example, the transmission wireless unit 211 can transmit the SRS using the upstream frequency and the SRS using the SUL frequency that form a pair. Further, the SRS transmission control unit 2060 can transmit a plurality of SRSs that respectively use a plurality of SUL frequencies.

<Operation example>
There are the following four operation examples.

1) Operation example 1 Uplink frequency selection using uplink radio channel quality 2) Operation example 2 Uplink frequency selection in random access procedure 3) Operation example 3 Setting of SUL frequency for each terminal 4) Operation example 4 Random access procedure failed In this case, setting of SUL frequency for each terminal 5) Operation example 5 SRS transmission using measurement gap Hereinafter, an operation example will be described in this order.

<1. Operation Example 1 Uplink Frequency Selection Using Uplink Radio Channel Quality>
6 and 7 are diagrams showing a sequence example of the operation example 1.

As shown in FIG. 6, the base station (gNB) 100 transmits an SRS transmission request (or an uplink reference signal transmission request) using the uplink frequency f0u and the SUL frequency f1u, which are a set, and control information related to SRS transmission, It transmits to the terminal (UE) 200 using the downlink frequency f0d which is a set (S10).

For example, the base station 100 performs the following processing. That is, the radio control unit 1062 creates an SRS transmission request using the upstream frequency f0u and the SUL frequency f1u, which are a set, and control information regarding SRS transmission. At this time, the radio control unit 1062 creates, as radio resources for SRS transmission, control information related to SRS transmission including a parameter for calculating the upstream frequency f0u and a parameter for calculating the SUL frequency f1u. Radio control section 1062 outputs the created SRS transmission request and control information related to SRS transmission to control signal creation section 108. Then, the radio control unit 1062 controls the transmission radio unit 110 to transmit the SRS transmission request and the control information regarding the SRS transmission using the downlink frequency f0d that is a set. As a result, the transmission radio unit 110 transmits the SRS transmission request using the upstream frequency f0u and the SUL frequency f1u of the set and the control information regarding the SRS transmission to the terminal 200 by using the downstream frequency f0d of the set. It becomes possible to do.

Next, the terminal 200 transmits the SRS using the upstream frequency f0u which is a set (S11). The terminal 200 transmits the SRS by using the uplink frequency f0u which is a group according to the SRS transmission request of the uplink frequency f0u which is a group.

For example, the terminal 200 performs the following processing. That is, the SRS transmission control unit 2060 calculates the uplink frequency f0u of the set according to the parameter included in the control information regarding the SRS transmission received in S10. The SRS transmission control unit 2060 outputs the calculated set of uplink frequencies f0u to the transmission wireless unit 211. In addition, the SRS creating unit 209 creates an SRS according to a parameter included in the control information regarding SRS transmission according to an instruction from the radio control unit 206, and transmits the created SRS via the transmission baseband processing unit 210 to a transmission radio unit. Output to 211. As a result, the transmission wireless unit 211 can transmit the SRS using the upstream frequency f0u which is a set.

FIG. 8A shows an example of SRS transmission using a pair of upstream frequencies f0u. In this way, the terminal 200 can transmit the SRS using the uplink frequency f0u.

Returning to FIG. 6, next, the base station 100 measures the uplink radio channel quality (S12). For example, the wireless quality measuring unit 105 measures the upstream wireless channel quality by using the SRS transmitted using the paired upstream frequency f0u.

Next, the terminal 200 transmits the SRS using the SUL frequency f1u (S13). The terminal 200 transmits the SRS in accordance with the SRS transmission request using the SUL frequency f1u in S10.

For example, the terminal 200 performs the following processing. That is, the SRS transmission control unit 2060 calculates the SUL frequency f1u according to the parameter included in the control information regarding SRS transmission received in S10. The SRS transmission control unit 2060 outputs the calculated SUL frequency f1u to the transmission wireless unit 211. In addition, the SRS creating unit 209 creates an SRS using parameters included in the control information related to SRS transmission according to an instruction from the radio control unit 206, and transmits the created SRS via the transmission baseband processing unit 210. Output to the wireless unit 211. Thereby, the transmission wireless unit 211 can transmit the SRS using the SUL frequency f0u.

FIG. 8(A) shows an example of SRS transmission using the SUL frequency f1u. In this way, the terminal 200 can transmit the SRS using the SUL frequency f1u.

Returning to FIG. 6, next, the base station 100 measures the uplink radio channel quality (S14). For example, the wireless quality measuring unit 105 measures the upstream wireless channel quality by using the SRS transmitted using the SUL frequency f1u.

Next, the base station 100 selects an upstream frequency (S15). For example, the uplink frequency control unit 1060 selects based on the radio channel quality measurement result for the uplink frequency f0u and the radio channel quality measurement result for the SUL frequency f1u, which are output from the radio quality measuring unit 105. For example, the upstream frequency control unit 1060 selects the upstream frequency with the better wireless channel quality. Here, the upstream frequency control unit 1060 will be described below assuming that the SUL frequency f1u is selected.

Next, the base station 100 transmits the selected upstream frequency f1u to the terminal 200 (S16). For example, the uplink frequency control unit 1060 transmits information regarding the selected SUL frequency f1u to the terminal 200 using the downlink frequency via the control signal creation unit 108 and the like.

Next, the base station 100 and the terminal 200 set up a wireless link using the upstream frequency f1u and the paired downstream frequency f0d (S17). For example, a random access procedure is executed between the random access control unit 1063 of the base station 100 and the random access control unit 2063 of the terminal 200, and control information (messages) related to random access is exchanged. As a result, a wireless line using the up frequency f1u and the down frequency f0d is set, and thereafter, wireless communication using these frequencies becomes possible.

Next, the base station 100 transmits control information regarding SRS transmission on the SUL frequency f1u to the terminal 200 (S18). The process after S18 is, for example, a process for selecting a radio resource within the SUL frequency f1u (in band) for use in transmitting uplink user data (uplink data).

FIG. 8B is a diagram showing an example of PUSCH (uplink radio shared channel or uplink radio data channel) and PUCCH (uplink radio control channel) in the SUL frequency f1u. In the processing of S18 and thereafter, the terminal 200 transmits the SRS included in the PUSCH, and the base station 100 selects the radio resource of the PUSCH in the SUL frequency f1u based on the SRS and allocates it to the terminal 200. Become.

In this process (S18), the base station 100 transmits control information regarding SRS transmission in order to cause the terminal 200 to transmit the SRS for wireless resource selection. In this case as well, as in S10, the radio control unit 1062 creates control information regarding SRS transmission including parameters that become the frequency f1u when the radio resource is calculated, and transmits the created control information to the terminal 200. Good.

Note that the control information related to SRS transmission when the base station 100 causes the terminal 200 to perform SRS transmission for wireless resource selection may be referred to as “SRS transmission control information #2”. Further, as in S10, the control information regarding SRS transmission when the base station 100 causes the terminal 200 to perform SRS transmission for upstream frequency selection may be referred to as “SRS transmission control information #1”. The SRS transmission control information #2 is for selecting a radio resource to be used from the radio resources within the selected frequency (frequency having a bandwidth) after selecting the uplink frequency, and the SRS transmission control information #1 is for selecting the uplink frequency. Since they are choices, they are clearly distinguished.

Returning to FIG. 6, next, the terminal 200 transmits the SRS by using the SUL frequency (S19). For example, the terminal 200 performs the following processing. That is, the SRS creating unit 209 creates an SRS according to an instruction from the wireless control unit 206 and outputs the SRS to the transmission wireless unit 211. In addition, the SRS transmission control unit 2060 creates the SUL frequency f1u as a resource for SRS transmission using the parameter included in the SRS transmission control information #2 (S18), and outputs the SUL frequency f1u to the transmission wireless unit 211. The transmission wireless unit 211 can transmit the SRS by using f1u.

Next, the base station 100 measures the uplink radio channel quality (S20 in FIG. 7). For example, the wireless quality measuring unit 105 measures the wireless line quality of the upstream frequency f1u using the SRS received in S19.

Next, the base station 100 selects the uplink radio resource of the terminal 200 (S21). For example, the radio resource control unit 1065 receives the measurement result from the radio quality measurement unit 105, and selects the radio resource in the upstream communication for the terminal 200 based on the received measurement result.

Next, the base station 100 transmits the uplink transmission radio resource to the terminal 200 (S22). For example, the radio resource control unit 1065 transmits the selected radio resource in the uplink communication to the terminal 200 via the control signal creation unit 108 and the like.

Next, the terminal 200 transmits user data to the base station 100 by using the received uplink transmission radio resource (S23). For example, the terminal 200 performs the following processing. That is, the radio resource control unit 2065 extracts the uplink transmission radio resource from the control signal, and instructs the transmission radio unit 211 to transmit the user data using the extracted radio resource. According to the instruction, the transmission wireless unit 211 transmits the user data output from the upper layer to the base station 100.

As described above, in the operation example 1, the terminal 200 transmits to the base station 100 the SRS using the upstream frequency and the SRS using the SUL frequency, which are a pair. Then, the base station 100 selects a pair of upstream frequency or SUL frequency. Therefore, the base station 100 can measure the two radio channel qualities of the uplink frequency and the SUL frequency, which are a set, by using the two SRSs, and select one of the uplink frequencies according to the result. It becomes possible.

Therefore, in the communication system 10, compared with the case where the uplink frequency is selected by using the radio channel quality of the downlink frequency, for example, the frequency in which the radio channel quality of the uplink communication is deteriorated is not used. It is possible to select a frequency with good uplink communication line quality. Therefore, in the communication system 10, it is possible to improve the transmission rate in uplink communication and improve the throughput of uplink communication.

<2. Operation Example 2 Uplink Frequency Selection in Random Access Procedure>
FIG. 9 is a diagram illustrating a sequence example of the operation example 2. The operation example 2 is an operation example in which the uplink frequency can be selected for the terminal 200 to which the wireless link is not set. The sequence example shown in FIG. 9 corresponds to a random access procedure based on “Non-contention based Random Access”.

However, it is assumed that the system information is transmitted (or broadcast) from the base station 100 and the system information is received by the terminal 200 before the sequence shown in FIG. 9 is performed. The system information includes, for example, an SRS transmission request, a pair of upstream frequencies, a plurality of SUL frequency candidates, control information regarding SRS transmission, an SRS transmission preamble (or an upstream control signal transmission preamble), and the like.

As described above, the control information related to SRS transmission includes a parameter that allows the terminal 200 to create a radio resource used for SRS transmission. In the second operation example, the control information regarding SRS transmission includes, for example, a parameter that allows a plurality of radio resources to be created in the terminal 200. That is, this control information includes, for example, a parameter capable of creating a radio resource of a pair of uplink frequencies and a parameter capable of creating a radio resource of one or a plurality of SUL frequencies. As will be described later, the random access procedure (S30 to S35) shown in FIG. 9 may be performed multiple times. At this time, in order to transmit the SRS at different frequencies every time, the base station 100 transmits, as the system information, control information regarding the SRS transmission including a parameter that allows a plurality of radio resources.

Also, the system information includes a preamble for SRS transmission. The preamble for SRS transmission is, for example, a preamble used when the terminal 200 transmits the SRS and the base station 100 selects the uplink frequency in the random access procedure. The preamble for SRS transmission is, for example, distinguishable from the preamble used in the normal random access procedure, and is a preamble that can be used individually by the terminal 200 or by a plurality of terminals 200.

Regarding the transmission and reception of such system information, the base station 100 and the terminal 200 perform the following processing, for example. That is, the system information setting management unit 1061 of the base station 100 reads out a set of upstream frequencies, a plurality of SUL frequency candidates, control information regarding SRS transmission, an SRS transmission preamble, and the like from the memory 107, and creates the SRS transmission. Create system information including requests and. Then, the system information setting management unit 1061 transmits (or informs (transmits as common information to unspecified number of terminals or specified number of terminals)) the created system information. The system information setting management unit 2061 of the terminal 200 receives this system information, and stores the SRS transmission request, a pair of upstream frequencies, a plurality of SUL frequency candidates, control information regarding SRS transmission, a preamble for SRS transmission, and the like in the memory 207. Remember. The system information is transmitted using broadcast or multicast.

After transmitting/receiving the system information, the terminal 200 transmits a Random Access Preamble (RAP) (or Message 1) to the base station 100 (S30). For example, the random access control unit 2063 reads the SRS transmission preamble stored in the memory 107 and transmits it.

Next, the base station 100 transmits a Random Access Response (RAR) (Message 2) including the SRS request (or SRS transmission request) to the terminal 200 (S31). RAR represents, for example, a line setting request.

FIG. 10 is a diagram showing a configuration example of the payload area in the MAC (Media Access Control) layer of RAR. As shown in FIG. 10, the RAR has an “R” area representing a Reserved bit (or a reserved (or reserved) bit). In the first embodiment, this “R” area is used to indicate the presence/absence of SRS Request. For example, when the "R" area is "1", there is SRS Request, and when it is "0", there is no SRS Request. For example, when receiving the RAP, the random access control unit 1063 creates an SRS including “1” in the “R” area as a response.

Note that, as shown in FIG. 10, the information about the wireless resource used when the terminal 200 transmits a subsequent Scheduled Transmission (Message 3) (hereinafter, may be referred to as “Message 3”) to the RAR. Is included in "UL grant". The base station 100 transmits, as the system information, the control information regarding the SRS transmission including the parameters capable of creating a plurality of radio resources. Therefore, in the base station 100, the information about the selected radio resource from the plurality of radio resources is included in the “UL Grant”. As a result, when the terminal 200 transmits the Message 3, the radio resource used for the transmission of the Message 3 and the radio resource used for the transmission of the SRS can be matched in the base station 100. .. Note that the Message 3 is also an RRC (Radio Resource Control) connection request message (or connection request), for example.

Returning to FIG. 9, next, the terminal 200 transmits Message 3 and SRS (S32). For example, the terminal 200 performs the following processing.

That is, when the RAR including the SRS Request is received, the random access control unit 2063 checks the bits included in the “R” area to confirm that the RAR includes the SRS transmission request. Then, the random access control unit 2063 reads out the control information regarding the SRS transmission from the memory 207, and instructs the SRS creating unit 209 to create the SRS according to the parameter included in the control information. Also, the random access control unit 2063 calculates the radio resource used for SRS transmission according to this parameter. At this time, as described above, the random access control unit 2063 can calculate a plurality of radio resources. The random access control unit 2063 confirms, among the plurality of radio resources, whether or not there is a radio resource matching the radio resource indicated by “UL grant” included in the RAR received in S31. Upon confirming that they match, the random access control unit 2063 instructs the transmission wireless unit 211 to transmit the Message 3 and the SRS by using the wireless resource. The random access control unit 2063 also creates Message 3 and outputs it to the transmission wireless unit 211. Further, the SRS creation unit 209 creates an SRS according to the instruction from the random access control unit 2063, and outputs it to the transmission wireless unit 211. From the transmission wireless unit 211, the Message 3 and the SRS are transmitted using the designated wireless resource. In this case, the SRS may be transmitted using, for example, the last symbol of the PUSCH used for transmitting the Message 3.

Next, the base station 100 measures the uplink radio channel quality (S33). For example, the wireless quality measuring unit 105 measures the wireless line quality using the SRS received in S32. Since the SRS is transmitted using the parameter of the radio resource included in the control information regarding SRS transmission, it is the SRS transmitted using a certain specific frequency. Therefore, the wireless quality measuring unit 105 can measure the wireless channel quality of the uplink frequency by measuring the wireless channel quality for the SRS transmitted using that frequency.

Next, the base station 100 selects an upstream frequency (S34). For example, the uplink frequency control unit 1060 may make a selection depending on whether or not the uplink radio channel quality measured in S33 is equal to or higher than the required quality (or threshold value). Here, it is assumed that the uplink radio channel quality is less than the threshold value and does not satisfy the required quality.

Next, the base station 100 transmits a Contention Resolution (Message 4) (hereinafter, sometimes referred to as “Message 4”) including an up link frequency change request to the terminal 200 (S35). The up link frequency change request is, for example, an SRS transmission frequency change request message requesting a change in the frequency for transmitting the SRS. Regarding the SRS transmitted by the terminal 200 in S32, the radio channel quality of the uplink frequency used for the SRS transmission did not satisfy the required quality. Therefore, the up link frequency change request causes the base station 100 to request the terminal 200 to transmit the SRS using an uplink frequency different from the uplink frequency used for the SRS transmission in S32. The up link frequency change request includes, for example, the changed SRS transmission frequency. For example, when the uplink frequency control unit 1060 confirms that the uplink radio line quality is less than the threshold value, it reads the changed uplink frequency information from the memory 107 and creates an up link frequency change request including this information. And transmits it to the terminal 200. Also in this case, the uplink frequency is, for example, the frequency included in the radio resource created by the radio resource creation parameter in the control information related to SRS transmission, which is transmitted by the base station 100 as system information. Note that the Message 4 is also an RRC connection setting request (or connection setup message), for example.

Then, the process shifts to S30 again. That is, the terminal 200 transmits the SRS transmission preamble to the base station 100 (S30).

Next, the base station 100 transmits the RAR including the SRS request to the terminal 200 (S31). At this time, the “UL grant” of the RAR includes, for example, information on the same radio resource as the SRS transmission frequency transmitted in S35. For example, the random access control unit 1063 may select such a radio resource and insert it into the “UL grant” area of the RAR.

Next, the terminal 200 transmits Message 3 and SRS at the upstream frequency designated in S35 (S32).

Next, the base station 100 measures the uplink radio channel quality using the received SRS (S33) and selects the uplink frequency (S34). Here, for example, the base station 100 determines that the uplink radio channel quality is equal to or higher than the threshold and satisfies the required quality.

Next, the base station 100 creates an up link frequency change request including an upstream frequency that satisfies the required quality. Then, the base station 100 transmits the Message 4 including the up link frequency change request to the terminal 200 (S35). For example, when the uplink frequency control unit 1060 determines that the uplink radio channel quality is equal to or higher than the threshold value, the uplink frequency used when the SRS is received in S32 (or the uplink frequency specified in S35, or “UL Grant” in S31). Select the transmitted uplink frequency).

For example, when the frequency at which the SRS is transmitted in S32 for the first time is the uplink frequency of the group, the base station 100 determines that the uplink radio channel quality by the uplink frequency of the group does not satisfy the required quality.

On the other hand, for example, when the frequency at which the SRS is transmitted in the second S32 is the SUL frequency, the base station 100 determines that the uplink radio channel quality at the SUL frequency satisfies the required quality. In this case, the base station 100 and the terminal 200 will set the wireless channel using the SUL frequency.

As described above, in the second operation example, the terminal 200 can transmit the SRS using the upstream frequency and the SRS using the SUL frequency in the random access procedure. Then, in the random access procedure, the base station 100 can select either the uplink frequency or the SUL frequency that is a set.

Thereby, for example, also in the operation example 2, as in the operation example 1, the two uplink radio channel qualities are measured by the SRS transmitted using the two frequencies, and the uplink frequency with good radio channel quality is selected. It becomes possible to do. Therefore, it is possible to improve the throughput of uplink communication as compared with the case where the uplink frequency is selected from the downlink radio channel quality.

In the above example, the process of S30 to S35 was repeated twice. For example, the processing from S30 to S35 may be repeated three times or more. In this case, the base station 100 changes the transmission frequency of the SRS transmitted in S32 every time so that the terminal 200 transmits the SRS at a different transmission frequency. The base station 100 may measure the uplink radio channel quality each time and select the best uplink frequency among all the uplink frequencies. Alternatively, the base station 100 may select the uplink frequency when the threshold is exceeded. Alternatively, the base station 100 and the terminal 200 perform the processing from S30 to S35 only once, and when the uplink radio channel quality at that time is equal to or higher than the threshold value, the uplink frequency (for example, a pair of uplink frequencies) May be selected.

Also, in the above example, the random access preamble for SRS transmission was explained. The random access preamble for SRS transmission may be, for example, one preamble for each terminal 200 or a plurality of preambles. In the case of a plurality of terminals, the terminal 200 selects any one of the plurality of random access preambles for SRS transmission transmitted as the system information, and transmits it (S30).

Furthermore, in the above-mentioned example, the example in which the SRS is transmitted in S32 has been described. For example, in S30, the SRS may be transmitted together with the random access preamble for SRS transmission. In this case, the terminal 200 calculates the radio resource by using the parameter included in the control information related to the SRS transmission received in the system information, and transmits the RAP and the SRS by using the calculated radio resource.

Specifically, the terminal 200 performs the following processing, for example. That is, the SRS transmission control unit 2060 calculates radio resources using the parameters included in the control information regarding SRS transmission, and instructs the transmission radio unit 211. Also, the random access control unit 2063 creates a RAP and outputs it to the transmission wireless unit 211. Further, the SRS creation unit 209 creates an SRS according to the instruction of the SRS transmission control unit 2060 and outputs it to the transmission wireless unit 211. The transmission wireless unit 211 transmits the RAP and the SRS using the designated wireless resource.

<3. Operation example 3 SUL frequency setting for each terminal>
11 and 12 are diagrams showing a sequence example in the operation example 3. Operation example 3 is an operation example of setting the SUL frequency for each terminal 200, for example.

As shown in FIG. 11, the terminal 200 selects the base station 100 by cell selection (S40).

Next, the base station 100 transmits system information including the paired up frequency fx and the paired down frequency fy (S41). For example, the system information setting management unit 1061 reads the two frequencies fx and fy from the memory 107, creates system information including these frequencies, and transmits the system information. The terminal 200 receives the system information transmitted from the base station 100.

Next, the base station 100 and the terminal 200 perform wireless line setting based on the paired up frequency fx and the paired down frequency fy (S42). The base station 100 and the terminal 200 set up a wireless channel with two frequencies fx and fy according to a normal random access procedure.

Next, the base station 100 transmits control information (“SRS transmission control information #2”) related to SRS transmission at the uplink frequency fx to the terminal 200 (S43). The base station 100 may transmit an SRS transmission request using the uplink frequency fx to the terminal 200 together with control information regarding SRS transmission.

Next, the terminal 200 uses the control information relating to the SRS transmission received in S43 to create the SRS, calculates the upstream frequency fx, and transmits the created SRS using the upstream frequency fx (S44). The SRS in this case is for selecting a radio resource within the uplink frequency fx in the base station 100, as shown in FIG. 8B, for example.

Returning to FIG. 11, next, the base station 100 measures the uplink radio channel quality (S45). For example, the radio quality measurement unit 105 measures the uplink radio channel quality using the SRS transmitted using the uplink frequency fx.

Next, the base station 100 selects an upstream radio resource (S46). For example, the radio resource control unit 1065 receives the uplink radio channel quality from the radio quality measurement unit 105, and if the uplink radio channel quality is equal to or higher than a threshold value (or required quality), selects the uplink frequency fx used in S44, If not, the upstream frequency fx is not selected. Here, the radio resource control unit 1065 will be described below assuming that the uplink frequency fx is not selected because the uplink radio channel quality is lower than the threshold value.

For example, the wireless line quality of the uplink frequency fx is at a level at which the random access procedure can be successful, but is not at a level at which user data is transmitted (QoS (Quality of Service) etc.). Therefore, the threshold may be a value corresponding to this QoS.

The base station 100 transmits a plurality of SUL frequency candidate (f1, f2, f3,...) Notifications when the uplink radio channel quality by the pair of uplink frequencies fx does not satisfy the required quality (S47). For example, the wireless control unit 1062 reads a plurality of SUL frequency candidates from the memory 107, creates a SUL frequency candidate notification, and transmits the SUL frequency candidate notification to the terminal 200. At this time, the radio control unit 1062 instructs the transmission radio unit 110 to transmit the SUL frequency candidate notification using the downlink frequency fy set in S42. As a result, the transmission wireless unit 110 transmits the SUL frequency candidate notification using the downlink frequency fy.

Next, the base station 100 transmits control information regarding SRS transmission in the SUL frequency candidates f1, f2,... To the terminal 200 (S48). At this time, the base station 100 may include, for example, the SRS transmission terminal identifier that identifies the terminal 200 in the control information regarding SRS transmission. In FIG. 11, an RNTI (Radio Network Temporary Identification) (or an RNTI for SRS transmission) is used as an SRS transmission terminal identifier. Thereby, for example, in the base station 100, in the subsequent SRS transmission, it is possible to identify the plurality of SRSs transmitted from the terminal 200 and the plurality of SRSs transmitted from other terminals. In addition, the base station 100 may transmit the SRS transmission request to the terminal 200 together with the control information regarding the SRS transmission.

For example, the base station 100 performs the following processing. That is, the radio control unit 1062 reads, from the memory 107, control information regarding SRS transmission in the SUL frequency candidate f1 and control information regarding SRS transmission in the SUL frequency candidate f2. Further, the wireless control unit 1062 reads the SRS transmission RNTI from the memory 107. Radio control section 1062 creates control information relating to SRS transmission including RNTI for SRS transmission, and transmits it to terminal 200. Further, the wireless control unit 1062 may create an SRS transmission request and transmit it to the terminal 200 together with the control information. It should be noted that the value of the RNTI for SRS transmission may be different for the SUL frequency or the downlink frequency fy that is a pair with the uplink frequency fx, or may be the same value for at least some frequencies. Good.

Next, the terminal 200 transmits the SRS using each of the plurality of SUL frequency candidates (S49). For example, the SRS transmission control unit 2060 transmits the SRS of the SUL frequency candidate f1 by using the control information (S48) regarding the SUL frequency candidate f1, and uses the control information (S48) regarding the SUL frequency candidate f2 by using the SUL. The SRS of the frequency candidate f2 is transmitted.

The terminal 200 may have a frequency that the terminal 200 does not support (or cannot transmit) among the plurality of SUL frequency candidates f1, f2,.... In this case, the terminal 200 does not have to transmit the SRS using the unsupported SUL frequency, and may transmit the SRS using the corresponding SUL frequency.

Next, the base station 100 measures a plurality of uplink radio channel qualities by using the SRS transmitted using each of the plurality of SUL frequency candidates (S50).

Then, the base station 100 selects the upstream frequency from the plurality of SUL frequency candidates (S51). For example, the uplink frequency control unit 1060 selects the SUL frequency candidate having the best uplink radio channel quality from the plurality of uplink radio channel qualities. In the example of FIG. 11, the upstream frequency control unit 1060 selects the SUL frequency candidate f2. After that, the SUL frequency candidate f2 is used as the SUL frequency f2, not as a candidate.

Next, the base station 100 transmits a frequency change notification to the terminal 200 (S52 in FIG. 12). In the example of FIG. 12, the upstream frequency is changed from the upstream frequency fx, which is a set of the wireless channels set in S42, to the SUL frequency f2 selected in S51. For example, the uplink frequency control unit 1060 transmits the SUL frequency f2 selected in S51 as the changed frequency to the terminal 200 via the control signal generation unit 108 and the like.

Next, the base station 100 and the terminal 200 perform wireless line setting using the changed upstream frequency (SUL frequency f2) and the downstream frequency fy as a pair (S53). Here, for example, a normal random access procedure using the SUL frequency f2 and the downlink frequency fy may be performed to set the wireless line.

After that, S54 to S56 are, for example, the process for selecting the uplink radio resource described in FIG. 8B.

That is, the base station 100 transmits the control information regarding the SRS transmission on the SUL frequency f2 (“SRS transmission control information #2”) to the terminal 200 (S54). At this time, the base station 100 may transmit the SRS transmission request together with the control information. The terminal 200 transmits the SRS using the SUL frequency f2 by using the received control information regarding the SRS (S55). The base station 100 uses the received SRS to select an uplink radio resource within the SUL frequency f2 (S56). Then, the base station 100 transmits an uplink transmission radio resource including the selected uplink radio resource to the terminal 200 as the scheduling result (S57). The terminal 200 transmits the user data to the base station 100 by using the uplink transmission radio resource (S58).

As described above, in the present operation example 3, when the uplink frequency fx, which is a set of wireless channels, does not satisfy the required quality, the base station 100 sets the SUL frequency for each terminal 200 from the plurality of SUL frequency candidates. It is possible to do. In the example of FIG. 11, the base station 100 sets the SUL frequency f2 for the terminal 200, but may set another SUL frequency from the SUL frequency candidates f1, f2,.... Further, the base station 100 may set any SUL frequency from the SUL frequency candidates f1, f2,... For other terminals.

Therefore, for example, also in the operation example 3, as in the operation example 1, the SRS transmitted using the pair of the up frequency fx (S44) and the SUL frequency (S49) allows the up frequency with good radio channel quality to be obtained. Can be selected.

In addition, in this operation example 3, the base station 100 can select the SUL frequency from a plurality of SUL frequencies. Further, the base station 100 and the terminal 200 change the SUL frequency, and uplink communication is possible using the changed SUL frequency. At this time, the base station 100 can select the optimal SUL frequency by using the SRS for each terminal 200, and can control the SUL frequency for each terminal 200 individually.

Therefore, in the communication system 10 in the present operation example 3, it is possible to improve the throughput of the upstream communication as compared with the case where the upstream frequency is selected from the downlink wireless line quality.

<4. Operation Example 4 Setting of SUL Frequency for Each Terminal When Random Access Procedure Fails>
In the operation example 3, the example in which the random access procedure is successful has been described. In operation example 4, setting of the SUL frequency for each terminal when the random access procedure fails will be described.

Note that operation example 4 has two operation examples. The first is an example (operation example 4-1) in which the base station 100 sets the SUL frequency from the plurality of SUL frequency candidates f1, f2,.... Secondly, since the base station 100 does not satisfy the required quality after setting the wireless channel with the SUL frequency f1, an example of setting the SUL frequency from a plurality of other SUL frequency candidates f2, f3,... (Operation example 4-2) ). First, the operation example 4-1 will be described.

<4.1 Operation Example 4-1>
13 and 14 are diagrams showing a sequence example of the operation example 4-1.

As shown in FIG. 13, the terminal 200 selects the base station 100 by cell selection (S60).

Next, the base station 100 transmits (or notifies) system information including the SUL frequency candidates f1, f2, f3,... (S61). The terminal 200 receives this system information.

For example, the system information setting management unit 1061 of the base station 100 reads the SUL frequency candidates f1, f2, f3,... From the memory 107, creates system information including these, and transmits the system information to the terminal 200. In addition, for example, the system information setting management unit 2061 of the terminal 200 receives the system information transmitted from the base station 100.

Next, the base station 100 and the terminal 200 perform wireless line setting by the normal random access procedure, but fail the random access procedure (S62). In this case, the frequency for which the wireless line setting is attempted is the upstream frequency fx and the downstream frequency fy in the case of FDD, and the frequency fx in the case of TDD.

Next, the base station 100 transmits control information (“SRS transmission control information #1”) regarding SRS transmission in the plurality of SUL frequency candidates f1, f2,... To the terminal 200 (S63). Also in this case, the base station 100 includes the control information about SRS transmission including the SRS transmission RNTI as the SRS transmission terminal identifier in order to identify each terminal 200, as in the operation example 3 (S48 in FIG. 11). To send. The base station 100 may also transmit the SRS transmission request together with the control information.

Next, the terminal 200 transmits the SRS using each of the plurality of SUL frequency candidates (S64).

Next, the base station 100 measures the quality of each uplink radio channel based on the transmitted SRS using each SUL frequency candidate (S65) and selects the uplink frequency (S66). Also in this case, the base station 100 may select the SUL frequency candidate having the best quality among the plurality of uplink radio channel qualities. In the example of FIG. 13, the base station 100 selects the SUL frequency candidate f2.

Next, the base station 100 transmits the selected SUL frequency (f2) to the terminal 200 (S67).

Then, the base station 100 and the terminal 200 perform wireless line setting for the SUL frequency f2 (S68). In the case of FDD, the frequency for which the wireless line is set is the SUL frequency f2 and the downlink frequency fy, which is the set, and in the case of TDD, the SUL frequency f2 and the downlink frequency fx, which is the set.

Thereafter, S69 to S71 of FIG. 14 are processes for selecting a wireless resource within the SUL frequency f2. That is, the base station 100 transmits the control information (“SRS transmission control information #2”) regarding the SRS transmission on the SUL frequency f2 to the terminal 200 (S69). At this time, the base station 100 may transmit the SRS transmission request together with the control information. Next, the terminal 200 transmits the SRS to the base station 100 using the SUL frequency f2 (S70). The base station 100 may transmit the SRS transmission request together with the control information. Then, the base station 100 selects an uplink radio resource in the SUL frequency f2 based on the SRS (S71 in FIG. 14) and transmits the selected uplink radio resource to the terminal 200 as an uplink transmission radio resource ( S72). The terminal 200 transmits user data by using the SUL frequency f2 (S73).

<4.2 Operation Example 4-2>
15 and 16 are diagrams showing a sequence example of the operation example 4-2.

As shown in FIG. 15, the terminal 200 selects the base station 100 by cell selection (S80).

Next, the base station 100 transmits (or notifies) the system information (S81). In the case of FDD, the system information includes the SUL frequency f1 and the set frequency (the set up frequency fx and the set down frequency fy). In the case of TDD, the system information includes the SUL frequency f1 and the frequency fx. For example, the system information setting management unit 1061 may read the information regarding these frequencies from the memory 107, and include the information in the system information for transmission. The terminal 200 receives the system information transmitted from the base station 100.

Next, the base station 100 and the terminal 200 perform normal wireless line setting, but the setting fails (S82). The target frequency of the wireless line setting is an upstream frequency fx and a downstream frequency fy in the case of FDD, and a frequency fx in the case of TDD.

Note that the frequency fx in the case of TDD can be a downlink frequency and an uplink frequency depending on the timing, for example, so the frequency fx can be divided into a downlink frequency that is a set and an uplink frequency that is a set.

Next, the base station 100 and the terminal 200 perform wireless line setting by a random access procedure using SUL (S83). In this case, the target frequency of the wireless line setting is the downlink frequency fy which is a combination with the SUL frequency in the case of FDD, and the downlink frequency fx which is a combination with the SUL frequency in the case of TDD.

From S84 to S87, the process for selecting the upstream radio resource for the SUL frequency f1 for which the radio line is set is performed. That is, the base station 100 transmits control information (“SRS transmission control information #2”) related to SRS transmission on the SUL frequency f1 to the terminal 200 (S84). At this time, the base station 100 may transmit the SRS transmission request together with the control information. Next, the terminal 200 transmits the SRS using the SUL frequency f1 based on this control information (S85). Then, the base station 100 measures the uplink radio channel quality based on the received SRS (S86) and selects the uplink radio resource within the SUL frequency f1 (S87). However, in the example of FIG. 15, the base station 100 determines that the SUL frequency f1 cannot satisfy the required quality and the SUL frequency f1 cannot be selected.

Next, the base station 100 transmits a plurality of SUL frequency candidates f2, f3,... (S88). Further, the base station 100 transmits control information (“SRS transmission control information #1”) regarding SRS transmission in the plurality of SUL frequency candidates f2, f3,... (S89). At this time, the base station 100 may transmit the SRS transmission request together with the control information. Next, the terminal 200 transmits the SRS using each frequency of the plurality of SUL frequency candidates f2, f3,... (S90).

The base station 100 measures a plurality of uplink radio channel qualities based on a plurality of SRSs (S91) and selects a SUL frequency from SUL frequency candidates (S92 in FIG. 16). In the example of FIG. 16, the base station 100 selects the SUL frequency f2.

Next, the base station 100 transmits the changed SUL frequency f2 (S93).

Then, the base station 100 and the terminal 200 perform wireless line setting using the changed SUL frequency f2 (S94). In this case, in the case of FDD, the target frequency of the wireless link setting is the SUL frequency f2 for the upstream frequency, the frequency fy for the downstream frequency is a set, and the frequency for the TDD is the SUL frequency f2 for the downstream, and the frequency fy is the frequency for the downstream. Becomes

After that, the processing is for selecting a wireless resource within the SUL frequency f2 after the change. That is, the base station 100 transmits control information (“SRS transmission control information #2”) related to SRS transmission on the SUL frequency f2 to the terminal 200 (S95). At this time, the base station 100 may transmit the SRS transmission request together with the control information. The terminal 200 transmits the SRS using the SUL frequency f2 (S96). Based on the received SRS, the base station 100 determines that the SUL frequency f2 satisfies the required quality, selects the uplink radio resource within the SUL frequency f2 (S97), and transmits the uplink transmission radio resource to the terminal 200 ( S98). The terminal 200 transmits user data using the SUL frequency f2 (S99).

In operation examples 4-1 and 4-2, when the normal random access procedure fails, the base station 100 can set the SUL frequency for each terminal 200 from the plurality of SUL frequency candidates. Become. At that time, the base station 100 transmits control information regarding SRS transmission in a plurality of SUL frequency candidates, and the terminal 200 transmits an SRS using each of the plurality of SUL frequency candidates. Then, the base station 100 selects the SUL frequency from the plurality of SUL frequency candidates.

Therefore, also in the operation examples 4-1 and 4-2, the base station 100 can select the SUL frequency from a plurality of SUL frequencies, for example. In addition, the base station 100 and the terminal 200 change the SUL frequency, and uplink communication is possible with the changed SUL frequency. At this time, the base station 100 can select the optimum SUL frequency using the SRS for each terminal 200, and can set the SUL frequency for each terminal 200.

Note that, in the operation examples 4-1 and 4-2, for example, since the upstream frequency is changed without changing the downstream frequency, the upstream frequency can be considered as a handover to a different frequency.

<5. Operation example 5 SRS transmission using measurement gap>
In LTE, for example, when the terminal 200 is handed over to another base station instead of the connection destination base station 100, a measurement gap (measurement gap) is set in order to measure downlink radio channel quality with the other base station. A so-called no-communication period (GAP) is set. The terminal 200 receives a signal transmitted from another base station and measures the communication quality thereof during the non-communication period.

In this operation example 5, for example, a non-communication period (new GAP) is provided. The terminal 200 transmits the SRS using the frequency to be measured during the non-communication period. The frequencies to be measured include, for example, a pair of upstream frequency and SUL frequency. The conventional (LTE) measurement gap is a non-communication period for the terminal 200 to measure downlink radio channel quality, but here, since the base station 100 measures uplink radio channel quality, the terminal 200 uses the SRS. Is the period for sending. It can also be said to be a non-communication period because the communication with the base station 100 being connected (connected) is stopped.

FIG. 17(A) and FIG. 17(B) are diagrams showing a setting example of the non-communication period in the case of TDD. 17A shows a setting example at the frequency fa during communication, and FIG. 17B shows a setting example at the measurement target frequency fb. Note that one frame in FIG. 17A or the like represents a subframe (period), for example.

As shown in FIG. 17A, the base station 100 uses downlink communication at a certain timing to transmit control information regarding SRS transmission, and the terminal 200 receives control information regarding SRS transmission.

The base station 100 transmits to the terminal 200 the control information related to the SRS transmission including the information about the non-communication period such as the start time and the length of the non-communication period. As a result, as illustrated in FIG. 17B, the terminal 200 transmits the SRS using the measurement target frequency fb during the non-communication period (GAP).

The base station 100 performs the following processing, for example. That is, the radio control unit 1062 creates control information regarding SRS transmission including a parameter with which the frequency fb to be measured can be calculated and information regarding the non-communication period. The radio control unit 1062 controls the transmission radio unit 110 to transmit control information regarding SRS transmission during a certain downlink communication period at the frequency fa during communication. On the other hand, the SRS transmission control unit 2060 of the terminal 200 creates the SRS based on the control information regarding the SRS transmission, calculates the measurement frequency fb, and transmits the SRS using the measurement frequency fb.

FIG. 17C to FIG. 17F are diagrams showing setting examples of the non-communication period in the case of FDD. Of these, FIG. 17C and FIG. 17D respectively show setting examples of downlink communication (fa_dl) and uplink communication (fa_ul) at the frequency fa during communication. Further, FIGS. 17E and 17F respectively show setting examples of downlink communication (fb_dl) and uplink communication (fb_ul) at the measurement frequency fb.

As shown in FIG. 17(C), the base station 100 transmits control information regarding SRS transmission to the terminal 200 using the frequency fa during communication. As in the case of TDD, the control information includes information about the non-communication period such as the start time and length of the non-communication period. Then, as illustrated in FIG. 17F, the terminal 200 creates the SRS based on the control information regarding the SRS transmission, calculates the upstream frequency fb for measurement, and uses the upstream frequency fb in the upstream communication period. Then, the SRS is transmitted.

In both the case of TDD and the case of FDD, the base station 100 can set the measurement frequency fb to the upstream frequency or the SUL frequency as a set. As a result, the terminal 200 transmits the SRS using the uplink frequency that is a pair in the set no-communication period, and transmits the SRS using the SUL frequency in the next set no-communication period. It becomes possible to do. After that, as in the operation example 1 and the like, the base station 100 may measure the uplink radio channel quality based on, for example, the SRS, and select the uplink frequency or the SUL frequency as a set. In the above description, the case where the upstream frequency is changed between the upstream frequency and the SUL frequency that are a set has been described, but it is also possible to similarly change the upstream frequency between a plurality of SUL frequencies.

18A to 18F show other setting examples of the non-communication period. In FIGS. 17A to 17F, the control information is transmitted using the frequency fa during communication. 18A to 18F show an example in which control information is transmitted using the frequency fb to be measured.

That is, in the first non-communication period, the base station 100 transmits control information regarding SRS transmission using the frequency fb (or fb_dl) to be measured. Then, in the next non-communication period, the terminal 200 transmits the SRS by using the frequency fb (or fb_ul). Also in this case, by setting the measurement target frequency fb to the upstream frequency or the SUL frequency that is a group, the terminal 200 can transmit the SRS using the upstream frequency or the SUL frequency that is the group.

Above, operation examples 1 to 5 have been explained.

<6. Operation Example of Base Station in Operation Example 2>
Next, an operation example of the base station 100 of the operation example 2 will be described. Since the operation example 2 has been described, the upstream frequency selection process (S34 in FIG. 9) will be mainly described.

19 and 20 are flowcharts showing an operation example in the base station 100.

When the base station 100 starts processing (S100), it transmits system information (S101). The system information includes a set of upstream frequencies fu_0, a plurality of SUL frequencies fu_1,..., Fu_k, random access control information, control information regarding SRS transmission, and the like.

Next, the base station 100 sets n to “0” (n=0) and sets RSRP_max to “0” (S102). Here, for example, n is the number of repetitions (1≦n≦k), and RSRP_max represents the maximum value of uplink radio channel quality. As the wireless line quality, for example, RSRP is used. For example, the random access control unit 1063 stores n=0 and RSRP_max=0 in the memory 107.

Next, the base station 100 receives the RAP transmitted from the terminal 200 using the pair of upstream frequencies fu_0 (n=0 in fu_n) (S103). This is processing corresponding to S30 in FIG. For example, the random access control unit 1063 receives the RAP.

Returning to FIG. 19, next, the base station 100 transmits the RAR using the downlink frequency fd_0 that is a pair (S104). As described in S31 of FIG. 9, for example, the random access control unit 1063 transmits “RAR” by including “1” in the “R” area in the MAC payload of RAR.

Returning to FIG. 19, next, the base station 100 receives the Message 3 and the SRS transmitted from the terminal 200, using the pair of upstream frequencies fu_0 (S105). This corresponds to S32 in FIG. For example, the random access control unit 1063 receives the SRS with the frequency fu_0.

Returning to FIG. 19, next, the base station 100 measures the wireless line quality (S106). This corresponds to S33 of FIG. For example, the uplink frequency control unit 1060 measures RSRP based on the SRS received in S105, and stores it in the memory 107 as radio line quality RSRP_fu_0.

Next, the base station 100 determines whether or not the measured wireless line quality RSRP_fu_0 is greater than the maximum wireless line quality value RSRP_max (S107). For example, the uplink frequency control unit 1060 may read out the measured wireless channel quality RSRP_fu_0 and the maximum wireless channel quality RSRP_max from the memory 107 and compare them.

When the measured wireless channel quality RSRP_fu_0 is larger than the maximum wireless channel quality value RSRP_max (Yes in S107), the base station 100 sets the maximum wireless channel quality value RSRP_max to the measured wireless channel quality RSRP_fu_0, and fu=0. (S108). Here, fu represents, for example, an upstream frequency number. For example, the uplink frequency control unit 1060 substitutes the measured wireless line quality RSRP_fu_0 into the maximum value RSRP_max of the wireless line quality, and stores RSRP_max=RSRP_fu_0 and fu=0 in the memory 107.

On the other hand, when the measured wireless channel quality RSRP_fu_0 is less than or equal to the maximum wireless channel quality value RSRP_max (No in S107), the base station 100 shifts to S109 in FIG. 20 without performing the process of S108.

The base station 100 determines whether or not the number of repetitions n has become “k” when S108 of FIG. 19 is ended or when it is determined No in S107 (S109 of FIG. 20).

When the number of repetitions is not n=k (No in S109), the base station 100 uses the downlink frequency fd_0 to transmit the Message 4 including the up link frequency change request (S110). The upstream frequency change request includes, for example, the changed upstream frequency fu_1 and the SRS transmission request. Then, the process again moves to S103 in FIG. 19 and the random access procedure using the changed uplink frequency fu_1 is performed (S103 to S105).

Then, the base station 100 measures the wireless channel quality by using the SRS transmitted at the uplink frequency fu_1 (S106), and determines whether the measured wireless channel quality RSRP_fu_1 exceeds the maximum value RSRP_max of the wireless channel quality. A determination is made (S107). When exceeding (Yes in S107), the base station 100 sets the maximum value RSRP_max of the wireless channel quality to the measured wireless channel quality RSRP_fu_1 and sets fu=1 (S108), and otherwise (No in S107). , The maximum value RSRP_max of the wireless channel quality is maintained.

After that, the wireless channel quality is measured for all the SUL frequency candidates (n=k), and the best frequency is selected as the upstream frequency (S111 in FIG. 20).

For example, in S108 of FIG. 19, the maximum value of the wireless channel quality is stored in the memory 107 as RSRP_max, and the number n of the upstream frequency when the wireless channel quality becomes the maximum value is stored in the memory 107. The base station 100 confirms the number n stored in the memory 107 to set the uplink frequency.

That is, the base station 100 sets the upstream frequency fu_n having the number fu=n as the upstream frequency. For example, the upstream frequency control unit 1060 reads fu=n from the memory 107, and when n=0, sets the upstream frequency fu_0 to the upstream frequency fu=n, and when n≠0, the wireless channel quality is the best. The SUL frequencies fu_1,..., Fu_k are set to the upstream frequency fu_n. The uplink frequency control unit 1060 outputs the set uplink frequency fu_n to the transmission wireless unit 110.

Next, the base station 100 transmits the Message 4 and the set upstream frequency fu_n to the terminal 200 (S112). Then, the base station 100 ends the wireless line setting (S113) and ends the series of processes (S114).

As described above, the examples of FIGS. 19 and 20 represent an operation example in the case of selecting the upstream frequency fu_n having the best upstream wireless channel quality.

21 and 22 are also flowcharts showing an operation example of the base station 100 in the operation example 2. 21 and 22 show an example in which the base station 100 sets the measured radio channel quality larger than the threshold to the upstream frequency fu_n.

That is, the base station 100 sets n=0 (S121), performs a series of random access procedures (S103 to S105), measures the radio channel quality (S106), and the measured radio channel quality RSRP_fu_n is the threshold RSRP_th. It is determined whether it is larger than (S122).

When the measured radio channel quality RSRP_fu_n is larger than the threshold RSRP_th (Yes in S122), the base station 100 sets fu=n (S123) and sets the uplink frequency fu_n having the number fu=n to the uplink frequency. Yes (S111).

On the other hand, when the measured wireless channel quality RSRP_fu_n is less than or equal to the threshold RSRP_th (No in S122), the base station 100 shifts to S103 and repeats the above-described processing (loop from S103 to S110).

Such determination (S122) and setting of the upstream frequency fu_n (S123, S111 of FIG. 22) are performed by the upstream frequency control unit 1060, for example.

23 and 24 are also flowcharts showing an operation example in the base station 100 in the operation example 2. 23 and 24 show an example in which the base station 100 selects the uplink frequency with the best uplink radio channel quality and equal to or higher than the threshold.

That is, the base station 100 measures the wireless channel quality (S106), and determines whether the measured wireless channel quality RSRP_fu_n is larger than the maximum wireless channel quality value RSRP_max and larger than the threshold value RSRP_th (S131). ).

The base station 100 sets the maximum value RSRP_max to the measured wireless line quality RSRP_fu_n when the measured wireless line quality RSRP_fu_n is larger than the maximum value RSRP_max of the wireless line quality and larger than the threshold value RSRP_th (Yes in S131). In addition, the base station 100 sets fu=n (S108). Otherwise (No in S131), the maximum values RSRP_max and fu of the wireless channel quality are maintained.

Then, the base station 100 repeatedly sets the up frequency fu_n until all the SUL frequencies fu_1,..., Fu_k (Yes in S109). That is, the base station 100 sets the paired up frequency fu_0 to the up frequency fu_n when n=0. Further, when n≠0, the base station 100 sets the best SUL frequencies fu_1,..., Fu_k to the upstream frequency fu_0 (S111).

Such determination (S131) and setting (S108, S111) are performed by the upstream frequency control unit 1060, for example.

[Other Embodiments]
Next, other embodiments will be described.

FIG. 25 is a diagram showing a configuration example of the communication system 10.

The communication system 10 includes a base station 100 and a terminal 200. The base station 100 is a wireless communication device that provides services to the terminals 200 located in the cell range. On the other hand, the terminal 200 is a wireless communication device such as a smartphone, a feature phone, or a tablet terminal. The base station 100 and the terminal 200 perform wireless communication using the first uplink frequency that forms a pair with the downlink frequency, the second uplink frequency that is different from the first uplink frequency, and the downlink frequency. Is possible.

The base station 100 includes a first wireless controller 150 and a first receiver 155.

The first radio control unit 150 requests the uplink reference signal transmission requesting to transmit the first and second uplink reference signals using the first and second uplink frequencies, respectively, and the first and second uplinks. The control information regarding the reference signal is transmitted to the terminal 200. In addition, the first radio control unit 150 transmits frequency control information regarding the first or second upstream frequency to the terminal 200.

The first receiving unit 155 receives the first and second uplink reference signals transmitted from the terminal 200 using the first and second uplink frequencies, respectively.

The terminal 200 includes a second receiving unit 250 and a second wireless control unit 255.

The second receiving unit 250 receives the uplink reference signal transmission request and the control information regarding the first and second uplink reference signals transmitted from the base station 100. The second receiving unit 250 also receives the frequency control information.

The second radio control unit 255 transmits the first and second uplink control signals to the base station 100 based on the uplink reference signal transmission request and the control information, using the first and second uplink frequencies, respectively.

As described above, in the present embodiment, the base station 100 causes the terminal 200 to transmit the first and second uplink reference signals using the first and second uplink frequencies, respectively. For example, when the first uplink frequency is a pair of uplink frequencies and the second uplink frequency is a SUL frequency, the base station 100 uses the first reference signal using the pair of uplink frequencies and the SUL frequency. The second reference signal is transmitted from the terminal 200. In this case, the base station 100 receives the first and second reference signals and selects the first upstream frequency or the second upstream frequency. Then, the base station 100 can measure the radio channel quality at the first uplink frequency and the radio channel quality at the second uplink frequency from the two reference signals, and based on these two measurement results, It becomes possible to select the first or second upstream frequency.

Therefore, since the communication system 10 causes the terminal 200 to transmit the first and second uplink reference signals by using the first and second uplink frequencies, respectively, the uplink frequency is selected using these. It becomes possible. Therefore, the communication system 10 can improve the throughput of uplink communication as compared with the case of selecting the uplink frequency from the downlink radio channel quality.

The first wireless control unit 150 and the first receiving unit 155 correspond to the wireless control unit 106 and the receiving unit 120 in the first embodiment, respectively. Further, the second wireless control unit 255 and the second receiving unit 250 respectively correspond to the wireless control unit 206 and the receiving unit 220 in the first embodiment, for example.

Note that it is assumed that the frequencies described in Non-Patent Document 39 are used for setting the upstream frequency and the downstream frequency, but other frequencies may be used. For example, when a new frequency band is defined, that frequency may be used.

10: communication system 100: base station device (base station)
105: Radio quality measuring unit 106: Radio control unit 1060: Uplink frequency control unit 1061: System information setting management unit 1062: Radio control unit 1063: Random access control unit 1064: HO control unit 1065: Radio resource control unit 107: Memory 108 : Control signal creation unit 120: reception unit 130: control unit 140: transmission unit 200 (200-1, 200-2): terminal device (terminal)
204: control signal extraction unit 205: wireless quality measurement unit 206: wireless control unit 2060: SRS transmission control unit 2061: system information setting management unit 2062: wireless control unit 2063: random access control unit 2064: HO control unit 2065: wireless resource Controller 220: Receiver 230: Controller 240: Transmitter

Claims

In a base station device that performs wireless communication with a terminal device using a first uplink frequency that forms a pair with a downlink frequency, a second uplink frequency different from the first uplink frequency, and the downlink frequency ,
An uplink reference signal transmission request that requests transmission of the first and second uplink reference signals using the first and second uplink frequencies, respectively, and control information related to the first and second uplink reference signals. A radio controller for transmitting to the terminal device and transmitting frequency control information about the first or second upstream frequency to the terminal device;
And a receiving unit that receives the first and second uplink reference signals transmitted from the terminal device using the first and second uplink frequencies, respectively.
Furthermore, a radio quality measuring unit is provided for measuring the first and second uplink radio channel qualities from the first and second uplink reference signals, respectively.
The base station apparatus according to claim 1, wherein the radio control unit selects the first or second uplink frequency according to the first and second uplink radio channel qualities.
The base station apparatus according to claim 1, wherein the radio control unit broadcasts system information including control information regarding the first and second uplink reference signals.
The base station device according to claim 1, wherein the radio control unit transmits a line setting request including the uplink reference signal transmission request to the terminal device.
The receiving unit receives the connection request and the first uplink reference signal transmitted from the terminal device using the first uplink frequency, and uses the second uplink frequency from the terminal device. The base station apparatus according to claim 1, wherein the base station apparatus receives the connection request and the second uplink reference signal transmitted by transmitting the connection request.
The base station apparatus according to claim 1, wherein the radio control unit transmits the frequency control information or an uplink frequency change request to the terminal apparatus.
The base station apparatus according to claim 6, wherein the wireless control unit transmits a connection setting request and the frequency control information or the upstream frequency change request to the terminal apparatus.
The base station according to claim 1, wherein the radio control unit changes a frequency used for transmitting user data transmitted from the terminal device from the first uplink frequency to the second uplink frequency. apparatus.
The radio control unit transmits the second uplink frequency and a third uplink frequency different from the first and second uplink frequencies to the terminal device. Base station device.
The radio control unit includes the uplink reference signal transmission request including a request for transmitting the first to third uplink reference signals respectively using the first to third uplink frequencies, and the first to third uplinks. The base station device according to claim 9, wherein the control information regarding the reference signal is transmitted to the terminal device.
The radio control unit further identifies the second and third uplink reference signals transmitted from the terminal device from the second and third uplink reference signals transmitted from another terminal device. 11. The base station device according to claim 10, wherein a transmission terminal identifier is transmitted to the terminal device.
The base station device according to claim 9, wherein the radio control unit selects the second or the third uplink frequency.
Furthermore, a radio quality measuring unit for respectively measuring first to third uplink radio channel qualities from the first to third uplink reference signals is provided,
13. The base station apparatus according to claim 12, wherein the radio control unit selects the second or third uplink frequency having the second or third uplink radio channel quality with good radio channel quality, respectively. ..
The base station device according to claim 8, wherein the radio control unit transmits the changed second uplink frequency to the terminal device.
The base station according to claim 1, wherein the radio control unit broadcasts system information including the second uplink frequency and a third uplink frequency different from the first and second uplink frequencies. Station equipment.
The base station device according to claim 1, wherein the radio control unit broadcasts system information including the first and second upstream frequencies.
In a terminal device that wirelessly communicates with a base station device by using a first uplink frequency paired with a downlink frequency, a second uplink frequency different from the first uplink frequency, and the downlink frequency ,
Uplink reference signal transmission request for requesting transmission of first and second uplink reference signals using the first and second uplink frequencies, respectively, transmitted from the base station device, and the first and second uplink reference signals. And a receiving unit that receives the control information about the uplink reference signal and receive the frequency control information about the first or second uplink frequency,
The base station transmits the first and second uplink reference signals using the first and second uplink frequencies based on the uplink reference signal transmission request and control information about the first and second uplink reference signals. And a wireless control unit for transmitting to the device.
The receiving unit receives a line setting request including the uplink reference signal transmission request transmitted from the base station device,
The radio control unit transmits the connection request and the first uplink reference signal to the base station device using the first uplink frequency, or uses the second uplink frequency. The terminal device according to claim 17, wherein the connection request and the second uplink reference signal are transmitted.
The receiving unit receives the connection request and the frequency control information or the uplink frequency change request transmitted from the base station device,
The radio control unit transmits the connection request and the first uplink reference signal to the base station apparatus using the first uplink frequency, and when the uplink frequency change request is received, A frequency is changed to the second uplink frequency, and the connection request and the second uplink reference signal are transmitted to the base station apparatus by using the second uplink frequency. Item 17. The terminal device according to item 17.
A base station device,
Equipped with a terminal device,
The base station device and the terminal device wirelessly communicate with each other by using a first uplink frequency that forms a pair with a downlink frequency, a second uplink frequency different from the first uplink frequency, and the downlink frequency. In a communication system that performs communication,
The base station device,
The terminal receives an uplink reference signal transmission request for requesting transmission of first and second uplink reference signals using the first and second uplink frequencies, respectively, and control information related to the first and second uplink reference signals. A first radio controller for transmitting frequency control information regarding the first or second upstream frequency to the terminal device;
A first receiver that receives the first and second uplink reference signals transmitted from the terminal device using the first and second uplink frequencies, respectively,
The terminal device,
A second receiving unit that receives the uplink reference signal transmission request, the control information about the first and second uplink reference signals, and the frequency control information transmitted from the base station device;
The base station transmits the first and second uplink reference signals by using the first and second uplink frequencies based on the uplink reference signal transmission request and the control information on the first and second uplink reference signals. A communication system comprising: a second wireless control unit for transmitting to a device.