JP2004180158A - Base station controller, data transmission method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a congestion window in a server close to an optimum value. <P>SOLUTION: A base station controller is provided with a queue 321 for temporarily storing a data packet to be transmitted to a mobile device 10 as queue length, a radio frame transmitting part 33 for setting a transmission speed of the data packet to be transmitted to the mobile device 10, and a queue managing part 32 for determining the probability of discarding the data packet transmitted to the mobile device 10 from a server 50 in accordance with the transmission speed set by the radio frame transmitting part 33 and the size of the queue length stored in the queue 321. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
According to the present invention, a mobile station and a server that distributes a data packet are connected to a network, and a probability of discarding a data packet transmitted from the server to the mobile station is determined, or transmitted from the server to the mobile station. The present invention relates to a base station control device, a data transmission method, and a program for dividing a response packet to a set data packet into a predetermined reference number.
[0002]
[Prior art]
In recent years, with the spread of the Internet, access lines for accessing the Internet have been diversified. As a result, Internet access using wireless lines such as mobile phones, PHSs, and wireless LANs is increasing. Internet access using a third-generation or later wireless communication system represented by IMT-2000 realizes a high transmission speed by packet communication and has a feature that the transmission speed dynamically changes.
[0003]
The transmission speed to the relevant mobile station depends on the traffic volume, communication quality, available channels in the accommodated cell, communication channels other than that mobile station, and available channels of other mobile stations in the accommodated cell. It changes dynamically depending on the traffic volume of other mobile devices and the traffic volume between each mobile device. Most traffic on the Internet related to the transmission speed is processed by using a protocol having an independent congestion control method such as TCP.
[0004]
In the TCP congestion control method (RFC2581 TCP Congestion Control), when there is no packet loss between the server and the mobile device, the server increases the congestion window. That is, if the server can receive the ACK from the mobile device, the server increases the congestion window. Here, the congestion window includes, for example, the amount of packets that the server can transmit without receiving ACK from the mobile device.
[0005]
On the other hand, if the server receives three duplicate ACKs from the mobile device, or if the server does not receive an ACK for the new segment from the mobile device for a certain period of time, the server assumes that packet loss has occurred due to congestion. Judge and reduce the congestion window.
[0006]
If the congestion window decreases, the server increases the reduced congestion window. The rate of increase of the congestion window differs depending on whether the state is slow start or congestion avoidance. The difference between the slow start and the congestion avoidance states is determined by the relationship between the congestion window and ssthresh (threshold).
[0007]
This slow start state means that the congestion window is smaller than ssthresh (congestion window <ssthresh). When the state transitions to slow start, the server increases the congestion window by one segment each time an ACK is received. As a result, the server will exponentially increase the congestion window.
[0008]
On the other hand, the state of congestion avoidance is shifted when the congestion window is larger than ssthresh (congestion window <ssthresh). When the state is shifted to the congestion avoidance, the server increases the congestion window by 1 / congestion window every time an ACK is received. Thereafter, the server linearly increases the congestion window.
[0009]
The reason why the congestion window is reduced in each of the above-mentioned states is as follows. FIG. 7 is a diagram illustrating a change in the congestion window. The time in the figure means the time from when the server transmits the transmission data to the mobile device to when the server receives the ACK corresponding to the transmission data from the mobile device.
[0010]
The reduction of the congestion window mainly has two patterns. As the first pattern, as shown in FIG. 7, when the server receives three duplicate ACKs from the mobile station, the congestion window decreases. As a second pattern, the congestion window decreases when the server does not receive an ACK for a new segment within a certain time. When these congestion windows decrease, the server performs the following processing to bring the congestion window closer to the optimum value.
[0011]
That is, when the server receives three duplicate ACKs from the mobile station, the server stores half the value of the current congestion window in ssthresh and reduces the congestion window to half the value. On the other hand, if the server does not receive an ACK for a new segment within a certain period of time, the server stores half the value of the current congestion window in ssthresh to minimize the congestion window.
[0012]
A server that changes the congestion window to half or minimum of the previous congestion window increases the congestion window each time an ACK is received. The optimum value of the congestion window is generally defined by the relationship between the bandwidth and the delay time. FIG. 8 is a diagram illustrating the relationship between the optimum value and the limit value of the congestion window.
[0013]
Generally, the transmission speed of a wireless access line is lower than that of a wired line, and the excess of the congestion window is stored in a queue of a base station controller (a device that controls a base station). When a packet exceeding the limit value accumulates in the queue of the base station controller, the packet is discarded. Here, the base station control device transmits and receives data between the server and the mobile device.
[0014]
On the other hand, if the limit value is lower than the optimum value of the congestion window, the throughput decreases. For this reason, the limit value is fixedly set so that the optimum value of the congestion window linked to the dynamic change of the bandwidth is larger than the maximum value that can be taken.
[0015]
However, when the optimum value of the bandwidth and the congestion window is small, the difference between the limit value and the optimum value of the congestion window becomes large, and the base station controller wastes memory resources. In addition, packets in the congestion window exceeding the optimum value are accumulated in the queue of the base station control device, so that it takes time to be transmitted to the communication path.
[0016]
Furthermore, as a result, it takes time for the server to establish a new connection between the server and the mobile device, and there is a problem that data that requires real-time performance is lost. Was.
[0017]
As a conventional technique for avoiding this problem, in a communication system in which the transmission speed is variable, the buffer capacity of the variable capacity buffer is increased or decreased according to the transmission speed. The communication system in which the increase or decrease is performed sets an optimal buffer capacity (for example, see Patent Document 1). Accordingly, the communication system can minimize data that becomes invalid, and can transmit only valid data to the communication line.
[0018]
[Patent Document 1]
JP-A-10-174185 (Section 1-8, FIG. 2)
[0019]
[Problems to be solved by the invention]
However, in this prior art, the communication system enables the setting of the optimum buffer capacity according to the transmission speed. However, this communication system reduces the buffer capacity in conjunction with the decrease in the transmission speed. For this reason, the packets stored in the reduced buffer portion are discarded, and as a result, burst packet discarding occurs.
[0020]
On the other hand, in a protocol having an autonomous congestion control method such as TCP, when a burst-like packet loss occurs, a congestion window is often set to a minimum value, and discarded packets are retransmitted. The congestion window gradually increases from the minimum value each time the server receives an ACK from the mobile station. Over time, the congestion window will reach an optimal value, but it will take some time before it becomes so.
[0021]
As described above, when the limit value is set small, the throughput decreases when the bandwidth is large. On the other hand, if the limit value is set to a large value, the base station controller needs useless memory resources. For this reason, it takes a considerable amount of time to establish a new connection, and the effectiveness of data that requires real-time properties is lost.
[0022]
Therefore, the present invention has been made in view of the above points, and discards a data packet transmitted from a server to a mobile device with a predetermined probability, or a response packet transmitted from a mobile device to a server. It is an object of the present invention to provide a base station control device, a data transmission method, and a program that can make a congestion window in a server close to an optimum value by dividing under a predetermined condition.
[0023]
[Means for Solving the Problems]
The invention according to the present application has been made in order to solve the above-described problem, and has a probability that a mobile device and a server that distributes a data packet are connected to a network and a data packet transmitted from the server to the mobile device is discarded. When determining, the data packet to be transmitted to the mobile device is temporarily stored in a queue as a queue length, the transmission speed of the data packet to be transmitted to the mobile device is set, and the set transmission speed and the queue are stored. The probability of discarding a data packet transmitted from a server to a mobile device is determined according to the size of the queue length.
[0024]
According to the invention according to the present application, the base station control device transmits the data packet transmitted from the server to the mobile device in accordance with the set transmission speed and the size of the queue length stored in the queue. The probability of discarding (discarding probability) can be determined. Accordingly, the base station control device can discard the data packet transmitted from the server to the mobile device with the above-mentioned discard probability.
[0025]
If the discard probability determined by the base station controller increases, all packet data transmitted from the server to the mobile device will not be transmitted to the mobile device. For this reason, when the server times out without receiving the duplicate ACK or the ACK within a predetermined time, the server itself reduces the congestion window. If the congestion window is reduced, the base station control device can reduce the number of data packets transmitted from the server, and can quickly transmit the data packet to the corresponding mobile station without discarding the data packet. it can.
[0026]
In other words, when the base station controller appropriately changes the discard probability, the base station controller can consequently bring the congestion window in the server closer to the optimum value.
[0027]
Further, the invention according to the present invention is applicable to a case where a mobile device and a server that distributes a data packet are connected to a network and a response packet for a data packet transmitted from the server to the mobile device is divided into a predetermined reference number. Then, a data packet to be transmitted to the mobile device is temporarily stored in a queue as a queue length, a preset reference length is compared with a queue length stored in the queue, and when the reference length is larger than the queue length, , The response packet is divided into a predetermined reference number.
[0028]
According to the invention of this application, when the reference length is larger than the queue length, the base station control device can divide the response packet received from the mobile device into a predetermined reference number. Accordingly, the server can sequentially change the amount of packets (congestion window) to be transmitted to the mobile station according to the number of response packets divided by the base station control device.
[0029]
For example, even when a bursty packet loss occurs on the network and the congestion window in the server is set to a minimum value by a specific protocol, the base station control device sets the received response packet in advance. By dividing into the reference number, the congestion window in the server can be improved as a result.
[0030]
In the above invention, it is preferable that a difference between a preset reference length and a queue length stored in the queue is calculated, and the reference number is set according to the calculated difference. In this case, when the current reference length is larger than the queue length, the base station control device can set the number of references to be divided higher.
[0031]
Setting this reference number higher means that the base station controller can further increase the current queue length. If the reference number increases, the base station control device divides the response packet received from the mobile device by the high reference number. If the response packets increase due to this division, the server increases the congestion window based on the increased response packets.
[0032]
If the ACK increases due to this division, the server returns a large number of response packets, thereby increasing the congestion window. If the congestion window increases, the base station control device increases the data packets received from the server, and as a result, can increase the queue length. Thereby, the base station control device can make the congestion window in the server 50 close to the optimum value as a result.
[0033]
In the above invention, it is preferable that the transmission rate of the data packet to be transmitted to the mobile device is set, and the reference number is set according to the set transmission rate. In this case, since the base station control device can divide the response packet received from the mobile device by the reference number, the congestion window in the server can be consequently made closer to the optimum value.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
(Basic configuration of transmission control system)
An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating a transmission control system according to the present embodiment.
[0035]
As shown in the figure, the transmission control system according to the present embodiment includes mobile stations 10a and 10b, a base station 20, a base station control unit 30 (base station control device), a network 40, and a server 50. Prepare. The base station control unit 30 may be provided in the base station 20.
[0036]
In this embodiment, the mobile device 10 transmits a response packet for confirming the number of data packets received so far to the server 50, and the server 50 checks the response packet from the mobile device 10. Instead, the data packet is transmitted to the mobile device 10.
[0037]
The mobile device 10 transmits and receives data packets between the server 50 and the base station 20. The mobile device 10 is, for example, a mobile phone, a PDA, or the like. Specifically, the mobile device 10 transmits a response to the data packet transmitted from the server 50 to the server 50 as a response packet (ACK).
[0038]
The base station 20 transmits a data packet input from the base station control unit 30 to the corresponding mobile station 10. The base station 20 also outputs a data packet or ACK transmitted from the mobile device 10 to the base station control unit 30. The server 50 transmits a data packet to the mobile device 10 via the base station control unit 30 and the base station 20. Further, the server changes the amount of data packets to be transmitted to the mobile device 10 according to the number of response packets divided by the base station control unit 30, as described later.
[0039]
The server 50 and the base station controller 30 are connected to a network 40. In the present embodiment, the network 40 means a connection network constructed by wireless or wire. The server 50 and the mobile device 10 connected to the network 40 can communicate by TCP.
[0040]
In the present embodiment, as shown in FIG. 2, the base station control unit 30 includes a packet reception unit 31 (reception unit), a queue management unit 32 (discard probability determination unit), a radio frame transmission unit 33, A speed monitor 34, a queue length monitor 35, a radio frame receiver 36, an ACK packet divider 37 (divider), and a packet transmitter 38 are provided. The base station control unit 30 is connected to the base station 20 and the network 40.
[0041]
The packet receiving unit 31 receives a data packet from the server 50. Specifically, the packet receiving unit 31 receives a data packet transmitted from the server 50 and outputs the received data packet to the queue management unit 32.
[0042]
The queue management unit 32 includes a queue 321 for temporarily storing a data packet to be transmitted to the mobile device 10 as a queue length. In the present embodiment, the queue length means the number of packets stored in the queue, the length of the packets, or the amount of packets. The queue management unit 32 discards the data packet received by the packet reception unit 31 according to the transmission rate of the data packet set by the radio frame transmission unit 33 and the size of the queue length stored in the queue 321. This determines the probability (data packet drop probability).
[0043]
Specifically, the queue management unit 32 outputs the data packet stored in the queue 321 in the queue management unit 32 to the wireless frame transmission unit 33 based on the request from the wireless frame transmission unit 33. Until the wireless frame transmitting unit 33 transmits the data packet to the corresponding mobile station 10 and the wireless frame transmitting unit 33 requests the queue managing unit 32 to transmit a new data packet, the queue managing unit 32 Causes the data packet input from the packet receiving unit 31 to be stored in the queue 321 in the queue management unit 32 or to be discarded.
[0044]
Here, whether the input data packet is discarded or stored in the queue 321 by the queue management unit 32 can be performed using an ERD (Early Random Drop) algorithm in the present embodiment. This algorithm is not limited to ERD, and other algorithms such as RED (Random Early Detection) may be used.
[0045]
The algorithm used in the present embodiment may be any algorithm that can change the parameter of the discard probability according to the transmission rate and the queue length. As shown in FIG. 4, it is assumed in the present embodiment that the broken line characteristics (theoretical characteristics) relating to the queue length and the drop probability using this algorithm are predetermined.
[0046]
Each broken line characteristic is such that a minimum value of the queue length (min thresh for −−kbps) is used as a reference position, and a straight line having a predetermined inclination from the reference position is drawn in accordance with the queue length and the transmission speed. It is. The queue management unit 32 uses the polygonal line characteristics to find a point where the value of the transmission rate set by the radio frame transmission unit 33 intersects with the value of the queue length stored in the queue 321. The queue management unit 32 determines the size corresponding to the vertical axis of the obtained point as the discard probability.
[0047]
When performing packet reception, the queue management unit 32 that has determined the discard probability based on the relationship between the transmission speed and the queue length stores the received packet in the queue 321 or discards the packet according to the determined discard probability.
[0048]
The queue management unit 32 sets an optimum queue length (reference length) according to the transmission rate notified from the transmission rate monitoring unit 34 or the magnitude of the delay time measured by the ACK packet division unit 37. is there. In the present embodiment, the optimum queue length can be expressed by a function of the transmission speed and the delay time. Here, the delay time means a time (round trip time) from when the server 50 transmits data to the corresponding mobile device 10 until the server 50 receives an ACK for the data.
[0049]
The wireless frame transmitting unit 33 transmits the data packet stored in the queue 321 to the corresponding mobile device 10. The wireless frame transmitting unit 33 sets the transmission speed of data packets to be transmitted to the mobile device 10. Here, the transmission speed dynamically changes according to the communication status between the wireless frame transmitting unit 33 and the mobile device 10. This transmission rate varies mainly within the range of 64-384 kbps.
[0050]
The transmission speed monitoring unit 34 notifies the queue management unit 32 and the ACK packet division unit 37 of the transmission speed grasped by the radio frame transmission unit 33. The transmission rate monitoring unit 34 is connected to the radio frame transmission unit 33, the queue management unit 32, and the ACK packet division unit 37.
[0051]
When receiving the ACK (response packet) transmitted from the mobile device 10 to the server 50, the wireless frame receiving unit 36 outputs the received ACK to the ACK packet dividing unit 37. The queue length monitoring unit 35 notifies the ACK packet division unit 37 of the queue length in the queue 321 sequentially. The queue length monitoring unit 35 is connected to the queue management unit 32 and the ACK packet division unit 37.
[0052]
The ACK packet division unit 37 collates the optimum queue length set by the queue management unit 32 with the queue length stored in the queue 321, and when the optimum queue length is larger than the queue length, the wireless frame receiving unit 36 This divides the received ACK (response packet) into a predetermined reference number.
[0053]
The ACK packet division unit 37 calculates the difference between the optimal queue length set by the queue management unit 32 and the queue length stored in the queue 321, and sets the reference number according to the calculated difference. Is preferred. Alternatively, it is preferable that the ACK packet division unit 37 sets the reference number according to the transmission rate set by the radio frame transmission unit 33.
[0054]
Specifically, the ACK packet division unit 37 compares the optimal queue length set by the queue management unit 32 with the queue length notified from the queue length monitoring unit 35. The ACK packet dividing unit 37 that has made the comparison divides the ACK input from the radio frame receiving unit 36 into a predetermined reference number when the relationship of optimum queue length> queue length holds.
[0055]
The divided ACK packet divider 37 outputs the divided ACK to the packet transmitter 38 as a divided signal. The packet transmitting unit 38 transmits the input divided signal to the server 50. The server 50 to which the divided signal is input from the packet transmitting unit 38 changes the congestion window according to the number of ACKs corresponding to the input divided signal.
[0056]
On the other hand, when the relationship of “optimum queue length> queue length” does not hold, the ACK packet division unit 37 outputs the ACK input from the radio frame reception unit 36 to the packet transmission unit 38 as it is.
[0057]
FIG. 3 is a diagram showing how the congestion window changes. FIG. 9 is an example of a change in the congestion window when the reference number for dividing one ACK is fixedly set to two. As shown in the figure, when the transmission speed changes from 64 kbps → 128 kbps → 64 kbps → 384 kbps → 64 kbps → 384 kbps, the optimum value of the congestion window changes according to the transmission speed. Thereby, the base station control unit 30 can make the congestion window in the server 50 close to the optimal value as a result by performing each of the above processes.
[0058]
(Transmission control system, data transmission method using base station controller)
The data transmission method by the transmission control system and the base station control device having the above configuration can be implemented by the following procedure.
[0059]
(1) Procedure until base station control section 30 divides ACK
FIG. 5 is a flowchart showing a procedure until the base station control unit 30 divides the ACK. As shown in FIG. 5, first, the mobile device 10 requests a data packet to the server 50 (S101). Note that the server 50 may establish a TCP connection toward the mobile device 10.
[0060]
The server 50 that has received the data packet request from the mobile device 10 transmits the data packet to the base station control unit 30 (S102). The packet receiving unit 31 receives the data packet transmitted from the server 50 and outputs the received data packet to the queue management unit 32.
[0061]
Next, the wireless frame transmitting unit 33 transmits the data packet transmitted from the server 50 to the corresponding mobile device 10 (S103). Specifically, the queue management unit 32 outputs the data packet stored in the queue 321 in the queue management unit 32 to the wireless frame transmission unit 33 based on the request from the wireless frame transmission unit 33. The wireless frame transmission unit 33 to which the data packet has been input from the queue management unit 32 transmits the input data packet to the mobile device 10.
[0062]
Next, the mobile device 10 transmits a response corresponding to the data packet transmitted from the base station control unit 30 to the server 50 as an ACK (response packet) (S104). The radio frame receiving unit 36 that has received the ACK transmitted from the mobile device 10 to the server 50 outputs the received ACK to the ACK packet dividing unit 37.
[0063]
Thereafter, the queue management unit 32 calculates an optimum queue length (reference length) according to the transmission speed notified from the transmission speed monitoring unit 34 or the magnitude of the delay time measured by the ACK packet division unit 37 (S105). ).
[0064]
Next, the ACK packet division unit 37 compares the optimal queue length set by the queue management unit 32 with the queue length stored in the queue 321, and when the optimal queue length is larger than the queue length, the radio frame receiving unit The ACK (response packet) received at 36 is divided into a predetermined reference number (S106).
[0065]
The divided ACK packet divider 37 outputs the divided ACK to the packet transmitter 38 as a divided signal. The packet transmitting unit 38 transmits the input divided signal to the server 50 (S108). The server 50 to which the divided signal has been input from the packet transmitting unit 38 changes the congestion window according to the number of ACKs corresponding to the input divided signal (S109).
[0066]
On the other hand, when the relationship of “optimum queue length> queue length” does not hold, the ACK packet division unit 37 outputs the ACK input from the radio frame reception unit 36 to the packet transmission unit 38 as it is. The packet transmitting unit 38 transmits the input ACK to the server 50.
[0067]
(2) Procedure until the queue management unit 32 determines the discard probability
First, the queue management unit 32 specifies the transmission speed set by the wireless frame transmission unit 33. In addition, the queue management unit 32 specifies the queue length stored in the queue 321. After that, the queue management unit 32 determines the discard probability according to the transmission speed of the specified data packet and the size of the queue length stored in the queue 321.
[0068]
Specifically, the queue management unit 32 uses the polygonal line characteristic shown in FIG. Ask. The queue management unit 32 determines the size corresponding to the vertical axis of the obtained intersection as the discard probability.
[0069]
When performing packet reception, the queue management unit 32 that has set the discard probability based on the relationship between the transmission speed and the queue length stores the received data packet in the queue 321 or discards it according to the determined discard probability.
[0070]
(program)
The contents described above can be realized by executing a dedicated program for using a predetermined program language on a general-purpose computer such as a personal computer.
[0071]
Note that the program can be recorded on a recording medium. As shown in FIG. 6, the recording medium includes, for example, a hard disk 60, a flexible disk 70, a compact disk 80, an IC chip 90, a cassette tape 100, and the like. According to the recording medium on which such a program is recorded, a trader who handles the program can easily store, transport, and sell the program.
[0072]
(Operation and effect of base station control device, data transmission method and program)
According to the invention of the present application, the queue management unit 32 transmits the message from the server 50 to the mobile device 10 according to the set transmission speed and the size of the queue length stored in the queue 321. The probability of discarding a data packet (discard probability) can be determined. Thereby, the queue management unit 32 can discard the data packet transmitted from the server 50 to the mobile device 10 with the above-mentioned discard probability.
[0073]
If the drop probability determined by the queue management unit 32 increases, all packet data transmitted from the server 50 to the mobile device 10 is not transmitted to the mobile device 10. Therefore, the server 50 reduces the congestion window by itself when the server 50 times out without receiving the duplicate ACK or the ACK within a predetermined time. If the congestion window is reduced, the queue management unit 32 transmits the data packet to the corresponding mobile device 10 quickly without discarding the data packet because the data packet received from the server 50 is reduced. Can be.
[0074]
In other words, by appropriately changing the discard probability by the queue management unit 32, the queue management unit 32 can consequently bring the congestion window in the server 50 closer to the optimum value.
[0075]
When the optimum queue length is larger than the queue length, the ACK packet division unit 37 can divide the ACK received from the mobile device 10 into a predetermined reference number. Thus, the server 50 can sequentially change the congestion window according to the number of ACKs divided by the ACK packet division unit 37.
[0076]
For example, when a burst-like packet loss occurs on the network and the congestion window in the server 50 is set to a minimum value by a specific protocol, the ACK packet division unit 37 determines the received ACK based on a preset criterion. By dividing the number into a number, the congestion window in the server 50 can be improved as a result.
[0077]
Further, when the current optimum queue length is larger than the queue length, the ACK packet dividing unit 37 can set the reference number to be divided higher. Setting this reference number high means that the queue length stored in the queue 321 by the queue management unit 32 can be further increased because the optimum queue length is larger than the queue length.
[0078]
If the reference number increases, the ACK packet division unit 37 divides the ACK received from the mobile device 10 with a high reference number. If ACKs increase due to this division, the server 50 increases the congestion window because many ACKs are returned. If the congestion window increases, the queue management unit 32 increases the data packet received from the server 50, and as a result, can increase the queue length. As a result, the ACK packet division unit 37 can make the congestion window in the server 50 close to the optimum value as a result.
[0079]
【The invention's effect】
As described above, according to the present invention, a data packet transmitted from a server to a mobile device is discarded at a predetermined probability, or a response packet transmitted from a mobile device to a server is transmitted under a predetermined condition. As a result, the congestion window in the server can be made closer to the optimal value.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of a transmission control system according to an embodiment.
FIG. 2 is a diagram showing an internal structure of a transmission control system according to the embodiment.
FIG. 3 is a diagram illustrating a state in which a congestion window according to the present embodiment changes with time.
FIG. 4 is a diagram illustrating a relationship between a transmission speed and a queue length according to the present embodiment.
FIG. 5 is a diagram showing a procedure of a data transmission method according to the embodiment.
FIG. 6 is a diagram showing a recording medium according to the embodiment.
FIG. 7 is a conventional diagram showing how a congestion window changes according to the size of time (part 1).
FIG. 8 is a conventional diagram showing how a congestion window changes according to the size of time (part 2).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Mobile station, 20 ... Base station, 30 ... Base station control part, 31 ... Packet receiving part, 32 ... Queue management part, 33 ... Radio frame transmission part, 34 ... Transmission speed monitoring part, 35 ... Queue length monitoring part, 36: Wireless frame receiving unit, 37: ACK packet dividing unit, 38: Packet transmitting unit, 40: Network, 50: Server, 60: Hard disk, 70: Flexible disk, 80: Compact disk, 90: IC chip, 100: Cassette Tape, 321 ... queue

Claims (12)

A mobile station and a server that distributes data packets are connected to a network, and a base station controller that determines a probability of discarding a data packet transmitted from the server to the mobile station,
A queue for temporarily storing a data packet to be transmitted to the mobile device as a queue length,
Speed setting means for setting a transmission rate of a data packet to be transmitted to the mobile device,
A probability of discarding a data packet transmitted from the server to the mobile device is determined according to the transmission rate set by the speed setting unit and the size of the queue length stored in the queue. A base station control device comprising: a discard probability determining unit. A base station control device, wherein a mobile station and a server that distributes data packets are connected to a network, and divides a response packet for a data packet transmitted from the server to the mobile station into a predetermined reference number, ,
A queue for temporarily storing a data packet to be transmitted to the mobile device as a queue length,
Dividing means for comparing a preset reference length with the queue length stored in the queue, and when the reference length is larger than the queue length, dividing the response packet into the preset reference number; And a base station controller. The base station control device according to claim 2,
A base unit that calculates a difference between a preset reference length and the queue length stored in the queue, and sets the reference number according to the calculated magnitude of the difference; Station control device. The base station control device according to claim 2,
Having a speed setting means for setting a transmission speed of a data packet to be transmitted to the mobile device,
The base station control device, wherein the dividing unit sets the reference number according to the transmission speed set by the speed setting unit. A data transmission method for determining a probability of discarding a data packet transmitted from the server to the mobile device, wherein the mobile device and a server that distributes the data packet are connected to a network,
A first step of temporarily storing a data packet to be transmitted to the mobile device in a queue as a queue length,
A second step of setting a transmission rate of a data packet to be transmitted to the mobile device,
According to the size of the queue length stored in the queue in the first step and the transmission rate set in the second step, the data packet transmitted from the server to the mobile device, A third step of determining a probability of discarding. A data transmission method, wherein a mobile device and a server that distributes data packets are connected to a network, and a response packet for a data packet transmitted from the server to the mobile device is divided into a predetermined reference number, A first step of temporarily storing a data packet to be transmitted to the mobile device in a queue as a queue length,
A second step of comparing a preset reference length with the queue length stored in the queue and dividing the response packet into the preset reference number when the reference length is larger than the queue length. And a data transmission method. The data transmission method according to claim 6, wherein
The second step is characterized in that a difference between a reference length set in advance and the queue length stored in the queue is calculated, and the reference number is set according to the calculated magnitude of the difference. Data transmission method. The data transmission method according to claim 6, wherein
The data transmission method according to claim 2, wherein in the second step, the reference number is set according to a transmission rate of a data packet transmitted to the mobile device. A program for determining a probability of discarding a data packet transmitted from the server to the mobile device, wherein the mobile device and a server that distributes the data packet are connected to a network,
On the computer,
A first step of temporarily storing a data packet to be transmitted to the mobile device in a queue as a queue length,
A second step of setting a transmission rate of a data packet to be transmitted to the mobile device,
According to the size of the queue length stored in the queue in the first step and the transmission rate set in the second step, the data packet transmitted from the server to the mobile device, And a third step of determining a probability of discarding the program. A mobile device and a server that distributes data packets are connected to a network, and a program that divides a response packet for a data packet transmitted from the server to the mobile device into a predetermined reference number,
A first step of temporarily storing a data packet to be transmitted to the mobile device in a queue as a queue length,
A second step of comparing a preset reference length with the queue length stored in the queue and dividing the response packet into the preset reference number when the reference length is larger than the queue length. And a program for executing a process having a step. The program according to claim 10, wherein:
The second step is for calculating a difference between a preset reference length and the queue length stored in the queue, and executing a process of setting the reference number according to the calculated magnitude of the difference. Program. The program according to claim 10, wherein:
The second step is a program for executing a process of setting the reference number according to a transmission rate of a data packet to be transmitted to the mobile device.

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