JP6081871B2 - Transition control apparatus and method - Google Patents

Description

  The present invention relates to a transition control apparatus and method.

  2. Description of the Related Art Conventionally, in a wireless communication field, a technique for determining a connection destination of a wireless terminal according to the quality of the wireless signal (whether the radio wave is strong or weak) has been provided for the wireless terminal that autonomously determines the wireless connection destination. Yes. For example, in an area where a high frequency band and a relatively low frequency band are set by the base station, it is determined which band the terminal connects to based on the radio field intensity from the base station. In such a technique, Patent Literature 1 and Patent Literature 2 that realize load distribution of a base station to which a terminal is connected are known.

  Patent Document 1 provides a technique for reducing the possibility of a mobile terminal entry being removed during or after a handover in a handover for distributing the load between base stations. In Patent Literature 1, when a load of a first frequency, which is one of a plurality of allocated frequencies, satisfies a predetermined load condition, the base station uses a carrier wave of each mobile terminal connected at the first frequency. Measure the interference to noise ratio. Then, the base station causes the mobile terminal selected from the mobile terminals connected at the first frequency based on the carrier-to-interference noise ratio to perform handover to the second frequency different from the first frequency.

  Patent Document 2 provides a wireless communication system that takes into account the load of each cell and the interference between cells. The wireless communication system of Patent Literature 2 adjusts parameters for interference reduction scheduling and handover promotion processing based on mutual load information in a handover candidate base station and a handover source base station. Then, when the handover candidate base station for load distribution is a cell having a large cell radius, adjustment for performing transmission power control and frequency scheduling is performed in consideration of the load state of the cell edge. Further, when the handover source base station is a cell having a small radius, both interference control and load distribution are achieved by adjusting the number of terminals to be handed over in consideration of the load status of the handover candidate base station.

JP 2012-15838 A JP 2011-216936 A

The techniques in Patent Document 1 and Patent Document 2 realize load distribution of the connected base stations by adjusting the transmission power of the base station or the terminal.
However, none of these techniques is a technique for controlling the transition to the band used by the wireless terminal and distributing the load of the base stations having a plurality of bands.
For example, when the base station provides a band of 2 GHz and a band of 800 MHz, the wireless terminal is basically an 800 MHz band which is easily diffracted and easily diffracted (good S / N ratio). Tend to choose. As a result, in the conventional technique, the 800 MHz band is easily crowded, and the load on the base station cannot be distributed.

  The present invention relates to a transition control apparatus and method for controlling a transition probability of a wireless terminal so as to quickly equalize a band usage rate of a congested band and a band usage rate of a quiet band among bands used by the wireless terminal. The purpose is to provide.

As described above, the 800 MHz band (hereinafter referred to as band 800M) is more crowded than the 1.5 GHz band (hereinafter referred to as band 1.5G) and the 2 GHz band (hereinafter referred to as band 2G). This state can be considered that there is a natural inflow of wireless terminals only in the band 1.5G or the band 2G to the band 800M. Therefore, consider setting such control that pushes back the inflow from the band 800M to the band 1.5G or the band 2G. The algorithm of the present invention can quickly calculate this set value.
Specifically, the following solutions are provided.

  (1) A transition control device that controls transition of a wireless terminal that transitions based on a transition probability for transitioning from one band to another band among a plurality of bands of a base station, Usage rate acquisition means for acquiring each band usage rate, and a congested sector detection means for detecting, as a congested sector, a band having the highest bandwidth usage rate acquired by the usage rate acquisition means among the plurality of bands, Among the plurality of bands, a quiet sector detection unit that detects a band having the lowest band usage rate acquired by the usage rate acquisition unit as a quiet sector, and a band of the crowded sector detected by the congestion sector detection unit Target calculation means for calculating a target usage rate based on the usage rate and the band usage rate of the quiet sector detected by the quiet sector detection means; Based on a target difference which is a difference between a transition probability distribution means for distributing a transition probability to the wireless terminal, a band usage rate of the crowded sector, and the target usage rate calculated by the target calculation means, the congestion sector Initial value setting means for calculating the initial value of the transition probability to the quiet sector and distributing the calculated initial value to the congested sector by the transition probability distribution means, and the initial value is set by the initial value setting means. After the distribution, the target usage rate is calculated by the target calculation means at every elapse of a predetermined period, and the bandwidth usage rate of the congested sector is determined based on the change in the bandwidth usage rate of the congested sector. A transition control device comprising: control means for controlling the rate so as to be a rate.

  According to the configuration of (1), the transition control device according to (1) is a wireless terminal that transitions based on a transition probability for transitioning from one band to another band among a plurality of bands of the base station. A transition control device that controls transitions, acquires each band usage rate in a plurality of bands, and sets a band having the lowest band usage rate as a congested sector among a plurality of bands. Detect as a loose sector. Then, the transition control device calculates a target usage rate based on the detected bandwidth usage rate of the congested sector and the detected bandwidth usage rate of the quiet sector, and sets a target of the bandwidth usage rate of the congested sector and the target usage rate. Based on the difference, calculate the initial value of the transition probability from the congested sector to the light sector, distribute the calculated initial value to the wireless terminals of the congested sector, and after the initial value is distributed, The target usage rate is calculated, and control is performed so that the bandwidth usage rate of the congested sector becomes the target usage rate based on the change in the bandwidth usage rate of the congested sector.

That is, the transition control device according to (1) calculates a target usage rate based on a bandwidth usage rate of a congested sector detected from a plurality of bands and a bandwidth usage rate of a quiet sector, and calculates the calculated target usage rate and the congestion sector. After calculating the initial value of the transition probability based on the target difference from the band usage rate of, and distributing the calculated initial value to the wireless terminals in the congested sector, the target usage rate is calculated every certain period of time, Based on the change in the band usage rate of the congested sector, control is performed so that the band usage rate of the congested sector becomes the target usage rate.
Therefore, the transition control device according to (1) can quickly equalize the band usage rate of a congested band and the band usage rate of a quiet band among the bands used by the wireless terminal.

  (2) The control unit determines whether or not the target difference is smaller than a threshold, a band usage rate before the transition probability is distributed, and a band usage after the transition probability is distributed. An expected value calculation means for calculating an expected value of the transition probability for causing the bandwidth usage rate of the congested sector to be the target usage rate based on the rate of change of the bandwidth usage rate calculated from the rate. The control means distributes the predicted value calculated by the predicted value calculation means to the congested sector by the transition probability distribution means, and the target difference is determined by the determination means after elapse of the predetermined period. The calculation of the predicted value by the predicted value calculation unit and the distribution of the calculated predicted value by the transition probability distribution unit are repeated until it is determined that the value is smaller than a threshold value. Transfer control device.

  According to the configuration of (2), the transition control device according to (2) determines whether or not the target difference is greater than or equal to the threshold, and if it is determined that the target difference is greater than or equal to the threshold, before the transition probability is distributed Based on the change rate of the bandwidth usage rate calculated from the bandwidth usage rate and the bandwidth usage rate after the transition probability is distributed, the transition to make the bandwidth usage rate of the congested sector become the target usage rate Calculate the predicted value of the probability, distribute the calculated predicted value to the congested sector, and calculate the predicted value and distribute the calculated predicted value until it is determined that the target difference is smaller than the threshold after a certain period of time. repeat.

  Therefore, the transition control device according to (2) can level the band usage rate of a congested band and the band usage rate of a quiet band more quickly among the bands used by the wireless terminal.

  (3) The control means performs the detection of the congested sector by the congested sector detection means and the detection of the non-congested sector by the non-congested sector detection means every time a predetermined period elapses, and the detected congested sector The transition control device according to (1) or (2), wherein the bandwidth usage rate is controlled so as to become the target usage rate.

  Therefore, the transition control device according to (3) quickly equalizes the band usage rate of the congested band and the band usage rate of the quiet band among the bands used by the wireless terminal, and uses each band of the plurality of bands. The rate can be leveled.

  (4) The transition control method executed by the transition control device according to (1), wherein the usage rate acquisition unit acquires a bandwidth usage rate of each of the plurality of bandwidths, and the congestion A sector detecting unit detects a band having the highest band usage rate acquired by the usage rate acquiring step among the plurality of bands as a congested sector, and the quiet sector detecting unit includes the plurality of bands. Among the bands, the quiet sector detecting step for detecting the band with the lowest band usage rate acquired by the usage rate acquiring step as a quiet sector, and the target calculating means, the target calculating means is detected by the congestion sector detecting step Based on the bandwidth usage rate of the busy sector and the bandwidth usage rate of the quiet sector detected by the quiet sector detection step. A target calculation step for calculating a target usage rate, and the initial value setting means, based on a target difference that is a difference between a bandwidth usage rate of the congested sector and the target usage rate calculated by the target calculation step. An initial value setting step of calculating an initial value of the transition probability from the crowded sector to the light sector, and distributing the calculated initial value to the crowded sector by the transition probability distribution unit; and After the initial value of the transition probability is distributed in the initial value setting step, the target calculation step is performed by the target calculation means every time a fixed period elapses, and the congestion is determined based on a change in the bandwidth usage rate of the congested sector. And a control step of controlling the bandwidth usage rate of the sector to be the target usage rate.

  Therefore, the transition control method according to (4), as in (1), quickly equalizes the band usage rate of the congested band and the band usage rate of the quiet band among the bands used by the wireless terminals. Can do.

  According to the present invention, it is possible to quickly equalize a band usage rate of a band that is congested among bands used by a wireless terminal and a band usage rate of a quiet band. Further, according to the present invention, even for three or more bands, by repeating the leveling of the band usage rate of the crowded band detected from among those bands and the band usage rate of the quiet band, The bandwidth usage rate of each of the three or more bandwidths can be leveled.

It is a figure for demonstrating a crowded sector and a quiet sector in this invention. It is a figure for demonstrating the transition of the radio | wireless terminal in this invention. It is a figure which shows the structure of the transition control apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the processing content of the transition control apparatus which concerns on Embodiment 1 of this invention. It is a figure for demonstrating the example of the calculation process of the expected value which the transition control apparatus which concerns on Embodiment 1 of this invention calculates. It is a figure which shows the example of the computer simulation result of control by the transition control apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows the processing content of the transition control apparatus which concerns on Embodiment 2 of this invention.

[Embodiment 1]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining a congested sector and a light sector in the present invention.
As shown in FIG. 1, the transition includes a transition controlled by the transition probability and a transition autonomously (natural inflow / outflow). The quiet sector is a band in which the wireless terminal 50 has flowed out to another sector due to autonomous transition, and the band usage rate is the lowest among a plurality of bands of the base station. The congested sector is a band in which the wireless terminal 50 has flowed in from other sectors due to autonomous transition and has the highest band usage rate among a plurality of bands of the base station.
The transition control device 10 controls the transition probability in the congested sector, thereby transitioning the transition terminal from the congested sector to the light sector, and leveling the congested sector and the light sector.

FIG. 2 is a diagram for explaining the transition of the wireless terminal 50 in the present invention.
The transition terminal among the radio terminals 50 refers to a terminal that can transition from one band to another band among a plurality of bands of the same base station. That is, the transition terminal transitions from one band to another band by a transition based on the transition probability R or a transition based on the natural outflow probability r. Insensitive terminals among wireless terminals 50 are terminals that remain in the same sector.
As shown in FIG. 2, the probability that the wireless terminal 50 will remain in the sector 1 after a certain period of time is 1-R1-r1, and the bandwidth usage rate by the wireless terminal 50 in the sector 1 is the same as that of the transition terminal that has flowed in. This is the sum of the bandwidth usage rate 101 by the transition terminal and the bandwidth usage rate 102 by the dead terminal. Similarly, the probability that the wireless terminal 50 remains in the sector 2 is 1-R2-r2, and the bandwidth usage rate by the wireless terminal 50 in the sector 2 is the bandwidth usage rate 201 by the transition terminal that has flowed in and the transition terminal that has remained. And the bandwidth usage rate 202 by the insensitive terminal.

FIG. 3 is a diagram illustrating a configuration of the transition control device 10 according to an embodiment of the present invention.
The wireless terminal 50 makes a transition based on a transition probability for making a transition from one band to another among a plurality of bands of the base station. The transition control device 10 includes a usage rate acquisition unit 11, a crowded sector detection unit 12, a quiet sector detection unit 13, a target calculation unit 14, an initial value setting unit 15, an expected value calculation unit 16, and a transition probability distribution. Means 17, determination means 18, and control means 19 are provided, and the transition of the wireless terminal 50 is controlled. Hereinafter, each means will be described in detail.

  The usage rate acquisition means 11 acquires each bandwidth usage rate in a plurality of bandwidths. Specifically, the usage rate acquisition unit 11 receives, for example, the bandwidth usage rate of the bandwidth 2G, the bandwidth usage rate of the bandwidth 1.5G, and the bandwidth usage rate of the bandwidth 800M from the base station having a plurality of bandwidths. To do. The bandwidth usage rate may be anything as long as the load state for each bandwidth is measured. For example, it may be the number of terminals used with respect to the number of terminals that can be accommodated, and may be a resource block usage rate in LTE (Long Term Evolution).

  The congestion sector detection unit 12 detects a band having the highest band usage rate acquired by the usage rate acquisition unit 11 as a congestion sector among a plurality of bands. Specifically, the congested sector detecting means 12 compares the band usage rate of each band with respect to a plurality of bands, detects a band with the highest band usage rate, and regards the detected band as a congested sector.

  The loose sector detection means 13 detects a band having the lowest bandwidth usage rate acquired by the usage rate acquisition means 11 as a quiet sector among a plurality of bandwidths. Specifically, the quiet sector detection means 13 compares the band usage rates of the respective bands with respect to a plurality of bands, detects a band with the lowest band usage rate, and regards the detected band as a quiet sector.

  The target calculation unit 14 calculates the target usage rate based on the bandwidth usage rate of the congested sector detected by the congestion sector detection unit 12 and the bandwidth usage rate of the light sector detected by the light sector detection unit 13. Specifically, the target calculation unit 14 calculates, for example, an average value of the band usage rate of the congested sector and the band usage rate of the quiet sector as the target usage rate.

  The transition probability distribution unit 17 distributes the transition probability to the wireless terminal 50. Specifically, the transition probability distribution unit 17 transmits the transition probability to the wireless terminal 50 using each band. The transition probability distribution unit 17 may transmit the transition probability from one band to another for each band to the wireless terminal 50, and the wireless terminal 50 determines all transition probabilities from one band to another for each band. May be sent to.

  The initial value setting means 15 determines the initial value of the transition probability from the congested sector to the light sector based on the target difference that is the difference between the band usage rate of the congested sector and the target usage rate calculated by the target calculating means 14. The calculated initial value is distributed to the congested sector by the transition probability distribution means 17. Specifically, the initial value setting means 15 calculates, for example, a predetermined ratio of the target difference as an initial value of the transition probability based on the target difference between the bandwidth usage rate of the busy sector and the target usage rate. The initial value is transmitted to the radio terminal 50 of the congested sector as a transition probability from the congested sector to the light sector.

  After the initial value is distributed by the initial value setting unit 15, the control unit 19 calculates the target usage rate every time a fixed period elapses, and based on the change in the bandwidth usage rate of the congested sector, the bandwidth of the congested sector Control the usage rate so that it reaches the target usage rate.

Further, the control unit 19 includes a determination unit 18 and an expected value calculation unit 16.
The judging means 18 judges whether or not the target difference is smaller than a threshold value. Specifically, the determination unit 18 calculates a target difference that is the difference between the band usage rate of the busy sector and the target usage rate, and determines whether the calculated target difference is smaller than a threshold value.

  The expected value calculation means 16 calculates the bandwidth of the congested sector based on the change rate of the bandwidth usage rate calculated from the bandwidth usage rate before the transition probability is distributed and the bandwidth usage rate after the transition probability is distributed. The expected value of the transition probability is calculated so that the usage rate becomes the target usage rate. Specifically, the predicted value calculation means 16 calculates the change rate of the bandwidth usage rate from the bandwidth usage rate before the transition probability is distributed and the bandwidth usage rate after the transition probability is distributed, for example, the transition probability. Calculated as a change in bandwidth utilization with respect to the change. Next, the predicted value calculation means 16 predicts transition probabilities based on the calculated rate of change, for example, so that the band usage rate of the congested sector becomes the target usage rate, as shown in FIG. Calculate the value.

  The control unit 19 distributes the predicted value calculated by the predicted value calculation unit 16 to the congested sector by the transition probability distribution unit 17, and calculates the target usage rate by the target calculation unit 14 every time a certain period of time elapses. Until the determination means 18 determines that the target difference is smaller than the threshold value, the calculation by the predicted value calculation means 16 and the distribution by the transition probability distribution means 17 of the calculated predicted value are repeated. Specifically, the control means 19 distributes the calculated expected value to the radio terminals 50 in the congested sector, calculates the target usage rate every time a fixed period elapses, and uses the bandwidth usage rate and the target usage rate in the congested sector. Until it is determined that the target difference, which is the difference with the rate, is smaller than the threshold, for example, as shown in FIG. 5 described later, calculation of the predicted value and distribution of the calculated predicted value are repeated.

  For example, when the band 800M is detected as a congested sector and the band 2G is detected as a quiet sector, the band usage rate of the band 800M as a congested sector is higher than the band usage rate of the band 2G as a congested sector due to the distribution of transition probabilities. Even if it becomes smaller, the control means 19 calculates and distributes the transition probability from the band 800M to the band 2G (transition probability smaller than the previous time).

If the bandwidth usage rate of the band regarded as the congested sector does not change as expected even after the distribution of the transition probability, the control means 19 does not flow into the congested sector as expected (for example, And the control is returned to the initial state.
The band usage rate does not change as expected when the bandwidth usage rate hardly changes even though the transition probability is distributed (in this case, the calculated expected value becomes a negative value or exceeds a predetermined value) The bandwidth usage rate increases without decreasing even though the transition probability is increased (consecutively n times), or the bandwidth usage rate is reduced despite the transition probability being decreased. If it decreases without increasing (continuous n times), the bandwidth usage rate of the congested sector decreases more than expected and falls far below the target usage rate (eg, 50%) and exceeds the predetermined bandwidth usage rate (eg, 30%). When it gets smaller, etc. In such a case, the control means 19 may perform detection of a congested sector and a light sector again and return the control to the initial state.

  FIG. 4 is a flowchart showing the processing contents of the transition control apparatus 10 according to the first embodiment of the present invention. The transition control device 10 is configured by hardware included in a computer and its peripheral devices, and software that controls the hardware, and the following processing is processing that is executed by a control unit (for example, CPU) according to predetermined software.

  In step S <b> 101, the CPU (usage rate acquisition unit 11, crowded sector detection unit 12, and loose sector detection unit 13) detects a crowded sector and a quiet sector. More specifically, the CPU compares the band usage rate of each band acquired from the base station with respect to a plurality of bands, detects the band with the highest band usage rate as a congested sector, and has the highest bandwidth usage rate. A low band is detected as a quiet sector and stored.

  In step S102, the CPU (the usage rate acquisition unit 11 and the target calculation unit 14) acquires the bandwidth usage rate of the congested sector and the bandwidth usage rate of the quiet sector, stores them in chronological order, and calculates the target usage rate. To do. More specifically, the CPU acquires the bandwidth usage rate of the congested sector and the bandwidth usage rate of the quiet sector among the bandwidth usage rates of each band acquired from the base station, and sets the target usage rate as, for example, the congestion sector. The average value of the bandwidth usage rate of the current sector and the bandwidth usage rate of the quiet sector is calculated.

  In step S103, the CPU (control unit 19) determines whether the band usage rate of the congested sector is within the target usage rate range. That is, the CPU determines whether or not the difference between the acquired band usage rate of the congested sector and the target usage rate is within a threshold value. If this determination is YES, the CPU ends the process, and if this determination is NO, the CPU moves the process to step S104.

  In step S104, the CPU (control unit 19) determines whether or not the control is the first time. If this determination is YES, the CPU moves the process to step S105, and if this determination is NO, the CPU moves the process to step S106.

  In step S105, the CPU (initial value setting means 15) distributes the initial value of the transition probability to the wireless terminals 50 in the congested sector. More specifically, the CPU calculates an initial value of the transition probability based on the difference between the band usage rate of the busy sector and the target usage rate, and transmits the initial value to the radio terminal 50 of the busy sector. The CPU stores the band usage rate and the congestion sector band before transmitting the transition probability. Thereafter, the CPU moves the process to step S111.

In step S <b> 106, the CPU (usage rate acquisition unit 11) corrects the previous band usage rate based on the change in the sum of the congested sector and the light sector. More specifically, the CPU uses the previous bandwidth usage rates (referred to as Rc_old and Rq_old, respectively) of the congested sector and the light sector, and the current bandwidth usage rates (referred to as Rc_new and Rq_new, respectively) of the busy sector and the light sector. The previous band usage rate of the congested sector is corrected on the basis of the change.
That is, S = (Rc_new + Rq_new) / (Rc_old + Rq_old) is obtained, Rc_old = S * Rc_old after correction is calculated, and the band utilization rate of the previous congestion sector is corrected.

  In step S107, the CPU (expected value calculation means 16) calculates the change rate of the band usage rate of the congested sector. More specifically, the CPU obtains the rate of change of the bandwidth usage rate from the bandwidth usage rate acquired and stored last time and corrected in step S106 and the bandwidth usage rate acquired this time. For example, it is calculated as a change in bandwidth usage rate with respect to a change in transition probability.

  In step S108, the CPU (expected value calculation means 16) calculates the expected value of the transition probability. More specifically, based on the calculated change rate, the CPU, for example, as shown in FIG. 5 to be described later, the current coordinate point (previous transition probability specified this time, band usage rate of the congested sector acquired this time) and , Calculate the rate of change in bandwidth usage from the previous coordinate point (transition probability specified last time, bandwidth usage rate of the congested sector acquired last time), and use the calculated rate of change as the slope. The transition probability when the straight line passing through the coordinate point becomes the target usage rate is calculated as an expected value. When there is no previous transition probability (for example, in the case of the second control), the previous transition probability is set to 0.0.

  In step S109, the CPU (control unit 19) determines whether or not the predicted value is out of the range. More specifically, the CPU determines whether or not the calculated predicted value is a negative value, and whether or not the calculated predicted value is a predetermined value or more. Furthermore, even if the CPU distributes the transition probability n times consecutively, whether or not the bandwidth usage rate of the congested sector has increased without decreasing, the transition probability is decreased n times continuously. Even if it is distributed, it is determined whether the bandwidth usage rate of the congested sector is decreasing without increasing, and whether the bandwidth usage rate of the congested sector is smaller than a predetermined bandwidth usage rate. If this determination is YES, the CPU moves the process to step S112, and if this determination is NO, the CPU moves the process to step S110.

  In step S110, the CPU (transition probability distribution means 17) distributes the expected value of the transition probability to the wireless terminals 50 in the congested sector. More specifically, the CPU transmits the predicted value of the transition probability calculated in step S108 to each wireless terminal 50 in the congested sector. The CPU stores the bandwidth usage rate before transmitting the expected value of the transition probability.

  In step S111, the CPU (control unit 19) waits for a certain period of time. More specifically, the CPU waits for a certain period of time under the OS that controls the software until the wireless terminal 50 makes a transition according to the transition probability and becomes a steady state, and then the CPU steps the processing. Move to S102.

  In step S112, the CPU (control unit 19) initializes control. More specifically, the CPU clears the stored previous band usage rate and the previous predicted value of the transition probability, detects a congested sector and a light sector, and recalculates the target usage rate. Thereafter, in order to perform the initial control, the CPU moves the process to step S105.

  FIG. 5 is a diagram for explaining an example of an expected value calculation process calculated by the transition control apparatus 10 according to the first embodiment of the present invention. The Y axis shows the band usage rate of the congested sector, and the X axis shows the transition probability for prompting the terminal to transition from the congested sector to the light sector. Assuming that the transition control device 10 increases and distributes the transition probability at equal intervals, the relationship between the band usage rate after the wireless terminal 50 transitions based on the distributed transition probability and the distributed transition probability is as shown by a curve C1. It can be expressed as That is, if the error, the number of wireless terminals 50, the autonomous outflow probability, and the like do not change, a downwardly convex curve is obtained. For example, assuming that the bandwidth usage rate of the congested sector is 78% and the bandwidth usage rate of the light sector is 22%, the transition control device 10 calculates an average value (50%) as the target usage rate. A straight line L1 indicates the target usage rate. Hereinafter, a description will be given with reference to FIG.

  (1) First, the transition control device 10 calculates the initial value of the transition probability as, for example, 0.01 as the transition probability, and distributes it to the wireless terminals 50 in the congested sector. When the transition control device 10 distributes the initial value of the expected value to the wireless terminal 50, the coordinate point P1 (transition probability is 0.0, the band usage rate is 78%) in FIG. It is assumed that the transition probability is 0.01 and the band usage rate is 77%). The transition control device 10 determines whether or not the difference between the band usage rate (77%) of the congested sector after the transition probability is distributed and the target usage rate (50%) is greater than or equal to a threshold (for example, 3%). To do.

  (2) If the transition control device 10 determines that the difference is equal to or greater than the threshold (outside the target usage rate range), then the transition control device 10 includes a straight line L2 connecting the coordinate point P1 and the coordinate point P0, The intersection K1 with the straight line L1 is calculated as an expected value of the transition probability (for example, 0.125). When the expected value of the transition probability calculated by the transition control device 10 is distributed, it is assumed that the coordinate point P2 (the transition probability is 0.125 and the bandwidth usage rate is 58%) after a certain period has elapsed. The transition control device 10 determines whether or not the difference between the bandwidth usage rate (58%) of the congested sector after the transition probability is distributed and the target usage rate (50%) is greater than or equal to a threshold value (for example, 3%). To do.

  (3) If the transition control device 10 determines that the difference is equal to or greater than the threshold (outside the target usage rate range), then the transition control device 10 includes a straight line L3 connecting the coordinate point P2 and the coordinate point P1, and The intersection K2 with the straight line L1 is calculated as an expected value of the transition probability (for example, 0.17). When the expected value of the transition probability calculated by the transition control device 10 is distributed, it is assumed that the coordinate point P3 (the transition probability is 0.17 and the bandwidth usage rate is 54%) is reached after a certain period of time. The transition control device 10 determines whether or not the difference between the band usage rate (54%) of the congested sector after the transition probability is distributed and the target usage rate (50%) is equal to or greater than a threshold (for example, 3%). To do.

(4) If the transition control device 10 determines that the difference is equal to or greater than the threshold (outside the target usage rate range), then the transition control device 10 includes a straight line L4 connecting the coordinate point P3 and the coordinate point P2, and The intersection K3 with the straight line L1 is calculated as an expected value of the transition probability.
In this way, the transition control device 10 calculates the change rate of the bandwidth usage rate from the bandwidth usage rate before the transition probability is distributed and the bandwidth usage rate after the transition probability is distributed, and the calculated change rate. Based on the above, the expected value of the transition probability is calculated. Then, the transition control device 10 calculates the expected value of the transition probability and distributes the calculated predicted value of the transition probability until it determines that the difference between the band usage rate of the busy sector and the target usage rate is smaller than the threshold value. Is repeated to quickly find the optimum value of the transition probability so that the band usage rate of the congested sector falls within the target usage rate range.

  In this way, the transition control device 10 uses the property that when the transition probability is increased, the bandwidth usage rate of the congested sector decreases, skips the middle of changing the transition probability, and the transition probability from the congested sector to the light sector. Expect the optimum value and quickly find it. Even if the expected value of the transition probability is distributed, even if the bandwidth usage rate becomes smaller than the target usage rate, the next expected value is calculated as the intersection point with an expected value smaller than the previous expected value. Therefore, the transition control apparatus 10 can obtain | require an optimal value rapidly by repeating the same process.

FIG. 6 is a diagram illustrating an example of a computer simulation result of control by the transition control apparatus 10 according to the first embodiment of the present invention. In the example of FIG. 6, the transition control device 10 distributes the initial value of the transition probability to the congested sector in “initial value distribution” of FIG. 6, and the rate of change in the band usage rate after a certain period of time has elapsed after distribution. Based on the above, the predicted value of the transition probability is calculated, the predicted value is calculated until the bandwidth usage rate of the congested sector reaches the target usage rate, and the calculated predicted value is distributed ("first distribution", "first 2 distribution ”and“ third distribution ”).
In the example of FIG. 6A, in the congested sector, there is no change in the bandwidth usage rate 102 of the dead terminal, the bandwidth usage rate 101 of the transition terminal decreases, and the overall bandwidth usage rate 103 is within the target usage rate range. It has become.
Similarly, in the example of FIG. 6B, in the quiet sector, there is no change in the bandwidth usage rate 202 of the dead terminal, the bandwidth usage rate 201 of the transition terminal increases, and the overall bandwidth usage rate 203 becomes the target usage rate. Indicates that it is within range.

[Embodiment 2]
In the second embodiment, the transition control device 10 detects a congested sector and a light sector from three or more bands, and performs leveling of the detected congested sector and a light sector every time a certain period of time is detected. When the leveling of the congested sector and the light sector is completed, after waiting for the elapse of a predetermined period, the congestion sector and the light sector are newly detected from the three or more bands, and leveling is performed. The band usage rate of each band in the above bands is leveled.
The configuration of the transition control device 10 is the same as that of the first embodiment.

  The control means 19 performs detection of a congested sector by the congested sector detecting means 12 and detection of a congested sector by the light sector detecting means 13 at every elapse of a predetermined period.

  FIG. 7 is a flowchart showing the processing contents of the transition control apparatus 10 according to the second embodiment of the present invention.

  In step S <b> 201, the CPU (the usage rate acquisition unit 11, the crowded sector detection unit 12, and the loose sector detection unit 13) detects a crowded sector and a quiet sector. More specifically, the CPU compares the band usage rate of each band acquired from the base station with respect to a plurality of bands, detects the band with the highest band usage rate as a congested sector, and has the highest bandwidth usage rate. A low band is detected as a quiet sector and stored.

  Each process from step S202 to step S212 is the same as each process from step S102 to step S112 in the first embodiment. However, in step S203 (corresponding to step S103 of the first embodiment), if the determination is YES, the CPU moves the process to step S213, and in step S213, the CPU waits for a predetermined period of time, and then the CPU The process moves to step S201.

According to the first embodiment, the transition control device 10 detects a band having the highest band usage rate from a plurality of bands as a congested sector, and detects a band having the lowest band usage rate as a quiet sector. Then, the transition control device 10 calculates a target usage rate based on the detected bandwidth usage rate of the congested sector and the bandwidth usage rate of the quiet sector, and a target that is the difference between the bandwidth usage rate of the busy sector and the target usage rate. Based on the difference, the initial value of the transition probability from the congested sector to the light sector is distributed to the radio terminals 50 in the congested sector. Next, the transition control device 10 calculates a target usage rate for every elapse of a certain period, determines whether the target difference is equal to or greater than a threshold value, and determines that the target difference is equal to or greater than the threshold value. Based on the rate of change in bandwidth usage calculated from the bandwidth usage before distribution of the bandwidth and the bandwidth usage after the transition probability is distributed, the bandwidth usage of the congested sector becomes the target usage. The expected value of the transition probability to make Then, the transition control device 10 distributes the calculated predicted value to the wireless terminals 50 in the congested sector, and repeats the calculation of the predicted value and the distribution of the calculated predicted value until it is determined that the target difference is smaller than the threshold value. .
Therefore, the transition control apparatus 10 can quickly equalize the band usage rate of a band that is congested among the bands used by the wireless terminal 50 and the band usage rate of a quiet band.

According to the second embodiment, when the transition control device 10 detects a congested sector and a light sector from three or more bands, and performs the detection of the detected congested sector and the leveling of the light sector, the transition control device 10 After the elapse of this period, a congestion sector and a light sector are newly detected and leveled, and the band usage rate of each band in three or more bands is leveled.
Therefore, the transition control apparatus 10 repeats the leveling of the congestion sector and the light sector detected from a plurality of bands (for example, three or more bands), thereby repeating the plurality of bands (for example, three bands). The band usage rate of each band in the above band) can be quickly leveled.

  As mentioned above, although embodiment of this invention was described, this invention is not restricted to embodiment mentioned above. The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

In the present embodiment, the transition control device 10 transmits the transition probability to the wireless terminal 50, but the distribution device (not shown) may transmit the wireless terminal 50. That is, the transition control device 10 passes a transition probability by specifying a band to the distribution device, and the distribution device updates the set transition probability (initial value is 0) to the passed transition probability, The data is transmitted to the wireless terminal 50 in the designated band. If there is no change in the transition probability, the distribution device continuously transmits.
In this way, the transition control device 10 can quickly distribute the transition probability to the wireless terminal 50 that has newly entered the band.

DESCRIPTION OF SYMBOLS 10 Transition control apparatus 11 Usage rate acquisition means 12 Congested sector detection means 13 Quiet sector detection means 14 Target calculation means 15 Initial value setting means 16 Expected value calculation means 17 Transition probability distribution means 18 Judgment means 19 Control means 50 Wireless terminal

Claims (4)

A transition control apparatus that controls transition of a wireless terminal that transitions based on a transition probability for transitioning from one band to another band among a plurality of bands of a base station,
Usage rate acquisition means for acquiring each bandwidth usage rate in the plurality of bands;
Among the plurality of bands, a congestion sector detection unit that detects a band with the highest band usage rate acquired by the usage rate acquisition unit as a congestion sector;
Of the plurality of bands, a quiet sector detecting means for detecting a band having the lowest bandwidth usage rate acquired by the usage rate acquiring means as a quiet sector;
Target calculation means for calculating a target usage rate based on the band usage rate of the busy sector detected by the busy sector detection means and the bandwidth usage rate of the quiet sector detected by the quiet sector detection means;
Transition probability distribution means for distributing the transition probability to the wireless terminal;
Based on a target difference that is a difference between the band usage rate of the crowded sector and the target usage rate calculated by the target calculation means, an initial value of the transition probability from the crowded sector to the light sector is calculated. Initial value setting means for causing the transition probability distribution means to distribute the calculated initial value to the wireless terminals in the congested sector;
After the initial value is distributed by the initial value setting unit, the target usage rate is calculated by the target calculation unit at every elapse of a predetermined period, and based on a change in the bandwidth usage rate of the congested sector, the The predicted value of the transition probability is calculated so that the bandwidth usage rate of the congested sector becomes the target usage rate, and the calculated predicted value of the transition probability is distributed to the wireless terminals of the congested sector. Control means distributed by means;
A transition control device comprising:
The control means includes
Determining means for determining whether the target difference is smaller than a threshold;
Based on the change rate of the bandwidth usage rate calculated from the bandwidth usage rate before the transition probability is distributed and the bandwidth usage rate after the transition probability is distributed, the bandwidth usage rate of the congested sector is calculated as follows. An estimated value calculating means for calculating an expected value of the transition probability for achieving the target usage rate,
The control unit causes the transition probability distribution unit to distribute the predicted value calculated by the predicted value calculation unit to the wireless terminals in the congested sector , and the target difference is set to a threshold value by the determination unit after the predetermined period has elapsed. 2. The transition control device according to claim 1, wherein calculation of the predicted value by the predicted value calculating unit and distribution of the calculated predicted value by the transition probability distributing unit are repeated until it is determined to be smaller than .
The control means detects the congestion sector by the congestion sector detection means, detection of the light sector by the light sector detection means , and calculation of an expected value of the transition probability at every elapse of a predetermined period. Wherein the transition probability distribution means distributes the expected value of the transition probability to the wireless terminals of the crowded sector so that the detected bandwidth usage rate of the congestion sector becomes the target usage rate. 3. The transition control device according to 1 or 2.
A transition control method executed by a transition control device that controls a transition of a wireless terminal that transitions based on a transition probability for transitioning from one band to another band among a plurality of bands of a base station ,
By the transition control device,
A usage rate acquisition step of acquiring each bandwidth usage rate in the plurality of bands;
Among the plurality of bands, a congested sector detecting step for detecting, as a congested sector, a band having the highest band usage rate acquired by the usage rate acquiring step;
Of the plurality of bands, a quiet sector detection step of detecting a band having the lowest band usage rate acquired by the usage rate acquisition step as a quiet sector;
A target calculation step of calculating a target usage rate based on the bandwidth usage rate of the busy sector detected by the busy sector detection step and the bandwidth usage rate of the quiet sector detected by the quiet sector detection step;
A transition probability distribution step of distributing the transition probability to the wireless terminals;
Based on a target difference that is a difference between the bandwidth usage rate of the busy sector and the target usage rate calculated by the target calculation step, an initial value of the transition probability from the busy sector to the light sector is calculated. An initial value setting step for distributing the calculated initial value to the wireless terminal of the congestion sector by the transition probability distribution step ;
After the initial value of the transition probability is distributed by the initial value setting step, the target calculation step by the target calculation step is performed at every elapse of a predetermined period, and based on the change in the bandwidth usage rate of the congested sector, The predicted value of the transition probability is calculated so that the bandwidth usage rate of the congested sector becomes the target usage rate, and the calculated predicted value of the transition probability is distributed to the wireless terminals of the congested sector. Control steps distributed by steps;
A transition control method comprising:

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