JP6111095B2 - Base station apparatus and radio communication method - Google Patents

Description

  The present invention relates to a base station apparatus and a wireless communication method.

In a wireless communication system, a user wirelessly transmits a random access channel (RACH) signal from a terminal apparatus (UE) to a base station apparatus (eNB), and thereby a user terminal on the base station apparatus side. Identifies the device and assigns a data channel to the terminal device.
Here, the direction from the terminal apparatus to the base station apparatus is referred to as “up” (up), and the direction from the base station apparatus to the terminal apparatus is referred to as “down” (down).

FIG. 9 shows an example of the flow of connection processing for establishing a session between the base station apparatus (eNB) 1001 and the terminal apparatus (UE) 1002 in the uplink physical channel of the wireless communication system.
First, terminal apparatus 1002 wirelessly transmits a random access preamble signal to base station apparatus 1001 using RACH (process T1). The base station apparatus 1001 receives the random access preamble signal transmitted from the terminal apparatus 1002, and assigns (assigns) uplink resources.
Next, the base station apparatus 1001 wirelessly transmits (responds) uplink resource allocation information to the terminal apparatus 1002 as a random access response (Random Access Response) signal (process T2).

Next, the terminal device 1002 creates an RRC (Radio Resource Control) connection request message signal, and transmits the signal wirelessly to the base station device 1001 using the channel region according to the allocation notified by the base station device 1001. (Processing T3). This is a scheduled transmission (Scheduled Transmission).
Next, the base station apparatus 1001 authenticates the terminal apparatus 1002, and transmits a signal of an RRC connection setup message for starting radio resource control to the terminal apparatus 1002 by radio (process T4). Thereby, the session of the base station apparatus 1001 and the terminal device 1002 is established. This realizes contention resolution.

  Here, the RACH region is limited within the radio resource. For this reason, when many terminal apparatuses wirelessly transmit RACH signals to one base station apparatus, the base station apparatus cannot determine the terminal apparatus and cannot allocate uplink resources to the terminal apparatus. . This is due to the collision of RACH signals, and the same preamble signals wirelessly transmitted from a plurality of terminal devices overlap and collide.

FIG. 10 shows an example of a flow of connection processing for establishing a session between the base station apparatus (eNB) 1101 and the terminal apparatus (UE) 1102 when a RACH signal collision occurs in the uplink physical channel of the wireless communication system. (For example, refer nonpatent literature 1.).
First, the terminal apparatus 1102 wirelessly transmits a random access preamble signal to the base station apparatus 1101 using RACH (process T11). The random access preamble signal includes channel quality information (CQI: Channel Quality Indicator) indicating the quality of the channel, power headroom information regarding the power of the terminal device, buffer size information regarding the buffer size of the terminal, and the like.

  When a response to the signal is not received from the base station apparatus 1101 during a predetermined time (for example, random time) from the time of transmission of the RACH signal (random access preamble signal), the terminal apparatus 1102 transmits transmission power. And retransmits the RACH signal (random access preamble signal) (process T12). Then, similar processing is repeated as necessary.

  Further, even if the terminal apparatus 1102 increases the RACH transmission power to the maximum transmission power of the terminal apparatus 1102 and retransmits the RACH signal (random access preamble signal), the response to the signal is the base station apparatus 1101. If not received, the RACH signal (random access preamble signal) is transmitted by radio to different frequency bands.

  When the base station apparatus 1101 receives the RACH signal (random access preamble signal) transmitted from the terminal apparatus 1102, the base station apparatus 1101 wirelessly transmits a random access response signal to the terminal apparatus 1102 (process T13). The random access response signal includes timing advance information indicating the time to be connected, information for permitting uplink resources (UL resource permission information), information for controlling power (power control information), and the like.

  Next, when the random access response signal transmitted from the base station apparatus 1101 is received, the terminal apparatus 1102 wirelessly transmits the RRC connection request message signal to the base station apparatus 1101 (process T14). The signal of the RRC connection request message includes channel quality information (CQI) indicating the quality of the channel, information for reporting the radio environment (radio environment report information), and the like.

Next, when the base station apparatus 1101 receives the signal of the RRC connection request message transmitted from the terminal apparatus 1102, the RRC contention resolution signal for controlling the wireless communication of the plurality of terminal apparatuses not to collide Is transmitted wirelessly to the terminal device 1102 (process T15).
Further, the base station apparatus 1101 transmits a signal of an RRC connection setup message to the terminal apparatus 1102 by radio (process T16). As a result, a session between the base station apparatus 1101 and the terminal apparatus 1102 is established.

Here, the frequency band in which the terminal device tries to connect to the base station device preferentially is called an upper band. Further, frequency bands other than the upper band are called lower bands.
For example, in a wireless communication system having a plurality of frequency bands, a base station apparatus distributes and allocates frequency bands for transmitting RACH signals to terminal apparatuses, thereby avoiding collision of RACH signals in higher bands. Technologies and technologies for limiting the number of terminal devices connected to higher bands by reducing the RACH region in which RACH signals are transmitted from the terminal device to the base station device have been studied.
For example, the base station apparatus in the mobile communication system transmits a downlink control channel including an area where downlink radio resource allocation information is arranged to the mobile station apparatus, and a random access channel from the mobile station apparatus When the first means includes a predetermined value in a predetermined area including an area where the downlink radio resource allocation information is arranged, the second means for detecting a preamble transmission using A technique has been studied in which an identification number used for designating the preamble is included in an area other than the predetermined area of the downlink control channel and transmitted to the mobile station apparatus (see, for example, Patent Document 1).

  In addition, in communication standards such as LTE (Long Term Evolution), it is possible to separate the U-plane of the protocol layer that handles user data and the C-plane of the protocol layer that performs control, and communicate in different frequency bands. Yes.

JP 2011-229170 A

R1-050850 “Physical Channel and Multiplexing in Evolved UTRA Uplink”, 3GPP TSG RAN WG1 Meeting # London, UL, August 29-September 2, 2005

As described above, in a wireless communication system, a terminal device identifies a random access channel (RACH) signal that is wirelessly transmitted to a base station device, and assigns a data channel to the terminal device. A session is established.
However, in such a wireless communication system, if the number of terminal apparatuses accommodated in the communication area of the base station apparatus temporarily increases, a shortage of control channels (here, RACH) occurs, so the terminal apparatus and the base station There was a problem that a session with the device could not be established.

  For example, as described above, by distributing the frequency band (standby band) for transmitting the RACH signal first from the terminal device, collision of the RACH signal in the upper band frequently occurs and the terminal device is connected to the base station device. It is possible to avoid a state where it cannot be done. However, in such a configuration, in order to distribute and allocate standby bands in the terminal device, at least the terminal device exists in the communication area of the base station device and receives a plurality of frequency bands in advance. There is a need. For this reason, when a large number of terminal devices enter the communication area from outside the communication range of the base station device, the base station device cannot disperse the standby band, and the collision of RACH signals in the upper band frequently occurs. There was a problem.

  Further, for example, as described above, a terminal device newly entering the communication area of the base station apparatus by reducing the area of the upper band RACH is newly communicated in the wireless communication system connected to the lower frequency band. Since the terminal device that has entered the area tries to connect to the lower frequency band after transmitting the RACH signal a plurality of times, the time required for the terminal device to connect to the base station device and the power consumption increase. was there.

  The present invention has been made in consideration of such circumstances, and can reduce the collision of RACH signals and effectively establish a session between the base station apparatus and the terminal apparatus. It is another object of the present invention to provide a wireless communication method.

(1) In order to solve the above-described problem, a base station apparatus according to the present invention detects a situation detection unit that detects information indicating a situation regarding the degree of congestion of a RACH signal from a terminal device, and the situation detection unit detects the situation. When it is determined that the RACH signal from the terminal device is congested based on predetermined information based on predetermined information, the terminal device tries to connect to the base station device with priority. A channel setting unit configured to set a channel region so as to temporarily extend a control channel region including a RACH region in an upper band predetermined as a frequency band , and the channel setting unit includes the upper band The control channel region including the RACH region is temporarily expanded in the lower band other than the upper band and the control channel region is included in the control channel region. To set the channel region so as to temporarily reduce the area, and wherein the.

  (2) The present invention includes, in the base station device described in (1) above, a channel notification unit that notifies the terminal device of the contents of the channel region setting performed by the channel setting unit by broadcast. It is characterized by that.

(3) In a base station apparatus according to any one of the above (1) or the above (2), the terminal device connected using RACH region of the upper band, the A scheduling unit that allocates resources of a lower band other than an upper band as a data channel region, and a schedule notification unit that notifies a result of a scheduling process performed by the scheduling unit to the terminal device.

( 4 ) The present invention provides a base station apparatus according to any one of (1) to ( 3 ) described above, to a terminal apparatus connected using the RACH region of one type of base station apparatus. On the other hand, a scheduling unit that allocates resources of other types of base station apparatuses as data channel regions is provided.

( 5 ) In order to solve the above-described problem, in the wireless communication method according to the present invention, the situation detection unit provided in the base station apparatus detects information indicating the situation regarding the degree of congestion of the RACH signal from the terminal apparatus. When the channel setting unit provided in the base station apparatus determines that the RACH signal from the terminal apparatus is congested according to a predetermined condition based on information detected by the situation detection unit Is configured to set a channel region so as to temporarily extend a control channel region including a RACH region in an upper band predetermined as a frequency band in which the terminal device tries to connect to the base station device with priority. gastric row, the channel setting unit is configured to extend the control channel region including the RACH region in the upper band temporarily, before To set the channel region to temporarily reduce the control channel region in the lower band other than the upper band, characterized in that.

  ADVANTAGE OF THE INVENTION According to this invention, the collision of a RACH signal can be reduced and the establishment of the session of a base station apparatus and a terminal device can be implement | achieved effectively.

1 is a block diagram showing a schematic configuration of a wireless communication system according to an embodiment of the present invention. It is a block diagram which shows the schematic structure of the base station apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows the schematic structure of the terminal device which concerns on one Embodiment of this invention. It is a figure for demonstrating the channel setting process which concerns on 1st Embodiment of this invention. It is a figure for demonstrating the scheduling process which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the schematic structural example of the multi-site radio | wireless communications system which concerns on 3rd Embodiment of this invention. It is a block diagram which shows the schematic structural example of the radio | wireless communications system of the D-RAN structure which concerns on 3rd Embodiment of this invention. It is a block diagram which shows the schematic structural example of the radio | wireless communications system of the C-RAN structure which concerns on 3rd Embodiment of this invention. It is a figure which shows an example of the flow of the connection process in which a base station apparatus (eNB) and a terminal device (UE) establish a session in the uplink physical channel of a radio | wireless communications system. It is a figure which shows an example of the flow of the connection process in which a base station apparatus (eNB) and a terminal device (UE) establish a session when the collision of the RACH signal arises in the uplink physical channel of a radio | wireless communications system. 1 is a block diagram illustrating a schematic configuration of a multi-site wireless communication system. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Outline of wireless communication system]
FIG. 1 is a block diagram showing a schematic configuration of a wireless communication system according to an embodiment of the present invention.
The radio communication system according to the present embodiment includes a base station device (eNB, as an example) 1-1 and a plurality (N, which is a plurality in the present embodiment) of terminal devices (UE as an example) 2-1. 2-N and line 3 are provided.

Here, the radio communication system according to the present embodiment includes one or more other base station apparatuses in addition to the base station apparatus 1-1, and these plurality of base station apparatuses can communicate via the line 3. It is connected to the.
As the line 3, for example, a wired line may be used, or a wireless line may be used. The line 3 is an X2 line as an example.
Various base station apparatuses may be used.
Various devices may be used as each of the terminal devices 2-1 to 2-N. For example, a mobile station device or a fixed station device can be used.
In addition, FIG. 1 shows a wireless communication area 11-1 of the base station apparatus 1-1.

In the wireless communication system according to the present embodiment, the base station device 1-1 and the terminal devices 2-1 to 2-N existing in the communication area 11-1 of the base station device 1-1 communicate by radio. .
Further, the terminal device 2-1 identifies the random access channel (RACH) signal wirelessly transmitted to the base station device 1-1 on the base station device 1-1 side, and the terminal device 2-1 By assigning a data channel to 2-N, a session between the terminal device 2-1 to 2-N and the base station device 1-1 is established. In the wireless communication system according to the present embodiment, a plurality of different frequency bands (frequency bands) can be used, and terminal devices 2-1 and 2-2 newly entering the communication area 11-1 of the base station device 1-1. -N is set to wirelessly transmit a RACH signal using a predetermined frequency band (upper band).
The base station apparatus 1-1 can communicate various types of information with other base station apparatuses via the line 3, for example, information exchange with other base station apparatuses, Perform processing such as handover.

[Outline of base station equipment]
FIG. 2 is a block diagram showing a schematic configuration of the base station apparatus 1 according to the embodiment of the present invention. In the present embodiment, since the base station apparatus 1-1 and other base station apparatuses shown in FIG. 1 have the same configuration and perform the same operation, in FIG. The station apparatus 1 will be described.
The base station apparatus 1 according to the present embodiment includes an antenna 21, a wireless communication unit 22, a line communication unit 23, a storage unit 24, and a control unit 25.
The control unit 25 includes a status detection unit 31, a channel setting unit 32, a channel notification unit 33, a scheduling unit 34, and a schedule notification unit 35.

The wireless communication unit 22 communicates (transmits or receives) wirelessly with the terminal devices 2-1 to 2-N through the antenna 21.
The line communication unit 23 communicates (transmits or receives) with other base station apparatuses via the line 3 shown in FIG.
The storage unit 24 stores various types of information.
The control unit 25 executes various processes and controls in the base station apparatus 1 by reading and executing a predetermined program.

The processing units 31 to 35 provided in the control unit 25 will be described in the following embodiments in which the respective processing units are used.
Note that the configuration and operation of the base station apparatus 1 shown in FIG. 2 are examples, and for example, a part of the processing unit included in the base station apparatus 1 shown in FIG. 2 may not be provided. Other processing units that are not included in the base station device 1 may be provided.

[Overview of terminal equipment]
FIG. 3 is a block diagram showing a schematic configuration of the terminal device 2 according to the embodiment of the present invention. In the present embodiment, the terminal devices 2-1 to 2-N (and other terminal devices if present in the wireless communication system) shown in FIG. In order to perform the operation, these will be collectively described as the terminal device 2 in FIG.
The terminal device 2 according to the present embodiment includes an antenna 51, a wireless communication unit 52, a storage unit 53, and a control unit 54.
The control unit 54 includes a channel setting unit 61 and a schedule setting unit 62.

The wireless communication unit 52 communicates (transmits or receives) wirelessly with the base station device (base station device 1-1 and other base station devices) via the antenna 51.
The storage unit 53 stores various types of information.
The control unit 54 executes various processes and controls in the terminal device 2 by reading and executing a predetermined program.

The processing units 61 to 62 included in the control unit 54 will be described in the following embodiments in which the respective processing units are used.
Note that the configuration and operation of the terminal device 2 illustrated in FIG. 3 are merely examples, and for example, a part of the processing unit included in the terminal device 2 illustrated in FIG. 3 may not be included, and the terminal illustrated in FIG. Other processing units not provided in the device 2 may be provided.

[First Embodiment]
A first embodiment will be described.
In the radio communication system shown in FIG. 1, the base station apparatus 1 shown in FIG. 2 and the terminal apparatus 2 shown in FIG. 3 will be described as examples.
FIG. 4 is a diagram for explaining channel setting processing according to the present embodiment.
Specifically, FIG. 4 illustrates three frequency bands that can be used in the wireless communication system according to the present embodiment (frequency band_1 that is an upper band, frequency band_2 that is a lower band, and frequency band_3). Shows an example of channel assignment of radio resource blocks (RB) in one subframe. In the graph shown in FIG. 4, the horizontal axis represents time, and the vertical axis represents frequency.

Here, in the base station apparatus 1 and the terminal apparatus 2 in the wireless communication system according to the present embodiment, the frequency band_1, which is the lowest frequency band among the three different frequency bands, is set in advance as an upper band. In addition, frequency band_2 and frequency band_3, which are other frequency bands higher than that, are set as lower bands.
In this embodiment, a resource block is used as an example of a resource.

  The base station apparatus 1 determines that there are not many RACH signal collisions from the terminal apparatus 2 in the communication area of the base station apparatus 1 (hereinafter referred to as communication area 11) based on a predetermined condition. Sometimes (normal time), for all frequency bands, control channel regions are allocated to the first two resource blocks in one subframe composed of nine resource blocks, and the remaining seven resources Allocate a data channel area to the block.

  Taking FIG. 4 as an example, the base station apparatus 1 normally allocates control channel regions to the first two resource blocks B1-1 to B1-2 in one subframe for the frequency band_1, Data channel regions are allocated to the remaining seven resource blocks B1-3 to B1-9. For frequency band_2, in one subframe, control channel regions are assigned to the first two resource blocks B2-1 to B2-2, and data is assigned to the remaining seven resource blocks B2-3 to B2-9. Allocate channel area. For frequency band_3, in one subframe, control channel regions are allocated to the first two resource blocks B3-1 to B3-2, and data is allocated to the remaining seven resource blocks B3-3 to B3-9. Allocate channel area.

  On the other hand, when the base station device 1 determines that there are many RACH signal collisions from the terminal device 2 in the communication area 11 of the base station device 1 based on a predetermined condition (during congestion), With respect to time, for frequency band_1, which is an upper band, in one subframe, a control channel region is allocated to the first two resource blocks, and a control channel region is also allocated to the subsequent three resource blocks, Data channel regions are allocated to the remaining four resource blocks. In addition, for frequency band_2 and frequency band_3, which are other frequency bands, a control channel region and a data channel region are allocated in one subframe as in the normal case.

  Taking FIG. 4 as an example, when the base station apparatus 1 is congested, the first two resource blocks B1-1 to B1-2 and the following three resources in one subframe are transmitted for the frequency band_1. A control channel region is allocated to blocks B1-3 to B1-5, and a data channel region is allocated to the remaining four resource blocks B1-6 to B1-9. For frequency band_2, in one subframe, control channel regions are assigned to the first two resource blocks B2-1 to B2-2, and data is assigned to the remaining seven resource blocks B2-3 to B2-9. Allocate channel area. For frequency band_3, in one subframe, control channel regions are allocated to the first two resource blocks B3-1 to B3-2, and data is allocated to the remaining seven resource blocks B3-3 to B3-9. Allocate channel area.

  Here, for the frequency band_1, which is an upper band, the control channel region allocated to the three resource blocks B1-3 to B1-5 at the time of congestion is a control channel region that is temporarily expanded at the time of congestion. At this time, a part (three resource blocks B1-3 to B1-5) of the data channel region in the upper band normal time is switched to the control channel region.

In the present embodiment, the RACH region is set and included at a predetermined position (frequency and time) in the resource block of each control channel region. For this reason, the RACH region is temporarily increased (expanded) in the frequency band_1, which is the upper band, at the time of congestion as compared with the normal time.
The control channel region other than the RACH is used for communicating various control signals such as signals other than the RACH shown in FIG. 9 and FIG.

With reference to FIG.2 and FIG.3, the operation | movement performed in the base station apparatus 1 and the operation | movement performed in the terminal device 2 are demonstrated.
With reference to FIG. 2, the operation performed in the base station apparatus 1 will be described.
<Description of the situation detection unit 31>
The situation detection unit 31 is when the number of RACH signal collisions from the terminal device 2 in the communication area 11 of the base station device 1 is not high (normal time) or high (congested) based on a predetermined condition. Information to be referred to in order to determine whether or not. In addition, such information is not only information used for determining whether it is normal or congested, but also determines the degree of congestion (congestion degree) during normal or congested times. It may be information used to do this.

Here, the situation detection unit 31 detects information representing a situation regarding the degree of congestion (degree of collision) of the RACH signal from the terminal apparatus 2 in the communication area 11 of the base station apparatus 1.
As this information, it is straightforward and preferable to use information representing the status of the RACH signal congestion level itself, but the present invention is not limited to this, and various information indirectly suggesting such a situation may be used. it can. For example, normally, the congestion degree of the RACH signal from the terminal apparatus 2 in the communication area 11 of the base station apparatus 1 and the terminals existing in the communication area 11 of the base station apparatus 1 (for example, newly entered terminals) There is a correlation with the number of devices 2.

  In general, the number of users who have established a session with the base station device 1 (in this embodiment, the number of terminal devices 2) can be determined (detected) from the occupation rate (utilization rate) of the control channel region. When a collision between RACH signals frequently occurs and a session between the terminal apparatus 2 and the base station apparatus 1 is not established, a control channel region is not allocated to the terminal apparatus 2, and thus a terminal apparatus (for example, a plurality of terminal apparatuses) ), The occupation ratio of the control channel area is low. In this case, in any case, the base station device 1 is in a case where the occupation rate of the control channel region is low because the number of the terminal devices 2 existing in the communication area 11 of the base station device 1 is small. Cannot be determined.

Therefore, (congestion degree determination method 1) to (congestion degree determination method 3) will be described as an example of a method of determining the congestion degree (collision degree) of the RACH signal from the terminal apparatus 2 on the base station apparatus 1 side. .
Here, as the degree of congestion (collision degree) of the RACH signal, for example, directly or indirectly, the number of RACH signals at a predetermined time, the number of RACH signal collisions at a predetermined time, or It represents the RACH signal collision rate at a predetermined time.
Such a degree of congestion of the RACH signal is, for example, log information regarding the transmission of the RACH signal from the terminal device 2, the occupation rate of the control channel, or the terminal device 2 existing in the communication area 11 of the base station device 1. It is possible to estimate based on information such as an increase or decrease in the number of.

(Congestion degree determination method 1)
The status detection unit 31 monitors (monitors) information related to the terminal device 2 (for example, the RACH signal from the terminal device 2) regarding the degree of congestion of the RACH signal from the terminal device 2.
As an example, the status detection unit 31 acquires and detects information on the number of times of RACH signal transmission required until the terminal device 2 establishes a session with the base station device 1 as log information. Then, the state detection unit 31 detects (determines) the degree of congestion of the RACH signal based on the acquired information on the number of times of transmission of the RACH signal. That is, the status detection unit 31 detects (determines) the degree of congestion of the RACH signal according to the number of times of transmission of the RACH signal of the terminal device 2 that has established a session with the base station device 1.

Here, as illustrated in FIG. 10, in the present embodiment, the terminal device 2 does not receive a response from the base station device 1 even when the RACH signal (random access preamble signal) is wirelessly transmitted. Each time, the transmission power of the RACH signal is increased by a predetermined amount (for example, 2 dB). The initial power value of the RACH signal is set in advance, and the terminal apparatus 2 can receive the response from the base station apparatus 1 even if the transmission power of the RACH signal is set to a predetermined upper limit. The transmission power of the RACH signal is returned to the initial value, and the frequency band for transmitting the RACH signal is switched.
In the base station apparatus 1, the situation detection unit 31 detects the power of the RACH signal received from the terminal apparatus 2, and detects the number of transmissions of the RACH signal by the terminal apparatus 2 based on the detected power.

The correspondence between the number of RACH signal transmissions required until the terminal device 2 establishes a session with the base station device 1 and the congestion degree of the RACH signal is set in advance, for example. It can be considered that the higher the number of times of transmission is, the higher (large) the congestion degree of the RACH signal is.
Such (congestion degree determination method 1) is, for example, when the number of terminal devices 2 existing in the communication area 11 of the base station device 1 increases step by step, It can be detected that the degree of congestion is high, and is particularly effective in the subsequent stage.

(Congestion degree determination method 2)
The situation detection unit 31 monitors the occupancy rate of the control channel region with respect to the degree of congestion of the RACH signal from the terminal device 2.
As an example, the situation detection unit 31 acquires and detects information on the occupation rate of the control channel region in the upper band as log information. In this embodiment, such control channel area occupancy information is managed by, for example, the control unit 25 of the base station apparatus 1 (the function of the status detection unit 31 or other functions thereof), and log information Is stored in the storage unit 24. Then, the status detection unit 31 detects (determines) the degree of congestion of the RACH signal based on information on the occupation rate of the control channel region in the upper band.

The correspondence relationship between the information on the occupation ratio of the control channel region in the upper band and the degree of congestion of the RACH signal is set in advance, for example.
As an example, the higher the occupation ratio of the control channel region other than the RACH in the upper band, the more the terminal device 2 tends to exist in the communication area 11 of the base station device 1, and the RACH signal It can be considered that the degree of congestion is high (large).
As another example, if RACH collisions occur frequently, the base station apparatus 1 cannot determine the RACH. Therefore, even when the RACH occupancy is low (small), the RACH signal congestion is considered high (large). Can do.
As another example, regarding the occupation ratio of the RACH area in the control channel area in the upper band, when the occupation by the new terminal apparatus 2 is small or the occupation by the new terminal apparatus 2 decreases, the base It can be considered that there are many RACH signal collisions from the terminal device 2 in the communication area 11 of the station device 1, and the degree of congestion of the RACH signal is high (large).

  Here, for example, the situation detection unit 31 compares the current situation (control channel area occupancy in the upper band) with a predetermined past situation (control channel area occupancy in the upper band). It is also possible to detect the degree of congestion of the RACH signal based on the comparison result (for example, difference or ratio). As the past situation, for example, various situations such as an arbitrary normal situation, a situation on the previous day, and a situation on the same day of the week before one week can be used. Information on past situations is stored in the storage unit 24, for example.

(Congestion degree determination method 3)
The situation detection unit 31 monitors (monitors) information related to the situation (for example, movement) of the terminal device 2 predicted (predicted) in advance with respect to the degree of congestion of the RACH signal from the terminal device 2.
As an example, the situation detection unit 31 detects time, and detects (determines) the degree of congestion of the RACH signal based on information on the correspondence between the preset time and the degree of congestion of the RACH signal. For example, the correspondence information is stored in the storage unit 24.

  In such (congestion degree determination method 3), for example, the area of the communication area 11 of the base station device 1 covers a platform of a predetermined subway station, and a subway vehicle enters the platform according to the timetable. Sometimes when the passenger terminal device 2 riding in the vehicle suddenly increases the number of terminal devices 2 to be accommodated and the RACH signal congestion level is predicted to increase suddenly. ,It is valid.

Here, the information on the correspondence relationship between the time and the degree of congestion of the RACH signal may be set in advance, for example, or may be set in advance, or may be the control unit 25 of the base station apparatus 1 (the function of the status detection unit 31 among them) (Or other functions) may be changed (updated) according to the actual situation in the past, and the changed information may be set in advance compared to when the information is used.
In addition, the situation detection unit 31 corrects this shift when the correspondence between the time and the RACH signal congestion is deviated, for example, when there is a delay in the operation of the subway. The correspondence relationship between the time and the RACH signal congestion level can be corrected and used (referenced).

In the above-described (congestion degree determination method 1) to (congestion degree determination method 3) and the like, in this embodiment, the congestion degree of the RACH signal is represented by a value.
As an example of the value of the degree of congestion, a numerical value that changes continuously can be used as an example, and a numerical value that changes in steps (discrete numerical values) can be used as another example. Binary values (for example, a combination of 0 value and 1 value, etc.) indicating whether the RACH signal collision from the terminal device 2 in the communication area 11 of the base station device 1 is normal or congested Can be used.

<Description of Channel Setting Unit 32>
The channel setting unit 32 is based on information detected by the situation detection unit 31 (information indicating the situation regarding the degree of congestion (degree of collision) of the RACH signal from the terminal apparatus 2 in the communication area 11 of the base station apparatus 1). Whether the collision of RACH signals from the terminal apparatus 2 in the communication area 11 of the base station apparatus 1 is not large (normal time) or large (congested time) based on a predetermined condition. judge. Then, the channel setting unit 32 sets a channel region (control channel region or data channel region) based on the determination result.

  Here, a condition (predetermined condition) used for determining whether it is a normal time or a congestion time with respect to a RACH signal collision from the terminal device 2 in the communication area 11 of the base station device 1 For example, various conditions may be used. For example, when information detected by the situation detection unit 31 (in this embodiment, the value of the RACH signal congestion level) is less than a predetermined threshold. Is determined to be normal, and if the information detected by the situation detection unit 31 (in this embodiment, the value of the degree of congestion of the RACH signal) exceeds a predetermined threshold, it is determined that it is congestion Conditions can be used. Note that when the information detected by the situation detection unit 31 (in this embodiment, the value of the degree of congestion of the RACH signal) is the same value as a predetermined threshold, it is determined that it is normal time. It may be used, or a configuration that determines that it is congested may be used.

If the channel setting unit 32 determines that it is normal time, the channel setting unit 32 sets the control channel region and the data channel region according to the normal time mode (when the control channel region is not temporarily expanded). On the other hand, when it is determined that the channel setting unit 32 is congested, the channel setting unit 32 sets the control channel region and the data channel region according to the mode during congestion (when the control channel region is temporarily expanded).
Specific examples of these are as shown in FIG.

In the present embodiment, the channel setting unit 32 sets the channel region (control channel region or data channel region) at the normal time at the timing when it is determined that it is congested in the state where it is determined that it is normal. The state shifts from the state to the channel region setting state at the time of congestion.
Further, in the present embodiment, the channel setting unit 32 determines the normal channel from the channel region setting state at the time of the congestion at the timing determined to be the normal time in the state of being determined to be the congestion time. Transitions to return to the area setting state.

Here, the timing at which the channel setting unit 32 starts a state in which the control channel region is temporarily expanded and the timing at which the state in which the control channel region is temporarily expanded are ended are various timings. May be used.
For example, as a configuration example different from the present embodiment, the channel setting unit 32 sets the channel region at the normal time at a timing when a predetermined time has elapsed after starting the channel region setting state at the time of congestion. It is also possible to use a configuration that makes a transition to return to the state.
In the present embodiment, the channel setting unit 32 switches between a state in which the control channel region is temporarily expanded and a state in which the control channel region is not expanded in units of subframes.

  In the present embodiment, the channel setting unit 32 uses only one state (the state shown in FIG. 4 in the present embodiment) as the channel region setting state at the time of congestion. When the information detected by the situation detection unit 31 (in this embodiment, the value of the congestion degree of the RACH signal) can take two or more different values at the time of congestion, the values of the respective congestion degrees at the time of congestion Accordingly, it is also possible to switch between two or more different states as the channel region setting state at the time of congestion. Here, various states may be used as the two or more different states (the channel region setting state at the time of congestion). For example, the one with a higher congestion degree temporarily expands. A state in which the control channel region is enlarged (in this embodiment, a state in which the number of resource blocks allocated to the control channel region to be temporarily expanded is increased) can be used. When the number of resource blocks included in one subframe is constant, the total value of the number of resource blocks allocated to the control channel area and the number of resource blocks allocated to the data channel area is one. The total number of resource blocks in a subframe.

  Here, various methods may be used as a channel setting method in which the channel setting unit 32 allocates a control channel region and a data channel region for each frequency band. For example, various ratios between the control channel region and the data channel region may be used, and in one subframe, the same channel region (control region) is not necessarily included in a plurality of consecutive resource blocks. (Channel region or data channel region) may not be assigned, and the same channel region may be assigned to a plurality of resource blocks partially or entirely discrete.

  Further, for example, when the channel setting unit 32 sets a state in which the control channel region of the upper band is temporarily expanded at the time of congestion, one or more of the other frequency bands (lower bands) are used instead. It is also possible to set a state in which the control channel region is temporarily reduced (in this embodiment, the number of resource blocks allocated to the control channel region is reduced in one subframe) for the frequency bands. In this configuration, the upper-band control channel area is temporarily expanded during congestion, and the upper-band data channel area is reduced, while the lower-band control channel area is temporarily reduced to reduce the lower-band control channel area. By increasing the data channel area of the band, the data channel area in the lower band can be increased by the same or different amount as the decrease in the data channel area in the upper band, and can be compensated for each other.

  Further, for example, the channel setting unit 32 can also perform setting for switching the frequency band used by the terminal device 2 as setting of the channel region (control channel region or data channel region). As an example, the channel setting unit 32 is set to transmit a RACH signal using the upper band by the terminal device 2 in the initial state, whereas any one or more of the channel setting unit 32 is set by the terminal device 2. It is possible to set to change the RACH signal using the lower band (change the setting contents).

<Description of Channel Notification Unit 33>
The channel notification unit 33 transmits the contents of the channel region setting (control channel region and data channel region setting) performed by the channel setting unit 32 to the terminal device 2 existing in the communication area 11 of the base station device 1. To notify. In the present embodiment, the channel notification unit 33 notifies the terminal device 2 by wirelessly transmitting a signal including the setting contents of the channel region by the wireless communication unit 22 using a broadcast signal (notification signal). .

  In the present embodiment, the channel notification unit 33 shifts from the channel region setting state in the normal state to the channel region setting state in the congested state, or before and after that, at a predetermined timing. The terminal device 2 is notified of the contents of the channel area setting after the transition. In addition, the channel notification unit 33 performs the transition from the channel area setting state at the time of congestion to the channel area setting state at the normal time, or before and after the transition at a predetermined timing. The terminal device 2 is notified of the contents of the channel area setting in FIG.

As described above, the channel notification unit 33 notifies the terminal device 2 of the setting contents of the channel region that is variably controlled by the channel setting unit 32.
As an example, the channel notification unit 33 may change the channel region after the switching at a predetermined timing before or after the channel region setting state is switched according to the value of the congestion level. It is also possible to notify the terminal device 2 of the contents of the area setting.

<Description of Scheduling Unit 34>
The scheduling unit 34 communicates (transmits and receives) signals with the terminal device 2 to the terminal device 2 with which communication (session) is established by the RACH signal transmitted from the terminal device 2. A scheduling process for allocating resource blocks in a channel area to be used (control channel area or data channel area) is performed.
Here, the control channel region is used for communicating control signals, and the data channel region is used for communicating data (user data).
Further, the scheduling unit 34 performs a scheduling process for a plurality of frequency bands (three frequency bands in the example of FIG. 4), for example.

<Description of schedule notification unit 35>
The schedule notification unit 35 notifies the corresponding terminal device 2 of the result of the scheduling process performed by the scheduling unit 34 (contents of a schedule for allocating resource blocks in the channel area). In the present embodiment, the schedule notification unit 35 notifies the terminal device 2 by wirelessly transmitting a signal including the result of the scheduling process by the wireless communication unit 22.

With reference to FIG. 3, the operation performed in the terminal device 2 will be described.
<Description of Channel Setting Unit 61>
The channel setting unit 61 sets channel regions (control channel region and data channel region) notified by the channel setting unit 32 of the base station device 1 based on the signal received from the base station device 1 by the wireless communication unit 52. The content of (setting) is detected, and the channel region according to this content is set to be used. In the present embodiment, the terminal apparatus 2 transmits a RACH signal based on the setting contents of the channel region (here, in particular, the RACH region) set by the channel setting unit 61.

  Here, in the present embodiment, in the initial setting, the terminal device 2 has the first two resource blocks of the subframe in the frequency band_1 that is the upper band (in the example of FIG. 4, resource blocks B1-1 to B1-1). It is set to transmit a RACH signal using the RACH region of B1-2). Further, when the content of the channel region setting is notified from the base station device 1, the terminal device 2 performs subsequent communication according to the notified content (the content after the change here).

<Description of Schedule Setting Unit 62>
The schedule setting unit 62 detects the content of the schedule notified by the schedule notification unit 35 of the base station device 1 based on the signal received from the base station device 1 by the wireless communication unit 52, and the channel according to this content Settings are made so that resource blocks in the region (control channel region and data channel region) are used. The terminal device 2 transmits a signal based on the content of the channel area setting set by the schedule setting unit 62.

<Summary of First Embodiment>
As described above, in the present embodiment, in a wireless communication system having multibands (a plurality of frequency bands), the base station apparatus 1 uses each frequency according to the situation regarding the degree of congestion of the RACH signal from the terminal apparatus 2. The control channel region in the band (in this embodiment, the control channel region in the upper band) is dynamically changed. For example, the base station apparatus 1 autonomously controls the channel area when there are a large number of terminal apparatuses 2 temporarily in the communication area 11 of the base station apparatus 1, and controls the control channel of the upper band. The RACH area is temporarily expanded by temporarily expanding the area.

Therefore, in the present embodiment, when many users (terminal devices 2) are temporarily concentrated (or predicted to be concentrated), the base station device 1 uses the same time zone (this embodiment) from the terminal device 2. In the mode, the number of uplink RACH signals (accommodation number) that can be received in the same subframe is temporarily increased to temporarily cause a shortage of control channel area (here, RACH). The area shortage) is resolved, the number of terminal apparatuses 2 that cannot be connected to the base station apparatus 1 is reduced, and an environment in which the terminal apparatus 2 can easily connect to the base station apparatus 1 can be realized. Thus, when the base station apparatus 1 temporarily increases the RACH region and the terminal apparatus 2 is easily connected to the base station apparatus 1, the RACH signal transmitted from the terminal apparatus 2 to the base station apparatus 1 is obtained. Therefore, the time and power consumption required for the terminal apparatus 2 to connect to the base station apparatus 1 can be reduced.
As described above, according to the base station apparatus 1 and the terminal apparatus 2 in the wireless communication system according to the present embodiment, it is possible to reduce the collision of RACH signals and effectively establish a session between the base station apparatus 1 and the terminal apparatus 2. Can be realized.

[Second Embodiment]
A second embodiment will be described.
In this embodiment, a further configuration example in the first embodiment is shown.
In the radio communication system shown in FIG. 1, the base station apparatus 1 shown in FIG. 2 and the terminal apparatus 2 shown in FIG. 3 will be described as examples.
FIG. 5 is a diagram for explaining the scheduling process according to the present embodiment.
Specifically, FIG. 5 shows three frequency bands that can be used in the wireless communication system according to the present embodiment (frequency band_1 being an upper band, frequency band_2 being a lower band, and frequency band_3). Shows an example of channel assignment of radio resource blocks (RB) in a plurality of subframes and an example of scheduling. In the graph shown in FIG. 5, the horizontal axis represents time, and the vertical axis represents frequency.

Here, channel allocation (control channel region, data channel region, control channel region temporarily extended) in each subframe of each frequency band is the same as that shown in FIG.
In the example of FIG. 5, for the frequency band_1 that is the upper band, nine resource blocks B1-1 to B1-9 that constitute one subframe and one subframe that follows the resource blocks B1-1 to B1-9 Nine resource blocks B1-19 to B1-27 are shown. In addition, for frequency band_2, which is a lower band, nine resource blocks B2-1 to B2-9 that constitute one subframe, and nine resources that constitute one subsequent subframe Blocks B2-19 to B2-27 are shown. In addition, for frequency band_3, which is a lower band, nine resource blocks B3-1 to B3-9 constituting one subframe and nine resources constituting one subsequent subframe Blocks B3-19 to B3-27 are shown.

Then, the base station device 1 causes the scheduling unit 34 to send the resource block B1- of the frequency band_1 that is the upper band to the first terminal device (UE-1) existing in the communication area 11 of the base station device 1. 2 is assigned as a control channel region, and resource block B1-25 of the same frequency band_1 is assigned as a data channel region.
Thus, the base station apparatus 1 can assign the control channel region and the data channel region to the upper band for the terminal device 2.

Also, the base station device 1 causes the scheduling unit 34 to send the resource block B1- of the frequency band_1 that is the upper band to the second terminal device (UE-2) existing in the communication area 11 of the base station device 1. 5 is assigned as a control channel region, and resource block B3-22 of frequency band_3, which is a lower band, is assigned as a data channel region.
Thus, the base station apparatus 1 can assign the control channel area to the upper band and the data channel area to the lower band for the terminal apparatus 2.

Further, the base station device 1 causes the scheduling unit 34 to send a resource block B1- of the frequency band_1 that is an upper band to the third terminal device (UE-3) existing in the communication area 11 of the base station device 1. 3 is assigned as a control channel region, and resource block B2-23 of frequency band_2, which is a lower band, is assigned as a data channel region.
Thus, the base station apparatus 1 can assign the control channel area to the upper band and the data channel area to the lower band for the terminal apparatus 2.

Also, the base station device 1 causes the scheduling unit 34 to send a resource block B2- of the frequency band _2, which is a lower band, to the fourth terminal device (UE-4) existing in the communication area 11 of the base station device 1. 2 is assigned as a control channel region, and resource block B2-21 of the same frequency band_2 is assigned as a data channel region.
Thus, the base station apparatus 1 can assign the control channel region and the data channel region to the lower band for the terminal device 2. In the example of FIG. 5, the base station apparatus 1 assigns the control channel region and the data channel region to the same lower band (frequency band — 2), but can also assign the control channel region and the data channel region to different lower bands. It is.

  In the present embodiment, since the terminal device 2 is initially set to use the upper band resource block as the control channel region (here, the RACH region), the first terminal shown in FIG. As a state of the device (UE-1) to the third terminal device (UE-3), the RACH signal is used using the resource block of the frequency band_1 that is the upper band as a control channel region (here, RACH region). May be in a state prior to receiving control channel region allocation (scheduling result) from the base station apparatus 1.

<Summary of Second Embodiment>
As described above, in this embodiment, the base station device 1 receives the RACH signal in the control channel region (here, RACH region) of the upper band and establishes a session with the terminal device 2 that has established a session. An unused data channel region including a frequency band other than (for example, a data channel region of a lower band that is a frequency band different from the upper band) is allocated.

Therefore, in the present embodiment, the shortage of the upper-band data channel region caused by temporarily increasing the upper-band control channel region by the base station apparatus 1 is resolved, and the throughput decreases (for example, the extreme throughput decreases). ) Can be prevented.
In the present embodiment, the frequency utilization efficiency of the lower band can be improved. For example, the base station device 1 detects the utilization rate of the data channel region in each frequency band, and the terminal device 2 accommodated using the control channel region (here, RACH region) in the upper band, By preferentially allocating a data channel region in a frequency band having a low utilization rate of the data channel region, it is possible to improve frequency utilization efficiency.
Further, in the present embodiment, in the wireless communication system having multibands, the base station apparatus 1 is compared with the case where the base station apparatus 1 allocates the upper band data channel region to the terminal apparatus 2 accommodated in the upper band. The data channel area that can be allocated to the terminal device 2 accommodated in the upper band can be increased.

For example, when the number of terminal apparatuses 2 in the communication area 11 of the base station apparatus 1 temporarily increases, the terminal apparatus 2 newly entering the communication area 11 transmits a RACH signal to the upper band. Wireless transmission. For this reason, the lower band accommodates only the terminal devices 2 that existed so far, and usually the resource block is less crowded than the upper band, and this embodiment uses this.
In addition, the configuration in which the control channel region and the data channel region are assigned to different frequency bands includes, in particular, a C-plane (Control-plane) for communicating control signals and a U-plane (User) for communicating user data signals. -Plane) can be applied to a separated radio communication system. As a wireless communication system in which C-plane and U-plane are separated as described above, for example, there is an LTE wireless communication system.

[Third Embodiment]
A third embodiment will be described.
In this embodiment, the further structural example in 1st Embodiment or 2nd Embodiment is shown.
In the radio communication system shown in FIG. 1, the base station apparatus 1 shown in FIG. 2 and the terminal apparatus 2 shown in FIG. 3 will be described as examples.

FIG. 11 is a block diagram illustrating a schematic configuration of a multi-site wireless communication system according to the background art. This wireless communication system is a HetNet (Heterogeneous Network) system in which a macro cell (macro station cell) and a pico cell (pico station cell) are mixed.
The wireless communication system according to the example of FIG. 11 includes a macro station apparatus 2001 and a pico station apparatus 2002 as base station apparatuses. In addition, the wireless communication system according to the example of FIG. 11 includes a line 2003 that connects these base station apparatuses so that they can communicate with each other, and a plurality of terminal apparatuses 2021-1 to 2021-5.
Further, FIG. 11 shows a communication area 2011 of the macro station apparatus 2001 and a communication area 2012 of the pico station apparatus 2002. The communication area 2011 of the macro station apparatus 2001 is relatively larger (larger) than the communication area 2012 of the pico station apparatus 2002, and in the example of FIG. 11, the communication area 2011 of the macro station apparatus 2001 is the pico station apparatus 2002. Communication area 2012.
In the wireless communication system according to the example of FIG. 11, the terminal devices 2021-1 to 2021-3 existing in the communication area 2012 of the pico station device 2002 are connected to the pico station device 2002, and the pico station device 2002 Communication is performed using the control channel region and the data channel region. Also, the terminal devices 2021-4 to 2021-5 existing in the communication area 2011 of the macro station apparatus 2001 are connected to the macro station apparatus 2001 and use the control channel area and data channel area of the macro station apparatus 2001. And perform communication.

FIG. 6 is a block diagram illustrating a schematic configuration example of the multi-site wireless communication system according to the present embodiment. This wireless communication system is a HetNet system in which a macro cell (macro station cell) and a pico cell (pico station cell) are mixed.
The wireless communication system according to the present embodiment includes a macro station apparatus 101 and a pico station apparatus 102 as base station apparatuses. The wireless communication system according to the present embodiment includes a line 103 that connects these base station apparatuses so that they can communicate with each other, and a plurality of terminal apparatuses 121-1 to 121-3.
Further, FIG. 6 shows a communication area 111 of the macro station apparatus 101 and a communication area 112 of the pico station apparatus 102. The communication area 111 of the macro station apparatus 101 is relatively larger (larger) than the communication area 112 of the pico station apparatus 102, and in the example of FIG. 6, the communication area 111 of the macro station apparatus 101 is the pico station apparatus 102. Communication area 112.
In the wireless communication system according to the present embodiment, the terminal devices 121-1 to 121-3 existing in the communication area 112 of the pico station device 102 are connected to the pico station device 102 and controlled by the pico station device 102. Communication is performed using the channel region and the data channel region of the macro station apparatus 101.

Here, each of the macro station apparatus 101 and the pico station apparatus 102 has the same configuration as that shown in FIG. 2, and has a function of performing the same operation. Each of the macro station apparatus 101 and the pico station apparatus 102 further has a function described in the present embodiment.
When the pico station apparatus 102 receives a RACH signal from a terminal apparatus (for example, the terminal apparatus 121-3) existing in the communication area 112 of the pico station apparatus 102 and connects to the terminal apparatus 121-3. The scheduling unit 34 of the pico station apparatus 102 sets (assigns) the resource block of the pico station apparatus 102 to be used by the terminal apparatus 121-3 as a control channel region, and sets the resource block of the macro station apparatus 101. The terminal device 121-3 is set (assigned) to be used as a data channel region. Then, the pico station apparatus 102 notifies the terminal apparatus 121-3 of the contents of the setting (the contents of the result of the scheduling process) by the schedule notification unit 35 of the pico station apparatus 102.

Also, the pico station apparatus 102 transmits the contents of the setting (the contents of the result of the scheduling process) to the macro station apparatus 101 via the line 103 by the schedule notification unit 35 of the pico station apparatus 102 and notifies it. .
The macro station apparatus 101 performs the scheduling process by the scheduling unit 34 of the macro station apparatus 101 according to the content of the scheduling process result regarding the terminal apparatus 121-3 notified from the pico station apparatus 102.

  Here, in this embodiment, in the pico station apparatus 102, the scheduling unit 34 of the pico station apparatus 102 performs the data channel region scheduling processing for the terminal apparatus 121-3. However, as another configuration example, a macro station In the apparatus 101, the scheduling unit 34 of the macro station apparatus 101 may perform a data channel region scheduling process for the terminal apparatus 121-3. Note that the macro station apparatus 101 and the pico station apparatus 102 can exchange information necessary for processing via the line 103.

The terminal device 121-3 has a configuration similar to that shown in FIG. 3, and has a function of performing the same operation. Further, the terminal device 121-3 further has a function described in the present embodiment.
The terminal device 121-3 has a function of performing wireless communication with the macro station device 101 and a function of performing wireless communication with the pico station device 102 by the wireless communication unit 52. As an example, the terminal device 121-3 connects the macro station device 101 and the pico station device 102 that exist in a position where wireless communication is possible with either one of the station devices (base station device) as a primary (Primary), and The other station device (base station device) is connected as a secondary.
Then, when the terminal apparatus 121-3 wirelessly transmits a RACH signal and is connected to the pico station apparatus 102, the terminal apparatus 121-3 performs the control channel region signal according to the contents of the scheduling process result notified from the pico station apparatus 102. Communicates (transmits or receives) using the resource block of the pico station apparatus 102, and communicates (transmits or receives) the data channel region signal using the resource block of the macro station apparatus 101.

Next, with reference to FIGS. 7 and 8, a further configuration example of the multi-site wireless communication system as shown in FIG. 6 will be described.
FIG. 7 is a block diagram illustrating a schematic configuration example of a wireless communication system having a D-RAN (Distributed-Radio Access Network) configuration according to the present embodiment.
The wireless communication system according to the example of FIG. 7 is similar to the wireless communication system shown in FIG. 6, the macro station device 201, the pico station device 202, the line 203 connecting them, and a plurality of terminal devices 231-1. To 231-4.
7 shows a communication area 211 of the macro station device 201, a communication area 212 of the pico station device 202, and a network 204 connected to each station device (here, the macro station device 201 and the pico station device 202). It is shown.

In the wireless communication system according to the example of FIG. 7, the macro station apparatus 201 includes a baseband unit (BBU) 221 at the location, and the pico station apparatus 202 includes a baseband unit (BBU) at the location. 222.
In such a configuration, it is necessary to exchange information between the baseband unit 222 of the pico station apparatus 202 and the baseband unit 221 of the macro station apparatus 201 for cooperation.

FIG. 8 is a block diagram illustrating a schematic configuration example of a wireless communication system having a C-RAN (Centralized-Radio Access Network) configuration according to the present embodiment.
The wireless communication system according to the example of FIG. 8 is similar to the wireless communication system shown in FIG. 6, the macro station device 301, the pico station device 302, the line 303 connecting them, and a plurality of terminal devices 341-1. To 341-6.
FIG. 8 also shows a communication area 311 of the macro station device 301, a communication area 312 of the pico station device 302, and a network 304 connected to each station device (here, the macro station device 301 and the pico station device 302). It is shown.

In the wireless communication system according to the example of FIG. 8, the network 304 includes a BBU pooling (BBU Pooling) 321. Further, the BBU pooling 321 includes BBUs 331 and 332 for controlling the macro station device 301 and the pico station device 302.
As described above, in the C-RAN configuration, the network 304 is provided with the BBU pooling 321 in which the functions of the BBUs 331 and 332 of a plurality of station apparatuses (base station apparatuses) are integrated in one place. For this reason, in the C-RAN configuration, the BBU functions of a plurality of station apparatuses (base station apparatuses) are aggregated in one place (BBU pooling 321), so that the BBUs of the plurality of station apparatuses (base station apparatuses) are linked. Can be facilitated. In the example of FIG. 8, cooperation between the BBU 331 of the macro station apparatus 301 and the BBU 332 of the pico station apparatus 302 can be facilitated.

Here, as the functions of the BBUs 331 and 332 provided in the BBU pooling 321, in the example of FIG. 8, a configuration corresponding to two station devices (base station devices) is shown, but as another configuration example, there are three functions. It may correspond to the above station apparatus (base station apparatus).
Further, as the BBU provided in the BBU pooling 321, for example, each BBU may correspond to one station apparatus (base station apparatus), or one BBU includes two or more stations. It may correspond to a device (base station device). Conversely, two or more BBUs may correspond to one station device (base station device).
Note that D-RAN, C-RAN, BBU, and BBU pooling are known techniques.

<Summary of Third Embodiment>
As described above, in the present embodiment, in a multi-site system configured by including a plurality of sites (here, the base station apparatus 1), one site is an upper band control channel region (here, RACH region). A data channel region of a different site is allocated to the terminal device 2 accommodated by using. For example, as illustrated in FIGS. 6 to 8, macro station apparatuses 101, 201, 201, 201, 201, 301 data channel regions are allocated.

Therefore, in the present embodiment, the data channel of the upper band of the one site generated by temporarily increasing the control channel area of the upper band by one site (the pico station apparatus in the examples of FIGS. 6 to 8). It is possible to solve the shortage of area and prevent a decrease in throughput (for example, an extreme decrease in throughput).
Further, in the present embodiment, it is possible to improve the frequency utilization efficiency of sites other than the one site (macro station apparatus in the examples of FIGS. 6 to 8). For example, the one site (or another site, an upper device of a plurality of sites, etc.) detects the utilization rate of the data channel region in each site (or each frequency band of each site), and The terminal device 2 accommodated using the control channel region (here, the RACH region) in the upper band of the one site gives priority to the data channel region in the frequency band of the site where the utilization rate of the data channel region is low By assigning to, frequency utilization efficiency can be improved.
Further, in the present embodiment, in the wireless communication system having multi-sites, the one site is compared with the case where the data channel region of the one site is allocated to the terminal device 2 accommodated by the one site in the upper band. Can increase the data channel region that can be allocated to the terminal device 2 accommodated in the upper band.

Further, in the present embodiment, by adopting a C-RAN configuration in a multi-site system, it is possible to facilitate allocation of data channel regions between sites for a plurality of sites (here, the base station device 1). it can.
Here, as the base station device 1 provided in the multi-site system, for example, various types of station devices (base station devices) may be used in addition to the macro station device and the pico station device. Also, any number of station devices (base station devices) of each type provided in the multi-site system may be used.

In addition, the configuration according to the second embodiment and the configuration according to the third embodiment can be combined.
For example, in a wireless communication system such as LTE having multiple bands and multiple sites, when using C-plane and U-plane separately, it is possible for the user (terminal device 2) without sacrificing frequency utilization efficiency. The ease of connection with the base station apparatus 1 can be improved.
For example, in frequency (frequency band) allocation and resource block allocation in a wireless communication system, it is possible to shorten the band search time and cell search time when the RACH signal is congested.

[Configuration example of the above embodiment]
In the radio communication system shown in FIG. 1, the base station apparatus 1 shown in FIG. 2 and the terminal apparatus 2 shown in FIG. 3 will be described as examples.
As a configuration example (the configuration example described in the first embodiment), a situation detection unit 31 that detects information indicating a situation related to the degree of congestion of the RACH signal from the terminal device 2 and the situation detection unit 31 detect the situation. Based on the information, when it is determined that the RACH signal from the terminal device 2 is congested according to a predetermined condition, a predetermined upper band (frequency band_1 in the example of FIG. 4) is determined. And a channel setting unit 32 that sets a channel region (in the example of FIG. 4, a control channel region and a data channel region) so as to temporarily expand a control channel region including the RACH region. Is the base station apparatus 1.

  As one configuration example (configuration example described in the first embodiment), a channel notification unit 33 that notifies the terminal device 2 of the contents of the channel region setting performed by the channel setting unit 32 by broadcasting is provided. The base station apparatus 1 is characterized by this.

  As one configuration example (configuration example described in the first embodiment), the channel setting unit 32 temporarily extends a control channel region including a RACH region in the upper band, and lower bands other than the upper band. (In the example of FIG. 4, the base station apparatus 1 is characterized in that the channel region is set so as to temporarily reduce the control channel region in the frequency band_2 and the frequency band_3).

  As one configuration example (the configuration example described in the second embodiment), the terminal device 2 connected using the RACH region of the upper band (frequency band_1 in the example of FIG. 5) is other than the upper band. 5, a scheduling unit 34 that allocates resources (resource blocks in the example of FIG. 5) as data channel regions, and scheduling performed by the scheduling unit 34. And a schedule notification unit (35) for notifying the terminal device (2) of the processing result.

  As one configuration example (configuration example described in the third embodiment), a terminal device (FIG. 6) connected using the RACH region of one type of base station device (in the example of FIG. 6, pico station device 102). In the example, the terminal device 121-3) includes a scheduling unit 34 that allocates resources of other types of base station devices (macro station device 101 in the example of FIG. 6) as a data channel region. Base station apparatus 1 to be operated.

[Summary of the above embodiments]
As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.
In addition to devices (for example, base station devices and terminal devices), the present invention includes systems (for example, wireless communication systems), methods (for example, wireless communication methods), programs (for example, wireless communication programs), etc. It is also possible to grasp as.

  Further, a program for realizing the function of each device (for example, the base station device 1 or the terminal device 2) according to each embodiment described above is recorded on a computer-readable recording medium, and recorded on this recording medium. Processing may be performed by causing the computer system to read the executed program and executing it.

The “computer system” mentioned here may include an operating system (OS) and hardware such as peripheral devices.
The “computer-readable recording medium” means a flexible disk, a magneto-optical disk, a ROM (Read Only Memory), a writable nonvolatile memory such as a flash memory, a portable medium such as a DVD (Digital Versatile Disk), A storage device such as a hard disk built in a computer system.

Further, the “computer-readable recording medium” refers to a volatile memory (for example, DRAM (DRAM)) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. Dynamic Random Access Memory)) that holds a program for a certain period of time is also included.
The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting a program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.
Further, the above program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, what is called a difference file (difference program) may be sufficient.

1, 1-1 ... base station apparatus, 2, 2-1 to 2-N, 121-1 to 121-3, 231-1 to 231-4, 341-1 to 341-6, 2021-1 to 2021- 5 ... Terminal device 3, 103, 203, 303, 2003 ... Line, 11-1, 111-112, 211-212, 311-312, 2011-2012 ... Communication area, 21, 51 ... Antenna, 22, 52 ... Wireless communication unit, 23 ... line communication unit, 24, 53 ... storage unit, 25, 54 ... control unit, 31 ... status detection unit, 32, 61 ... channel setting unit, 33 ... channel notification unit, 34 ... scheduling unit, 35 ... schedule notification unit, 62 ... schedule setting unit, B1-1 to B1-9, B1-19 to B1-27, B2-1 to B2-9, B2-19 to B2-27, B3-1 to B3-9 , B3-19 to B3-2 ... resource blocks, 101,201,301,2001 ... macro station, 102,202,302,2002 ... pico station apparatus, 204, 304 ... network, 221~222,331~332 ... BBU, 321 ... BBU Pooling

Claims (5)

A status detection unit that detects information indicating a status related to the congestion degree of the RACH signal from the terminal device;
When it is determined that the RACH signal from the terminal device is congested according to a predetermined condition based on information detected by the situation detection unit, the terminal device A channel setting unit configured to set a channel region so as to temporarily expand a control channel region including the RACH region in an upper band predetermined as a frequency band to be preferentially connected ;
Equipped with a,
The channel setting unit includes a control channel including a RACH region in the upper band.
While temporarily expanding the area, control channels in lower bands other than the upper band are used.
Set the channel area to temporarily reduce the channel area,
A base station apparatus. A channel notification unit for notifying the terminal device of the content of the channel area setting performed by the channel setting unit by broadcast;
The base station apparatus according to claim 1. A scheduling unit for allocating resources of lower bands other than the upper band as data channel regions to terminal devices connected using the RACH region of the upper band;
A schedule notification unit for notifying the terminal device of a result of the scheduling process performed by the scheduling unit;
The base station apparatus according to any one of claims 1 or claim 2, characterized in that it comprises a. A scheduling unit that allocates resources of other types of base station devices as data channel regions to terminal devices connected using the RACH region of one type of base station device;
The base station apparatus according to any one of claims 1 to 3 , characterized in that: The status detection unit provided in the base station device detects information indicating the status related to the congestion degree of the RACH signal from the terminal device,
When the channel setting unit provided in the base station apparatus determines that the RACH signal from the terminal apparatus is congested according to a predetermined condition based on information detected by the situation detection unit Is configured to set a channel region so as to temporarily extend a control channel region including a RACH region in a higher band predetermined as a frequency band in which the terminal device attempts to connect to the base station device preferentially. There line,
The channel setting unit includes a control channel including a RACH region in the upper band.
While temporarily expanding the area, control channels in lower bands other than the upper band are used.
Set the channel area to temporarily reduce the channel area,
A wireless communication method.

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