JP5207903B2 - Frequency band allocating apparatus and frequency band allocating method - Google Patents

Description

  The present invention relates to a technical field of radio communication, and more particularly to a frequency band allocation apparatus and a frequency band allocation method in a radio communication system in which a plurality of mobile stations communicate with a base station using a frequency division multiple access (FDMA) system. .

  Hereinafter, a conventional wireless communication system will be described. In the FDMA system, which is one of the multiple access methods between a plurality of mobile stations and one base station, a frequency bandwidth is allocated to each mobile station, and the mobile station can occupy the bandwidth. For example, there is a satellite communication system described in Non-Patent Document 1 below as an example of a wireless communication system employing the FDMA scheme. In this system, a base station and a mobile station communicate using a single carrier having a fixed frequency bandwidth (non-multirate method).

  On the other hand, in the following Patent Document 1, with respect to the system described in Non-Patent Document 1 below, resources (frequency, power of satellite repeater, etc.) prepared in the system are not fully utilized in a situation where the number of simultaneous connections is small. On the contrary, it is pointed out as a problem that the maximum value of the number of simultaneously connected mobile stations decreases when the frequency bandwidth allocated to the mobile station is increased. As a solution to this problem, the following Patent Document 1 describes a method of fairly dividing a system band between mobile stations in consideration of QoS (Quality of Service) request, received CNR, capability of each mobile station, and the like. Disclosure. As a result, when the number of mobile stations is large, the frequency bandwidth allocated to each mobile station is reduced to increase the number of simultaneously connected mobile stations, and conversely when the number of mobile stations is small, the allocated frequency bandwidth is increased to make system resources effective. It is supposed to be used for.

JP 2006-333405 A “Domestic mobile satellite communication system using S band”, ARIB STD-T49 version 3.0, Radio Industry Association, p. 5, p. 10, May 2001

  However, according to the technique of the above-mentioned conventional Patent Document 1, frequency band allocation request and release request from each mobile station, or change in constraint condition of each mobile station (change in received CNR, change in QoS request, etc.) Each time an event occurs, the frequency bandwidth allocated to the mobile station is calculated, and the calculation result is reflected simultaneously on all connected mobile stations. Therefore, in order to realize the technique of the above-mentioned Patent Document 1, a change in the frequency band to be used is notified to a mobile station in which the above-described change event has not occurred, and a control signal is transmitted. Therefore, there is a problem that the radio resource is used and the radio resource is not effectively used.

  In addition, a mobile station in which no change event has occurred may cause a temporary communication disconnection due to the frequency bandwidth switching, and this communication disconnection may adversely affect the operation of the upper application (TCP (Transmission There is a possibility that the Control Protocol) may perform a slow start operation).

  In addition, as the above change event, when the QoS request changes, a change period such as a change in call attributes such as switching between voice and data, a change in the amount of data generated by the application, etc. Some have a relatively short change period. In the latter case, there is a problem that it is necessary to notify each mobile station of a change event, and radio resources are used to transmit the control signal, and radio resources are not effectively used.

  The present invention has been made in view of the above, and obtains a frequency band allocating apparatus and a frequency band allocating method that do not make unnecessary changes to frequency band allocation values and that can effectively use radio resources. For the purpose.

  In order to solve the above-described problems and achieve the object, the present invention provides a frequency band allocating apparatus for allocating a frequency band to a mobile station, from allocation of a frequency band to the mobile station until cancellation of the allocation. Usage rate measuring means for obtaining a usage rate which is a ratio between an uplink allocation time which is a time and a time during which data transmission is performed using a frequency band to which the mobile station is allocated within the uplink allocation time, for each mobile station; Radio resource management means for determining a frequency band allocated to the transmission source mobile station based on a usage rate of a transmission source mobile station that is a transmission source of the request when the frequency allocation request is received, The frequency band is notified to the source mobile station.

  According to this invention, when there is a frequency band allocation request from the mobile station, the radio resource management means determines the frequency bandwidth to be allocated based on the past usage rate for the mobile station. There is an effect that unnecessary switching of bandwidth allocation is not performed and radio resources can be effectively used.

  Hereinafter, embodiments of a frequency band allocating device and a frequency band allocating method according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of a first embodiment of a communication system according to the present invention. The communication system of the present embodiment includes a base station 11, a satellite repeater 12 mounted on a satellite and relaying communication, a plurality of mobile stations 14 existing in a service area 13 which is a service area of the base station 11, Consists of. In the present embodiment, an example in which the base station 11 has a function as a frequency band allocating device according to the present invention will be described.

  The mobile station 14 can change the frequency bandwidth to be transmitted, and the base station 11 communicates with a plurality of mobile stations 14 simultaneously by the FDMA method. Communication between the base station 11 and the mobile station 14 is performed via the satellite repeater 12. A control signal between the base station 11 and the mobile station 14 is transmitted using a control channel, and a data signal is transmitted using a communication channel. The base station 11 controls the transmission signal frequency band of the mobile station 14 by the control signal transmitted through this control channel. Note that the control channel and the communication channel indicate logical divisions and do not necessarily exist on physically independent lines.

  FIG. 2 is a diagram illustrating a functional configuration example of the base station 11 and the mobile station 14 according to the present embodiment. The mobile station 14 of the present embodiment includes a transmission buffer 21, a communication request control unit 22, and a transmitter 23. The base station 11 includes a receiver 24, a usage rate measurement unit 25, a line quality measurement unit 26, and a radio resource management unit 27.

  Next, the operation of the present embodiment will be described. First, the transmission buffer 21 of the mobile station 14 temporarily stores transmission data generated by the mobile station 14 when a communication (data) channel is not allocated to the mobile station 14. The communication request control unit 22 allocates a communication channel to the base station 11 using the control channel when the communication channel is not allocated to the own station and data is stored in the transmission buffer 21. Send the requested signal. Further, the communication request control unit 22 transmits a signal requesting the base station 11 to release the communication channel when the communication channel is no longer necessary.

  The transmitter 23 transmits a signal to the base station 11 via the satellite repeater 12 using the frequency and frequency bandwidth instructed from the base station 11. Further, the receiver 24 of the base station 11 receives a signal transmitted from the mobile station 14 via the satellite repeater 12.

The usage rate measuring unit 25 of the base station 11 takes the time for which resources are allocated for transmission of the uplink signal of the mobile station 14 (uplink resource allocation time) for each communication channel allocated to the mobile station 14. On the other hand, the rate at which actually valid data is transmitted (called usage rate) is measured and reported to the radio resource management unit 27. In this embodiment, the usage rate is defined by the following formula (1).
Usage rate = Sum of actual usage time actually used for data transmission / uplink resource allocation time (1)

  FIG. 3 is a diagram illustrating an example of a relationship between uplink resource allocation time and actual usage time. First, (1) a bandwidth allocation request is transmitted from the mobile station 14, and the base station 11 returns a (2) bandwidth allocation response. The mobile station 14 transmits data at the allocated frequency and frequency bandwidth, and when the data transmission is completed, (3) transmits a bandwidth release request to the base station 11. Then, the base station 11 returns (4) a band release response. Of the uplink allocation time, data transmission is not always performed once, but may be transmitted in two or more intervals with a gap.

  In addition, the communication request control unit 22 of the mobile station 14 activates a band hold timer when data transmission is completed, and waits for the next transmission data to be generated (waits for data to be accumulated in the transmission buffer 21). I will do it. The band hold timer is built in the communication request control unit 22 and times out when a predetermined set time elapses. When the communication request control unit 22 detects a time-out of the bandwidth hold timer, (3) a bandwidth release request is transmitted. The communication request control unit 22 clears the band hold timer when the generation of transmission data is detected before the band hold timer times out (when data is accumulated in the transmission buffer 21).

  The example of FIG. 3 is an example in which the data is transmitted in three times, the first and second data transmissions are performed without interruption, and between the second data transmission and the third data transmission. , There is free time (free time associated with data generation waiting). After the third data transmission, the bandwidth hold timer times out and (3) a bandwidth release request is transmitted.

  In the case of the example of FIG. 3, as shown on the right side of the figure, the uplink resource allocation time at this time includes the free time associated with the propagation delay, the actual usage time, the free time associated with data generation wait, and the free time associated with the hold timer (Time until the bandwidth hold timer times out). Of these, the idle time associated with the hold timer is a fixed time, and the idle time associated with the propagation delay is substantially a fixed time. Therefore, it is the idle time and the actual usage time that are associated with waiting for data that change within the uplink resource allocation time.

  The channel quality measurement unit 26 of the base station 11 measures the channel quality of the communication channel received by the receiver 24 from each mobile station 14 and reports the channel quality to the radio resource management unit. The channel quality may be a received CNR (Carrier vs. Noise Ratio), SIR (Signal to Interference Ratio) or the like, or may be another quantity representing the signal quality.

  Then, the radio resource management unit 27 of the base station 11 receives a request signal for bandwidth allocation request and allocation release request from the mobile station 14. The request signal includes identification information of the mobile station 14 and information indicating the content of a request such as a new allocation request or a release request. When the radio resource management unit 27 receives a bandwidth allocation request signal (band allocation request signal), the radio resource management unit 27 determines a frequency and a frequency bandwidth to be allocated to the transmission source mobile station 14, and transmits the transmission source mobile station. 14 is notified. When an allocation release request signal (allocation release request signal) is received, the resource of the source mobile station 14 is released, and the resource can be allocated to another mobile station 14.

  Hereinafter, the resource allocation operation of the radio resource management unit 27 will be described. Based on the usage rate reported from the usage rate measurement unit 25, the radio resource management unit 27 determines the frequency bandwidth to be allocated next, and sets it as the first upper limit value. FIG. 4 is a diagram illustrating a concept of a method for determining a frequency bandwidth based on the usage rate. Uplink resource allocation times T1, T2, and T3 are times from when the base station 11 allocates the frequency bandwidth to the mobile station A until the allocation is canceled. Allocated frequency bandwidths B1, B2, and B3 indicate frequency bandwidths allocated to the mobile station A. The rectangle in the figure is the time when the mobile station A actually performed transmission in the assigned frequency band. As shown in FIG. 4, the allocated frequency bandwidth B2 of the uplink resource allocation time T2 is determined based on the usage rate for the uplink resource allocation time T1, and the uplink resource allocation time is determined based on the usage rate for the uplink resource allocation time T2. The allocated frequency bandwidth B3 of T3 is determined.

  FIG. 5 is a diagram showing the value of the past usage rate (the usage rate for the uplink resource allocation time before the allocation is performed), its cause, and the operation and effect of the radio resource management unit 27. As described above, the reason why the past usage rate is low is considered that data having a short allocation time (time to transmit using the allocation frequency) is intermittently transmitted, and the past usage rate is high. This may be because data having a long allocation time is continuously transmitted. As an operation of the radio resource management unit 27 of the present embodiment, the allocated bandwidth is reduced when the past usage rate is low. Thereby, the effect that the resource which the mobile station uses can be reduced can be acquired. Further, when the past usage rate is high, the allocated bandwidth is increased. Thereby, the effect that the transmission of the mobile station can be completed in a short time can be obtained.

  FIGS. 6A and 6B are diagrams illustrating the concept of a method for determining an allocated frequency bandwidth based on the usage rate. FIG. 6A shows an example where the past usage rate is high, and FIG. 6-2 shows an example where the past usage rate is low. As shown in FIG. 6A, when the frequency bandwidth is once released and allocation to the same mobile station is performed again, if the past usage rate is high, the frequency bandwidth allocated to the mobile station is increased. As a result, the transmission time required to transmit the same data can be shortened compared to before increasing the allocated frequency bandwidth. The actual use time R indicates the time when the mobile station actually performs transmission, and the shortening time ΔT indicates the shortened transmission time by increasing the allocated frequency bandwidth.

  Also, as shown in FIG. 6B, when the past usage rate is low, the frequency bandwidth allocated to the mobile station is reduced. As a result, it is possible to reduce the radio resources for the mobile station to be allocated compared to before reducing the allocated frequency bandwidth, and it is possible to effectively use the radio resources as a system.

  In addition, as a method of increasing or decreasing, for example, the usage rate and the increase or decrease ratio are defined by a calculation formula or a table and the increase or decrease is made based on the definition. Any method that determines the amount to increase or decrease based on the usage rate, such as defining the amount to decrease with a formula or table, and increasing or decreasing based on that definition. The method may be used.

  When the past usage rate to be referred to cannot be used, such as at the time of the first allocation to the mobile station, a preset initial value is used as the upper limit value of the frequency bandwidth to be allocated. Moreover, although the example which uses the usage rate at the time of the latest allocation was shown as the past usage rate which should be referred in FIG. 4, it is not restricted to this, The average of the usage rate about the past multiple times of uplink resource allocation time A value may be used.

  In addition, the radio resource management unit 27 further sets the second frequency bandwidth to be allocated next based on the past “channel quality” of the uplink data channel from the allocation target mobile station reported from the channel quality measurement unit 26. Determine the upper limit of. The frequency bandwidth that can be allocated to the mobile station depends on conditions such as the communication environment of each mobile station. The frequency bandwidth allocated to the mobile station is limited to the frequency bandwidth when the received CNR measured by the base station 11 on the receiving side matches the required CNR when the mobile station transmits a signal with the maximum transmission power. It becomes. This is because even if a larger frequency bandwidth is allocated to the mobile station, the required CNR cannot be realized at the base station.

  If the past “channel quality” data to be referred to cannot be used, such as at the time of initial allocation to the mobile station, the allocated frequency bandwidth to the mobile station is set to a preset initial value. . The initial value is, for example, the narrowest bandwidth in order to maximize the probability of satisfying the required CNR.

  The “line quality” may be derived based on the uplink quality of other uplink channels (for example, uplink control channel), or the channel quality of the downlink channel (for example, downlink control channel or downlink data channel). It may be used.

  Further, the radio resource management unit 27 further determines a frequency bandwidth to be allocated next based on the “congestion degree”, and sets the frequency bandwidth as a third upper limit value. FIG. 7 is a diagram illustrating an example of the ratio of the free bandwidth and the operation and effect of the present embodiment. Here, the ratio of the free band indicates the ratio of the free band to all the frequency bands that can be used by the base station 11. The radio resource management unit 27 calculates the percentage of free bandwidth.

  As shown in FIG. 7, when the base station 11 receives a request signal for bandwidth allocation, and an event occurs in which the percentage of free bandwidth is low (in the example of FIG. It is conceivable that the number of mobile stations 14 connected (accommodating) to the base station 11 is large and congested. If an event occurs in which the ratio of the free bandwidth is high (in the example of FIG. 7, the specified value is 2% or more), the cause may be that the number of mobile stations 14 connected to the base station 11 is small and free.

  FIG. 8 is a diagram showing the concept of frequency allocation when the accommodation number is small (when the accommodation number is small) and when the accommodation number is large (when the accommodation number is large). When the number of accommodations is small, the number of accommodations can be increased by increasing the assigned frequency bandwidth as shown in the upper part and reducing the assigned frequency bandwidth as shown in the lower part.

  In the present embodiment, the radio resource management unit 27 reduces the frequency bandwidth allocated to the request source mobile station 14 in response to the allocation request when the ratio of the free bandwidth is low. As a result, the vacant frequency band increases, so that the number of mobile stations 14 to be accommodated can be increased. Further, when the ratio of the free bandwidth is low, the radio resource management unit 27 decreases the frequency bandwidth allocated to the requesting mobile station 14 in response to the allocation request. Thereby, high-speed transmission can be realized.

  In the present embodiment, when each of the above events occurs once, the above operation is performed according to the ratio of the free bandwidth. However, the present invention is not limited to this. If it occurs, the above operation may be performed.

  The radio resource management unit 27 determines the smallest frequency bandwidth among the upper limits of the first to third frequency bandwidths obtained as described above as the maximum frequency bandwidth that can be allocated to the mobile station. To do. Then, the radio resource management unit 27 selects an allocatable frequency band that is available at that time, and selects an allocatable band that is less than or equal to the obtained maximum frequency bandwidth, and assigns the allocated frequency band to the mobile station. And

  In the present embodiment, the upper limit values of the first to third frequency bandwidths are obtained, but only one of the first to third or only two upper limit values are obtained. Alternatively, the maximum frequency bandwidth that can be allocated may be determined.

  In this embodiment, the base station 11 and the mobile station 14 communicate with each other via the satellite repeater 12, but the base station 11 and the mobile station 14 perform wireless communication without using the satellite repeater 12. You may make it perform operation | movement of this Embodiment with a communication system.

  Thus, in the present embodiment, when a frequency band allocation request is made from the mobile station 14, the radio resource management unit 27 sets the first frequency bandwidth for the mobile station 14 based on the past usage rate. , The second upper limit value of the frequency bandwidth is determined based on the line quality, the third upper limit value of the frequency bandwidth is determined based on the ratio of the free frequency band, and the first to third 3 The frequency bandwidth allocated to the mobile station 14 is determined based on one frequency bandwidth. For this reason, it is not necessary to notify the mobile station 14 to which the frequency band allocation request has not been transmitted of the band change, and unnecessary control signals can be reduced.

  In addition, since the base station 11 can detect a change in the amount of data to be transmitted, such as when an application used by the mobile station 14 is changed, the change is notified from the mobile station 14. There is no need. Therefore, unnecessary control signals can be reduced and appropriate frequency allocation can be performed, and system resources can be effectively utilized.

Embodiment 2. FIG.
Next, the frequency band allocation method according to the second embodiment of the present invention will be described. The configuration of the communication system, terminal, and base station of the present embodiment is the same as that of the first embodiment. In the first embodiment, the upper limit value of the frequency band to be allocated is always determined based on the past “usage rate” (except when referring to the initial value), but there may be cases where this method is not optimal.

  FIG. 9 is a diagram illustrating an example of a case where the method of determining the upper limit value of the frequency bandwidth to be allocated based on the past “usage rate” is not optimal. First, the initial allocation is data with a low usage rate (for example, signaling data for call setting), and the second allocation reflects the usage rate of the initial allocation, so the allocated frequency bandwidth is reduced and the frequency bandwidth is low. Suppose that it can only be assigned. However, it is assumed that a large amount of data (for example, file upload) is actually transmitted in the second allocation in spite of such allocation. In this case, since only a small frequency bandwidth is allocated, the data transmission time may become long. In such a case, an appropriate frequency bandwidth is finally allocated by the third allocation.

  In order to deal with such a problem, when determining the second allocated bandwidth for the mobile station, the usage rate for the first allocation is not considered. That is, in the case of the first frequency allocation for each mobile station, the usage rate related to the communication performed based on the first allocation is not considered, and in the second allocation, the first upper limit value is excluded from consideration. A frequency bandwidth allocated to the mobile station is determined based on the second upper limit value. Then, from the third allocation, the first upper limit value of the frequency bandwidth is determined based on the usage rate. By doing so, it is possible to prevent an insufficient frequency bandwidth from being allocated in the second allocation, and to shorten the transmission time of user data. From the third allocation, the operation is as described in the first embodiment. The operation of the present embodiment other than the operation described above is the same as that of the first embodiment.

  In the above description, only the initial allocation is not considered, but the first upper limit value is determined based on the usage rate from the allocation after the specified predetermined number of times based on the traffic characteristics.

  As described above, in the present embodiment, it is possible to specify the number of allocations for starting the calculation of the first upper limit value based on the usage rate. For this reason, in addition to the effects of the first embodiment, it is possible to perform appropriate band allocation corresponding to the traffic characteristics.

Embodiment 3 FIG.
Next, the frequency band allocation method according to the third embodiment of the present invention will be described. The configuration of the communication system, terminal, and base station of the present embodiment is the same as that of the first embodiment. In the first embodiment, the upper limit value of the frequency band to be allocated is always determined based on the channel quality (except when referring to the initial value), but the channel quality at a time away from each other with little correlation is referred to. It may not be appropriate to do. In the first embodiment, the channel quality to be referred to uses the result measured when the previous allocation was performed to the allocation target mobile station.

  Therefore, in the present embodiment, the frequency bandwidth based on the channel quality is used only when the time difference between the most recently measured channel quality measurement time (time when the previous allocation was performed) and the current time is less than a predetermined threshold. The second upper limit value is obtained. When the time difference is equal to or greater than the threshold value, an initial value set in advance as the second upper limit value of the frequency bandwidth is used.

  FIG. 10 is a diagram illustrating an example of the relationship between the line quality measurement time and the frequency band allocation. Frequency allocation times 31 to 34 in the figure are times during which frequency allocation is performed for a certain mobile station (from when the base station 11 allocates a frequency band to when an allocation release request is received from the mobile station). Since the time interval between the frequency allocation time 31 and the frequency allocation time 32 and between the frequency allocation time 32 and the frequency allocation time 33 is not long (less than the threshold value), it is based on the line quality at the time of the previous allocation. A second upper limit value is obtained. In addition, regarding the allocation of the frequency allocation time 34, since the time interval with the previous allocation (frequency allocation time 33) is long (more than the threshold value), the second upper limit value is set as an initial value.

  As described above, in this embodiment, when the time difference from the previous allocation is larger than the threshold value, the line quality is not referred to, and the second upper limit value is set to the initial value. For this reason, it is possible to avoid referring to past line quality that is almost unrelated to the current line quality state, and to reduce the risk of determining an erroneous upper limit value of the frequency bandwidth.

  In general, a “call” is set between a mobile station and a network, and bandwidth allocation is performed multiple times within the call. However, the line quality is limited for allocation within a single “call”. Reference may be made, and the line quality information at the time of frequency band allocation for different calls before that call may not be referred to.

Embodiment 4 FIG.
Next, the frequency band allocation method according to the fourth embodiment of the present invention will be described. The configuration of the communication system, terminal, and base station of the present embodiment is the same as that of the first embodiment.

  In the present embodiment, when the traffic characteristics transmitted by the mobile station using the uplink communication channel are given in advance as a static QoS request, the frequency bandwidth based on the usage rate shown in the first embodiment The first upper limit value is not calculated, and the first upper limit value of the frequency bandwidth is determined based on a given static QoS request.

  FIG. 11 is a diagram illustrating an example of an operation when file download or file upload is requested as a static QoS request. As shown in FIG. 11, in the case of file download, traffic is discretely distributed in the upstream direction to the extent of delivery confirmation. In the case of file upload, the traffic is large-capacity continuous traffic in the upward direction.

  Therefore, in the present embodiment, the radio resource management unit 27 sets the allocated frequency bandwidth to a small value in the case of file download. As a result, the number of accommodated mobile stations can be increased or the data transmission speed of other users can be increased. In addition, in the case of file upload, the radio resource management unit 27 sets the allocated frequency bandwidth to a predetermined large value. Thereby, high-speed file upload becomes possible. These small and large values are set in advance.

  Information indicating events such as file upload and file download may be included in, for example, a frequency band allocation request or transmission data transmitted from the mobile station, or may be set by other means separately. Good. Further, it may be possible to switch between the determination of the first upper limit value based on the static QoS request and the determination of the first upper limit value of the first embodiment. Other operations of the present embodiment are the same as those of the first embodiment.

  As described above, in the present embodiment, when a static QoS request is given in advance, the first upper limit value of the frequency bandwidth is obtained based on the static QoS request. Thereby, in addition to the effects of the first embodiment, it is possible to perform bandwidth allocation that matches a given QoS request.

Embodiment 5 FIG.
Next, the base station and frequency band allocation method according to the fifth embodiment of the present invention will be described. The configuration of the communication system and the configuration of mobile station 14 in the present embodiment are the same as those in the first embodiment. The description of the same parts as those in Embodiment 1 is omitted. In the first embodiment, all the three items of “usage rate”, “line quality”, and “free bandwidth ratio” are considered, and the upper limit values of the first to third frequency bandwidths are obtained. In the present embodiment, only one of the first to third or any two upper limit values may be obtained and determined as the maximum frequency bandwidth that can be allocated.

  For example, when it is assumed that the usage rate is low when flowing traffic in which data having a short usage time such as TCP delivery confirmation traffic is intermittently transmitted, the first upper limit value using the usage rate is not necessary. Need not be considered as a restriction on frequency bandwidth determination. Further, if the system design is guaranteed to satisfy the required CNR in any frequency bandwidth in the entire service area, the second upper limit value based on “line quality” is considered as a restriction for bandwidth determination. There is no need. If the number of mobile stations requiring connection does not need to be increased even if the number of mobile stations that require connection is increased, the third upper limit value based on the percentage of free bandwidth is considered as a restriction on frequency bandwidth determination. do not have to.

  The base station of this Embodiment becomes a structure which abbreviate | omitted the function regarding the item which is not made into a restriction | limiting matter from the base station 11 of Embodiment 1 as mentioned above. For example, when the first upper limit value based on “usage rate” is not used, the usage rate measurement unit 25 is not necessary, and when the second upper limit value based on “line quality” is not used, the channel quality measurement unit. 26 is not necessary, and when the third upper limit value based on the “ratio of free bandwidth” is not used, the radio resource management unit 27 does not need to obtain the rate of free bandwidth. The operation and configuration of the present embodiment other than those described above are the same as those of the first embodiment.

  In the present embodiment, the case of using any one of the first to third or the two upper limit values of the first embodiment has been described. However, the present invention is not limited to this, and the second, third, and third embodiments are described. Alternatively, in the case of 4, any one of the first to third, or any two upper limit values may be used.

  Thus, in the present embodiment, only necessary items are reflected in the upper limit value according to the system. For this reason, the effects of the first embodiment can be realized, and unnecessary processes and components can be reduced.

  As described above, the frequency band allocating device and the frequency band allocating method according to the present invention are useful for a radio communication system, and particularly for a radio communication system in which a plurality of mobile stations communicate with a base station using a frequency division multiple access scheme. Is suitable.

It is a figure which shows the structural example of Embodiment 1 of the communication system concerning this invention. 3 is a diagram illustrating a functional configuration example of a base station and a mobile station according to Embodiment 1. FIG. It is a figure which shows an example of the relationship between uplink resource allocation time and real use time. It is a figure which shows the concept of the determination method of the frequency bandwidth based on a utilization rate. It is a figure which shows the value of the past usage rate, its cause, and the operation | movement and effect of a radio | wireless resource management part. It is a figure which shows the concept of the determination method of the allocation frequency bandwidth based on a utilization rate. It is a figure which shows the concept of the determination method of the allocation frequency bandwidth based on a utilization rate. It is a figure which shows an example of the ratio and the operation | movement of 1st Embodiment, and an effect. It is a figure which shows the concept of the frequency allocation in the case of a small accommodation number, and the case of a large accommodation number. It is a figure which shows an example when the method of determining the upper limit of the frequency bandwidth allocated based on the past "usage rate" is not optimal. It is a figure which shows an example of the relationship between the measurement time of channel quality, and frequency band allocation. It is a figure which shows an example of operation | movement when file download or file upload is requested | required as a static QoS request | requirement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Base station 12 Satellite repeater 13 Service area 14 Mobile station 21 Transmission buffer 22 Communication request control part 23 Transmitter 24 Receiver 25 Usage rate measurement part 26 Channel quality measurement part 27 Radio | wireless resource management part T1, T2, T3 Uplink resource allocation Time B1, B2, B3 Allocated frequency bandwidth R Actual use time ΔT Reduction time 31-34 Frequency allocation time

Claims (9)

A frequency band allocation device that allocates a frequency band to a mobile station,
An uplink allocation time, which is a time from when a frequency band is allocated to the mobile station, to the cancellation of the allocation, and a time when data transmission is performed using the frequency band to which the mobile station is allocated within the uplink allocation time A usage rate measuring means for obtaining a usage rate as a ratio for each mobile station;
Radio resource management means for determining an allocated frequency band to the source mobile station based on a usage rate of a source mobile station that is a source of the request when a frequency allocation request is received;
With
A frequency band allocating apparatus that notifies the transmission source mobile station of the allocated frequency band. Reception quality measuring means for measuring reception quality of a signal received from the mobile station;
Further comprising
The frequency band allocating apparatus according to claim 1, wherein the radio resource management unit further determines an allocated frequency band to the source mobile station based on reception quality.   3. The radio resource management means obtains a ratio of free bands to all frequency bands that can be allocated, and further determines an allocated frequency band for the source mobile station based on the ratio. The frequency band allocating device described in 1.   The frequency band allocation apparatus according to claim 1, 2 or 3, wherein the radio resource management means uses the usage rate as a usage rate related to an uplink allocation time nearest to the transmission source mobile station.   4. The radio resource management unit according to claim 1, wherein the radio resource management unit sets the usage rate to an average value of a predetermined number of usage rates of transmission source mobile stations obtained by the usage rate measurement unit. Frequency band allocation device.   The radio resource management means counts the number of allocations to the transmission source mobile station, and determines an allocation frequency band to the transmission source mobile station based on the usage rate when the number of allocations is a predetermined number or more. The frequency band allocating device according to claim 1, 2, or 3. When traffic characteristics are known for each type of QoS request, the method of increasing / decreasing the allocated frequency band is stored as static QoS information in association with the type of QoS request,
The radio resource management means further extracts a QoS request type from data transmitted from the mobile station, and an allocation frequency band increase / decrease method corresponding to the extracted QoS request type is included in the static QoS information. The frequency band allocating device according to any one of claims 1 to 6, wherein an allocated frequency band to the transmission source mobile station is determined based on an increase / decrease method. And the reception time of the request, if the difference between the measurement time of the reception quality is within a predetermined time interval, to claim 2 for determining the allocated frequency bands to the transmission source mobile station based on the reception quality The frequency band allocating device described. A frequency band allocation method for allocating a frequency band to a mobile station,
An uplink allocation time, which is a time from when a frequency band is allocated to the mobile station, to the cancellation of the allocation, and a time when data transmission is performed using the frequency band to which the mobile station is allocated within the uplink allocation time A usage rate measuring step for obtaining a usage rate as a ratio for each mobile station;
A radio resource management step of determining an allocated frequency band to the transmission source mobile station based on the usage rate of the transmission source mobile station that is a transmission source of the request when a frequency allocation request is received;
A notification step of notifying the transmission source mobile station of the allocated frequency band;
A frequency band allocating method comprising:

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