JP2008099171A - Wireless data communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide wireless data communication device for improving the throughput of communication, including a wireless section, using a communication protocol suitable for a cable network that is equipped with a function of confirming delivery of packets. <P>SOLUTION: A wireless data communications device 13 is configured to perform data communication, including a wireless section by using a communication protocol equipped with a function for confirming delivery of a packet, and is provided with a transmission ACK holding part 22 and a protocol processing part 23. The transmission ACK holding part 22 holds the number of transmission ACKs, predetermined according to the line quality of the wireless section. A protocol processing part 23 transmits ACK packets corresponding in number to transmission ACKs held by the transmission ACK holding part 22, when the ACK packets are transmitted with respect to a data packet received by the processing of the communication protocol. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to wireless data communication.

  With the rapid spread of mobile phones and wireless LANs (Local Area Networks), wireless data communication has become common in recent years. In the future, broadband wireless data communication systems such as HSDPA (High Speed Downlink Packet Access) and WiMAX (Worldwide Interoperability for Microwave Access) are expected to become popular. As the wireless data communication system becomes broadband, the ratio of wireless communication or mobile communication in the field of data communication represented by the Internet increases.

  FIG. 8 is a block diagram illustrating a configuration example of a wireless data communication system. Referring to FIG. 8, the wireless data communication system includes a base station 91, a server 92, and a mobile terminal 93. In this example, a wireless section is between the base station 91 and the mobile terminal 93. Base station 91 and server 92 are connected by a wired network.

  In this type of wireless data communication system, TCP / IP (Transmission Control Protocol / Internet Protocol) is used as a communication protocol, similarly to wired data communication. In the wireless data communication system of FIG. 8, the mobile terminal 93 and the base station 91 or the server 92 terminate TCP / IP.

  TCP / IP is a connection-type communication protocol, and has a packet delivery confirmation and retransmission function, and thus is highly reliable as a stable and efficient protocol (see Patent Document 1). FIG. 9 is a diagram illustrating an example of a TCP / IP communication sequence. Here, an example is shown in which data is transmitted from the transmitting device to the receiving device. In downlink data communication, the base station 91 is a transmitting device, and the mobile terminal 93 is a receiving device. In uplink data communication, the mobile terminal 93 is a transmission side device, and the base station 91 is a reception side device. Data transfer is started after a connection is established in advance between the transmission side device and the reception side device.

  The transmission side apparatus packetizes the data, assigns a sequence number to the packet, and transmits the packet to the reception side apparatus. The sequence number is a number indicating the order of packets, and the value differs for each packet. Referring to FIG. 9, a packet with a sequence number of 1000 (Seq1000) is sent, and then a packet with a sequence number of 2000 (Seq2000) is sent.

  When receiving the data packet from the transmission side apparatus, the reception side apparatus transmits an ACK packet in which the sequence number assigned to the packet is described to the transmission side apparatus. This ACK packet indicates that the packet with the described sequence number has been normally received. In order to improve communication efficiency, the receiving side apparatus often returns a single ACK packet after receiving a plurality of packets from the transmitting side apparatus. In FIG. 9, one ACK packet (ACK2000) in which a sequence number 2000 is written is returned for two packets of a Seq1000 packet and a Seq2000 packet.

  FIG. 10 is a diagram illustrating another example of the sequence of TCP / IP communication. This is an example in which an ACK packet is lost. As shown in FIG. 10, since the ACK packet for the Seq1000 packet and the Seq2000 packet is lost, the transmitting side apparatus cannot confirm that these two packets have been delivered to the receiving side apparatus. Therefore, the transmission side apparatus retransmits the Seq1000 packet and the Seq2000 packet after timeout.

  As shown in FIGS. 9 and 10, in TCP / IP, the transmission side device and the reception side device ensure the stability and reliability by advancing data transfer while confirming the delivery of the packet.

In this type of wireless data communication, the downlink speed is more important than the uplink, and the theoretical value of the downlink is often set higher than the theoretical value of the uplink.
JP 2006-50295 A

  However, TCP / IP is a protocol originally developed with the intention of being used in a wired network environment, and is not intended for wireless communication. In wireless communication, noise and interference are more likely to occur than in a wired network environment, and transmission errors and packet losses frequently occur. In data communication by TCP / IP in such an unstable wireless environment, the frequency of retransmissions increases, and communication performance (throughput) as in a wired network environment cannot be obtained.

  In particular, in communication in an environment where the received signal strength (RSSI: Received Signal Strength Indicator) is low, not only data packet loss but also ACK packet loss occurs as shown in FIG. Similarly, when a handover occurs, a loss occurs not only in the data packet but also in the ACK packet. If the ACK packet is lost, since the delivery of the data packet cannot be confirmed, the transmitting side apparatus retransmits the data packet.

  A method for improving the total throughput by using a protocol suitable for the wireless environment only in the wireless section can be considered against such a decrease in communication performance due to packet loss in the wireless section. However, it is not practical to apply a dedicated communication protocol to the wireless section at the present time when the wireless communication system and the wired communication system are integrated and all-IP is being realized.

  An object of the present invention is to provide a wireless data communication apparatus having a packet delivery confirmation function and capable of improving communication throughput including a wireless section using a communication protocol suitable for a wired network. .

In order to achieve the above object, a wireless data communication apparatus of the present invention provides:
A wireless data communication apparatus that performs data communication including a wireless section using a communication protocol having a packet delivery confirmation and retransmission function,
A transmission ACK number holding unit that holds a predetermined number of transmission ACKs according to the channel quality of the radio section;
A protocol processing unit that transmits ACK packets for the number of transmission ACKs held in the transmission ACK number holding unit when transmitting an ACK packet for the data packet received in the processing of the communication protocol; ing.

  According to the present invention, the wireless data communication apparatus transmits the ACK packet for the received data packet by the number of transmission ACKs determined in advance according to the channel quality in the wireless section, so that the retransmission of the data packet due to the loss of the ACK packet Can be suppressed, and the throughput of communication including the wireless section can be improved.

  Further, it further includes a transmission ACK number control unit that measures the channel quality in the radio section and dynamically controls the number of transmission ACKs held in the transmission ACK number holding unit according to the obtained channel quality. It may be.

  According to this, the number of transmission ACKs is dynamically controlled according to the channel quality in the radio section, and ACK packets corresponding to the number of transmission ACKs are transmitted for received data packets. Increase the number to suppress retransmission of data packets, reduce the number of ACK packets when the line quality is good, excess traffic flows on the network, and waste of the second and subsequent ACK packets in the opposite device It is possible to reduce processing and improve throughput.

  In addition, the transmission ACK number control unit may determine the number of transmission ACKs according to the received signal strength of the radio section.

  Further, it may be a mobile terminal that performs data communication by wireless connection with a base station of a wireless communication system.

  According to this, only the function of transmitting the number of ACK packets according to the quality of the radio section is added to the mobile terminal, and the speed is emphasized without changing the communication protocol of the apparatus on the radio communication system side. Downlink throughput can be improved.

In addition, each data packet is given a sequence number of a different value,
The protocol processing unit may transmit an ACK packet describing a sequence number given to the received data packet by the number of transmission ACKs held in the transmission ACK number holding unit.

  The communication protocol may be TCP / IP.

  According to the present invention, the wireless data communication apparatus transmits the ACK packet for the received data packet by the number of transmission ACKs determined in advance according to the channel quality in the wireless section, so that the retransmission of the data packet due to the loss of the ACK packet Can be suppressed, and the throughput of communication including the wireless section can be improved.

  Embodiments for carrying out the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of a wireless data communication system according to the first embodiment. Referring to FIG. 1, the wireless data communication system includes a base station 11, a server 12, and a mobile terminal 13. In this example, a wireless section is between the base station 11 and the mobile terminal 13. Base station 11 and server 12 are connected by a wired network. In this system, TCP / IP is used as a communication protocol, and the mobile terminal 13 and the base station 11 or the server 12 terminate TCP / IP.

  The mobile terminal 13 and the base station 11 or the server 12 exchange data with each other. Here, as an example, it is assumed that the downlink speed from the base station 11 or the server 12 to the mobile terminal 13 is emphasized, and the theoretical value of the downlink is set higher than the theoretical value of the uplink. The data communication on the downlink will be mainly described.

  The base station 11 or the server 12 that terminates TCP / IP has a function of terminating known TCP / IP. The base station 11 or the server 12 packetizes data by TCP / IP and transmits it to the mobile terminal 13. At this time, if the ACK packet from the mobile terminal 13 is not returned, the base station 11 or the server 12 retransmits the data packet due to timeout.

  The mobile terminal 13 has a function for terminating the improved TCP / IP. When the mobile terminal 13 receives a TCP / IP packet from the base station 11 or the server 12, the mobile terminal 13 returns an ACK packet. At that time, in the improved TCP / IP, the mobile terminal 13 returns a plurality of the same ACK packets. This reduces the occurrence of data packet retransmission due to loss of ACK packets.

  FIG. 2 is a block diagram showing the configuration of the mobile terminal according to the first embodiment. Referring to FIG. 2, the mobile terminal 13 includes a data communication unit 21, a transmission ACK number holding unit 22, and a protocol processing unit 23.

  The data communication unit 21 performs data communication in accordance with, for example, an application or a user instruction. In data communication, the data communication unit 21 transmits data to or receives data from a counterpart device (not shown) via the protocol processing unit 23.

  The protocol processing unit 23 processes a communication protocol with the base station 11 or the server 12 and enables the data communication unit 21 to transmit and receive data. Here, TCP / IP is used as a communication protocol.

  In the data transmission process, the protocol processing unit 23 packetizes the data received from the data communication unit 21 and transmits the data packet to the base station 11. Then, the protocol processing unit 23 confirms whether or not the data packet has been delivered by the ACK packet from the base station 11. In this confirmation, the protocol processing unit 23 associates the data packet with the ACK packet by comparing the sequence number assigned to the transmitted data packet with the sequence number described in the received ACK packet. If the ACK packet can be received, the protocol processing unit 23 determines that the data packet has been delivered to the base station 11 or the server 12 that terminates TCP / IP. If the ACK packet cannot be received within a predetermined time from the transmission of the data packet, the protocol processing unit 23 determines that the data packet has not been delivered and retransmits the data packet.

  In the data reception process, when receiving a data packet from the base station 11, the protocol processing unit 23 extracts a sequence number given to the data packet, and generates an ACK packet describing the sequence number. Then, the protocol processing unit 23 acquires the transmission ACK number from the transmission ACK number holding unit 22, and repeats transmission of the ACK packet by the number of times indicated by the transmission ACK number. The same sequence number is described in the ACK packet transmitted at that time. In order to improve communication efficiency, the protocol processing unit 23 may transmit one ACK packet after receiving a plurality of data packets. In this case, the ACK packet describes the sequence number assigned to the last received data packet.

  The transmission ACK number holding unit 22 holds a transmission ACK number indicating the number of times to transmit the same ACK packet. The number of transmission ACKs may be arbitrarily set according to, for example, the communication environment in the wireless section.

  FIG. 3 is a diagram illustrating an example of a communication sequence according to the first embodiment. Here, an example in which data is transmitted from the base station 11 to the mobile terminal is shown. Data transfer is started after a connection is established in advance between the base station 11 and the mobile terminal 13.

  The base station 11 packetizes the data, assigns a sequence number to the data packet, and transmits it to the mobile terminal 13. In the example of FIG. 3, a packet with a sequence number of 1000 (Seq1000) is first sent, and then a packet with a sequence number of 2000 (Seq2000) is sent.

  When the mobile terminal 13 receives the data packet from the base station 11, the mobile terminal 13 transmits a plurality of ACK packets describing the sequence numbers given to the data packet to the mobile terminal 13.

  Here, it is assumed that the number of transmission ACKs is set to “3”. Here, in order to improve the communication efficiency, the mobile terminal 13 receives two packets from the base station 11 and then returns one type (three) of ACK packets. Referring to FIG. 3, three ACK packets (ACK2000) in which sequence number 2000 is described are returned for two packets of a Seq1000 packet and a Seq2000 packet.

  When receiving one ACK packet, the base station 11 ignores or discards it even if it receives an ACK packet in which the same sequence number is described thereafter. Then, the base station 11 continues to transmit subsequent data packets (Seq3000, Seq4000).

  FIG. 4 is a diagram illustrating another example of a communication sequence according to the first embodiment. This is an example in which an ACK packet is lost. Referring to FIG. 4, two of the three ACK packets (ACK2000) for the Seq1000 packet and the Seq2000 packet are lost. However, one ACK packet is received by the base station 11. Since the base station 11 can confirm that the data packet has been delivered to the mobile terminal 13 by receiving the ACK packet, the base station 11 can continue to transmit subsequent data packets (Seq3000, Seq4000).

  As described above, according to the present embodiment, since the mobile terminal 13 transmits a plurality of ACK packets for the received data packet, the occurrence of retransmission of the data packet due to the loss of the ACK packet is suppressed, and the radio section is transmitted. It is possible to improve the throughput of communication including.

  Further, in the present embodiment, only the function of transmitting a plurality of ACK packets to the mobile terminal 13 is added, and the speed down is emphasized without changing the TCP / IP processing of the base station 11 or the server 12. Link throughput can be improved.

(Second Embodiment)
In the first embodiment, the number of transmission ACKs is a fixed value set in advance, but in the second embodiment, the number of transmission ACKs is dynamically controlled according to the channel quality of the radio section. This reduces the number of ACK packet transmissions by suppressing the number of ACK packet transmissions when the line quality is poor, reduces the number of ACK packet transmissions when the line quality is good, and reduces waste of ACK packet discard processing, etc. Can do. Thereby, the communication throughput can be further improved.

  The wireless data communication system according to the second embodiment has the same configuration as the wireless data communication system according to the first embodiment shown in FIG. The second embodiment differs from the first embodiment only in the internal configuration of the mobile terminal 13.

  FIG. 5 is a block diagram showing the configuration of the mobile terminal according to the second embodiment. Referring to FIG. 5, the mobile terminal 13 includes a data communication unit 21, a transmission ACK number holding unit 22, a protocol processing unit 23, and a transmission ACK number control unit 31. The data communication unit 21, the transmission ACK number holding unit 22, and the protocol processing unit 23 are the same as those in the first embodiment shown in FIG.

  The transmission ACK number control unit 31 measures the channel quality in the radio section and controls the number of transmission ACKs held in the transmission ACK number holding unit 23 according to the channel quality. As a specific example, it is assumed that received signal strength (RSSI) is used as the channel quality of the radio section. The transmission ACK number control unit 31 may acquire the RSSI measurement value periodically, determine the transmission ACK number corresponding to the measurement value, and set the transmission ACK number in the transmission ACK number holding unit 22. Here, as an example, the time interval for controlling the number of transmission ACKs is 100 msec.

  FIG. 6 is a table showing the correspondence between RSSI and the number of transmission ACKs in the control of the number of transmission ACKs according to the second embodiment. If RSSI is 20% or less, the number of transmission ACKs is “3”. If the RSSI is greater than 20% and less than or equal to 50%, the number of transmission ACKs is “2”. If RSSI is larger than 50%, the number of transmission ACKs is “1”. In the example of FIG. 6, the RSSI measurement value is displayed as a percentage, but may be displayed in decibels or absolute value.

  FIG. 7 is a flowchart showing the control operation of the number of transmission ACKs in the mobile terminal according to the second embodiment. Referring to FIG. 7, the transmission ACK number control unit 31 of the mobile terminal 13 first acquires RSSI (step 101). Subsequently, the transmission ACK number control unit 31 determines whether the RSSI is greater than 50% (step 102). If the RSSI is greater than 50%, the transmission ACK number control unit 31 determines the transmission ACK number as “1” (step 103).

  If the RSSI is 50% or less, the transmission ACK number control unit 31 determines whether or not the RSSI is greater than 20% (step 104). If the RSSI is greater than 20%, the transmission ACK number control unit 31 determines the transmission ACK number as “2” (step 105). If the RSSI is 20% or less, the transmission ACK number control unit 31 determines the transmission ACK number as “3” (step 106).

  Finally, the transmission ACK number control unit 31 sets the transmission ACK number in the transmission ACK number holding unit 22 (step 107).

  As described above, according to the present embodiment, the mobile terminal 13 dynamically controls the number of transmission ACKs according to the channel quality of the radio section, and the ACK packet corresponding to the number of transmission ACKs with respect to the received data packet. Send. Therefore, when the line quality is poor, it is possible to increase the number of ACK packets as in the first embodiment to suppress retransmission of data packets and improve throughput. In addition, when the line quality is good, the number of ACK packets is reduced, excess traffic flows on the network, and the base station 11 or the server 12 reduces unnecessary processing for discarding the second and subsequent ACK packets. Throughput can be improved.

1 is a block diagram showing a configuration of a wireless data communication system according to a first embodiment. It is a block diagram which shows the structure of the mobile terminal by 1st Embodiment. It is a figure which shows an example of the sequence of communication by 1st Embodiment. It is a figure which shows the other example of the sequence of communication by 1st Embodiment. It is a block diagram which shows the structure of the mobile terminal by 2nd Embodiment. It is a table | surface which shows a response | compatibility with RSSI and the number of transmission ACKs in control of the number of transmission ACKs of 2nd Embodiment. 6 is a flowchart showing a control operation of the number of transmission ACKs in the mobile terminal according to the second embodiment. It is a block diagram which shows the structural example of a radio | wireless data communication system. It is a figure which shows an example of the sequence of TCP / IP communication. It is a figure which shows the other example of the sequence of TCP / IP communication.

Explanation of symbols

11 base station 12 server 13 mobile terminal 21 data communication unit 22 transmission ACK number holding unit 23 protocol processing unit 31 transmission ACK number control unit 101 to 107 steps

Claims (6)

A wireless data communication device that performs data communication including a wireless section using a communication protocol having a packet delivery confirmation function,
A transmission ACK number holding unit that holds a predetermined number of transmission ACKs according to the channel quality of the radio section;
A protocol processing unit that transmits an ACK packet for the number of transmission ACKs held in the transmission ACK number holding unit when transmitting an ACK packet for the data packet received in the processing of the communication protocol; Data communication device.   The transmission ACK number control unit that measures the channel quality of the radio section and dynamically controls the number of transmission ACKs held in the transmission ACK number holding unit according to the obtained channel quality. The wireless data communication apparatus according to 1.   The wireless data communication apparatus according to claim 2, wherein the transmission ACK number control unit determines the transmission ACK number according to the received signal strength of the wireless section.   The wireless data communication apparatus according to any one of claims 1 to 3, wherein the wireless data communication apparatus is a mobile terminal that performs wireless data connection with a base station of a wireless communication system. Each data packet is given a different sequence number,
The protocol processing unit transmits an ACK packet that describes a sequence number assigned to the received data packet by the number of transmission ACKs held in the transmission ACK number holding unit. The wireless data communication apparatus according to any one of the above.   The wireless data communication apparatus according to claim 1, wherein the communication protocol is TCP / IP.

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