JP2007043251A - Mobile communications system, wireless control station and transmission rate control method used for the same, and transmission rate control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile communication system or the like, capable of increasing utilizing efficiency of wireless resources, while keeping constant the frequency of transmission rate switching executed by a wireless control station, as it is. <P>SOLUTION: When a data amount stored in a buffer 15 exceeds an upper limit threshold continuously for a switching start time or over, the rate switching section 24 of the wireless control station 2 performs switching so as to make the transmission rates of individual wireless channels increase. The switching start time is set shorter, the higher the transmission rate becomes, by each transmission rate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mobile communication system, a radio control station, a transmission rate control method used therein, and a transmission rate control program. The present invention relates to a transmission rate control method and a transmission rate control program.

  An example of a conventional transmission rate control method is described in Non-Patent Document 1. In the W-CDMA (Wideband-Code Division Multiple Access) wireless communication system, when packet communication is started between a wireless base station and a mobile station, an individual wireless line is established. There are several types of lines (for example, lines with an upper limit of 64 kbps, 128 kbps, and 256 kbps) having different upper limits of transmission rates. A buffer exists in a radio control station or a radio base station that controls radio communication with a mobile station, and data from the network to the mobile station stops in these buffers. If a state in which the amount of data existing in the buffer in the wireless control station exceeds a predetermined threshold is maintained for a certain period of time while using a wireless line with a specific transmission rate, a wireless line with a higher transmission rate is allocated, and another predetermined When the state below the threshold is maintained for a certain period of time, a wireless line with a low transmission rate is assigned. However, whether or not the transmission rate can be assigned is determined by comparing the load on the radio line with a predetermined threshold. The load on the radio link is the load of the individual radio link defined by the value obtained by dividing the required reception quality (SIR: Signal to Interference Ratio) of the radio link by the spreading factor (SF) within the cell. It is assumed to be added to all the individual wireless lines that are present, and corresponds to the state of consumption of the spreading code that is a radio resource and the transmission power of the radio base station.

Supervised by Keiji Tachikawa, “W-CDMA mobile communication system” Maruzen Co., Ltd., June 25, 2001, p. 171-174, 193-194

In the transmission rate control method described above, the transmission rate is switched when the amount of data in the buffer continuously exceeds a predetermined threshold (below) for a certain period of time. This “certain time” uses a constant value regardless of the current transmission rate. As a result, radio resources are released at the same frequency both when the transmission rate is a high transmission rate with a large amount of radio resources used and when the transmission rate is a low transmission rate with a small amount of radio resources used.
For this reason, an individual radio channel to which a high transmission rate is assigned can be released originally, and radio resources such as spreading codes and radio base station transmission power that should be used for establishing a new individual radio channel are lengthened. There is a problem that the radio resources are used for a long time and use efficiency of radio resources is lowered.

  Therefore, the present invention provides a mobile communication system, a radio control station, and a transmission rate control method used for them, which can increase the utilization efficiency of radio resources while keeping the frequency of transmission rate switching performed in the radio control station constant. An object is to provide a transmission rate control program.

The transmission rate switching unit of the radio control station according to the present invention, when the information indicating that the amount of data stored in the buffer exceeds the upper limit threshold and is maintained for the switching start time or longer is received from the traffic measurement unit Switch to increase the transmission rate of the line.
Here, the switching activation time is set to be shorter as the transmission rate becomes higher for each transmission rate (Claims 1 to 6).

According to the radio control station, the transmission rate is increased when the amount of data in the buffer exceeds the upper threshold for a certain time (switching activation time) or longer, that is, when the amount of transmission data is large and communication is stagnant. Switch to Since the switching activation time is set shorter as the transmission rate is higher, the higher the transmission rate of the individual wireless line, the faster the transmission rate is switched, and a large amount of data can be sent and received in a short time. it can.
As a result, it is possible to suppress the state where the individual radio link requires a high transmission rate in a short time, and increase the use efficiency of radio resources while keeping the transmission rate switching frequency performed at the radio control station constant as a whole. Can be made.

In the above wireless control station, the transmission rate switching unit operates when the traffic measurement unit is informed that the amount of data in the buffer falls below a preset lower threshold and the switching activation time is maintained. You may make it provide the rate fall switching function switched so that a rate may be reduced (Claim 2).
In this way, when there is a margin in the transmission rate assigned to the individual radio line, the probability of switching to lower the transmission rate increases as the current transmission rate increases.
Therefore, individual radio lines assigned with a high transmission rate will not continue to occupy a large amount of radio resources for an unnecessarily long time, and the frequency of transmission rate switching performed by the radio control station remains constant as a whole. The utilization efficiency of radio resources can be increased.

In the radio control station, the switching activation time may be different depending on whether the switching start time is switched to a direction in which the transmission rate is lowered or switched to a direction in which the transmission rate is increased (Claim 3).
In this way, the switching timing can be controlled more finely, and the utilization efficiency of radio resources can be further improved.

In the wireless control station, when switching to a direction in which the transmission rate is decreased, the wireless control station may be switched to a predetermined value regardless of the transmission rate before switching. This predetermined value may be the lowest transmission rate that can be assigned.
In this way, a large amount of radio resources can be released when switching in the direction of decreasing the transmission rate.

In the above radio control station, a load measuring unit for measuring the load of the radio base station is provided in the transmission rate switching unit so that when the cell load is larger than the load threshold, switching is not performed so as to increase the transmission rate. (Claim 6).
In this way, when the load on the cell is high, the transmission rate is not changed in the direction in which the currently established individual radio link consumes more radio resources. Consumption can be suppressed and radio resources can be prevented from being depleted.

In the transmission rate control method according to the present invention, when the amount of data stored in the buffer continuously exceeds the upper limit threshold for the switching activation time or longer, switching is performed so as to increase the transmission rate of the individual radio channel. Further, when the amount of data stored in the buffer continuously falls below the lower limit threshold for the switching start time or longer, switching is performed so as to lower the transmission rate of the individual wireless line.
Here, the switching activation time is set to be shorter as the transmission rate is higher for each transmission rate. (Claim 7)

According to the transmission rate control method, the switching activation time is set shorter as the transmission rate is higher. Therefore, the transmission rate is switched faster as the transmission rate of the individual radio line is higher. That is, when the amount of communication data is large, the transmission rate is increased to promote data processing, and when the amount of communication data is small, the transmission rate is decreased to release excess radio resources. As often as it happens.
Therefore, it is possible to increase the utilization efficiency of radio resources while keeping the transmission rate switching frequency performed in the radio control station constant as a whole.

The transmission rate control program according to the present invention includes a step of switching so as to increase the transmission rate of the individual radio line when the amount of data stored in the buffer continuously exceeds the upper limit threshold for the switching start time or more; When the amount of data stored in the buffer continuously falls below the lower limit threshold for the switching start time or longer, the computer is caused to perform a switching step so as to decrease the transmission rate of the individual wireless line.
Here, the switching activation time is set to be shorter for each transmission rate as the transmission rate becomes higher.

According to the above program, since the switching start time is set shorter as the transmission rate is higher, the computer switches the transmission rate faster as the transmission rate of the individual wireless line is higher. That is, when the amount of communication data is large, the transmission rate is increased to promote data processing, and when the amount of communication data is small, the transmission rate is decreased to release excess radio resources. As often as it happens.
Therefore, it is possible to increase the utilization efficiency of radio resources while keeping the transmission rate switching frequency performed in the radio control station constant as a whole.

In the radio communication system according to the present invention, a radio control station controls packet communication performed between a radio base station and a mobile station.
The radio control station has a transmission rate switching unit, and the transmission rate switching unit reports that the amount of data stored in the buffer continuously exceeds the upper limit threshold for the switching activation time or more and performs traffic measurement. Switch to increase the transmission rate of the individual radio link. In addition, when the traffic measurement unit reports that the amount of data stored in the buffer has continued below the switching activation time and has fallen below the lower threshold, the transmission rate switching unit sets the transmission rate of the individual radio line. Switch to lower.
Here, the switching activation time is set to be shorter for each transmission rate as the transmission rate increases (claim 9).

According to the wireless communication system, the switching activation time is set shorter as the transmission rate is higher. Therefore, the transmission rate is switched faster as the transmission rate of the individual wireless line is higher. That is, when the amount of communication data is large, the transmission rate is increased to promote data processing, and when the amount of communication data is small, the transmission rate is decreased to release excess radio resources. As often as it happens.
Therefore, it is possible to increase the utilization efficiency of radio resources while keeping the transmission rate switching frequency performed in the radio control station constant as a whole.

According to the present invention, since the switching activation time is set shorter as the transmission rate is higher, the transmission rate switching unit quickly switches the transmission rate as the transmission rate is higher, and transmits and receives a large amount of data early. Can be ended.
As a result, it is possible to suppress the state where the individual radio link requires a high transmission rate in a short time, and increase the use efficiency of radio resources while keeping the transmission rate switching frequency performed at the radio control station constant as a whole. Can be made.

  Hereinafter, the configuration and operation of the mobile communication system 10 according to the first embodiment of the present invention will be described with reference to the drawings.

(Configuration of mobile communication system 10)
FIG. 1 shows a schematic configuration of the mobile communication system 10.
A mobile communication system 10 employs a W-CDMA mobile communication system as a radio access system, and includes a radio control station 2 directly connected to a wired network 1 and a radio base station connected to the radio control station 2. And a mobile station 5 that performs wireless communication with any one of the radio base stations 3a and 3b. The mobile station 5 is, for example, a mobile phone, a PDA, a personal computer equipped with a data communication card, or the like.
FIG. 1 shows a state in which one mobile station 5 belongs to a cell 4a formed by the radio base station 3a. Although only two radio base stations are shown in FIG. 1, three or more radio base stations may be used. In addition, although one cell is formed by each radio base station, one radio base station 3a or 3b can form a plurality of cells. Furthermore, the number of mobile stations 5 belonging to one cell may be plural.
The radio base stations 3a and 3b have the same configuration, and form cells 4a and 4b, respectively, and can perform wireless communication with the mobile station 5 in each cell. The cells 4a and 4b represent areas where the radio base stations 3a and 3b can communicate with the mobile station 5 by radio.
The mobile station 5 transmits an individual radio channel establishment request to the radio control station 2 when making a connection to the radio base station 3a.
The radio control station 2 controls radio channel settings for the mobile stations in the radio base stations 3 a and 3 b and receives a radio channel establishment request from the mobile station 5.

FIG. 2 shows a schematic configuration of the radio control station 2.
The radio control station 2 includes a CPU 11 that controls the radio control station 2 as a whole, a main storage device 13 that stores programs and data executed by the CPU 11, an I / O 12 that is an input / output interface of the CPU 11, a radio base station 3a, A communication unit 14 that performs communication with 3b, a buffer 15 that temporarily stores data to be transmitted to the mobile station 5, and an individual radio channel established between the mobile station 5 and the base stations 3a and 3b. A transmission rate control function unit 20 for controlling the transmission rate.

FIG. 3 shows a main configuration of the transmission rate control function unit 20 of the radio control station 2.
The transmission rate control function unit 20 includes an individual radio channel establishment request accepting unit 21 that accepts an individual radio channel establishment request from the mobile station 5, an initial transmission rate allocating unit 22 that assigns an initial transmission rate used in the radio channel, and a cell 4a. A cell load measuring unit 23 for measuring the load of the mobile station, a first rate switching unit 24 for switching the transmission rate, and a traffic measuring unit for measuring the amount of data transmitted from the network 1 to the mobile station 5 for each mobile station. 25 and a radio resource release unit 26 that releases radio resources after the end of data transmission.

Each of these means generally operates as follows.
The individual radio channel establishment request receiving unit 21 receives an individual radio channel from the mobile station 5 that newly requests establishment of an individual radio channel when no radio channel is established or when a common radio channel is established. Receive an establishment request.

When an individual radio channel establishment request is input, the initial transmission rate allocating unit 22 sets a transmission rate of a newly established individual radio channel as one of Ri + 1 initial transmission rates Ri ( i is an integer from 0 to N.
The initial transmission rate allocation unit 22 reports the cell load corresponding to Ri to the cell load measurement unit 23, and receives a determination result from the cell load measurement unit 23 as to whether or not an individual radio line can be established with Ri. If an individual radio line can be established, an individual radio line with a transmission rate Ri is established. If the establishment is impossible, the individual wireless line is not established, and the process waits until the next individual wireless line establishment request is input.

The cell load measurement unit (load measurement unit) 23 measures the load in the cell and determines whether or not an individual radio line can be established. The load for each individual radio link is defined as the required reception quality (SIR: Signal to Interference Ratio) of the radio channel divided by the spreading factor (SF), and all individual radios established in the cell The cell load is obtained by adding the line load.
When a report indicating that a radio resource is newly allocated to the individual radio channel is received from the initial transmission rate allocating unit 22 or the first rate switching unit 24, the cell load obtained by adding the load of the individual radio channel differs from the transmission rate. A predetermined cell load threshold Li is compared. Li is a threshold value corresponding to the transmission rate Ri. When the cell load is equal to or lower than Li, a report indicating that radio resources can be allocated to the individual radio channel is transmitted to the initial transmission rate allocation unit 22 or the first rate switching unit 24. When the cell load exceeds Li, a report indicating that radio resources cannot be allocated to the individual radio channel is transmitted to the initial transmission rate allocation unit 22 or the first rate switching unit 24. The cell load measurement unit stores the same number of threshold values Li as the transmission rate.

The rate switching unit (transmission rate switching unit) 24 switches the rate among N + 1 transmission rates R0,..., Ri,. carry out. However, the value of the transmission rate is R0 <•• <Ri <•• <RN. i is an integer of 0 or more and N or less.
The rate is switched as follows. While using an individual wireless line with a specific transmission rate, the state in which the amount of data in the buffer 15 reported from the traffic measurement unit 25 exceeds the upper threshold (hereinafter referred to as “Aup”) is maintained for more than the switching activation time. Then, a wireless line having a transmission rate higher than the transmission rate before switching is allocated. When the state in which the amount of data in the buffer 15 is equal to or lower than the lower threshold (hereinafter referred to as “Adown”) is maintained for the switching activation time or longer, a wireless line having a transmission rate lower than the transmission rate before switching is allocated.

Aup (upper limit threshold) and Adown (lower limit threshold) are set to constant values regardless of the transmission rate.
The switching start time, which is the time required for switching the transmission rate that satisfies the conditions for the amount of data in the buffer, is set differently for each transmission rate and when the transmission rate is increased or decreased. To do. Specifically, N of Tup, 1, ..., Tup, i, ..., Tup, N as the transmission rate increases (Tup, 1> ... Tup, i> ... Tup, N) Tdown, 0, ..., Tdown, i, ..., Tdown, N-1 (Tdown, 0> ... Tdown, i> ... Tdown, N-1) Set. Here, Tup, i represents the switching activation time when the transmission rate is switched from Ri-1 to Ri, and Tdown, i represents the switching activation time when the transmission rate is switched from Ri + 1 to Ri.
The upper limit threshold value, the lower limit threshold value, and the switching activation time are stored in advance in the main storage device 13 in the form of a table, for example. Alternatively, the switching operation may be directly incorporated in the program logic.

The traffic measurement unit 25 measures the amount of data transmitted from the network 1 to the mobile station 5 and stored in the buffer 15 in the radio control station 2. Hereinafter, the amount of data stored in the buffer is abbreviated as BV (Buffer Volume). The unit is byte. The BV measurement result is periodically reported to the first rate switching unit 24.
The radio resource release unit 26 releases the radio resource allocated to the individual radio channel after the data transmission is completed.

(Operation of Mobile Communication System 10)
Next, the transmission rate switching operation in the radio control station 2 will be described in detail with reference to the flowchart of FIG.
Assume that an individual wireless line with a transmission rate Ri is established (step S101 in FIG. 4).
BV is reported from the traffic measurement unit 25 to the first rate switching unit 24, and comparison with thresholds Adown and Aup is performed (steps S102 and S103). As long as BV does not satisfy the predetermined condition, the transmission rate Ri is continuously assigned to the individual radio line (the determinations in steps S102 and S103 are no, and the process returns to step S101).

When the state where BV exceeds Aup continues for Tup, i + 1, the transmission rate to be allocated is set to Ri + 1 (Ri + 1> Ri) (Yes in step S103, step S104).
The cell load measuring unit 23 determines whether Ri + 1 can be assigned. The cell load obtained by subtracting the load corresponding to the old rate Ri and adding the load corresponding to the new rate Ri + 1 is compared with the load threshold Li + 1 (step S105). If the cell load is equal to or lower than Li + 1 (Yes in step S105), radio resource allocation is permitted, and an individual radio line with a transmission rate Ri + 1 is established (step S106). If the cell load exceeds Li + 1 (No in step S105), radio resource allocation is rejected, and the transmission rate remains Ri (step S101). When the BV satisfies a predetermined condition after a certain period of time, an attempt to increase the rate is made again.

  When the state where BV is equal to or lower than Adown continues for Tdown, i-1 (Yes in step S102), the transmission rate is set to Ri-1 (Ri-1 <Ri) (step S107). Since the load corresponding to the new rate Ri-1 is smaller than the load corresponding to the old rate Ri, the determination of radio resource allocation in the cell load measuring unit 23 is not performed, and an individual radio channel of the transmission rate Ri-1 is established. Is done.

  The transmission rate control method of the present embodiment is configured such that when the amount of data stored in a buffer that temporarily stores a packet to be transmitted to a mobile station continuously exceeds the upper limit threshold for a time equal to or longer than the switching start time, And causing the computer to execute a step of switching so that the transmission rate is lower than before switching when the amount of data continues for a time equal to or longer than the switching start time and falls below a lower threshold. The switching activation time can be implemented as a transmission rate control program characterized in that the switching activation time is set shorter as the transmission rate before switching is higher.

According to the mobile communication system 10, since the switching start time (Tup, i and Tdown, i) is set shorter as the transmission rate is higher, the transmission rate is switched faster as the transmission rate of the individual radio line is higher. Is called. That is, the more the individual radio line uses more radio resources, the more frequently the transmission rate is switched and the more radio resources can be released.
Therefore, it is possible to increase the utilization efficiency of radio resources while keeping the transmission rate switching frequency performed by the radio control station 2 constant as a whole.

Next, the configuration and operation of the mobile communication system 10a according to the second embodiment of the present invention will be described with reference to the drawings.
As in the mobile communication system 10 shown in FIG. 1, the overall configuration of the mobile communication system 10a employs a W-CDMA mobile communication system as a wireless access system, and is directly connected to a wired network 1 The radio control station 2 includes radio base stations 3a and 3b connected to the radio control station 2, and a mobile station 5 that performs radio communication with any one of the radio base stations 3a and 3b. The mobile station 5 is, for example, a mobile phone, a PDA, a personal computer equipped with a data communication card, or the like.
The radio base stations 3a and 3b have the same configuration, and form cells 4a and 4b, respectively, and can perform wireless communication with the mobile station 5 in each cell.
The mobile station 5 transmits an individual radio channel establishment request to the radio control station 2 when making a connection to the radio base station 3a.
The radio control station 2 controls radio channel settings for the mobile stations in the radio base stations 3 a and 3 b and receives a radio channel establishment request from the mobile station 5.

  As shown in FIG. 2, the radio control station 2 includes a CPU 11 that controls the entire radio control station 2, a main storage device 13 that stores programs and data executed by the CPU 11, and an I / O 12 that is an input / output interface of the CPU 11. Between the mobile station 5 and the base stations 3a and 3b, a communication unit 14 that performs communication between the radio base stations 3a and 3b, a buffer 15 that temporarily stores data to be transmitted to the mobile station 5, and And a transmission rate control function unit 20 for controlling the transmission rate of the established individual radio link.

FIG. 5 shows a main configuration of the transmission rate control function unit 20 of the radio control station 2. The configuration of the transmission rate function control unit 20 is the same as that in FIG. 3, but the operation of the second rate switching unit 27 in the case of switching in the direction of decreasing the transmission rate is the same as that of the first rate switching unit 24 in FIG. Not the case.
The switching start-up time when the rate is reduced varies depending on the transmission rate. Tdown, 1, ..., Tdown, i, ..., N of Tdown, N (Tdown, 1> ... Tdown, i> ... > Tdown, N) respectively. Here, Tdown, i represents the switching activation time for the transmission rate to change from Ri to R0. R0 is the lowest rate that can be assigned by the radio network controller 2.
When switching in the direction of decreasing the transmission rate, the second rate switching unit 27 switches at once to R0, which is the lowest rate, regardless of the current transmission rate.

With reference to the flowchart of FIG. 6, the rate switching operation in the radio control station 2 will be described in detail.
The difference from the case of the first embodiment in FIG. 4 is that steps S102 and S107 are replaced with steps S102a and S107a, respectively.
BV is reported from the traffic measurement unit 25 to the second rate switching unit 27, and comparison with thresholds Adown and Aup is performed (steps S102a and S103). As long as BV does not satisfy the predetermined condition, the transmission rate Ri is continuously assigned to the individual radio channel (no determination in steps S102a and S103, both in step S101).
When the state where BV is equal to or lower than Adown continues for Tdown, i (Yes in step S102a), the transmission rate is set to R0 (step S107a).
The operation for increasing the transmission rate (steps S104 to S106) is the same as in FIG.

According to the present embodiment, the transmission rate switching unit 27 reduces the transmission rate to the lowest transmission rate R0 at a stroke when switching to a direction in which the transmission rate is decreased.
Therefore, a large amount of radio resources can be released at a time.

Next, a first embodiment of the present invention will be described with reference to FIG. This example corresponds to the first embodiment of the present invention.
The transmission rates that can be allocated in the cell are 256 kbps, 128 kbps, and 64 kbps (N = 2). At this time, R0 = 64 kbps, R1 = 128 kbps, R2 = 256 kbps, and the initial transmission rate is 64 kbps. Further, it is assumed that there is a margin in the cell load.

As shown in FIG. 7, it is assumed that the upper limit threshold Aup and the lower limit threshold Adown are set as shown in the graph with the horizontal axis representing time and the vertical axis representing BV. When BV exceeds the threshold value Aup at time t0 and the state continues for Tup, 1, the transmission rate is switched from 64 kbps to 128 kbps at time t1.
If Tup, 2 (<Tup, 1) elapses from t1 while the state where BV exceeds Aup is maintained, the transmission rate is switched from 128 kbps to 256 kbps at time t2.

Thereafter, the transmission rate is switched from 256 kbps to 128 kbps at time t3 when the state where BV decreases and becomes equal to or lower than the threshold Adown is Tdown, 1. Further, when Bdown decreases and Tdown, 0 (> Tdown, 1) elapses after the rate is switched, the transmission rate is switched from 128 kbps to 64 kbps at time t4.
FIG. 7 shows the case where the transmission rate is switched to 256 kbps, but when the transmission rate remains 128 kbps and BV decreases, switching to 64 kbps is performed at the time when the state of the threshold Adown or lower continues at Tdown, 0. .

Next, a second embodiment of the present invention will be described with reference to FIG. This example corresponds to the second embodiment of the present invention.
The transmission rates that can be allocated in the cell are 256 kbps, 128 kbps, and 64 kbps (N = 2). At this time, R0 = 64 kbps, R1 = 128 kbps, R2 = 256 kbps, and the initial transmission rate is 64 kbps. Further, it is assumed that there is a margin in the cell load.

As shown in FIG. 8, it is assumed that the upper limit threshold Aup and the lower limit threshold Adown are set as shown in the graph with the horizontal axis representing time and the vertical axis representing BV. When BV exceeds the threshold value Aup at time t0 and the state continues for Tup, 1, the transmission rate is switched from 64 kbps to 128 kbps at time t1.
If Tup, 2 (<Tup, 1) elapses from t1 while the state where BV exceeds Aup is maintained, the transmission rate is switched from 128 kbps to 256 kbps at time t2.

  Thereafter, the transmission rate is switched from 256 kbps to 64 kbps, that is, the lowest transmission rate at time t3 when BV decreases and the state where the threshold value Adown is equal to or lower than Tdown, 2 continues. Although FIG. 8 shows the case where the transmission rate is switched to 256 kbps, when the transmission rate remains 128 kbps and BV decreases, the state where the threshold Adown or less continues to Tdown, 1 (> Tdown, 2) to 64 kbps. Is switched.

1 is an overall view of a mobile communication system according to a first embodiment of the present invention. It is a functional block diagram which shows the structure of the radio control station of FIG. It is a block diagram which shows the structure of the transmission rate control function part of FIG. 3 is a flowchart illustrating a transmission rate switching operation of the transmission rate control function unit of FIG. 2. It is a functional block diagram which shows the structure of the transmission rate control function part which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the transmission rate switching operation | movement of the transmission rate control function part of FIG. It is a figure which shows the specific example of operation | movement of the transmission rate control function part of FIG. It is a figure which shows the specific example of operation | movement of the transmission rate control function part of FIG.

Explanation of symbols

1: Network 2: Radio control stations 3a, 3b: Radio base stations 4a, 4b: Cell 5: Mobile station 10: Mobile communication system 11: CPU
12: I / O
15: Buffer 20: Transmission rate control function unit 21: Individual radio channel establishment request reception unit 22: Initial transmission rate allocation unit 23: Cell load measurement unit (load measurement unit)
24: First rate switching unit (transmission rate switching unit)
27: Second rate switching unit (transmission rate switching unit)
25: Traffic measurement unit 26: Radio resource release unit

Claims (9)

In a radio control station including a transmission rate switching unit for switching a transmission rate assigned to an individual radio channel established at the start of packet communication between a radio base station and a mobile station,
The transmission rate switching unit is provided with a buffer that temporarily holds data to the mobile station and a traffic measurement unit that measures the amount of data in the buffer,
The transmission rate switching unit operates when the information indicating that the data amount in the buffer exceeds a preset upper limit threshold value and the switching start time is maintained from the traffic measurement unit, and the transmission rate It has a rate increase switching function that switches to increase
The radio switching station characterized in that the switching activation time is set shorter for each transmission rate as the transmission rate before switching is higher. In the radio control station according to claim 1,
The transmission rate switching unit operates when information indicating that the amount of data in the buffer falls below a preset lower limit threshold and the switching activation time is maintained from the traffic measurement unit, and the transmission rate A radio control station having a rate reduction switching function for switching so as to reduce the frequency.   3. The radio control station according to claim 2, wherein the switching start time is set to a different value when switching to decrease the transmission rate and when switching to increase the transmission rate. 4. .   4. The radio control station according to claim 2, wherein the transmission rate switching unit switches the transmission rate to a predetermined value when switching so as to decrease the transmission rate. 5.   The radio control station according to claim 4, wherein the predetermined value is the lowest transmission rate that can be allocated. A load measuring unit that measures the cell load of the radio base station is provided in the transmission rate switching unit,
6. The radio according to claim 1, wherein the transmission rate switching unit does not switch so as to increase the transmission rate when a load of the cell is larger than a load threshold. Control station. In a transmission rate control method for switching a transmission rate assigned to an individual radio line established at the start of packet communication between a radio base station and a mobile station,
Switching is performed so that the transmission rate is increased when the amount of data stored in a buffer that temporarily stores packets to be transmitted to the mobile station exceeds a preset upper threshold for a time equal to or longer than the switching start time. Steps,
Switching the transmission rate so that the transmission rate is lower than before switching when the amount of data falls below a preset lower limit threshold continuously for a time equal to or longer than the switching activation time,
The transmission rate control method, wherein the switching activation time is set shorter as the transmission rate before switching is higher. In a transmission rate switching program for switching a transmission rate assigned to an individual radio line established at the start of packet communication between a radio base station and a mobile station,
Switching to increase the transmission rate when the amount of data stored in a buffer for temporarily storing packets to be transmitted to the mobile station continuously exceeds the upper limit threshold for a time equal to or longer than the switching activation time;
Causing the computer to perform a step of switching so that the transmission rate is lower than before switching when the amount of data continues for a time equal to or longer than the switching start time and falls below a lower threshold.
A transmission rate control program characterized in that the switching activation time is set shorter as the transmission rate before switching is higher. In a radio communication system in which packet communication between a radio base station and a mobile station is controlled by a radio control station,
The radio control station
A transmission rate switching unit that switches a transmission rate assigned to an individual wireless line established at the start of the packet communication;
The transmission rate switching unit is provided with a buffer that temporarily holds data to the mobile station and a traffic measurement unit that measures the amount of data in the buffer,
The transmission rate switching unit operates when the information indicating that the data amount in the buffer exceeds a preset upper limit threshold value and the switching start time is maintained from the traffic measurement unit, and the transmission rate A rate increase switching function for switching to increase
The rate reduction that is activated when the information indicating that the amount of data in the buffer falls below a preset lower threshold value and the switching activation time is maintained is made from the traffic measurement unit, and the transmission rate is lowered. It has a switching function,
The mobile communication system, wherein the switching activation time is set shorter as the transmission rate before the switching is higher.

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