JP2011188429A - Radio communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication device that can shift to processing under congestion-evasion release from processing under congestion-evasion at an appropriate timing. <P>SOLUTION: A portable telephone set 1 includes: a communication section 40 to transmit data by radio; an ECN control section 31 that, when the congestion of network is detected, reduces the transmission window size than that before the congestion is detected, to avoid the congestion and controls it to extend gradually; a token control section 32 that sets the control method to a congestion-evasion mode when the network is under congestion-evasion and sets the control method to a normal mode when it is not under congestion-evasion; and a memory section 50 that stores the transmission window size at the timing when the congestion is detected, as a first value. The ECN control section 31 informs the token control section 32 of the starting of the congestion-evasion when the congestion is detected, and after the congestion is detected, it informs the token control section 32 of the completion of the congestion-evasion when the transmission window size becomes a second value specified on the basis of the first value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wireless communication apparatus that performs traffic control.

  Conventionally, a wireless communication device that is connected to an external electronic device such as a PC (Personal Computer) or performs wireless communication independently is known. In addition, in such a wireless communication apparatus, there is a traffic control method called a token bucket method for controlling a communication speed (throughput) so that network resources are not used excessively.

  The token bucket mechanism includes a packet buffer that stores input packets and a token bucket that stores tokens. When a predetermined amount of tokens accumulates in the token bucket, packets are output from the packet buffer, and the token bucket tokens decrease. In this way, the throughput of packets output to the external network is controlled by the amount (token rate) at which token tokens are replenished per unit time. This token rate dynamically changes depending on a predetermined parameter and the network environment, and is adjusted to be low when the network is congested and high when the network is free (see, for example, Patent Document 1).

  One of the congestion control methods of TCP (Transmission Control Protocol) is ECN (Explicit Congestion Notification). ECN is a method for avoiding congestion by limiting the transmission speed by allowing the TCP sender to detect congestion and notifying the TCP sender of congestion information.

JP 2007-189592 A

  By the way, when the traffic control (token bucket) and the congestion control (ECN) compete with each other, the traffic control may negate the effect of avoiding the congestion by the congestion control due to a delay in the traffic control. Therefore, in traffic control, it is desirable to detect the start and end of the congestion avoidance operation and switch between processing during congestion avoidance and processing during cancellation of congestion avoidance.

  However, even if the occurrence of congestion can be detected by notification from the external network, it is difficult to detect the end timing of the congestion avoiding operation by the congestion control, that is, the timing to shift to the processing during the cancellation of congestion avoidance.

  An object of the present invention is to provide a wireless communication apparatus capable of shifting from processing during congestion avoidance to processing during congestion avoidance cancellation at an appropriate timing.

  The wireless communication apparatus according to the present invention includes a communication unit that wirelessly transmits data to a network, and after detecting the congestion of the network, to reduce the transmission window size before the congestion detection in order to avoid the congestion Determining whether or not congestion is being avoided in the congestion control unit and controlling the communication speed by the communication unit in the congestion avoiding mode. If it is not being avoided, a traffic control unit that sets the control method to a normal mode and a storage unit that stores a transmission window size at the time when the congestion control unit detects congestion as a first value are provided. When the congestion control unit detects congestion, the congestion control unit notifies the traffic control unit that the avoidance of the congestion has started, and after detecting the congestion, When Usaizu becomes a second value which is specified based on the first value stored in the storage unit, to notify that the avoidance of the congestion has been completed to the traffic control unit.

  The second value is preferably smaller than the first value and larger than the transmission window size at the time when the congestion control unit reduces the second value.

  In addition, when the traffic control unit determines that congestion is being avoided in the normal mode, the traffic control unit switches to the congestion avoidance mode. When the traffic control unit determines that congestion is being avoided in the congestion avoidance mode, the congestion control mode is maintained. It is preferable to do.

  The congestion control unit preferably detects the congestion in response to receiving a data packet indicating that congestion has occurred in the network.

  A wireless communication apparatus according to the present invention includes a communication unit that wirelessly transmits data provided by a congestion control mechanism that executes a predetermined congestion avoidance operation when network congestion is detected, and congestion of the network. And determining whether or not congestion is being avoided in the congestion control mechanism, and if it is being avoided, the communication speed control method by the communication unit is set to a congestion avoidance mode, and if not being avoided, A traffic control unit that sets the control method to a normal mode; and a storage unit that stores a first time that is an elapsed time since the last time congestion was detected when the traffic control unit detected congestion of the network; When the congestion is detected, the traffic control unit determines that the congestion control mechanism has started avoiding the congestion, and detects the congestion. It determines after, when the second time has elapsed which is specified based on the first time stored in the storage unit, and the avoidance of the congestion has ended.

  The second time is preferably shorter than the first time.

  In addition, when the traffic control unit determines that congestion is being avoided in the normal mode, the traffic control unit switches to the congestion avoidance mode. When the traffic control unit determines that congestion is being avoided in the congestion avoidance mode, the congestion control mode is maintained. It is preferable to do.

  Moreover, it is preferable that the traffic control unit detects the congestion in response to receiving a data packet indicating that congestion has occurred in the network.

  The wireless communication apparatus according to the present invention is preferably connected to an external electronic device having the congestion control mechanism, and the communication unit transfers data received from the external electronic device to the network.

  ADVANTAGE OF THE INVENTION According to this invention, in the traffic control of a radio | wireless communication apparatus, it can transfer to the process in congestion avoidance cancellation | release at an appropriate timing.

It is a block diagram which shows the function of the mobile telephone which concerns on 1st Embodiment. It is a sequence diagram of congestion control by ECN according to the first embodiment. It is a figure which shows the time change of the congestion window size which concerns on 1st Embodiment. It is a block diagram which shows the structure of the upstream data flow in the token control part which concerns on 1st Embodiment. It is a figure which shows the time change of the congestion window size which concerns on 1st Embodiment, and the time change of the mode in a token control part. It is a figure which shows the transition pattern of the state in the token control part which concerns on 1st Embodiment. It is a sequence diagram which shows the flow of a process of the ECN control part and token control part which concern on 1st Embodiment. It is a block diagram which shows the function of the card terminal and PC which concern on 2nd Embodiment. It is a figure which shows the time change of the congestion window size which concerns on 2nd Embodiment, and the time change of the mode in a token control part. It is a figure which shows the transition pattern of the state in the token control part which concerns on 2nd Embodiment. It is a sequence diagram which shows the flow of a process of the token control part which concerns on 2nd Embodiment.

<First Embodiment>
The first embodiment of the present invention will be described below. In the present embodiment, a mobile phone 1 will be described as an example of a wireless communication device. The mobile phone 1 performs TCP data transmission / reception by an application such as a browser or a mailer.

FIG. 1 is a block diagram showing functions of the mobile phone 1 according to the present embodiment.
The mobile phone 1 includes an operation unit 10, a display unit 20, a control unit 30, a communication unit 40, an antenna 41, a storage unit 50, and an audio unit 60.

  The control unit 30 controls the entire mobile phone 1, and performs predetermined control on the display unit 20, the communication unit 40, the audio unit 60, and the like, for example. In addition, the control unit 30 receives input from the operation unit 10 or the like and executes various processes. And the control part 30 controls the memory | storage part 50 in the case of a process execution, reads various programs and data, and writes data.

  Further, the control unit 30 includes an ECN control unit 31 (congestion control unit) and a token control unit 32 (traffic control unit), and through these processes, the throughput of data transmitted from the communication unit 40 to the external network It has a function to adjust.

  The ECN control unit 31 sets the transmission rate of the data packet transmitted from the application of the mobile phone 1 based on the presence / absence of data indicating the occurrence of congestion in the external network (an ECE flag described later) as a congestion window size (transmission window size). Adjust by.

  FIG. 2 is a sequence diagram of congestion control by ECN according to the present embodiment. In this example, a TCP sender (mobile phone 1) and a TCP receiver communicate with each other via a router.

  The router determines that the network is congested when the amount of use of the buffer for storing packets waiting for transfer exceeds a certain threshold. When the router determines that the network is congested, it sets a CE flag indicating that it is experiencing congestion in the ToS field of the IP header of the packet, and forwards the packet to the TCP receiver (step S1).

  When the TCP receiver receives a packet in which the CE flag is set in the IP header, the TCP receiver sets an ECE (ECN-Echo) flag in the TCP header and transmits an acknowledgment packet (ACK) to the TCP sender. This is continued until a packet having a CWR (Congestion Window Reduced) flag in the TCP header is received from the TCP sender (step S2).

  The ECN control unit 31 determines that congestion has occurred when receiving a packet in which the ECE flag is set in the TCP header. Then, the ECN control unit 31 reduces the congestion window size to the slow start threshold (ssthresh: Slow Start Threshold) to lower the transmission rate, and sets the CWR flag in the TCP header of the packet to be transmitted thereafter and transmits the packet (Step S31). S3).

  When the TCP receiver receives a packet having the CWR flag set in the TCP header, the TCP receiver stops setting the ECE flag in the acknowledgment packet (step S4).

Here, a method for adjusting the congestion window size by slow start, which is the flow control method of the ECN control unit 31, will be described.
FIG. 3 is a diagram illustrating a temporal change in the congestion window size adjusted by the control of the ECN control unit 31 according to the present embodiment.

  The congestion window size is a data size that can be transmitted at one time without waiting for an ACK, and is controlled in units of MSS (Maximum Segment Size), that is, the maximum size of data that can be stored in one packet. The ECN control unit 31 determines the transmittable data size while increasing or decreasing the value with the reception window size notified from the TCP receiver as the upper limit.

  First, at the start of TCP communication, the ECN control unit 31 initializes the congestion window size with “MSS × 1”. That is, the ECN control unit 31 transmits data for one packet at the start of TCP transmission and waits for reception of an ACK. Thereafter, every time an ACK is received, the ECN control unit 31 increases the congestion window size by “MSS × number of received ACKs” (slow start mode). That is, under an ideal environment, the congestion window size during the slow start mode increases exponentially.

At time t1, when the ECN control unit 31 detects congestion,
ssthresh = congestion window size when congestion is detected ÷ 2 (1)
To update the value of ssthresh and set this value as the new congestion window size.

  Here, the ECN control unit 31 switches the congestion window increment. Specifically, every time an ACK is received, the ECN control unit 31 increases the congestion window size by “MSS × 1 ÷ congestion window size”. That is, if the ECN control unit 31 receives ACK for all the packets after sending data packets corresponding to the congestion window size, the congestion window size increases by “MSS × 1”. That is, under an ideal environment, the congestion window size during the congestion avoiding operation increases linearly.

  At time t2, when the ECN control unit 31 detects congestion during the congestion avoiding operation, the ECN control unit 31 updates ssthresh according to the equation (11), and updates the congestion window size value to the updated ssthresh value. Thereafter, the ECN control unit 31 repeats the same processing.

  ECN needs to have this function implemented in all the components of the TCP sender, TCP receiver, and router. Accordingly, when even one of the components is not mounted, the ECN control unit 31 cannot receive the ECE flag indicating the occurrence of congestion from the router. In this case, the ECN control unit 31 determines that congestion has occurred when the same ACK (duplicate ACK) is received a plurality of times (for example, three times).

  The token control unit 32 temporarily accumulates data packets transmitted according to the congestion window size controlled by the ECN control unit 31, and transmits the data packets to the external network via the communication unit 40 by traffic control called a token bucket scheme. The throughput of the data being sent.

  FIG. 4 is a block diagram showing the configuration of the upstream data flow in the token control unit 32 according to the present embodiment.

  First, a data packet to be transmitted to an external network is input to the token control unit 32 and stored in the packet buffer 321. In addition, tokens are added to the token bucket 322 for packet transmission at regular intervals (for example, 30 msec).

  If there is a sufficient amount of tokens in the token bucket 322, the token control unit 32 outputs the packets stored in the packet buffer 321 to the external network via the communication unit 40, and decreases the tokens in the token bucket 322. . When there are no more tokens in the token bucket 322, packets are not output until tokens are accumulated, and continue to accumulate in the packet buffer 321.

  That is, the token control unit 32 adjusts the throughput of data transmitted to the external network by controlling the token rate at which tokens are added to the token bucket 322.

  Here, the token control unit 32 is provided with two types of modes having different control contents, such as a token rate calculation method, in order to suppress a decrease in throughput due to competition with the congestion control by the ECN control unit 31. In other words, the token control unit 32 switches the processing content to the congestion avoidance mode when the ECN control unit 31 suppresses the transmission rate of the data packet and to the normal mode in the other state (congestion avoidance release state). . Details of the switching process will be described later.

  Returning to FIG. 1, the communication unit 40 communicates with an external device (base station) in a predetermined use frequency band (for example, a 2 GHz band, an 800 MHz band, or the like). The communication unit 40 demodulates the signal received from the antenna 41, supplies the processed signal to the control unit 30, modulates the signal supplied from the control unit 30, and transmits from the antenna 41 to the external device. Send to.

  The storage unit 50 includes, for example, a working memory and is used for arithmetic processing by the control unit 30. In addition, various programs according to the present embodiment are stored. Furthermore, the storage unit 50 stores a congestion window size (first value) at the time when the ECN control unit 31 detects congestion of the external network, a ssthresh, or a threshold (catresh: Congestion) used for determining congestion termination termination described later. (Avoidance Threshold, second value) is stored.

  The audio unit 60 performs predetermined audio processing on the signal supplied from the communication unit 40 under the control of the control unit 30, and outputs the processed signal to a receiver (not shown). The receiver outputs the signal supplied from the audio unit 60 to the outside. Note that this signal may be output from a speaker (not shown) instead of or together with the receiver.

  In addition, the voice unit 60 processes a signal input from a microphone (not shown) under the control of the control unit 30, and outputs the processed signal to the communication unit 40. The communication unit 40 performs a predetermined process on the signal supplied from the audio unit 60 and outputs the processed signal from the antenna 41.

  Hereinafter, the processing contents of the ECN control unit 31 and the token control unit 32 regarding the switching between the congestion avoidance mode and the normal mode will be described in detail. The token control unit 32 determines the switching timing between the above-described congestion avoidance mode and the normal mode by receiving a notification from the ECN control unit 31.

  FIG. 5 is a diagram illustrating a temporal change in the congestion window size and a temporal change in the mode in the token control unit 32 according to the present embodiment.

  At time t3, the ECN control unit 31 detects congestion of the external network and changes the congestion window size from “z” to “0.5z”. At this time, the ECN control unit 31 notifies the token control unit 32 that congestion avoidance has started. Upon receiving this start notification, the token control unit 32 determines that the ECN control unit 31 is in congestion avoidance, transitions to the congestion avoidance mode, and executes the congestion avoiding operation and the process at the time of contention.

At this time, the ECN control unit 31 is based on the congestion window size (z) when the congestion is detected.
cathresh = congestion window size × α (0.5 <α <1) (2)
Thus, the value of catresh, which is a congestion avoidance end determination threshold, is calculated. Here, catresh is smaller than the congestion window size (= z) at the time of detecting congestion and larger than ssthresh (= 0.5z).

Thereafter, the ECN control unit 31 gradually increases the congestion window size.
At time t4, the ECN control unit 31 detects that the congestion window size is equal to or greater than cathresh. Then, the ECN control unit 31 notifies the token control unit 32 that the congestion avoidance has been completed. Upon receiving this end notification, the token control unit 32 determines that the ECN control unit 31 is not in congestion avoidance, cancels the congestion avoidance mode, transitions to the normal mode, and performs normal processing that does not compete with the congestion avoidance operation. Execute.

  Note that the token control unit 32 maintains the congestion avoidance mode when it receives further notification of congestion avoidance during the congestion avoidance mode.

  Here, α in Expression (2) is such that the time from the start to the end of congestion avoidance is not too short (so as not to be close to 0.5), and further congestion avoidance starts during the congestion avoidance mode. It is preferable that the value is in the vicinity of “0.75” so that the notification is not received as much as possible (so as not to be in the vicinity of 1).

  FIG. 6 is a diagram showing a state (mode) transition pattern in the token control unit 32 according to the present embodiment.

  When the token control unit 32 receives the congestion avoidance start notification from the ECN control unit 31, it shifts to the congestion avoidance mode if it is in the normal mode, and maintains the current mode if it is in the congestion avoidance mode. Further, when the token control unit 32 receives the congestion avoidance end notification from the ECN control unit 31, if it is in the congestion avoidance mode, the token control unit 32 cancels the congestion avoidance mode and transitions to the normal mode. When the token control unit 32 receives the congestion avoidance end notification from the ECN control unit 31, the token control unit 32 is always in the congestion avoidance mode after receiving the start notification before, so it is not in the normal mode.

  FIG. 7 is a sequence diagram illustrating a processing flow of the ECN control unit 31 and the token control unit 32 according to the present embodiment.

  When the token control unit 32 is in the normal mode (S11), when the ECN control unit 31 detects the ECN congestion avoidance start notification, that is, the ECE flag of the TCP header (S12), the ECN control unit 31 transfers to the token control unit 32. The start of congestion avoidance is notified (S13).

  Upon receiving the congestion avoidance start notification, the token control unit 32 transitions to the congestion avoidance mode (S14). Further, the ECN control unit 31 once decreases the congestion window size to ssthresh (S15), and then gradually increases it.

  Thereafter, when the congestion window size increases and becomes equal to or greater than cathrest (S16), the ECN control unit 31 notifies the token control unit 32 of the end of congestion avoidance (S17). Upon receiving the congestion avoidance termination notification, the token control unit 32 cancels the congestion avoidance mode and transitions to the normal mode (S18).

  Thus, according to the present embodiment, the mobile phone 1 determines that congestion avoidance is started when the ECN control unit 31 detects congestion. In addition, the mobile phone 1 calculates a congestion avoidance end determination threshold (cathresh) based on the congestion window size at the time of detecting the congestion, and determines that the congestion avoidance ends when the congestion window size increases from ssthresh to cathresh. Therefore, the token control unit 32 can transition between the congestion avoidance mode and the normal mode at an appropriate timing by receiving the notification of the determination result.

  In the present embodiment, the wireless communication device has been described as the mobile phone 1, but in addition to a data dedicated terminal that does not have a voice call function, PHS (registered trademark; Personal Handyphone System), PDA (Personal Digital Assistant), Various devices such as a game machine, a navigation device, and a PC equipped with a wireless communication function may be used.

Second Embodiment
Hereinafter, a second embodiment of the present invention will be described. In the present embodiment, a card terminal 1a will be described as an example of a wireless communication device. The card terminal 1a is connected to the PC 2 (external electronic device), and transfers a data packet transmitted from the PC 2 to the external network by the communication unit 40. In addition, about the structure which is common in 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted or simplified.

FIG. 8 is a block diagram showing functions of the card terminal 1a and the PC 2 according to the present embodiment.
The card terminal 1a includes a control unit 30a, a communication unit 40, an antenna 41, and a storage unit 50a.

The PC 2 includes an ECN control unit 31a (congestion control mechanism), and performs TCP data transmission / reception by an application such as a browser or a mailer.
The ECN control unit 31a has the same function as the ECN control unit 31 of the first embodiment, and is transmitted from the application of the PC 2 based on the presence / absence of data indicating the occurrence of congestion in the external network (the ECE flag in the TCP header). The transmission rate of the data packet to be adjusted is adjusted by the congestion window size (transmission window size).

  The control unit 30a controls the entire card terminal 1a and performs predetermined control on each unit. Further, the control unit 30a receives input from the PC 2 or the like and executes various processes. Then, the control unit 30a controls the storage unit 50a to read various programs and data and write data when executing processing.

  Furthermore, the control unit 30a includes a token control unit 32a. Similar to the token control unit 32 of the first embodiment, the token control unit 32a has a function of adjusting the throughput of data transmitted from the communication unit 40 to the external network by the token bucket method.

  The storage unit 50a includes, for example, a working memory, and is used for arithmetic processing by the control unit 30a. In addition, various programs according to the present embodiment are stored. Furthermore, when the token control unit 32 detects congestion in the external network, the storage unit 50a has a congestion avoidance mode time (first time) that is an elapsed time since the previous congestion detection, or congestion avoidance described later. The expiration time of the congestion avoidance timer used for determining the end of the is stored.

  Hereinafter, the processing content of the token control unit 32a regarding the switching between the congestion avoidance mode and the normal mode will be described in detail. The token control unit 32a switches to the congestion avoidance mode in response to detecting data indicating the occurrence of congestion in the external network (ECE flag in the TCP header), and in response to the expiration of a congestion avoidance timer described later, the congestion avoidance mode. Release.

  FIG. 9 is a diagram showing a time change of the congestion window size and a time change of the mode in the token control unit 32a according to the present embodiment.

  At time t5, when detecting the occurrence of congestion in the external network, the token control unit 32a determines that the ECN control unit 31a is in congestion avoidance, transitions to the congestion avoidance mode, and performs processing to avoid congestion avoidance operation and contention. Execute. At this time, the ECN control unit 31a reduces the congestion window size to ssthresh and then gradually increases it. When the token control unit 32a transits to the congestion avoidance mode, the token control unit 32a stores the current time t5 in the storage unit 50a.

  At time t6, the token control unit 32a detects the occurrence of congestion again and shifts to the congestion avoidance mode. At this time, the token control unit 32a stores the current time t6 in the storage unit 50a and, at the same time, the congestion avoidance mode time s (= t6−) that is the elapsed time from the time t5 when the congestion was detected last time to the current time t6. t5) is calculated.

Further, the token control unit 32a, based on the congestion avoidance mode time (s),
Congestion avoidance timer expiration time = congestion avoidance mode time (s) × β (0 <β <1) (3)
Thus, the congestion avoidance timer expiration time used for determining whether to avoid congestion avoidance is calculated. Here, the expiration time of the congestion avoidance timer is greater than 0 and smaller than the congestion avoidance mode time (s). The expiration time of the congestion avoidance timer indicates the time until the end of congestion avoidance, and it is assumed that the congestion avoidance mode time is close to the previous time.

Further, the token control unit 32a detects the occurrence of congestion at time t6, and starts time measurement by the congestion avoidance timer when the transition to the congestion avoidance mode is made.
At time t7, the token control unit 32a detects that the congestion avoidance timer has expired, that is, the congestion avoidance timer expiration time has elapsed from time t6. Then, the token control unit 32a determines that the ECN control unit 31a is not in congestion avoidance, cancels the congestion avoidance mode, transitions to the normal mode, and executes normal processing that does not compete with the congestion avoidance operation.

  Note that the token control unit 32 maintains the congestion avoidance mode when it receives further notification of congestion avoidance during the congestion avoidance mode.

  Here, β in the expression (3) indicates that the time from the start to the end of congestion avoidance is not too short (so as not to be close to 0), and further the notification of congestion avoidance start is issued during the congestion avoidance mode. It is preferable to be in the vicinity of “0.5” so as not to be received as much as possible (so as not to be near 1).

  FIG. 10 is a diagram showing a state (mode) transition pattern in the token control unit 32a according to the present embodiment.

  When receiving the congestion avoidance start notification (ECE flag in the TCP header) from the external network (router) from the external network (router), the token control unit 32a starts the congestion avoidance timer and transitions to the congestion avoidance mode. On the other hand, if in the congestion avoidance mode, the token control unit 32a restarts the congestion avoidance timer and maintains the current state.

  Further, when the congestion avoidance timer expires, the token control unit 32 stops the congestion avoidance timer and cancels the congestion avoidance mode and transitions to the normal mode if the congestion avoidance timer is in the congestion avoidance mode. Note that the token control unit 32 is supposed to be in the congestion avoidance mode when the congestion avoidance timer starts, and therefore is not in the normal mode when the congestion avoidance timer expires.

  FIG. 11 is a sequence diagram illustrating a processing flow of the token control unit 32 according to the present embodiment.

  When the token control unit 32a is in the normal mode (S21), when the token control unit 32a detects the ECN congestion avoidance start notification, that is, the ECE flag in the TCP header (S22), the token control unit 32a is in the ECN control unit 31a. It is determined that the congestion avoidance operation is started.

  Then, the token control unit 32a calculates the congestion avoidance mode time and the congestion avoidance timer expiration time, starts the congestion avoidance timer (S23), and transitions to the congestion avoidance mode (S24).

  Thereafter, when time elapses and the congestion avoidance timer expires (S25), the token control unit 32a cancels the congestion avoidance mode and transitions to the normal mode (S26).

  Thus, according to the present embodiment, the card terminal 1a determines that congestion avoidance starts when the token control unit 32a detects congestion. The card terminal 1a calculates the congestion avoidance timer expiration time based on the time from the previous congestion detection time to the current congestion detection time, and when the elapsed time from the congestion detection time becomes the congestion avoidance timer expiration time, It is determined that congestion avoidance has ended. Therefore, by detecting occurrence of congestion and expiration of the timer in the token control unit 32a, even when the ECN control unit 31 is not provided on the card terminal 1a side, the congestion avoiding mode and the normal mode are set at appropriate timing. You can transition with.

  In the present embodiment, the wireless communication device has been described as the card terminal 1a that performs wireless communication by directly connecting to a PC or the like via USB or PCMCIA. However, the wireless communication device may be a communication module connected to an in-vehicle computer. . The wireless communication device may be various devices such as a mobile phone, a PHS (registered trademark), and a PDA used as a data communication modem.

  The same processing may be performed even when the ECN control unit 31a is provided on the wireless communication device side. The wireless communication device in this case may be various devices similar to those in the first embodiment.

  As mentioned above, although preferred embodiment was described, this invention can be implemented with a various form, without being limited to embodiment mentioned above. In addition, the effects described in the above-described embodiments are merely a list of the most preferable effects resulting from the present invention, and the effects according to the present invention are not limited to those described above.

  The ECN by the ECN control unit 31 (or 31a) and the token bucket by the token control unit 32 (or 32a) are examples of congestion control and traffic control, respectively, and the present invention is not limited to this.

1 Mobile phone (wireless communication device)
1a Card terminal (wireless communication device)
10 Operation unit 2 PC
20 Display unit 30, 30a Control unit 31, 31a ECN control unit (congestion control unit)
32, 32a Token control unit (traffic control unit)
40 Communication unit 41 Antenna 50, 50a Storage unit 60 Audio unit

Claims (9)

A communication unit for wirelessly transmitting data to the network;
A congestion control unit that controls the transmission window size to be gradually increased after the transmission window size is reduced from before the congestion detection in order to avoid the congestion when the network congestion is detected;
The congestion control unit determines whether or not congestion is being avoided. If the congestion is being avoided, the communication speed control method by the communication unit is set to a congestion avoidance mode. The traffic control unit to be mode,
A storage unit that stores a transmission window size at a time when the congestion control unit detects congestion as a first value;
When detecting the congestion, the congestion control unit notifies the traffic control unit that the congestion avoidance has been started, and after detecting the congestion, the transmission window size is stored in the storage unit. A wireless communication apparatus that, when the second value specified based on the value of 1 is reached, notifies the traffic control unit that the congestion avoidance has been completed.   2. The wireless communication apparatus according to claim 1, wherein the second value is smaller than the first value and larger than the transmission window size at the time when the second window is reduced by the congestion control unit.   The traffic control unit switches to the congestion avoidance mode if it is determined that congestion is being avoided in the normal mode, and maintains the congestion avoidance mode if it is determined that congestion is being avoided in the congestion avoidance mode. Item 3. A wireless communication device according to item 1 or item 2.   The wireless communication device according to any one of claims 1 to 3, wherein the congestion control unit detects the congestion in response to receiving a data packet indicating that congestion has occurred in the network. A communication unit that wirelessly transmits data provided by a congestion control mechanism that executes a predetermined congestion avoidance operation when network congestion is detected;
While detecting congestion of the network, it is determined whether or not congestion is being avoided in the congestion control mechanism, and if it is being avoided, the communication speed control method by the communication unit is set to a congestion avoidance mode and is being avoided. Otherwise, a traffic control unit that sets the control method to the normal mode,
A storage unit that stores a first time that is an elapsed time since the last time congestion was detected when the traffic control unit detected congestion of the network;
When detecting the congestion, the traffic control unit determines that the congestion control mechanism has started avoiding the congestion, and after detecting the congestion, based on the first time stored in the storage unit A wireless communication apparatus that determines that the avoidance of the congestion has ended when the specified second time has elapsed.   The wireless communication apparatus according to claim 5, wherein the second time is shorter than the first time.   The traffic control unit switches to the congestion avoidance mode if it is determined that congestion is being avoided in the normal mode, and maintains the congestion avoidance mode if it is determined that congestion is being avoided in the congestion avoidance mode. Item 7. The wireless communication device according to Item 5 or Item 6.   The wireless communication apparatus according to claim 5, wherein the traffic control unit detects the congestion in response to receiving a data packet indicating that congestion has occurred in the network. Connected to an external electronic device having the congestion control mechanism,
The wireless communication apparatus according to claim 5, wherein the communication unit transfers data received from the external electronic device to the network.

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