JP2009071585A - Base station apparatus and mobile terminal transmission output adjustment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base station device capable of suitably adjusting a transmission output of a mobile terminal and a transmission output adjusting method of the mobile terminal.
The base station apparatus 10 of the present invention transmits a control command for adjusting the transmission output of the MS 20 to the MS 20 in response to reception of the ranging request message transmitted from the MS 20, thereby transmitting the transmission output of the MS 20. Based on the received ranging request message, the detection unit 14a for detecting the received signal level value, the received signal level value detected by the detecting unit 14a, and the control target value of the received signal level value A control command generation unit 14b for generating a control command for adjusting the transmission output of the MS 20, and a control target value adjustment unit 14c for adjusting the control target value.
[Selection] Figure 2

Description

  The present invention relates to a base station apparatus for a radio communication system used in a broadband mobile radio communication system and the like, and a transmission output adjustment method for a mobile terminal.

In recent years, as a communication system capable of covering a wide area wirelessly and providing a high-speed broadband service, for example, a broadband mobile wireless communication system (Broadband Wireless Access System) called “WiMAX” defined in IEEE 802.16, Hereinafter, the BWA system) is attracting attention.
The BWA system includes a base station apparatus and a mobile terminal that establishes wireless communication with the base station apparatus, and the base station apparatus provides a broadband wireless communication service to the mobile terminal. I will provide a.
In the BWA system, ranging is performed in order to ensure communication quality between the base station apparatus and the mobile terminal. Ranging is a process of adjusting the signal transmission conditions of the mobile terminal and adjusting the signal level, signal timing, etc. detected from the received signal from the mobile terminal received by the base station device to a predetermined appropriate value. This is performed by repeating transmission / reception of a ranging request message and a ranging response message between the station apparatus and the mobile terminal (see, for example, Non-Patent Document 1).

Takeshi Hattori, Masanobu Fujioka, “Revised Wireless Broadband Textbook High-Speed IP Wireless”, First Edition, Impress R & D Inc., June 21, 2006, p. 177-181

  In the above ranging, regarding the adjustment of the received signal level of the signal from the mobile terminal received by the base station, the base station apparatus transmits a ranging response message storing a control command for adjusting the transmission output of the mobile terminal. It is done by sending it to. In response to the control command, the mobile terminal adjusts the transmission output according to the control command and transmits a signal to the base station apparatus. The base station device detects a received signal level value when receiving a signal with an adjusted transmission output, and if the received signal level value is within a numerical range determined by a predetermined control target value, the control command Stops sending and ends the adjustment.

As described above, the control target value of the received signal level value, which is a reference for adjusting the transmission output of the mobile terminal, considers a plurality of types of modulation schemes applied to the mobile terminal, and provides a margin such as fading. By taking into account, it was set to a relatively high value to cover all conditions.
On the other hand, depending on the type of modulation method, the installation environment of the base station apparatus, etc., it may be possible to ensure sufficient communication quality if a lower received signal level value is ensured. There was a case where I requested. In this way, when a mobile terminal requests more transmission power than necessary, the mobile terminal wastes power consumption or requests a relatively high transmission power from the mobile terminal. There was a risk of causing the problem of narrowing.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a base station apparatus and a mobile terminal transmission output adjustment method capable of suitably adjusting the transmission output of a mobile terminal.

  In order to achieve the above object, the present invention provides the mobile terminal by transmitting a control command for adjusting the transmission output of the mobile terminal to the mobile terminal in response to reception of a ranging request transmitted from the mobile terminal. A base station apparatus that adjusts a transmission output of a terminal, a detection unit that detects a reception signal level value based on a received ranging request, and a control of the reception signal level value and the reception signal level value detected by the detection unit A control command generation unit that generates a control command for adjusting the transmission output of the mobile terminal based on a target value; and the control target value for adjusting the transmission output of the mobile terminal via the control command. And a control target value adjustment unit for adjustment.

According to the base station apparatus configured as described above, the control target value adjusting unit adjusts the control target value of the received signal level value, and through a control command generated based on the control target value. Thus, the transmission output of the mobile terminal can be adjusted. Therefore, the base station apparatus can adjust the transmission output of the mobile terminal according to the situation.
Further, the control target value adjustment unit may be configured to adjust the control target value based on a state of the mobile terminal or a communication state with the mobile terminal. A control command corresponding to the state or the like can be transmitted to the mobile terminal, and the transmission output of the mobile terminal can be suitably adjusted according to the situation.

  In addition, the control target value adjustment unit adjusts to the first control target value when the ranging request is a first ranging request for initial ranging, and for other ranging than the initial ranging. In the case of the second ranging request, the control target value is adjusted to a second control target value, and the control target value adjusting unit further sets the first control target value to be greater than the second control target value. In this case, in the initial ranging, the target received signal level value can be lowered as compared with other ranging, and transmission requested to the mobile terminal is possible. Since the output is also set to a relatively low value, the power consumption of the mobile terminal can be suppressed, and the adjustment of the transmission output can be completed more quickly.

  Further, the control target value adjustment unit may adjust the control target value according to the modulation scheme of the mobile terminal, and in this case, the transmission output of the mobile terminal is suitable for the modulation scheme. Value can be set.

The base station apparatus further includes an instantaneous level fluctuation value estimation unit that obtains an estimated value of the instantaneous level fluctuation value of the received signal, and the control target value adjustment unit is configured to obtain the estimation obtained by the instantaneous level fluctuation value estimation unit. The control target value may be adjusted according to the value. In this case, the transmission output of the mobile terminal can be set to a suitable value according to the estimated value of the instantaneous fluctuation level fluctuation value.
Further, in this case, the instantaneous level fluctuation value estimation unit is configured to determine the estimated value based on at least one of reception strength of a pilot signal included in a transmission signal transmitted from the mobile terminal and a CN ratio of the pilot signal. May be required.

  The present invention is also a mobile terminal transmission output adjustment method performed by receiving a control command for adjusting a transmission output, which is transmitted from a base station apparatus in response to transmission of a ranging request. A detecting step for detecting a received signal level value based on a ranging request transmitted from the mobile terminal; a control target value adjusting step for adjusting a control target value of the received signal level value; and the detecting unit. And a control command generation step for generating a control command for adjusting the transmission output of the mobile terminal based on the detected received signal level value and the control target value.

  According to the transmission output adjustment method of the mobile terminal configured as described above, the control target value of the received signal level value can be adjusted by the control target value adjustment step, so the transmission output of the mobile terminal is adjusted. be able to. Therefore, in the control target value adjustment step, if the control target value is adjusted based on the state of the mobile terminal or the communication state with the mobile terminal, the control command corresponding to the state of the mobile terminal or the like is transferred. It can transmit to a terminal and the transmission output of a mobile terminal can be suitably adjusted according to the condition.

  As described above, according to the base station apparatus and the mobile terminal transmission output adjustment method of the present invention, the transmission output of the mobile terminal can be suitably adjusted by adjusting the control target value of the received signal level value. it can.

[Overall configuration of communication system]
Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing an overall configuration of a broadband mobile radio communication system (BWA system). In this BWA system, for example, a communication system defined in IEEE 802.16 that supports an Orthogonal Frequency Division Multiple Access (OFDMA) system in order to realize broadband wireless communication is adopted. And a mobile terminal 20 that can move (hereinafter also referred to as MS 20).
The BS 10 sets a cell S that is a range in which wireless communication is possible with the MS 20 around the BS 10, and provides high-speed broadband service by wireless communication to the MS 20 located in the cell S. Further, the cells S are set so as to overlap each other with the adjacent cells S, and the entire service area of the present BWA system is configured by these many cells S.
Between the BS 10 and the MS 20 with which communication has been established, information can be transmitted / received by placing information in a predetermined communication frame, and the MS 20 can send an entry to an external network by transmitting / receiving this information. It becomes possible.

[Configuration of base station]
FIG. 2 is a block diagram showing the configuration of the BS 10 and the MS 20. The BS 10 includes an antenna 11 that transmits and receives a signal for performing wireless communication with the MS 20, a transmission unit 12 that performs conversion processing of a transmission signal, a reception unit 13 that performs conversion processing of a reception signal, and the like. A control unit 14 that controls the transmission / reception units 12 and 13 and performs various processing of transmission / reception signals, an interface unit 15 that is interposed between the transmission / reception units 12 and 13 and the control unit 14 and transmits transmission / reception signals, And a communication unit 16 for connecting to a network.
The receiving unit 13 includes a bandpass filter 13a connected to the antenna 11, and further, an amplifier 13b, an attenuator 13c, and a quadrature demodulator connected in order from the bandpass filter 13a toward the interface unit 15. 13d and an A / D converter 13e. The receiving unit 13 and the transmitting unit 12 perform amplification, modulation / demodulation, A / D, D / A conversion, and the like of a signal wave transmitted / received from the antenna 11.

The interface unit 15 is an interface conforming to the IEEE 802.16 standard, and mediates transmission / reception of signals between the transmission / reception units 12 and 13 and the control unit 14. The communication unit 16 is a communication interface compliant with a standard such as Ethernet (registered trademark), and mediates exchange of information between the control unit 14 and an external upper network.
The control unit 14 is configured by a microcomputer having a CPU, a memory (RAM), a storage device (hard disk or ROM), and the BS 10 performs processing necessary for establishing communication with the MS 20, or the MS 20 The reception information included in the communication frame of the received signal from the mobile station is extracted and transmitted to the higher level network, or the information transmitted from the higher level network to the MS 20 is loaded on the communication frame.
In addition, the control unit 14 performs ranging, which will be described later, performed when the BS 10 receives a reception signal from the MS 20, such as generating and transmitting a ranging response message in response to the ranging request message from the MS 20. Has a function for. Further, the control unit 14 is a functional unit for adjusting the transmission output of the MS 20 performed during the ranging, and includes a detection unit 14a, a control command generation unit 14b, a control target value adjustment unit 14c, and instantaneous level fluctuation A value estimation unit 14d is included. These will be described in detail later.

[Configuration of mobile terminal]
The MS 20 that performs wireless communication with the BS 10 includes an antenna 21 for transmitting and receiving signals to and from the BS 10, a communication unit 22 to which the antenna 21 is connected, and a control unit for comprehensively controlling the functions of the MS 20. 23 and input / output units 24 and 25 for inputting / outputting information exchanged between the BS 10 and the MS 20.
The control unit 23 is constituted by a microcomputer having a CPU, a memory (RAM), a storage device (hard disk or ROM), etc., and performs processing for establishing wireless communication with the BS 10 by controlling the communication unit 22. Information is extracted from the communication frame of the received signal received by the communication unit 22 and output to the output unit 25, or the information input to the input unit 24 is put on the communication frame to enable transmission.

Further, the control unit 23 has a function of determining to perform ranging and generating and transmitting a ranging request message (ranging request) for requesting ranging to the BS 10. Here, ranging means adjusting the signal output, signal timing, etc. of the MS 20, and adjusting the received signal level value, signal timing value, etc. detected from the received signal from the MS 20 received by the BS 10 to a predetermined appropriate value. The MS 20 can start adjusting its transmission output by transmitting this ranging request message to the BS 10.
Further, the control unit 23 receives a ranging response message transmitted from the BS 10 in response to the ranging request message, and adjusts the transmission output of the MS 20 based on an adjustment parameter control command described later stored in the ranging response message. Also have.
The MS 20 scans a transmission signal from the BS 10 by turning on the main power supply, and establishes communication with the BS 10 when the transmission signal is captured. The MS 20 is configured to be able to enter an external network by receiving a service by wireless communication from the BS 10 and to exchange information with the outside.

[Ranging and mobile terminal transmission output adjustment]
In the BWA system, ranging is performed in order to ensure communication quality between the BS 10 and the MS 20. As described above, ranging is a process of adjusting the signal transmission condition of the MS 20 and adjusting the received signal level value, signal timing, etc. detected from the received signal from the MS 20 received by the BS 10 to a predetermined appropriate value. Yes, the transmission output of the MS 20 is adjusted during the ranging process.
As described later, the ranging is performed by repeating transmission / reception of a ranging request message generated and transmitted by the MS 20 and a ranging response message generated and transmitted by the BS 10 between the MS 20 and the BS 10.
The control unit 14 of the BS 10 generates and transmits a ranging response message including adjustment parameters for adjusting various transmission conditions of the MS 20 in response to the ranging request message from the MS 20. In this adjustment parameter, in addition to a control command for adjusting the transmission output of the MS 20, information for synchronizing signal timing and frequency is stored.
When the MS 20 receives the ranging response message including the adjustment parameter, the MS 20 adjusts the transmission output and the timing based on the information stored in the adjustment parameter.

  For ranging, in addition to the initial ranging performed when the MS 20 enters the network, the periodic ranging performed periodically with the MS 20 that has been continuously established, from the serving BS The handover ranging that is performed at the time of the handover process, which is the process of continuously taking over the service to the target BS, is defined.

  The initial ranging is the ranging performed at the time of network entry as described above, and is performed after the MS 20 captures the transmission signal from the BS 10 by scanning the nearest BS at the time of network entry. The MS 20 generates a ranging request message based on information such as a UL_MAP message including information related to ranging included in the transmission signal. This ranging request message is transmitted from the MS 20 to the BS 10 to start the initial ranging.

Similarly to the initial ranging, the periodic ranging is started when the MS 20 acquires a ranging interval from information such as a UL_MAP message and generates and transmits a ranging request message.
Handover ranging is a ranging performed at the time of a handover process, and when a service provided to the MS 20 is taken over from a BS 10 (serving BS) that has established communication with the MS 20 to an adjacent BS 10 (target BS). First, it is performed between the MS 20 and the target BS. Also in ranging at the time of this handover, the MS 20 transmits a ranging request message to the target BS. This starts ranging.

As described above, in any ranging, ranging starts when a ranging request message is transmitted from the MS 20. The transmission output adjustment of the MS 20 is performed in any of the above ranging cases.
Note that, in any ranging, the MS 20 generates a ranging request message based on information included in a UL_MAP message or the like that is broadcast from the BS 10. The ranging request message generated based on the information included in the UL_MAP message includes information for identifying which ranging is generated for each ranging.

[Functional part of the control part]
As described above, the control unit 14 of the BS 10 of the BWA system according to the present embodiment is a functional unit for performing transmission output adjustment of the MS 20 in ranging. The detection unit 14a, the control command generation unit 14b, and the control target value adjustment unit. 14c and an instantaneous level fluctuation value estimation unit 14d.
The detection unit 14a detects the received signal level value P based on a ranging request message as a received signal received by the BS 10. The detection unit 14a detects the received signal level value P at the level of the input end of the A / D converter 13e.

The control target value adjustment unit 14c has a function of adjusting a control target value Ps that is a setting target of the reception signal level value P detected by the detection unit 14a.
Here, the control target value Ps will be described. As described above, this control target value Ps is a setting target of the received signal level value P detected at the level of the input end of the A / D converter 13e, and as shown in the following equation (1), This is obtained by adding a margin value M for allowing an instantaneous level fluctuation that occurs in the detected received signal level value to the target value Pm that is at least required to establish the communication.
Ps = Pm + M (1)

For example, in the receiving unit 13 of the present embodiment, when the MS20 modulation scheme is QPSK1 / 2 and the margin value M is 0, the target value at the input end level of the antenna 11 is the required CN ratio and device noise. In consideration, the target value Pm at the input end level of −93 dBm and A / D converter 13e is 20 dBm from the dynamic range of A / D converter 13e. A value obtained by adding the margin value M to the control target value Ps (for example, when the margin value M is 10 dBmV, the control target value Ps is 30 dBmV).
The range adjustment of the received signal level value at the input end of the A / D converter 13e is performed by the control target value adjusting unit 14c using the target value at the input end level of the antenna 11 and the A / D converter 13e. This is done by adjusting and setting the attenuator 13c in consideration of the dynamic range.
The control target value Ps determined as described above is set to the lower limit value of the numerical value range indicating whether or not the adjustment is completed when the ranging request message is received in the transmission output adjustment of the MS 20 in ranging. This is the standard for adjustment.

  Further, the control target value adjustment unit 14c determines whether the ranging request message from the MS 20 is an initial ranging or a ranging request message other than that (periodic ranging or handover ranging). It has a function of adjusting the control target value Ps to a different value according to the determination. Furthermore, the control target value adjustment unit 14c also has a function of adjusting the control target value Ps according to the modulation scheme of the MS 20.

The control command generator 14b controls the transmission output of the MS 20 based on the received signal level value P detected by the detector 14a and the control target value Ps adjusted by the control target value adjuster 14c. Generate instructions.
More specifically, the control command generator 14b obtains the difference between the received signal level value P and the control target value Ps, and if the received signal level value P is smaller than the control target value Ps, the predetermined step A control command for increasing the transmission output of the MS 20 with a value is generated. On the other hand, if the received signal level value P is larger than the control target value Ps (or a value obtained by adding a predetermined threshold value to the control target value Ps), a control command for decreasing the transmission output of the MS 20 with the predetermined step value. Is generated.

  As described above, the control unit 14 stores the control command in an adjustment parameter, further stores the adjustment parameter in a ranging response message, and transmits it to the MS 20. Further, the control unit 14 stores “status” as information for notifying the MS 20 whether or not to continue the ranging, in the ranging response message, along with the adjustment parameter. The ranging response unit 16 f stores “success” in this “status”, thereby allowing the MS 20 to recognize that ranging has been completed. On the other hand, storing “continue” makes it possible to recognize that the ranging is continued.

While the BS 10 and the MS 20 establish communication, the instantaneous level fluctuation value estimation unit 14d determines the reception strength and CN ratio of the pilot signal stored in the upstream communication frame transmitted from the MS 20 for a predetermined time. And estimate the instantaneous level fluctuation value R based on the received intensity and CN ratio.
More specifically, for example, focusing only on the reception strength of the pilot signal, the transmission strength when the pilot signal is transmitted from the MS 20 is constantly transmitted at a known value. , And as shown in FIG. 3, the average level value K1 within a predetermined time and the minimum value K2 significantly lower than the average level value K1 are detected, and the displacement ΔK is obtained by obtaining these displacements ΔK. Can be an estimated value of the instantaneous level fluctuation value. As for the CN ratio of the pilot signal, an estimated value of the instantaneous level fluctuation value can be obtained as in the case of the reception strength.
In the present embodiment, the instantaneous level variation value estimation unit 14d is configured to obtain an estimated value R of the instantaneous level variation value based on the reception intensity and CN ratio of the pilot signal.
Here, although the pilot signal is observed on the time axis, it can also be observed on the frequency axis. In this case as well, an estimated value of the instantaneous level fluctuation value can be obtained in the same manner.

[Procedure for adjusting transmission output of mobile terminal]
Next, a procedure for adjusting the transmission output of the MS 20 by the BWA system configured as described above will be described. FIG. 4 is a diagram showing an outline of ranging in which transmission output adjustment of the MS 20 is performed. FIG. 4 shows the steps after the stage where the MS 20 decides to perform ranging and generates and transmits a ranging request message. In the figure, the MS 20 that has decided to perform ranging transmits a ranging request message (RNG_REQ) to the BS 10 (step S1).
The BS 10 that has received the ranging request message detects a received signal level value P, a signal timing value, a frequency value, and the like that are detected based on the ranging request message (step S2), and an adjustment parameter that is generated based on these values, And “status” which is set to “continue” is stored in the ranging response message (RNG_RSP) and transmitted to the MS 20 (step S3).
The MS 20 that has received the ranging response message adjusts its own signal transmission conditions based on the adjustment parameter (step S4), and transmits the ranging request message again (step S5).
When the above steps are repeated and the BS 10 determines that the received signal level value P, the signal timing value, and the frequency value are properly adjusted and ranging is completed, “success” is stored in “status”. Then, a ranging response message is transmitted (step S6). The MS 20 that has received the ranging response message in which “success” is stored stops transmission of the ranging request message (step S7) and completes the ranging.

Next, the procedure for adjusting the transmission output of the MS 20 in the ranging procedure will be described in more detail. FIG. 5 is a flowchart showing a more specific processing procedure of the transmission output adjustment of the MS 20 in the ranging shown in FIG. In actual ranging, as shown in steps S1 to S7 in FIG. 4, adjustment is performed for each of the signal timing and frequency in addition to the transmission output of the MS 20, but FIG. 5 facilitates understanding. For this reason, only the transmission output adjustment of the MS 20 will be described.
In FIG. 5, the MS 20 that has decided to perform ranging generates a ranging request message and transmits it to the BS 10 (step S101). The control unit 14 of the MS 20 that has received the ranging request message (step S102) first causes the detection unit 14a to detect the received signal level value P based on the received ranging request message (step S103).
Next, the control unit 14 informs the control target value adjusting unit 14c that the ranging request message received in step S102 is a message for initial ranging or other (periodic ranging or handover ranging) ranging. To determine whether the message is a message for use on the basis of information included in the ranging request message (step S104).
In the following description, a ranging request message for initial ranging is referred to as a first ranging request message, and a ranging request message for periodic ranging or handover ranging is referred to as a second ranging request message.

  Further, as described above, when the BS 10 receives the ranging request message transmitted from the MS 20, the step S103 constitutes a detection step of detecting the received signal level value based on the received ranging request message.

  Hereinafter, the case where the control target value adjusting unit 14c determines in step S104 that the ranging request message received in step S102 is a message for initial ranging, that is, a first ranging request message will be described.

[Transmission output adjustment in initial ranging]
When the ranging request message received in step S102 is determined to be a message for initial ranging in step S104, the control target value adjusting unit 14c sets the target value Pm, which is a basis for calculating the control target value Ps, to 20 dBmV, The margin value M is adjusted to 10 dBmV (step S105). In this case, the control target value Ps at the level of the input end of the A / D converter 13e is 30 dBmV.
Further, the control unit 14 stores a determination flag as information indicating the determination result of the control target value adjusting unit 14c in a memory or the like, and the control target value adjusting unit 14c determines that it is a ranging request message for initial ranging. If it is, “0” is stored in the determination flag. When the control target value adjustment unit 14c determines that the message is for other ranging, “1” is stored in the determination flag. Therefore, in step S105, the control unit 14 stores “0” in the determination flag.

Next, the control unit 14 resets the count value of the counter included in itself (step S106). This counter is for grasping the adjustment time at the time of adjusting the transmission output described later.
Then, the control unit 14 causes the control target value adjustment unit 14c to adjust the attenuator 13c based on each value set in step S105, and adjusts the range of the input end of the A / D converter 13e. (Step S107).

Next, the control unit 14 determines whether or not the reception signal level value P detected in step S102 is equal to or greater than the control target value Ps and equal to or less than a value obtained by adding a predetermined threshold L to the control target value Ps. Judgment is made (step S108).
In step S108, the numerical range defined by the control target value Ps and the threshold value L is used to determine whether or not the received signal level value P based on the current transmission output of the MS 20 is a value that can complete ranging. The threshold value L is set so as to be within a numerical range that allows communication with the MS 20 to be established even when added to the control target value Ps. That is, in order to complete ranging, it is necessary that the received signal level value P is located in the numerical range, and it is necessary that the received signal level value P is equal to or greater than the control target value Ps.

  If it is determined in step S108 that the received signal level value P is within the above numerical range, the control unit 14 stores an adjustment parameter storing a control command for maintaining the current transmission output and “status” as “status”. Is stored in the ranging response message, and the ranging response message is transmitted to the MS 20 (step S109). Receiving this (step S110), the MS 20 recognizes that the ranging (transmission output adjustment of the MS 20) has been completed, and completes the ranging by stopping the transmission of the ranging request message (step S111).

On the other hand, if it is determined in step S108 that the received signal level value P is not within the numerical range, the control unit 14 shifts to the adjustment mode (step S112).
FIG. 6 is a flowchart showing the procedure of the adjustment mode (step S112). In this adjustment mode, the control unit 14 causes the control command generation unit 14b to generate a control command for the adjustment parameter stored in the ranging response message.
First, the control command generator 14b determines whether or not the determination flag is “0” (step S201). Here, since “0” is stored in the determination flag as described above, the control instruction generation unit 14b proceeds to step S202, and subtracts a predetermined value M1 from the margin value M set in step S105. The value is set to a new margin value M (step S202).
The case where the determination flag is “1” will be described later.

Next, the control command generator 14b generates a control command for increasing the transmission output of the MS 20 by a predetermined step value S1, and stores it in the adjustment parameter (step S203).
When it is determined that this is the initial ranging, the transmission output of the MS 20 is adjusted so as to gradually increase from a predetermined initial value, and is adjusted to reach the receivable output of the BS 10. In step S108, the received signal level value P is substantially out of the numerical range when it is lower than the control target value Ps. Therefore, when it is determined that the initial ranging is required and the transmission output needs to be adjusted, the control command generation unit 14b determines that the transmission output of the MS 20 is to be increased, and increases the transmission output of the MS 20. Generate control instructions.

Next, the control unit 14 checks a counter included in itself and determines whether or not the count value of the counter is equal to or less than a predetermined value (step S204). When determining that the counter is equal to or less than the predetermined value, the control unit 14 proceeds to step S205 and counts up the count value of the counter (step S205).
Next, the control unit 14 stores “status” set to “continue” in the ranging response message together with the adjustment parameter including the control command generated by the above procedure, and transmits the ranging response message to the MS 20 (step S206). ).

  The MS 20 that has received the ranging response message (step S207) refers to the adjustment parameter and “status” stored in the message. Then, since “continue” is stored in “status”, the control unit 23 of the MS 20 adjusts its own transmission output based on the control command included in the adjustment parameter (step S208).

The control unit 23 of the MS 20 that has adjusted the transmission output generates a ranging request message again and transmits it to the BS 10 (step S209).
The control unit 14 of the BS 10 that has received the ranging request message causes the detection unit 14a to detect the received signal level value P based on the received ranging request message (step S210).

When the received signal level value P is detected in step S210, the control unit 14 returns to step S108 (FIG. 5), and the received signal level value P detected in step S210 is shown in the figure. It is determined whether or not the value is within a numerical range determined by the control target value Ps and the threshold value L (step S108).
As described above, the control unit 14 repeatedly performs the adjustment mode in step S112 until the condition is satisfied in the determination in step S108.

Here, in the adjustment mode (step S112), the value obtained by subtracting the predetermined value M1 from the margin value M is set as the new margin value M in step S202. Therefore, the value of the control target value Ps is adjusted in step S112. Each time the mode is advanced, the value is gradually decreased by the predetermined value M1. On the other hand, each time the MS 20 proceeds to the adjustment mode in step S112, the transmission output is increased by receiving a ranging response message storing a control command for increasing the transmission output of the MS 20 by a predetermined step value S1. Therefore, the received signal level value P at the BS 10 also increases accordingly.
That is, by repeating the adjustment mode, the control unit 14 can decrease the control target value Ps while increasing the reception signal level value P, and adjust the reception signal level value P so that the condition in step S108 is satisfied. it can.
For this reason, the MS 20 adjusts the transmission output by the above process, and at the same time, adjusts the BS 10 so that ranging is easy to complete. Therefore, the initial ranging completes the transmission output adjustment more quickly. And communication between the MS 20 and the BS 10 can be easily established.

  Here, in step S204 (FIG. 6) of the adjustment mode, the control unit 14 checks the counter included in itself and determines whether the count value of the counter is equal to or less than a predetermined value. However, if it is determined that the counter is not less than or equal to the predetermined value, the control unit 14 ends the transmission output adjustment process (step S214). In this case, the BS 10 repeatedly attempts to adjust the transmission output for the MS 20, but the adjustment is not reflected on the MS 20 side and it is determined that the communication cannot be established. If the adjustment mode is repeated a certain number of times, establishment of communication with the MS 20 is abandoned and the processing is stopped. It should be noted that the predetermined value that serves as a criterion for determining the count value is generally set to a value that allows it to be determined that communication with the MS 20 cannot be established.

Next, when it is determined in step S108 that the received signal level value P is within the above numerical range and satisfies the condition, the control unit 14 proceeds to steps S109 to S111 described above, and the MS 20 determines that ranging has been completed. Is recognized, the transmission of the ranging request message is stopped, and the ranging is completed.
Next, a case will be described in which the control target value adjustment unit 14c determines that the ranging request message received in step S102 is a message for other ranging than the initial ranging, that is, the second ranging request message.

[Transmission output adjustment in other ranging]
Referring to FIG. 5, when control target value adjustment unit 14c determines in step S104 that the ranging request message received in step S102 is the second ranging request message, control unit 14 sets “ 1 "is stored (step S113). Next, the control unit 14 causes the control target value adjustment unit 14c to set a target value Pm that is at least required to establish communication with the MS 20 (step S114).
In step S114, the control target value adjustment unit 14c is configured to set the target value Pm according to the modulation scheme of the MS 20. Here, in the system of the present embodiment, the modulation scheme of the MS 20 is set to any one of QPSK1 / 2, QPSK3 / 4, 16QAM1 / 2, and 16QAM3 / 4. The modulation scheme of the MS 20 is configured so that the control unit 14 of the BS 10 determines the communication status with the MS 20 and the like.

  FIG. 7 is a flowchart showing a procedure for setting the target value Pm in step S114. The control target value adjustment unit 14c first determines whether or not the modulation scheme of the MS 20 is QPSK1 / 2 (step S301). When determining that the modulation scheme of the MS 20 is QPSK1 / 2, the control target value adjustment unit 14c sets the target value Pm to 20 dBmV (step S302), and proceeds to step S115 in FIG. In this case, the target value at the input end level of the antenna 11 is −93 dBm as described above.

  If it is determined in step S301 that the modulation scheme of the MS 20 is not QPSK 1/2, the control target value adjustment unit 14c next determines whether or not the modulation scheme of the MS 20 is QPSK 3/4 (step S303). When determining that the modulation method of the MS 20 is QPSK3 / 4, the control target value adjustment unit 14c sets the target value Pm to 26 dBmV (step S304), and proceeds to step S115 in FIG. In this case, the target value at the input end level of the antenna 11 is −90 dBm.

If it is determined in step S303 that the modulation scheme of the MS 20 is not QPSK 3/4, the control target value adjustment unit 14c next determines whether or not the modulation scheme of the MS 20 is 16QAM1 / 2 (step S305). When determining that the modulation scheme of the MS 20 is 16QAM1 / 2, the control target value adjustment unit 14c sets the target value Pm to 31 dBmV (step S306), and proceeds to step S115 in FIG. In this case, the target value at the input end level of the antenna 11 is −87.5 dBm.
If it is determined in step S305 that the MS20 modulation scheme is not 16QAM1 / 2, the MS20 modulation scheme is 16QAM3 / 4, and the control target value adjustment unit 14c sets the target value Pm to 38 dBmV (step S307). The process proceeds to step S115 in step 5. In this case, the target value at the input end level of the antenna 11 is −84 dBm.
As described above, the control target value adjustment unit 14c can adjust and set the target value Pm according to the modulation method of the MS 20 in step S114 in FIG. As a result, the control target value Ps corresponding to the modulation scheme of the MS 20 can be adjusted and set, and the transmission output of the MS 20 described later can be set to a value suitable for the modulation scheme.

Returning to FIG. 5, next, the control target value adjusting unit 14c sets the margin value M in step S115. This margin value M is the instantaneous level fluctuation estimated by the instantaneous level fluctuation estimation unit 14d obtained from the reception intensity and CN ratio of the pilot signal stored in the uplink communication frame while the BS 10 and the MS 20 are establishing communication. Adjustment is set based on the estimated value R of the value.
In the present embodiment, the control target value adjusting unit 14c is configured to set the estimated value R as the margin value M. When the margin value M is set, the estimated value R may be set as it is as in the present embodiment, but the estimated value R can be corrected and set in consideration of other factors. .
As described above, the estimated value R of the instantaneous level fluctuation value is obtained based on the reception intensity of the pilot signal while the BS 10 and the MS 20 are establishing communication, and the margin value M is adjusted and set based on the estimated value R. By doing so, in the current communication between the BS 10 and the MS 20, the instantaneous level fluctuation actually generated by fading or the like can be reflected in the control target value Ps. Therefore, the control target value adjustment unit 14c can set the margin value M to a minimum necessary value, and does not request the MS 20 for a transmission output more than necessary.
As described above, the control target value adjusting unit 14c sets the target value Pm and the margin value M, whereby the control target value Ps is determined.

Further, the control target value Ps in the case of being determined as the second ranging request message is obtained from the target value Pm and the margin value M adjusted and set by the control target value adjusting unit 14c, but is determined to be initial ranging. In the case of the control target value Ps, the target value Pm is set to 20 dBmV, and is adjusted and set to gradually decrease by a predetermined value M1 every time the margin value M is processed in the adjustment mode.
That is, the control target value adjustment unit 14c controls the control target value Ps (first control target value) to be adjusted when the first ranging request message (in the case of initial ranging) is determined, and the second ranging. With the control target value Ps (second control target value) that is adjusted when the request message is determined, these control target values Ps can be adjusted and set to different values. Then, the control target value adjustment unit 14c adjusts and sets the control target value Ps when it is determined as the first ranging request message to be smaller than when it is determined as the second ranging request message. .
Therefore, in this case, in the initial ranging, the transmission output of the MS 20 can be lowered as compared with other ranging. Therefore, since the transmission output requested from the MS 20 is also set to a relatively low value, the power consumption of the MS 20 can be suppressed and the adjustment of the transmission output can be completed more quickly.

  As described above, in the system according to the present embodiment, the control target value adjusting unit 14c determines the MS20 state such as whether the current ranging is initial or other, the MS20 modulation method, the instantaneous level fluctuation value, and the like. The control target value Ps is adjusted based on a communication state with the MS 20 such as a factor.

  Further, step S105 in the initial ranging and steps S114 and S115 in the other ranging constitute a control target value adjusting step for adjusting the control target value Ps of the received signal level value P as described above.

Next, the control unit 14 causes the control target value adjustment unit 14c to adjust the attenuator 13c based on the control target value Ps set in steps S114 and S115, and the range of the input end of the A / D converter 13e. Adjustment is performed (step S107).
Then, the control unit 14 determines whether or not the received signal level value P detected in step S102 is equal to or greater than the control target value Ps and equal to or less than a value obtained by adding a predetermined threshold L to the control target value Ps. Judgment is made (step S108).

If the control unit 14 determines in step S108 that the above condition is satisfied, the process proceeds to steps S109 to S111 described above, and the MS 20 recognizes that the ranging is completed, stops transmission of the ranging request message, and performs ranging. Complete.
If it determines with not satisfy | filling the said conditions in step S108, the ranging part 16 will transfer to adjustment mode of signal transmission conditions to MS20 (step S112).

Referring to FIG. 6, the control command generator 14b determines whether or not the determination flag is “0” (step S201). Here, since “1” is stored in the determination flag as described above, the control command generation unit 14b proceeds to Step S211, and whether or not the received signal level value P is smaller than the control target value Ps. Is determined (step S211).
When determining that the received signal level value P is smaller than the control target value Ps, the control command generator 14b generates a control command for increasing the transmission output of the MS 20 by a predetermined step value S2, and stores it in the adjustment parameter. (Step S212), the process proceeds to Step S206.
On the other hand, if it is determined that the received signal level value P is not smaller than the control target value Ps, the received signal level value P is larger than the control target value Ps (a value obtained by adding the threshold L to the control target value Ps). The control command generation unit 14b generates a control command for decreasing the transmission output of the MS 20 by a predetermined step value S2, stores it in the adjustment parameter (step S213), and proceeds to step S206.

  Further, step S108 (FIG. 5) for determining whether or not to proceed to the adjustment mode based on the received signal level value P and the control target value Ps, steps S211 to S213, and step S203 in the initial ranging are detected. A control command generation step for generating a control command for adjusting the transmission output of the MS 20 based on the received signal level value P detected by the unit 14a and the control target value Ps is configured.

Next, as in the case of the transmission output adjustment in the initial ranging described above, the ranging response message and the ranging request message are repeatedly transmitted and received between the BS 10 and the MS 20, and the control unit 14 determines in step S108 in the determination in step S108. Until the condition is satisfied, the adjustment mode in step S112 is repeatedly performed.
During this time, the control unit 14 can transmit a control command generated on the basis of the control target value Ps adjusted and set by the control target value adjusting unit 14c to the MS 20, and the transmission output of the MS 20 is suitably set according to the current situation. Can be adjusted.
When the received signal level value P satisfies the condition in step S108, ranging is completed as described above.

According to the BS 10 of the BWA system configured as described above, the control target value adjustment unit 14c adjusts the control target value Ps of the received signal level value P, and is generated based on the control target value Ps. The transmission output of the MS 20 can be adjusted via the control command. Accordingly, the BS 10 can adjust the transmission output of the MS 20 according to the situation.
Further, in the system of the present embodiment, the control target value adjustment unit 14c is configured to determine whether the ranging currently being performed is initial or other, the state of the MS 20, or the modulation method or instantaneous level fluctuation value of the MS 20 The control target value Ps is adjusted based on the communication state with the MS 20 such as the above factors, and as described above, the control command according to the state of the MS 20 can be transmitted to the MS 20. The transmission output of the MS 20 can be suitably adjusted according to the situation.

  Moreover, in the system of this embodiment, since the transmission output of MS20 can be adjusted suitably according to the condition as mentioned above, it can suppress requesting the transmission output more than necessary from MS20. It is possible to suppress the MS 20 from wasting power and narrowing the area where communication can be established.

The present invention is not limited to the above embodiment. For example, in the above-described embodiment, as a factor that becomes a reference when adjusting the control target value Ps, the state of the MS 20 is determined as to whether the current ranging is initial or other, and communication is performed. As for the state, factors such as the modulation method of MS 20 or instantaneous level fluctuation value are taken into consideration. However, the present invention is not limited to these, and the control target value Ps is adjusted in consideration of other factors. Also good.
The instantaneous level fluctuation estimation unit 14d determines the instantaneous level fluctuation value estimated value R by observing both the reception intensity of the pilot signal and the CN ratio. An estimated value of the fluctuation value may be obtained.
In the above embodiment, in the case of ranging other than the initial ranging, the margin value M is adjusted and set based on the estimated value R by the instantaneous level fluctuation value estimating unit 14d. In some cases, the instantaneous level fluctuation value due to fading, multipath, or the like can be stably estimated depending on the city center or the suburbs. In such a case, the margin value M is a value that can be estimated depending on the installation location. It can also be fixed.

It is a figure which shows the whole structure of a broadband mobile radio | wireless communications system (BWA system). It is the block diagram which showed the structure of BS and MS. It is a figure which shows the aspect at the time of calculating | requiring the estimated value of an instantaneous level fluctuation value from the receiving strength of a pilot signal. It is the figure which showed the outline of the ranging by which transmission output adjustment of MS is performed. 5 is a flowchart showing a more specific processing procedure of transmission output adjustment of the MS 20 in the ranging shown in FIG. It is the flowchart which showed the process sequence of adjustment mode (step S112). It is the flowchart which showed the procedure which sets the target value Pm in step S114.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 BS (base station) 11 Antenna 12 Transmission part 13 Reception part 13a Band pass filter 13b Amplifier 13c Attenuator 13d Quadrature demodulator 13e A / D converter 14 Control part 14a Detection part 14b Control command generation part 14c Control target value adjustment part 14d Instantaneous level fluctuation value estimation unit 15 Interface unit 16 Communication unit 20 MS (mobile terminal) 21 Antenna 22 Communication unit 23 Control unit 24 Input unit 25 Output unit

Claims (7)

A base station apparatus that adjusts the transmission output of the mobile terminal by transmitting a control command for adjusting the transmission output of the mobile terminal to the mobile terminal in response to reception of a ranging request transmitted from the mobile terminal. There,
A detector that detects a received signal level value based on the received ranging request;
A control command generating unit that generates a control command for adjusting the transmission output of the mobile terminal based on the received signal level value detected by the detecting unit and the control target value of the received signal level value;
A control target value adjusting unit for adjusting the control target value to adjust the transmission output of the mobile terminal via the control command;
A base station apparatus comprising:   The base station apparatus according to claim 1, wherein the control target value adjustment unit is configured to adjust the control target value based on a state of the mobile terminal or a communication state with the mobile terminal.   When the ranging request is a first ranging request for initial ranging, the control target value adjusting unit adjusts to a first control target value and performs second ranging for other ranging than the initial ranging. The control target value is adjusted to the second control target value, and the control target value adjustment unit further reduces the first control target value to a value smaller than the second control target value. The base station apparatus according to claim 1, which adjusts to   The base station apparatus according to claim 1, wherein the control target value adjustment unit adjusts the control target value according to a modulation scheme of the mobile terminal. An instantaneous level fluctuation value estimating unit for obtaining an estimated value of the instantaneous level fluctuation value of the received signal;
The base station apparatus according to any one of claims 1 to 4, wherein the control target value adjustment unit adjusts the control target value according to the estimated value obtained by the instantaneous level fluctuation value estimation unit.   The instantaneous level variation value estimation unit obtains the estimated value based on at least one of a reception intensity of a pilot signal included in a transmission signal transmitted from the mobile terminal and a CN ratio of the pilot signal. 5. The base station apparatus according to 5. A mobile terminal transmission output adjustment method performed by receiving a control command for adjusting transmission output, transmitted from a base station apparatus in response to transmission of a ranging request,
The base station apparatus detects a received signal level value based on a ranging request transmitted from the mobile terminal; and
A control target value adjusting step for adjusting a control target value of the received signal level value;
A control command generation step of generating a control command for adjusting the transmission output of the mobile terminal based on the received signal level value detected by the detection unit and the control target value;
A transmission output adjustment method for a mobile terminal, comprising:

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