JP2009130894A - Base station apparatus and ranging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base station apparatus capable of improving the adjustment accuracy of the signal transmission condition of a mobile terminal in ranging, and a ranging method. <P>SOLUTION: The base station apparatus 10 includes a detection part 15a for detecting the signal characteristic value of user data signals which are transmission signals including user data among the received transmission signals from an MS 20, a decision part 15b for determining whether the detected signal characteristic value is within a prescribed target range, an adjustment instruction generation part 15c for generating adjustment instructions on the basis of the signal characteristic value when it is determined that the signal characteristic value is out of the target range by the decision part 15b, and a communication control part 15 for transmitting the adjustment instructions generated by the adjustment instruction generation part 15c to the MS 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a base station apparatus and a ranging method for a radio communication system used for a broadband mobile radio communication system and the like.

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 plurality of mobile terminals that establish wireless communication with the base station apparatus. The base station apparatus transmits a broadband wireless signal to the mobile terminal. Provide communication services.
In the BWA system, ranging for synchronizing signal output and signal timing is performed between the base station apparatus and the mobile terminal. This ranging includes initial ranging performed when the mobile terminal enters the network, handover ranging performed at the time of handover, and periodic ranging performed periodically by the mobile terminal in a connected state. (Periodic Ranging) is defined.
Among these, periodic ranging is a process performed to periodically synchronize when the base station apparatus and the mobile terminal establish communication with each other, and the mobile terminal transmits a CDMA ranging code (hereinafter referred to as a CDMA ranging code). Periodically transmitting a ranging code) to the base station apparatus, and the base station apparatus that has received the transmission transmits a ranging response message including a command for causing the mobile terminal to adjust signal output and the like. Done in

  FIG. 7 is a diagram illustrating a conventional periodic ranging procedure. The base station apparatus receives downlink subframe allocation information (DL-MAP) including area allocation information in downlink subframes and uplink subframe allocation information (UL-MAP) including area allocation information in uplink subframes. It is allocated within the subframe and is broadcasted to a plurality of mobile terminals (step S501). At the same time, a burst area for transmitting a user data signal, which is a transmission signal including user data, is also allocated in the downlink subframe. In addition, a burst area for transmitting a user data signal and a ranging area for transmitting a ranging code are allocated to the uplink subframe. Allocation information indicating allocation of these areas is allocated to the UL-MAP. Is stored.

When the mobile terminal determines to perform periodic ranging according to a predetermined period, the mobile terminal generates a ranging code for periodic ranging (step S502), and uses the ranging area to transmit the ranging code (Code) to a base station. It transmits to the apparatus (step S503).
The base station apparatus that has received the ranging code from the mobile terminal transmits the signal of the mobile terminal based on signal characteristic values such as a received signal level, a received signal timing, and a received signal frequency of the ranging code transmitted using the ranging area. An adjustment command for adjusting the condition (wireless parameter) is set. Then, a ranging response message (RNG_RSP) including this adjustment command and “status” which is information for notifying the mobile terminal whether or not the ranging has been completed is transmitted (step S504).

When the mobile terminal receives the ranging response message, the mobile terminal adjusts signal transmission conditions based on an adjustment command included therein. After adjusting the signal transmission conditions, the mobile terminal transmits the ranging code again to the base station apparatus (step S505).
By repeating the above steps S503 and S504, ranging is performed, and the base station apparatus causes the mobile terminal to adjust the signal transmission condition by transmitting an adjustment command to the mobile terminal, and receives the transmission signal from the mobile terminal to receive. Synchronize signal characteristic values. At this time, when the base station apparatus determines to continue the ranging, the base station apparatus transmits a ranging response message with “status” set to “continue”. On the other hand, when it is determined that the synchronization of the signal characteristic values is completed and the ranging is to be ended, a ranging response message is transmitted with “status” set to “success” (step S506). The mobile terminal that has received this stops transmission of the ranging code and ends the ranging.

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 periodic ranging described above, the adjustment command for adjusting the signal transmission condition of the mobile terminal transmitted from the base station apparatus to the mobile terminal is the signal level of the ranging code received by the base station apparatus, the signal frequency error value, And a signal timing error value. For this reason, in the above periodic ranging, the signal level, the signal frequency, and the signal timing of the ranging code transmitted in the ranging area are adjusted and synchronized.
In the periodic ranging, synchronization is performed based on a ranging code transmitted by a ranging area allocated separately from a burst area for transmitting a user data signal in an uplink subframe. For this reason, the user data signal that is a transmission signal including user data related to actual communication is not directly synchronized, but indirectly by adjusting the signal transmission condition of the mobile terminal based on the ranging code. Since synchronization is obtained, even if the ranging code is synchronized, the user data signal may be shifted in adjustment. This is because different subcarriers are used in the ranging area and the burst area for transmitting the user data signal. As described above, when a deviation occurs in the adjustment of the user data signal, there is a possibility that the synchronization cannot be accurately performed and the adjustment accuracy is lowered.
Further, for example, when the mobile terminal is in a state where frequency selective fading occurs, there is a possibility that the frequency and timing in the burst region cannot be adjusted accurately by the above periodic ranging.
Further, in the above periodic ranging, a contention method is adopted for transmission of ranging codes of the mobile terminal, and when a plurality of mobile terminals simultaneously transmit ranging codes to one base station apparatus, the ranging Since there is a limit to the number of ranging codes that can be received simultaneously depending on the area, collision may occur, and there is a problem that the opportunity for periodic ranging is lost.

  The present invention has been made in view of such circumstances, a base station apparatus capable of preventing loss of the trigger of ranging, and further improving the adjustment accuracy of signal transmission conditions of the mobile terminal in ranging, and It is an object of the present invention to provide a ranging method capable of further improving the adjustment accuracy of signal transmission conditions of a mobile terminal.

  In order to achieve the above object, the present invention provides a base station apparatus that performs ranging by transmitting an adjustment command to a mobile terminal so that the mobile terminal adjusts signal transmission conditions, and receives the received mobile terminal A detection unit that detects a signal characteristic value of a user data signal that is a transmission signal including user data, and determines whether the detected signal characteristic value is within a predetermined target range A determination unit; an adjustment command generation unit that generates the adjustment command based on the signal characteristic value when the determination unit determines that the signal characteristic value is outside the target range; and the adjustment command generation unit And a communication control unit that transmits the adjustment command generated by the mobile terminal to the mobile terminal.

According to the base station apparatus configured as described above, since it has the adjustment command generation unit that generates the adjustment command based on the signal characteristic value detected from the user data signal, the signal characteristic value of the user data signal Ranging can be performed by transmitting an adjustment command based on the above to the mobile terminal. Accordingly, when the signal transmission condition is adjusted by the mobile terminal, the adjustment based on the signal characteristic value detected from the user data signal can be performed. As a result, the signal characteristic value of the user data signal including the user data transmitted by the mobile terminal can be suitably adjusted, so that it is transmitted in a ranging area that is not used for user data transmission as in the conventional example. Compared with the case where the adjustment is performed indirectly based on the signal characteristic value of the ranging code, the adjustment accuracy of the signal transmission conditions of the mobile terminal in ranging can be increased.
Further, in the above-described conventional example, there is a possibility that a plurality of mobile terminals may cause a collision when transmitting ranging codes to the base station apparatus. However, in the base station apparatus according to the present invention, the base station apparatus is connected to the mobile terminal. Since the signal characteristic value of the user data signal is detected and the adjustment command is transmitted, the above-described collision does not occur. For this reason, ranging can be performed reliably without losing the trigger of ranging.

  The signal characteristic value includes at least a signal frequency error value and a signal timing error value when the base station apparatus receives the user data signal, and the determination unit performs the signal frequency error value or When it is determined that the signal timing error value is outside the target range, a user data area allocated to transmit the user data signal in the transmission area for transmitting the transmission signal is changed to the transmission area. The communication control unit may further include an area changing unit that changes to another area, and the communication control unit transmits the allocation information of the user data area changed to another area to the mobile terminal.

  In this case, when the signal frequency error value or the signal timing error value cannot be adjusted within the target range, the area change unit changes the user data area to another area in the transmission area, thereby detecting the detection target of the detection unit. The use frequency of the user data signal can be changed. As a result, even when the mobile terminal cannot be adjusted within the target range at a specific signal frequency or specific signal timing due to the environment or situation where the mobile terminal is located, or even under a situation where frequency selective fading occurs. By changing the use frequency of the user data signal, the signal frequency and the signal timing can be adjusted.

  Further, in the base station device, until the signal characteristic value is determined to be within the target range by repeatedly executing the processing by the detection unit, the determination unit, the adjustment instruction generation unit, and the communication control unit, The mobile terminal further includes a repeat control unit that repeatedly adjusts signal transmission conditions, and the region change unit is configured to perform the signal frequency error by the determination unit when the process by each unit is repeatedly executed by the repeat control unit. When at least one of the value and the signal timing error value is outside the target range and repeatedly determined a predetermined number of times, the user data area is changed to another area in the transmission area It may be a thing.

  In the above configuration, the region changing unit repeatedly adjusts the signal transmission condition of the mobile terminal and repeatedly determines that the signal frequency error value or the signal timing error value is outside the target range a predetermined number of times. Since the user data area is changed to another area, the environment or situation where the mobile terminal is currently located cannot be adjusted within the target range at a specific signal frequency or a specific signal timing, or frequency selective fading occurs. The determination of whether or not it is below can be made based on the number of times of repeated determination. Thereby, it is possible to more accurately determine whether to change the user data area to another area.

  The present invention is also a ranging method in a radio communication system comprising: a base station device that transmits an adjustment command; and a mobile terminal that adjusts a signal transmission condition by receiving the adjustment command. Detecting a signal characteristic value of a user data area used by the mobile terminal for transmission of user data in the transmission signal of the mobile terminal received by the mobile terminal, and the detected signal characteristic value is within a predetermined target range A determination step of determining whether or not there is an adjustment command generation step of generating the adjustment command based on the signal characteristic value when the determination step determines that the signal characteristic value is outside the target range And a transmission step of transmitting the adjustment command generated in the adjustment command generation step to the mobile terminal.

  According to the ranging method configured as described above, it is possible to prevent the chance of ranging from being lost, and to improve the adjustment accuracy of the signal transmission conditions of the mobile terminal in ranging.

  As described above, according to the base station apparatus and the ranging method of the present invention, it is possible to further improve the adjustment accuracy of the signal transmission conditions of the mobile terminal in ranging.

[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). For 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 listed as a candidate. (Hereinafter also referred to as BS10) and mobile terminal 20 (hereinafter also referred to as MS20) capable of moving.
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, the user data can be transmitted and received by placing user data in a predetermined communication frame. The MS 20 can enter the external network by transmitting and receiving this information. Is possible.

[Configuration of base station equipment]
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 / reception unit 12 that transmits and receives a signal wave using the antenna 11, and a signal wave that is transmitted and received by the transmission / reception unit 12. Modulation / demodulation 13 for performing modulation / demodulation, A / D, D / A conversion, and the like, a communication unit 14 for connecting to a higher level network, and a control unit 15 as a communication control unit for controlling these units. ing.

The control unit 15 is configured by a computer having a CPU, a memory (RAM), a storage device (hard disk or ROM), etc., and performs processing necessary for the BS 10 to establish communication with 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. Further, the control unit 15 has a function for executing the above-described initial ranging, handover ranging, and periodic ranging with the MS 20, and for example, decides to perform the initial ranging or the handover ranging. When the ranging code transmitted from the MS 20 is received, a ranging response message can be transmitted accordingly. In addition, the control unit 15 generates an adjustment command for adjusting the signal transmission condition (wireless parameter) of the transmission signal of the MS 20, stores it in the ranging response message, and transmits it to the MS 20.
In addition, the control unit 15 includes a detection unit 15a, a determination unit 15b, an adjustment command generation unit 15c, a repetition control unit 15d, and a region change unit 15e, which are functional units for performing the above-described ranging (particularly periodic ranging). Have. Further, the control unit 15 functionally includes three counters (an output counter, a frequency counter, and a timing counter) (not shown) used in periodic ranging described later. Each of these functional units 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 configured by a computer having a CPU, a memory (RAM), a storage device (hard disk or ROM), and performs processing for establishing wireless communication with the BS 10 by controlling the communication unit 22. The user data 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 user data input to the input unit 24 is transmitted by being placed on the communication frame. .

  Further, the control unit 23 determines to perform ranging (initial ranging, handover ranging) when establishing communication with the BS 10 or performing handover, and requests the BS 10 to perform ranging. It has a function to generate and transmit a ranging code. Further, the control unit 23 receives a ranging response message transmitted from the BS 10 according to the ranging code, and adjusts the signal output, signal timing, and signal frequency of the MS 20 based on the adjustment command stored in the ranging response message. In addition, it has a function of transmitting the adjusted ranging code again.

  Further, when the control unit 23 receives a ranging message for periodic ranging, which will be described later, transmitted from the BS 10 regardless of its own request, the control unit 23 transmits its own signal transmission condition (signal signal) based on the adjustment command stored therein. Level, signal timing, and signal frequency).

  When the MS 20 decides to communicate with the BS 10 to enter the network, the MS 20 performs the above initial ranging and establishes communication with the BS 10. Then, by receiving a service by wireless communication from the BS 10, entry to an external network becomes possible, and user data can be exchanged with the outside.

[About communication frames]
FIG. 3 is a diagram showing the configuration of the communication frame of this system. The communication frame of this system is composed of a downlink subframe to which a transmission signal transmitted from the BS 10 is allocated and an uplink subframe to which a transmission signal transmitted from the MS 20 is allocated. Both subframes have a predetermined time on the time axis. They are arranged alternately via gaps (TTG, RTG).

In the downlink subframe, a preamble signal (Preamble), a frame control header (FCH), downlink subframe allocation information (DL-MAP), and a downlink burst region DB for transmitting user data are allocated.
The DL-MAP includes information related to allocation positions such as user data in the downlink burst area DB.
Further, the downlink burst area DB is divided into a plurality of parts in order to transmit user data corresponding to each MS 20 establishing communication with the BS 10, and in the illustrated example, the first burst burst area db1 to the first downlink burst area DB are divided. Divided into seven of six downstream burst areas db7. Among these, uplink subframe allocation information (UL-MAP) is transmitted in the first downlink burst region db1 following the DL-MAP. This UL-MAP includes information related to the allocation position of user data and the like in the uplink burst area UB allocated to the uplink subframe.
Note that the BS 10 broadcasts DL-MAP and UL-MAP as described above.

In addition to the uplink burst area UB described above, a ranging area R for the MS 20 to transmit a ranging code is assigned to an uplink subframe that is a transmission area for transmitting a transmission signal of the MS 20.
Further, the upstream burst area UB is divided into a plurality of parts corresponding to each MS 20 establishing communication with the BS 10, and in the illustrated example, the first upstream burst area ub1 to the fourth upstream burst area ub4 are divided. It is divided into four along the time axis. Each of these uplink burst areas ub1 to ub4 is assigned to each MS 20 as a user data area for transmitting a user data signal, which is a transmission signal including user data, by MS 20 establishing communication with BS 10.

[Regarding the procedure of periodic ranging]
Next, a procedure for periodic ranging by the BS 10 and the MS 20 having the above-described configuration will be described. In the following description, the periodic ranging performed between the BS 10 and one MS 20 that has established communication with the BS 10 will be described. Further, the communication between the BS 10 and the MS 20 is performed based on the communication frame shown in FIG. 3. As an area for the BS 10 to transmit a transmission signal to the MS 20, for example, in a downlink subframe The second downlink burst area db2 is allocated, and for example, the first uplink burst area ub1 in the uplink subframe is allocated as the user data area for transmitting the user data signal transmitted from the MS 20 to the BS 10. It shall be.

4 and 5 are flowcharts showing a procedure of periodic ranging in the present embodiment, and both FIGS. 4 and 5 show one flowchart connected by A and B in the drawing.
The control unit 15 of the BS 10 performs periodic ranging by repeatedly executing the procedures of the flowcharts shown in FIGS. 4 and 5 at predetermined time intervals while establishing communication with the MS 20. . That is, the periodic ranging is not started in response to the reception of the ranging code from the MS 20, but the BS 10 decides to execute for the specific MS 20 and performs it spontaneously.
Further, when the BS 10 establishes communication with a plurality of MSs 20, periodic ranging is individually performed for each of the plurality of MSs 20.

Referring to FIG. 4, when control unit 15 first determines to perform periodic ranging for specific MS 20, count value n _p of the above output counter, count value n _f of frequency counter, and timing counter The count value n _{t of the} counter is set to “0” (step S100). In the following description, only the specific MS 20 will be described.

Next, the control unit 15 specifies from the UL-MAP that the user data area allocated to the MS 20 is the first uplink burst area ub1, and receives a transmission signal transmitted from the MS 20 (step S1). S101). Then, of the transmission signals from the MS 20, the detection unit 15a detects the signal level value P, the signal frequency error value ΔF, and the signal timing error value ΔT of the user data signal transmitted in the first upstream burst region ub1. (Step S102, detection step). Here, the signal frequency error value ΔF is an offset value (error value) between the signal frequency of the transmission signal transmitted by the MS 20 and the signal frequency when the BS 10 receives the transmission signal of the MS 20, and the signal timing error value ΔT. Is an offset value (error value) between the signal timing of the transmission signal transmitted by the MS 20 and the signal timing when the BS 10 receives the transmission signal of the MS 20.
The detection unit 15a of the control unit 15 has a function of detecting the signal level value P, the signal frequency error value ΔF, and the signal timing error value ΔT, which are signal characteristic values of the received user data signal from the MS 20. Yes.

Specifically, the detection unit 15a obtains the signal frequency error value ΔF by referring to a plurality of pilot subcarriers included in the slots constituting the burst region.
FIG. 6 is a schematic diagram showing a structure of a slot for transmitting a transmission signal of the MS 20. In FIG. 6, the vertical direction on the paper indicates the time axis, and the horizontal direction indicates the frequency axis. As shown in FIG. 6, the slot S is composed of six adjacent tiles T. The tile T has a plurality of subcarriers constituting a transmission signal. The subcarriers include eight data subcarriers (circles shown in white) and four pilot subcarriers (black). Circles shown). The data subcarriers and pilot subcarriers are arranged so as to have a predetermined arrangement as shown in FIG.
First, the detection unit 15a specifies the slot S for obtaining the signal frequency error value ΔF of the user data signal of the MS 20 from the burst region assigned to the MS 20. Then, based on the user data signal included in the specified slot S in the received transmission signal from the MS 20, the transmission channel frequency response h _k of each pilot subcarrier shown in the following equation (1) is _obtained . Note that k is a value indicating the arrangement order of the pilot subcarriers arranged in the time axis direction as shown in FIG.
h _k = r _k e ^jθk (1)

Next, the detection unit 15a calculates an integrated value h ′ _k of the complex conjugate value of the transmission channel frequency response of pilot subcarriers located adjacent to each other in the time axis direction and h _k as shown in the following formula (2) as time. All pilot subcarriers arranged in the axial direction are calculated for each series arranged in the frequency axis direction.
h ′ _k = r _k · r _{k + 1} ej ^{(θk−θk + 1)} (2)

Next, the detection unit 15a obtains the average value of each of the real part and the imaginary part in the complex conjugate integration value h ′ _k of each pilot subcarrier obtained above. Further, a phase difference angle is obtained by performing an arctangent calculation on the ratio of these average values (average value of imaginary part / average value of real part), and a signal frequency error value ΔF is obtained from the phase difference angle.
That is, in this case, it is assumed that there is no phase shift in the frequency axis direction, and the signal frequency error value ΔF is obtained by obtaining the phase difference between pilot subcarriers adjacent in the time axis direction.

  As for the signal timing error value ΔT, it is assumed that there is no phase shift in the time axis direction, and the signal timing error value ΔT is obtained from the phase difference angle between pilot subcarriers adjacent to each other in the frequency axis direction.

Returning to FIG. 4, the control unit 15 determines whether the signal level value P detected by the detection unit 15 a is a value between a predetermined upper limit value P _U and a lower limit value P _L. 15b is determined (step S103). When it is determined that the signal level value P is within the numerical range, the control unit 15 sets the count value n _p of the output counter to “0” (step S104). On the other hand, when it is determined that the value is out of the numerical range, the count value n _p of the output counter is set to “1” and the value necessary for the signal level value P to be within the numerical range is output adjusted. Set as a value (step S105). The output adjustment value is information indicating a value for adjusting the transmission output level in the signal transmission conditions of the MS 20, and is stored in the adjustment command by the adjustment command generation unit 15c as will be described later. Sent to.

Next, the control unit 15, the signal frequency error value ΔF is, to determine whether or not a value between the upper limit value F _U and the lower limit value F _L predetermined for judging unit 15b (step S106). When it is determined that the signal frequency error value ΔF is within the numerical range, the control unit 15 sets the count value n _f of the frequency counter to “0” (step S107). On the other hand, if it is determined that the value is out of the numerical range, “1” is added to the count value n _f of the frequency counter, and the value necessary for the signal frequency error value ΔF to be within the numerical range is adjusted. Set as a value (step S108). This frequency adjustment value is information indicating a value for adjusting the frequency in the signal transmission conditions of the MS 20 as in the case of the output adjustment value, and is stored in the adjustment command by the adjustment command generation unit 15c as will be described later. And sent to the MS 20 by a ranging message.

Next, the control unit 15 causes the determination unit 15b to determine whether or not the signal timing error value ΔT is a value between a predetermined upper limit value T _U and a lower limit value T _L (step S109). When it is determined that the signal timing error value ΔT is within the numerical range, the control unit 15 sets the count value n _t of the timing counter to “0” (step S110). On the other hand, when it is determined that the value is out of the numerical range, “1” is added to the count value n _t of the timing counter, and the value necessary for the signal timing error value ΔT to be within the numerical range is adjusted. Set as a value (step S111). Similar to the output adjustment value, this timing adjustment value is information indicating a value for adjusting the timing within the signal transmission conditions of the MS 20, and is stored in the adjustment instruction by the adjustment instruction generator 15c as will be described later. And sent to the MS 20 by a ranging message.

A numerical range determined by the upper limit value and the lower limit value of the signal level value P, the signal frequency error value ΔF, and the signal timing error value ΔT is a target range of the values P, ΔF, and ΔT that are signal characteristic values. The communication established between the BS 10 and the MS 20 is set to a value that can maintain a predetermined quality.
Further, as described above, the determination unit 15b has a function of determining whether or not each signal characteristic value detected by the detection unit 15a is within the target range. Steps S103, S106, and S109 are: A determination step is performed to determine whether or not the target range is satisfied.

Referring to FIG. 5, control unit 15 next causes control unit 15d to repeatedly determine whether or not the count values n _p , n _f , and n _{t of the} counters are all “0” (step S112). When it is determined that the count values n _p , n _f , and n _{t of} each counter are all “0”, the repetition control unit 15d ends the process. Count value n _p of the counter, n _f, if all n _t is determined to be "0", the signal characteristic value of the transmission signal MS20 received, the signal level value P, the signal frequency Since the error value ΔF and the signal timing error value ΔT are all determined to be within a predetermined numerical range, it is possible to maintain communication established between the BS 10 and the MS 20 without performing ranging. it can.

On the other hand, when the count value n _p of the counter, n _f, n _t is determined not to satisfy the condition of the step S112, the repetitive control unit 15d is the count value n _f or frequency counter, the timing counter It is determined whether or not any one of the count values n _t is larger than thresholds n _fs and n _ts determined in advance (step S113). When the condition of step S113 is not satisfied, that is, when both the count value n _f and the count value n _t do not satisfy the threshold values n _fs and n _ts , the process proceeds to step S114, and the control unit 15 Based on the adjustment values set in steps S105, S108, and S111, the adjustment command generation unit 15c generates an adjustment command for adjusting the signal transmission condition of the MS 20 (step S114, adjustment command generation step). .

The adjustment command has a command for adjusting each of the signal level, signal timing, and signal frequency set based on each adjustment value, which is the transmission signal condition of the MS 20. The BS 10 adjusts the transmission signal condition of the MS 20 by transmitting an adjustment command to the MS 20 as will be described later, and the signal level value P, the signal frequency error value ΔF, and the signal timing error value ΔT of the received user data signal. Each value is adjusted within a predetermined numerical range.
Note that the adjustment command corresponding to the signal characteristic value in which the count values n _p , n _f , and _nt are “0” is not generated. This is because when the count value is “0”, the corresponding signal characteristic value is within the target range and no adjustment is required.
As described above, when the determination unit 15b determines that the signal characteristic value is outside the target range, the adjustment command generation unit 15c issues an adjustment command based on the signal characteristic value (each adjustment value obtained). It has a function to generate.

  Next, the control unit 15 stores the adjustment command in a ranging message and transmits the ranging message to the MS 20 (step S115, transmission step). The control unit 15 transmits the ranging message in the second downlink burst region db2 in the downlink subframe. In the periodic ranging according to the present embodiment, since communication is established between the BS 10 and the MS 20, with respect to a specific MS 20 attempting to perform ranging using the assigned burst region. A ranging message can be sent.

In addition, when a ranging code that is allocated only for transmitting a ranging code is used to transmit the ranging code to the BS 10 as in the above-described conventional example, a collision occurs when a large number of MSs 20 transmit the ranging code at the same time. When starting ranging, there is a risk that a delay may occur or the trigger for ranging may be lost. On the other hand, in the present embodiment, the BS 10 detects the signal characteristic value of the user data signal of the MS 20, and transmits a ranging message using the burst area (second downlink burst area db2) assigned to the MS 20. Therefore, collision does not occur. For this reason, ranging can be performed reliably without causing a delay in the start of periodic ranging or losing the trigger of periodic ranging.
Further, since the MS 20 does not need to generate and transmit a ranging code for periodic ranging, it is possible to save radio resources.

In step S115, the MS 20 that has received the ranging message transmitted from the BS 10 adjusts the signal level, signal timing, and signal frequency, which are signal transmission conditions, based on the adjustment command stored in the ranging message. A transmission signal adjusted toward is transmitted.
In this manner, the control unit 15 has a function as a communication control unit that transmits a ranging message including the adjustment command generated by the adjustment command generation unit 15c to the MS 20.

Then, the control part 15 returns to step S101 (FIG. 4), receives the transmission signal from MS20 after signal transmission conditions were adjusted again, and repeats the above-mentioned procedure.
The control unit 15 repeats the above steps S101 to S115 to cause the MS 20 to adjust the signal transmission conditions, and to receive the signal characteristic values (signal level value P, signal frequency error value ΔF, And the signal timing error value ΔT) is repeated until the predetermined numerical range is reached. When each signal characteristic value of the received transmission signal of the MS 20 falls within a predetermined numerical range, the count values n _p , n _f , n _{t of} each counter are all set to “0” as described above. The control unit 15 ends the process in step S112 (FIG. 5).
In this way, the repetition control unit 15d determines whether or not the count values n _p , n _f , and n _{t of} each counter are all “0”, so that each signal characteristic value is within the target range. Until it is determined, the processing of each unit is repeatedly executed, and the MS 20 has a function of repeatedly adjusting the signal transmission condition.

Further, when the above-described steps S101 to S115 are repeatedly executed and it is determined that the signal frequency error value ΔF and the signal timing error value ΔT are continuously outside the predetermined numerical range, the count value n _f of the frequency counter, The count value n _t of the timing counter is cumulatively added in steps S108 and S111 each time the determination is repeated.
Further, when it is determined in step S113 that either one of these count values n _f and n _t is larger than the predetermined threshold values n _fs and n _ts , the control unit 15 The process proceeds from step S113 to step S116. Then, the region changing unit 15e of the control unit 15 assigns the region allocated as the user data region for the MS 20 to transmit the user data signal in the uplink subframe from the first uplink burst region ub1 in the uplink subframe. Change to another burst area, for example, the third upstream burst area ub3 (see FIG. 3) (step S116).

That is, when it is determined that the signal frequency error value ΔF or the signal timing error value ΔT is outside the target range, the region changing unit 15e changes the user data region of the MS 20 to another burst region in the uplink subframe. It has a function.
Further, when step S101 to step S115 are repeatedly executed, if at least one of the signal frequency error value ΔF and the signal timing error value ΔT is outside a predetermined numerical range, the threshold values n _fs , n _{If the} determination is repeated repeatedly for the number of times _ts , the region changing unit 15e has a function of changing the user data region of the MS 20 to another burst region in the uplink subframe.

  In this case, when the signal frequency error value ΔF and the signal timing error value ΔT cannot be adjusted within the above numerical range, the area changing unit 15e changes the user data area to another burst area in the uplink subframe. The use frequency of the user data signal that is the detection target of the detection unit 15a can be changed. Thereby, due to the environment and situation where the MS 20 is located, even if it is not possible to adjust within a target range at a specific signal frequency or a specific signal timing, or even under a situation where frequency selective fading occurs, By changing the use frequency of the user data signal, the signal frequency and the signal timing can be adjusted.

Furthermore, in the present embodiment, the region changing unit 15e continuously repeats when the signal transmission condition of the MS 20 is repeatedly adjusted and the signal frequency error value ΔF or the signal timing error value ΔT is outside the above numerical range. When the determination is made, the user data area is changed to another area, so that the environment or situation where the MS 20 is currently located cannot be adjusted within the target range at a specific signal frequency or a specific signal timing, or the frequency selection The determination as to whether or not a situation in which sex fading occurs can be made based on the number of times of repeated determination.
Specifically, a criterion for determining whether or not to change the user data area to another area can be set according to the values of the threshold values n _fs and n _ts .
Therefore, by suitably setting the threshold values n _fs and n _ts , it is possible to more accurately determine whether or not to change the user data area to another area.

As described above, after the area changing unit 15e changes the user data area of the MS 20 to another burst area in the uplink subframe in step S116, the control unit 15 sets the count value n _p of the output counter, and the frequency The count value n _{f of} the counter and the count value n _t of the timing counter are each set to “0” (step S117), and UL-MAP as assignment information reflecting the change of the assignment area of the MS 20 is transmitted to the MS 20 (Step S118).

  And the control part 15 returns to step S101 (FIG. 4), receives the transmission signal from MS20 after the signal transmission conditions were adjusted again, and repeats the above-mentioned procedure. When each signal characteristic value of the received transmission signal of MS 20 falls within a predetermined numerical range, control unit 15 ends the process in step S112 (FIG. 5).

  The BS 10 configured as described above includes the adjustment command generation unit 15c that generates the adjustment command based on the signal characteristic value detected from the user data signal. Periodic ranging can be performed by transmitting a base adjustment command to the MS 20. Therefore, when the signal transmission condition is adjusted by the MS 20, the adjustment based on the signal characteristic value detected from the user data signal can be performed. As a result, since the signal characteristic value of the user data signal including the user data transmitted by the MS 20 can be suitably adjusted, it is transmitted in a ranging area that is not used for transmitting the user data signal as in the conventional example. Compared with the case where the adjustment is performed indirectly based on the signal characteristic value of the ranging code, the adjustment accuracy of the signal transmission conditions of the MS 20 in the ranging can be increased.

  Further, in the BS 10 of the present embodiment, the BS 10 is configured to detect the signal characteristic value of the user data signal of the MS 20 and transmit the ranging message, so that no collision occurs as described above. . For this reason, ranging can be performed reliably without losing the trigger of ranging.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, for example, when the area changing unit 15e changes the user data area of the MS 20 to another burst area in the uplink subframe, the first uplink burst area ub1 changes to the third uplink burst area ub3. Although the mode of changing is shown as an example, the user data area only needs to be changed to another burst area in the uplink subframe, and the user data area is changed by completely changing the allocation of the entire uplink burst area UB. It can also be changed.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

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 structure of the communication frame of this system. It is a flowchart which shows the procedure of periodic ranging. It is a flowchart which shows the procedure of periodic ranging, and has shown continuously from FIG. It is a schematic diagram which shows the structure of the 1st upstream burst area | region for transmitting a user data signal. It is a figure which shows the procedure of the conventional periodic ranging.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 BS (base station apparatus) 11 Antenna 12 Transmission / reception part 13 Modulation / demodulation part 14 Communication part 15 Control part (communication control part)
15a detection unit 15b determination unit 15c adjustment command generation unit 15d repetition control unit 15e region change unit 20 MS (mobile terminal) 21 antenna 22 communication unit 23 control unit 24 input unit 25 output unit DB downlink burst region UB uplink burst region S slot T tile

Claims (4)

A base station apparatus that performs ranging by transmitting an adjustment command to a mobile terminal to cause the mobile terminal to adjust signal transmission conditions,
A detection unit that detects a signal characteristic value of a user data signal that is a transmission signal including user data among the received transmission signals from the mobile terminal;
A determination unit that determines whether or not the detected signal characteristic value is within a predetermined target range;
When the determination unit determines that the signal characteristic value is outside the target range, an adjustment command generation unit that generates the adjustment command based on the signal characteristic value;
And a communication control unit that transmits the adjustment command generated by the adjustment command generation unit to the mobile terminal. The signal characteristic value includes at least a signal frequency error value and a signal timing error value when the base station apparatus receives the user data signal,
When the determination unit determines that the signal frequency error value or the signal timing error value is out of the target range, to transmit the user data signal in a transmission region for transmitting the transmission signal An area changing unit for changing the allocated user data area to another area in the transmission area;
The base station apparatus according to claim 1, wherein the communication control unit transmits allocation information of the user data area changed to another area to the mobile terminal. Until the signal characteristic value is determined to be within the target range by repeatedly executing the processing by the detection unit, the determination unit, the adjustment command generation unit, and the communication control unit, the signal transmission condition is set to the mobile terminal. It further has a repeat control unit that repeatedly adjusts,
When the processing by each unit is repeatedly executed by the repetitive control unit, the region changing unit determines that at least one of the signal frequency error value and the signal timing error value is out of the target range by the determination unit. The base station apparatus according to claim 2, wherein when it is repeatedly determined that the predetermined number of times is continuous, the user data area is changed to another area in the transmission area. A base station device that transmits an adjustment command;
A mobile terminal that adjusts signal transmission conditions by receiving the adjustment command, and a ranging method in a wireless communication system comprising:
A detection step of detecting a signal characteristic value of a user data signal that is a transmission signal including user data among transmission signals of the mobile terminal received by the base station;
A determination step of determining whether or not the detected signal characteristic value is within a predetermined target range;
When the determination step determines that the signal characteristic value is outside the target range, an adjustment instruction generation step for generating the adjustment instruction based on the signal characteristic value;
A ranging method comprising: a transmission step of transmitting the adjustment command generated in the adjustment command generation step to the mobile terminal.

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