JP2006086611A - Information processor, information processing system, information processing method, and program thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To save power greatly while restraining a decrease in throughput as much as possible in data communication. <P>SOLUTION: A transmission side Web server 1 gives an ACK necessary/unnecessary flag for indicating whether data concerned are data segment requesting ACK or not when the data segment is transmitted. A reception side cellular phone 2 refers to the ACK necessary/unnecessary flag when it receives the data segment and returns ACK only to the data segment to which the ACK necessary/unnecessary flag is given, thus reducing the number of ACKs to be transmitted greatly and reducing power consumed by the Web server 1 and the cellular phone 2 greatly. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an information processing apparatus, an information processing system, an information processing method, and a program thereof capable of transmitting and receiving various types of data using a predetermined protocol.

  In conventional Internet systems, the emphasis was placed on how efficiently large volumes of data could be transmitted and received, so the system was designed with the highest priority on factors such as throughput and delay.

The transport layer communication protocol used in the Internet includes, for example, connectionless UDP (User Datagram Protocol) and TCP (Transmission Control Protocol) that secures reliability by performing a connection. The receiving side transmits a NACK (Negative ACKnowledgement) only when the data transmitted from the transmitting side cannot be normally received, and the transmitting side retransmits the data only for the NACK, thereby reducing network congestion. There has been proposed a transmission / reception apparatus capable of preventing and distributing data efficiently to a large number of users with high reliability (see Patent Document 1).
Japanese Patent Laid-Open No. 11-17737 (paragraph [0117], FIG. 3 etc.)

  By the way, there is a remarkable progress in wireless communication technology today, and wireless communication that can use a network without being restricted by a place is expected to have many influences in the industry. In particular, an ad hoc network constructed by a plurality of wireless terminals brings new innovation to services using the network, and is attracting attention in applications such as multi-hop sensor networks and mesh networks.

  In a network configured by wireless communication, it is important to design a power saving communication infrastructure. The biggest advantage of wireless communication is that it can move around freely from the limitations of communication cables. Since power supply in such wireless communication basically uses a battery, the power capacity is limited. In particular, in a sensor network formed by a plurality of sensor nodes, setting to a place where recharging of the node is difficult is also assumed, and thus power saving is a top priority in system design. However, in the conventional network system that places importance on performance such as throughput and delay as in the technique of the above-mentioned Patent Document 1, since it does not focus on realizing power-saving data communication, it is applied to wireless communication. In such a case, the power consumption becomes high.

  On the other hand, TCP, which is used in many current applications, is a robust communication protocol that has been improved a lot, but it is currently not optimized in terms of power saving. Although there is a movement to propose a communication protocol specialized for power saving, designing a reliable protocol that realizes performance higher than TCP when many connections share the same network resource with unicast communication It's not easy. In addition, when considering sustainability with the Internet environment, it is less burdensome to communicate with TCP than to perform protocol conversion with a relay node. Therefore, it can be said that TCP power saving is an important issue.

  In view of the circumstances as described above, an object of the present invention is to provide an information processing apparatus, an information processing system, an information processing method, and a program therefor, which can greatly reduce power consumption while minimizing a decrease in throughput in data communication. There is.

  In order to solve the above-described problem, an information processing apparatus of the present invention is an information processing apparatus connected to another information processing apparatus via a network, and receives data from the other information processing apparatus using a predetermined protocol. Receiving means for determining, determining means for determining whether or not it is necessary to transmit an acknowledgment for the received data, and an acknowledgment for data determined to be required to transmit the confirmation response out of the received data Is transmitted to the other information processing apparatus.

  Here, the predetermined protocol is, for example, Internet layer TCP, UDP, and other protocols. The confirmation response refers to an affirmative response for the data transmission destination computer to notify the transmission source computer that the data has been received, and is usually called ACK (ACKnowledgement).

  According to the above configuration, every time data is received from the other information processing apparatus, it is determined whether or not a confirmation response to the data is necessary, and only a necessary confirmation response is returned to the other information processing apparatus. Since it is possible to prevent the confirmation response from being transmitted, it is possible to greatly reduce the power consumed by transmitting such a useless confirmation response. In addition, throughput performance in conventional data communication can be maintained as much as possible while realizing power saving.

  In the information processing apparatus, the determination unit determines that it is necessary to transmit a confirmation response to the received data when the next data is not received for a predetermined time after the data is received. Also good.

  Here, the predetermined time is, for example, in the range of about 1 ms to 500 ms, and more preferably in the range of 1 ms to 10 ms. However, the network environment such as the number and distance of information processing devices sharing the network, applications used by the information processing devices, etc. Thus, it can be appropriately changed to other ranges. Confirmation sent to the other information processing apparatus by sending an acknowledgment only to the data received after the lapse of the predetermined time without transmitting an acknowledgment for the data received before the lapse of the predetermined time. Responses can be reduced, and as a result, data communication can be performed while saving power. Specifically, for example, a delay timer that times out for a predetermined time from the time when data is received is provided, and the delay timer is reset every time data is received before the elapse of the predetermined time. As a result, the confirmation response is not returned for data whose reception interval is shorter than the predetermined time, but is returned only for data whose reception interval is longer than the predetermined time.

  In the information processing apparatus, the received data is provided with a flag indicating whether the confirmation response transmission is necessary or not by the other information processing apparatus, and the determination unit refers to the flag to You may make it judge the necessity of transmission of a confirmation response. For example, when a series of data corresponding to the window size is transmitted / received by window control in TCP, the other information processing apparatus is given a flag indicating that a confirmation response is required only for the last data of the window, Other data is given a flag indicating that no confirmation response is required. By referring to the flag, it is possible to easily determine whether the confirmation response is necessary, and by transmitting only the necessary confirmation response, it is possible to perform power-saving data communication.

  In the information processing apparatus, the predetermined protocol is TCP, and the determination unit, when a control flag is attached to the received data, indicates a flag type indicating whether or not the confirmation response needs to be transmitted. Regardless, it may be determined that it is necessary to transmit an acknowledgment for the received data.

  Here, the control flag is a flag such as SYN (Synchronize Flag), FIN (Fin Flag), RST (Reset Flag), PUSH (Push Flag), URG (Urgent Flag), etc. in TCP. In the case of SYN, for example, the connection is started, the connection is ended if FIN, the connection is reset if RST, the data is immediately passed to the application if PUSH, and the data to be processed urgently if URG. For these control flags, even if the flag indicating whether or not the confirmation response is necessary is turned off, by sending the confirmation response, priority processing of the meaning of each control flag is executed. And compatibility with conventional TCP can be maintained.

  The information processing apparatus includes means for recognizing a first sequence number of data to be received next to the received data each time data is received, the recognized first sequence number, Means for comparing with the second sequence number of the data received first after the recognition, and when the result of the comparison is that the second sequence number is larger, Regardless of the type of flag indicating the necessity of transmission of the confirmation response given to the data of the second sequence number, the data of the sequence number immediately before the first sequence number has already been transmitted. It may be determined that the confirmation response needs to be transmitted again, and the transmission unit may perform control so that the number of retransmissions does not exceed four times.

  As a result, for example, if there is a missing sequence (sequence number) of a plurality of received data, even if the flag indicating whether the confirmation response transmission is necessary is off, the data of the missing sequence number By transmitting the confirmation response to the previous data, that is, the confirmation response requesting retransmission of the missing sequence number, it is possible to execute so-called TCP fast-retrans-mission. Therefore, compatibility with conventional TCP can be maintained. Further, by limiting the number of duplicate transmissions to three, it is possible to prevent as much as possible from consuming electric power by transmitting duplicate confirmation responses indefinitely.

  The information processing system of the present invention is a system in which a first information processing device and a second information processing device are connected via a network, and the first information processing device is the second information processing device. And a first transmission unit for transmitting the flag-added data according to a predetermined protocol to the data to be transmitted to the data. The second information processing apparatus is configured to receive the data transmitted from the first information processing apparatus according to the predetermined protocol and to the received data based on the assigned flag. A determination means for determining whether or not it is necessary to transmit an acknowledgment; and a confirmation response to the data determined to be required to be transmitted among the received data. And a second transmitting means for transmitting to the broadcast processing apparatus.

  With this configuration, the second information processing apparatus transmits the data to the second information processing apparatus with a flag indicating whether or not a confirmation response to the data transmitted by the first information processing apparatus is necessary. Since only the response is transmitted, the number of unnecessary confirmation responses is reduced. As a result, the power consumption of the second information processing apparatus can be greatly reduced. In addition, the throughput performance in the conventional data communication can be maintained as much as possible while realizing power saving.

  In the information processing system, the predetermined protocol is TCP, the first transmission unit continuously transmits a plurality of data by window control, and the assigning unit stores a plurality of data to be transmitted. Of these, a flag indicating that transmission of the confirmation response is required may be added to data having the largest sequence number, and a flag indicating that transmission of the confirmation response is not required may be added to other data. Thereby, for example, in the TCP window control, the first information processing apparatus transmits a series of data corresponding to the window size with a flag requesting only an acknowledgment for the last data of the window. The information processing apparatus can easily determine that it is only necessary to return a confirmation response to the last data in the received series of data with reference to the flag, without requiring complicated processing. Power saving can be realized.

  The information processing method of the present invention is a method in which an information processing apparatus connected to another information processing apparatus via a network processes information, and receives data from the other information processing apparatus using a predetermined protocol. Determining whether or not it is necessary to transmit an acknowledgment for the received data; and confirming an acknowledgment for data that is determined to need to be transmitted among the received data. And transmitting to the information processing apparatus.

  The program of the present invention includes a step of receiving data from the other information processing apparatus according to a predetermined protocol to an information processing apparatus connected to the other information processing apparatus via a network; A step of determining whether or not it is necessary to transmit an acknowledgment; and a step of transmitting an acknowledgment to the other information processing apparatus for the data determined to be necessary to transmit the acknowledgment from the received data. Is to execute.

  According to the present invention, in data communication, significant power saving can be achieved while suppressing a decrease in throughput as much as possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  An object of the present invention is to reduce power consumed in data communication, particularly wireless communication by a portable terminal. First, power consumption in wireless communication will be described. Here, the relationship between power consumption in IEEE802.11 used as a general wireless LAN (Local Area Network) and TCP will be described as an example.

  L. M. Feeney has modeled IEEE802.11 peer-to-peer power consumption from actual measurements. In this model, power consumption is expressed as Energy = m × size + b. In this embodiment, the power consumption is obtained using the measurement result of the 2.4 GHz IEEE802.11 11 Mbps WaveLAN PC Card. FIG. 1 illustrates the power consumed in data communication between the nodes A and B and the C, D, and E nodes existing in the vicinity when the packet is transmitted from the transmitting node A to the receiving node B. FIG. Two circles indicated by dotted lines in the space in the upper right of the figure indicate the communication ranges of the transmission node A and the reception node B, respectively.

  Packets transmitted and received in IEEE802.11 are unicast transmission / reception packets (packets transmitted / received by A / B in the figure), broadcast transmission / reception packets, and nodes other than the destination are unicast. The received packets received during the cast communication can be classified into a total of five types of packets, and the packets received by nodes other than the destination can be further classified into three types according to the position of the node. That is, a packet that can be received from both the transmitting node and the receiving node (a packet that can be received by node C in the figure), a packet that can be received only from the receiving node (a packet that can receive D in the figure), and a packet that can be received only from the transmitting node (Packet E can be received).

  In wireless communication, nodes other than the transmitting and receiving nodes consume power because of the characteristics of wireless communication that data reaches all nodes within the radio wave distance, and RTS / CTS (Request This is because power is consumed by communication control in the MAC (Media Access Control) layer such as “To Send / Clear to Send”.

By the way, in TCP, a transmitting node provides communication reliability by receiving an acknowledgment (hereinafter referred to as ACK) for transmitted data from a receiving node. In ACK, a cumulative acknowledgment system is used. This indicates that the subsequent ACK includes all the information of the previous ACK. In addition, ACK is not transmitted for all data, but can be broadly transmitted by the following three mechanisms.
(1) ACK is transmitted when a plurality of data is received. In many implementations, an ACK is sent (delay acknowledgment) every time two pieces of data are received.
(2) Each time the 200 ms periodic delay timer times out, it is checked whether there is data to be sent ACK, and if there is, ACK is sent.
(3) An ACK is transmitted when special flags (control flags) such as SYN, FIN, PUSH, RST, or data with different orders (sequence numbers are missing) are received.

  In this way, ACK is transmitted and received in addition to data in TCP. However, as shown in FIG. 1, the present inventors divide the amount of power consumption in TCP communication into data and ACK, respectively. Calculated. In addition, the influence on the peripheral nodes C, D and E in the peer-to-peer wireless communication was also examined at the same time. In TCP, information is transmitted and received in units called segments, and there are two types of segments: a data segment that includes data and an ACK segment that does not include data and includes ACK.

  In the figure, the data segment transmitted from the transmitting node A is 1460 bytes including a PLCP (Physical Layer Convergence Protocol) header (24 bytes), a MAC frame header (20 bytes), an IP header (20 bytes), and a TCP header (20 bytes). Assume that The ACK segment is 84 bytes because no data is included. Considering the most power-efficient environment with no data loss, an environment in which one ACK is transmitted for two pieces of data. In the figure, it is assumed that the transmitting node A transmits 1000 data and receives 500 ACKs from the receiving node B. The left bar of each graph indicates the power consumption required for data transmission, and the right bar indicates the power consumption required for ACK transmission.

  As a result of the above calculation, as shown in the figure, although the ACK segment has only about 17 times the data amount of the data segment, of the power consumed in transmitting information at each node, It can be seen that much power is consumed by the ACK segment. From this, the present inventors have recognized that if the amount of ACK segments to be transmitted can be reduced, it is possible to save power.

  However, even if the ACK can be reduced, if the performance (for example, throughput) of the conventional TCP is too low, even if the power saving is successful, it is not practical. Then, the present inventors examined the influence on the throughput by reducing the ACK segment. Specifically, assuming a topology in which a TCP transmission node and a reception node are connected by a link with a bandwidth of 10 Mbps and a delay of 10 ms, a network simulator called ns-2 (see www.isi.edu/nsnam/ns/) A simulation was performed. In this simulation, in order to examine the influence of the loss of each of the data segment and the ACK segment, a simulation was performed in which a loss model that randomly discards a segment is applied only to a one-way link. In the simulation, 1460 bytes of data were continuously transmitted for 5000 seconds.

  FIG. 2 is a diagram showing the relationship between the loss rate and the throughput when only the data segment is discarded at random. The X-axis and Y-axis display the log rate and throughput of the data segment, respectively. From the figure, it can be seen that the data segment has a loss of about 0.01 (1%) and the throughput has dropped to about 1 Mbps, which is 1/10.

  On the other hand, FIG. 3 is a diagram showing the relationship between the loss rate and throughput when only the ACK segment is randomly discarded. Similar to FIG. 2, the X-axis and Y-axis display the ACK segment loss rate and throughput in log form, respectively. From the figure, it can be seen that up to around 0.3 (30%), the loss of ACK hardly affects the throughput.

  Next, the experiment was repeated 1000 times with the same loss rate by shifting the loss rate of the ACK segment from 0.3 to 0.7 every 0.01. 4 and 5 are diagrams showing simulation results of loss rates of 0.3 to 0.5 and 0.5 to 0.7, respectively. As shown in FIG. 4, when the loss rate is 0.3 to 0.5, the ratio of data with a low throughput is gradually increased. Further, as shown in FIG. 5, when the loss rate is around 0.6, the throughput is nearly zero. However, it should be noted that even with a loss rate of 0.6 or later, data with a throughput of about 9 Mbps was rarely obtained.

  In view of the above, the present inventors examined in FIG. 5 focusing on the TCP mechanism why the difference in cloudiness appears in the throughput regardless of the loss rate of the same ACK. FIG. 6 shows three cases: (a) when the loss rate is 0%, (b) when the loss rate is 70% and the throughput is about 9 Mbps, and (c) when the loss rate is 70% and almost no throughput is obtained. It is the graph which plotted the sequence number of the transmission data segment in a node, and the reception ACK segment in time series. The upper part shows the transmission data segment, and the lower part shows the reception ACK segment. In each graph, the X axis indicates time (seconds), and the Y axis indicates a sequence number.

  In the figure, (a) shows ideal communication in a situation where no ACK loss occurs. The number of points plotted in the upper and lower graphs is equal. On the other hand, in (b) and (c), the reception ACK segment is smaller than the transmission data segment. This is because 70% of ACK segments are intentionally dropped.

  Looking at the graphs of the transmission data segments in (b) and (c), (b) is almost similar to (a), whereas in (c), what are the data segments of the same sequence number? You can see that it has also been transmitted. It should also be noted that the particle size of the X axis is completely different between (b) and (c).

  The difference between (b) and (c) will be described with reference to FIG. FIG. 7 is a diagram illustrating a state in which an ACK is transmitted for data transmitted from a transmission node in TCP communication.

  The biggest factor that degrades the performance of TCP is retransmission of data segments. As can be seen from the example of FIG. 6B, the performance (throughput) is not extremely deteriorated unless the data segment is retransmitted. As described above, the cumulative acknowledgment method is adopted in TCP, and ACK transmitted later means that all information of ACK transmitted previously is included. If no ACK is received, data retransmission is triggered. Further, TCP adopts the concept of a window (buffer area for storing data) and performs communication control (window control) using the window. That is, a plurality of data in the window (data corresponding to the window size) can be transmitted at a time without waiting for ACK. In FIG. 7, the window size is 4, the data segment of sequence numbers 1 to 4 in the window is transmitted at a time in the transmission node, and the number obtained by adding 1 to the sequence number of each data segment in the reception node. Are each returned as an ACK. The window size dynamically changes according to the communication status, and increases when communication is successful (ACK is received) and decreases when communication fails (retransmission is caused).

  From the above, it can be said that in TCP, the ACK for the last segment of the window (for example, ACK segment 5 in FIG. 7) is more important than other segments. This is because if the ACK for the last segment of the window is lost, retransmission is always caused on the transmission side. On the other hand, if only the ACK for the last segment of the window has arrived, no retransmission will be triggered. Henceforth, ACK with respect to the last segment of a window is called Significant ACK, and other ACK is called Negligible ACK.

  From the above experimental and discussion results, the present inventors can significantly reduce the number of ACK segments while ACK consumes a considerable amount of power in TCP and while maintaining the acceptable performance of TCP. Prove that there is. Therefore, the present inventors have made a change to the conventional TCP with the goal of eliminating all the negligible ACKs. The TCP design policy in the present invention will be described below.

  One concern with reducing TCP ACKs is that the window expansion rate decreases (as mentioned above, because the window size increases by receiving ACKs), but otherwise. In addition, it is necessary to consider the effect on ACK loss. For example, assume that the receiving side returns only a Significant ACK requesting 5 for the segment 4. If this reply arrives at the transmission side, the arrival of all the segments 1, 2, 3, and 4 is transmitted to the transmission side, so that no retransmission occurs. On the other hand, it is assumed that the Significant ACK in this case is lost during transmission. In this case, the transmission side temporarily recognizes that all the segments 1, 2, 3, and 4 have not arrived. Since the segment 1 is retransmitted here, the window size is reduced to 1. On the receiving side, when the retransmitted segment 1 is received, the ACK for the 1 becomes Significant ACK and returns a value of 5. Even in the conventional TCP, even if the ACK for the 1, 2, and 3 segments is returned, if the Significant ACK for the segment 4 is lost during transmission, the segment 4 is eventually retransmitted. In TCP and TCP with reduced ACK according to the present invention, the same number of data is transmitted in terms of processing.

  Here, the point in designing the TCP of the present invention is that even if Negligible ACK is reduced, the data of all the windows are not retransmitted, that is, the above segments 2, 3, and 4 are That is, the number of significant ACKs dynamically increases or decreases depending on the point of not being retransmitted and the data loss rate. Therefore, in order to investigate the relationship between Negligible ACK and Significant ACK, the present inventors changed the data loss rate from 0% to 0.1% in the same environment as that in FIGS. The ratio of the number of ACK and Significant ACK was measured. FIG. 8 is a diagram showing the measurement results.

  As shown in the figure, the ratio of Significant ACK increases as the data loss rate increases. Therefore, when an environment with severe congestion is assumed (for example, in an environment where the data loss rate is further larger than 0.1%), TCP cannot expand the window, and most ACKs may become Significant ACKs. There is also. As described above, since negligible ACK is dynamically reduced, high performance can be expected even in an environment with a high loss rate.

  Based on the above policy, a specific implementation method of TCP with reduced negligible ACK will be described in the following embodiments.

(First embodiment)
In the present embodiment, the TCPs at both ends of the transmission node and the reception node are changed in order to reduce the negligible ACK. Specifically, the transmitting node preliminarily assigns an identifier (flag) to the data segment to be transmitted to the receiving node, that is, the data segment requesting Negligible ACK or the data segment requesting Significant ACK, and transmits the data segment. The receiving node returns an ACK only to a data segment that requests a Significant ACK among the received data segments. Hereinafter, a communication system for realizing this method will be described. In this embodiment, a Web server is applied as a transmission node, and a mobile phone is applied as a reception node.

  FIG. 9 is a diagram showing a configuration of a communication system in the present embodiment. As shown in the figure, in this embodiment, a Web server 1 and a mobile phone 2 are connected via a hot spot (registered trademark) 3.

  The Web server 1 creates or stores HTML (Hyper Text Markup Language) documents, images, sounds, and other contents, and provides these contents in response to a request from a Web browser included in the mobile phone 2. The mobile phone 2 is connected to the hot spot 3 by, for example, a wireless LAN. The hot spot 3 is connected to the Web server 1 via the Internet 4 as an access point to the Web server 1 and provides the mobile phone 2 with an Internet connection service using a wireless LAN. TCP / IP is used as a communication protocol between the Web server 1 and the hot spot 3 and between the hot spot 3 and the mobile phone 2. The numbers of the web server 1, the mobile phone 2, and the hot spot 3 are not limited to the numbers shown in the figure.

  FIG. 10 is a diagram showing a hardware configuration of the Web server. As shown in the figure, the Web server 1 includes a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, a communication unit 14, an operation input unit 15, a display unit 16, and an HDD. (Hard Disk Drive) 17, which are connected by a bus 18.

  The CPU 11 is a main controller that controls the operation of the entire Web server 1, and executes various applications for creating Web pages and a TCP protocol stack on a platform provided by an OS (Operating System).

  The ROM 12 is a read-only nonvolatile memory that stores programs executed when the Web server 1 is powered on, data such as hardware control codes, programs, and the like. The RAM 13 is a writable volatile memory used for loading a program or the like necessary for creating / transmitting a Web page or writing work data of the program. In addition, the communication unit 14 performs a communication process such as transmitting a data segment constituting a Web page to the mobile phone 2 via the Internet and receiving an ACK for the data segment from the mobile phone 2.

  The operation input unit 15 includes, for example, a mouse, a keyboard, and the like. The operation input unit 15 inputs a user operation on the Web server 1 and notifies the CPU 11 of the operation information. The display unit 16 includes, for example, an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube), a PDP (Plasma Display Panel), an OEL (Organic Electroluminescence), and the like. A GUI (Graphical User Interface) or the like is displayed. The HDD 17 stores various programs and data that are loaded into the RAM 13 and executed by the CPU 11.

  Although not shown, the basic hardware configuration of the mobile phone 2 is the same as that of the Web server, and includes a CPU 21, ROM 22, RAM 23, communication unit 24, operation input unit 25, display unit 26, and HDD 27. In the mobile phone 2, the operation input unit 25 is a push button, a jog dial, or the like, and the display unit 26 is an LCD (Liquid Crystal Display), for example. Further, instead of the HDD 27, a card-type storage device such as a flash memory may be included. Programs and data such as a browser for downloading and displaying the OS and Web pages are stored in the HDD 27 or the flash memory.

  FIG. 11 is a block diagram illustrating a functional configuration example in the data transmission / reception process of the Web server 1. The functional block is realized, for example, by a TCP protocol stack implemented in the kernel portion of the OS of the Web server 1.

  As shown in the figure, the data communication processing of the Web server 1 includes a data control unit 31, a TCP control unit 32, a TCB (TCP Control Block) storage unit 33, a transmission buffer 34, a transmission unit 35, a reception unit 36, and a reception buffer. 37.

The data control unit 31 provides an interface part on the user side in the data transmission / reception process of the Web server 1. The data control unit 31 once reads data stored in the HDD 17 and writes the read data to the transmission buffer 34 based on an instruction input via the operation input unit 15 of FIG. Further, the data control unit 31 reads the data in the reception buffer 37 and writes it in the HDD 17 or uses it as it is in the program under the user's instruction input via the operation input unit 15.

  The TCP control unit 32 controls the transmission buffer 34, the transmission unit 35, the reception unit 36, and the reception buffer 37 while holding the state of the connection executed via the network in the TCB storage unit 33, and executes data transmission / reception processing To do.

  The TCP control unit 32 divides the data in the transmission buffer 34 written by the data control unit 31 into the size of the TCP segment, sets the number of data segments corresponding to the value of the TCP window (window size) as the TCP window, The data segment in the TCP window is supplied to the transmission unit 35. The window size indicates the amount of data segments to be transmitted, and gradually expands if there is no segment loss in the Internet 4. However, if a segment is lost, the window size returns to one segment. The TCP control unit 32 adjusts the amount of data segments to be transmitted using such a window size.

  At this time, for each data segment in the window, the TCP control unit 32 determines whether the data segment is a data segment requesting the negligible ACK or a data segment requesting the significant ACK (hereinafter referred to as an ACK request). (Referred to as a "No" flag) and send. Details of the operation when the flag is assigned will be described later.

  Further, in addition to the ACK necessity flag, if it is necessary to add a special flag, the special flag is also added. The special flag refers to a so-called control flag such as SYN (Synchronize Flag), FIN (Fin Flag), RST (Reset Flag), PUSH (Push Flag), URG (Urgent Flag), etc., and the flag is on (bit = 1). If it is SYN, it means that the connection is started, if FIN, the connection is terminated, if RST, the connection is reset, if PUSH, the data is immediately passed to the application, if URG, the data is urgently processed. .

  Further, when the data segment is transmitted from the transmission unit 35, the TCP control unit 32 starts a built-in retransmission timer. The retransmission timer stops when the receiving unit 36 receives a Significant ACK segment (hereinafter simply referred to as Significant ACK) from the mobile phone 2. The retransmission timer times out if a significant ACK is not received by the receiving unit 36 even after a predetermined time (retransmission timer operating time) has elapsed. The Significant ACK indicates that all the data segments in the window including the data segment requesting the Significant ACK have reached the mobile phone 2.

  The TCP control unit 32 performs a time counting operation using a retransmission timer and monitors the reception unit 36, and a Significant ACK corresponding to the data segment transmitted from the mobile phone 2 last time is within a predetermined time (retransmission timer operation time). It is determined whether or not the data has been received, and based on the determination, which data segment is supplied to the transmitter 35 is controlled.

  Specifically, when the receiving unit 36 receives a Significant ACK corresponding to the previously transmitted data segment, the TCP control unit 32 expands the value of the TCP window, and from the data segment requested by the received Significant ACK, A data segment corresponding to the window size is set as a TCP window, and the data segment in the TCP window is supplied to the transmission unit 35. For example, if the value of the TCP window is 5, five data segments starting from the data segment requested by the received Significant ACK are set as TCP windows, and the data segments in the TCP window are supplied to the transmission unit 35.

  On the other hand, when the receiving unit 36 does not receive the Significant ACK, the TCP control unit 32 contracts the value of the TCP window to 1 because there is a loss of the segment (Significant ACK or data segment) on the network, Among the previously transmitted data segments, the retransmission segment that is the data segment with the smallest sequence number is set as a TCP window, and the retransmission segment is supplied to the transmitter 35.

  The TCB storage unit 33 is configured by a memory or the like. The window size written by the TCP control unit 32, the segment size of each segment, the retransmission timer operating time, the minimum sequence number of the data segment that has been transmitted but has no ACK, and the following Holds the sequence number of the data segment to be transmitted. The transmission buffer 34 is composed of, for example, a 32-byte buffer, and once the data segment to be transmitted to the mobile phone 2 is accumulated, the accumulated data segment is deleted when transmitted by the transmission unit 35. As a result, the data control unit 31 can newly write data in the empty area of the transmission buffer 34.

  The receiving unit 36 receives the Significant ACK transmitted from the mobile phone 2 via the Internet 4. The reception buffer 37 is composed of, for example, a 32-byte buffer, and data written by the reception unit 36 is temporarily accumulated. The accumulated data is read by the data control unit 31.

  Although not shown, the cellular phone 2 is basically configured as described above, such as the data control unit 41, the TCP control unit 42, the TCB storage unit 43, the transmission buffer 44, the transmission unit 45, the reception unit 46, and the reception buffer 47. Although it has the same configuration as the functional configuration block diagram of the Web server 1, the TCP control unit 47 has the function that the TCP control unit 32 of the Web server 1 has a function of giving an ACK necessity flag for the data segment. It has a function of referring to the ACK necessity flag to determine whether or not it is necessary to transmit ACK to the Web server 1.

  That is, the TCP control unit 47 of the mobile phone 2 returns the Significant ACK via the transmission unit 35 when the data segment received from the Web server 1 is the data segment requesting the Significant ACK, and otherwise. ACK is not transmitted for the data segment. Further, since the mobile phone 2 mainly receives data from the Web server 1 rather than transmitting data to the Web server, the mobile phone 2 may not have a retransmission timer function in the Web server 1. . The TCB storage unit 43 holds the sequence number of the data segment to be received next, instead of the sequence number of the data segment to be transmitted next by the Web server 1.

  The receiving unit 36 receives the data segment received from the Web server 1 via the wireless LAN, and the reception buffer 37 temporarily stores the data. The accumulated data is read into the data control unit 31 and stored in the HDD 27 or passed to the application.

  Next, operations of the Web server 1 and the mobile phone 2 configured as described above will be described.

  First, the operation at the time of data segment transmission of the Web server 1 will be described. FIG. 12 is a flowchart for explaining the operation. In the figure, send_una is the minimum sequence number of the data segment transmitted from the Web server 1 to the mobile phone 2 but there is no ACK, and send_nxt is the sequence number of the data segment to be transmitted next to the mobile phone 2. The segment size of a segment is expressed as maxseg, and the window size is expressed as window. As described above, these data are stored in the TCB storage unit 33 and are loaded into, for example, the RAM 13 during the operation.

  As shown in the figure, first, the TCP control unit 32 of the Web server 1 sets the sequence number of the data segment to be transmitted next to the mobile phone 2 to send_nxt (step 51). Then, the value obtained by subtracting the send_una value from the send_nxt value is compared with the window value (step 52). As a result of the comparison, if the value of window is larger (YES in step 52), then the value obtained by adding maxseg to the value obtained by subtracting the value of send_una from the value of send_nxt, Are compared (step 53). If both are equal as a result of the comparison (YES in step 53), the bit of the ACK necessity flag is set to 1 (step 54). If they are not equal (NO in step 53), the bit of the ACK necessity flag is set to 0 (step 55). And the data segment which set the said ACK necessity flag is transmitted to the mobile telephone 2 via the transmission part 35 (step 56).

  In step 53, the case where both values are equal indicates that the data segment (send_nxt) to be transmitted next is the last data segment in the window. Therefore, in this case, the ACK necessity flag is set to 1 to request a Significant ACK for the last data segment in the window.

  For example, if window is 50, maxseg is 10, send_nxt is 40, and send_una is 10, in step 53, 40-10 + 10 = 40> 50, so the bit of the ACK necessity flag is set to 0. If window is 50, maxseg is 10, send_nxt is 50 (the last data segment in the window), and send_una is 10, then in step 53, 50-10 + 10 = 50, so the bit of the ACK necessity flag is Set to 1. That is, the ACK necessity flag is added so as to request only ACK for the last data segment in the window.

  Next, the operation when the mobile phone 2 receives the data segment will be described. FIG. 13 is a flowchart for explaining the operation. In the figure, the sequence number value of the data segment to be received next by the mobile phone 2 is represented by rcv_nxt, and the number of ACKs transmitted to the Web server 1 in duplicate is represented by dup_cnt.

  As shown in the figure, first, the mobile phone 2 receives the data segment transmitted from the Web server 1 (step 61). Subsequently, the sequence number of the received data segment is set to seqno (step 62). Then, with reference to the ACK necessity flag given to the received data segment, it is judged whether or not ACK transmission is necessary (step 63). That is, if the bit of the ACK necessity flag is 1 (YES in Step 63), ACK (Significant ACK) is transmitted to the Web server 1 via the hot spot 3 by the transmitting unit 45 (Step 64).

  As exception processing, even if the bit of the ACK necessity flag is 0 (NO in step 63), it is determined whether or not the special flag is assigned (step 65). If so (YES in step 65), an ACK is transmitted (step 64). As a result, the intention of the special flag can be reliably reflected, and compatibility with the conventional TCP can be maintained.

  Even if the special flag is not given (NO in step 65), the set sequence number seqno is compared with the above rcv_nxt (step 68). If seqno is larger, the value of dup_cnt is set. Count (step 67). That is, the fact that the set seqno is larger than the sequence number rcv_nxt of the data segment to be received next indicates that the order in which the data segments transmitted from the Web server 1 arrive is out of order. . For example, there are cases where the sequence numbers 1, 2, 4, 5, 6, 7 and 3 are missing and arrived. This is because the data segment transmitted later has arrived first because the transmitted data segment is lost on the Internet 4 or during communication with the hotspot 3 or due to congestion of the Internet 4 or wireless LAN. It depends. In such a case, an ACK for requesting the Web server 1 to retransmit the data segment to be received next, that is, an ACK for data of the sequence number immediately before the sequence number of the data segment to be received next ( In the above example, ACK requesting segment 3 for segment 2) is again transmitted again (step 64). However, the number of duplicates is counted by the dup_cnt, and the value of dup_cnt is controlled to be less than 4, that is, the number of duplicate ACKs to be transmitted is limited to three, and duplicate ACKs are not transmitted more than four times. (Step 69). By this processing, so-called high-speed retransmission control is performed in the Web server 1, and compatibility with conventional TCP can be maintained.

  If secno is smaller in step 66 (NO in step 66), and if dup_cnt is 4 or more in step 69, the process ends without sending any ACK. As a result, the transmission of the negligible ACK can be suppressed.

  The present inventors have verified how much the negligible ACK from the receiving side can be reduced when the data is transmitted using the method of the present embodiment, and what the throughput is. FIG. 14 shows a case where the data loss rate is increased from 0% to 0.02% every 0.001% and a method similar to the method in the present embodiment is used, and the current de facto standard of TCP. It is the figure which showed the result of having measured the throughput and the number of ACKs by the said simulator, respectively, when the TCP-Reno system which is used is used. In the figure, an environment is assumed in which one TCP for transmitting 100000 data segments flows through a 10 Mbps link. By setting the loss rate to a link, it is possible to drop a segment with an arbitrary probability. In the bar graph of the figure, the number of ACKs in TCP-Reno is shown in color, the number of ACKs in the method of the present embodiment is shown in shaded, and the points in the line are The rhombus indicates the throughput in TCP-Reno, and the square indicates the throughput in this embodiment.

  As shown in the figure, in TCP-Reno, a change in throughput of about 9.3 Mbps to 8.5 Mbps was observed, and the number of ACKs remained almost unchanged, and 50,000 or more ACKs were sent. On the other hand, when the method of the present embodiment is used, the throughput is about 6 Mbps to 7.5 Mbps, and when the loss rate is 0%, the throughput is deteriorated by about 30%. Further, as the loss rate increases, the performance of the technique of TCP-Reno and this embodiment approaches. This is because when the loss rate is high, the window becomes smaller due to TCP congestion control and the ratio of significant ACK increases. Next, paying attention to the number of ACKs, it can be seen that when the loss rate is 0%, the method according to the present embodiment is reduced by about 1/60 compared to TCP-Reno. That is, 98.3% of ACK is decreased. From this measurement result, it can be seen that when the method of the present embodiment is used, the number of ACKs transmitted by the conventional TCP can be drastically reduced while the throughput is kept within an acceptable range.

  FIG. 15 is a diagram in which the power consumed by transmission of the ACK segment on the receiving side is measured and compared in the case of the technique of the present invention and in the case of TCP-Reno. In the figure, the X axis indicates the data loss rate, and the Y axis indicates the power consumption. As shown in the figure, by using the method according to the present embodiment, the minimum (when the data loss rate is 0.1%) is about 40%, and the maximum (when the data loss rate is 0%) is about 85%. Power saving is realized. As described above, the decrease in ACK can dramatically reduce the power consumption of the Web server 1 and the mobile phone 2, and comfortable wireless communication using TCP can be performed. In particular, in wireless communication, the power consumption varies depending on the number of data rather than the data size, so the method of this embodiment for reducing the number of data (number of ACKs) is effective.

(Second Embodiment)
In the first embodiment described above, changes are made to the TCPs at both ends of the transmission side (Web server 1) and the reception side (mobile phone 2). However, since it is common to receive data in wireless communication, changing only the TCP on the receiving side is easy to implement in terms of mounting and is ideal. Therefore, in the present invention, it is also possible to realize a technique for changing only the TCP on the receiving side. Hereinafter, an embodiment in this case will be described.

  Although not shown, the network configuration in the present embodiment is configured by the Web server 1, the mobile phone 2, and the hot spot 3 in the same manner as the configuration described in FIG. 9 of the first embodiment. The Web server 1 can transmit data using a conventional method such as TCP-Reno. The hardware configuration of the mobile phone 2 is basically the same as that of the first embodiment, but the functions of the TCP control unit 42 and the like are different. In this embodiment, the data segment transmitted from the Web server 1 is the same as the data segment in the conventional TCP (no special processing such as the above ACK necessity flag is performed), so the received data It is necessary to determine whether or not to transmit ACK to a segment, that is, to distinguish between negligible ACK and significant ACK without referring to the ACK necessity flag or the like.

  As a method for discriminating between the negligible ACK and the significant ACK, the present inventors have focused on the fact that TCP performs communication control by a window. It is known that the transfer of data segments by window is bursty. The present inventors actually investigated the interval at which the conventional TCP transmits data segments in an environment where a single link is shared with a plurality of flows.

  FIG. 16 shows the results. In the figure, two types of experiments were performed: a case where a link is shared by 10 flows and a case where a link is shared by 200 flows. When the upper (a) is shared by 10 flows, the lower (b) shows the case of teaching by 200 flows. The X axis and the Y axis are each displayed as a log.

  As shown in the figure, in the case of (b), since 200 flows are shared, retransmission is performed more frequently than in the case of (a), and segment transmission / reception on the right side of the X-axis is performed. It can be seen that there is a distribution even in a portion where the interval is long. A point to be noted in these two graphs is the leftmost part of (a) and (b). In this part, nearly 40% of the entire segment with an interval of 1 ms or less was present. These segments were segments sent in bursts within the same window.

  From these results, it is reasonable to consider that there is some idle time from the transmission of the last segment of the window requesting Significant ACK to the transmission of the next segment. That is, with reference to FIG. 5B, it is considered that a distribution in which the transmission / reception interval is around 0.01 sec to around 0.1 sec indicates the idle time. It can be inferred that the portion on the right side is due to data segment retransmission.

  In the present embodiment, this feature is used to change the delay timer of the receiving node. Here, the receiving node in this embodiment is called a Flexible Delayed Timer (FDT). The delay timer of a conventional TCP receiving node times out at a fixed interval, and transmits an ACK when there is a segment to transmit an ACK at that time. The FDT of this embodiment is basically the same mechanism as a conventional delay timer, but is reset every time a segment is received without timing out at a fixed interval. Therefore, an ACK is transmitted when a data segment is not received during the FDT period. As a result, ACK can be returned only for the last data in the window. That is, it is possible to transmit only significant ACK and not transmit negligible ACK.

  Hereinafter, the operation of the mobile phone 2 in the present embodiment will be described. FIG. 17 is a flowchart showing an operation when the mobile phone 2 receives a data segment. Abbreviations such as seqno, rcv_nxt, and dup_cnt shown in the figure have the same meaning as in the first embodiment.

  As shown in the figure, first, when the mobile phone 2 receives the data segment transmitted from the Web server 1 by the receiving unit 36 (step 71), the TCP control unit 42 of the receiving unit receives the received data. The segment sequence number is set to secno (step 72). Then, a fixed value K of the FDT is set (step 73). The K is, for example, 1 to 10 ms. Subsequently, it is confirmed whether or not the set FDT timeout has occurred (step 74). If timed out (YES in step 74), an ACK for the data segment set in the above secno is transmitted to the Web server 1 by the transmitting unit 45 (step 75). On the other hand, the same processing as in FIG. 13 of the first embodiment is performed, such as whether the special flag is not given to the received data segment or whether the data segment arrives out of order. ACK is transmitted as necessary (steps 76 to 80). Note that in the present embodiment, immediately returning an ACK to the PUSH flag among the special flags is particularly effective in the case of a connection whose Bandwidth-Delay Produce is smaller than the TCP maximum window length. In this case, the segment flows continuously without time-out of the FDT in this embodiment.

  With the above processing, by using the FDT, as a result, an ACK is returned only to the last data segment of the window, and the negligible ACK can be reduced. In addition, by returning ACK to the special flag and performing high-speed retransmission control, compatibility with the conventional TCP can be maintained.

  As in the case of the first embodiment, the present inventors have verified the performance when the method in the present embodiment is used. FIG. 18 is a diagram showing the results of measuring the number of ACKs and the throughput when simulation is performed using the method according to the present embodiment. In this figure, as in the case of FIG. 14, an environment is assumed in which one TCP for transmitting 100000 data segments flows through a 10 Mbps link. In the method of the present embodiment, it is clear that the performance depends on the FDT timer granularity. Therefore, when the fixed value K of the FDT is set to 6 patterns of 1 ms, 5 ms, 10 ms, 50 ms, 100 ms, and 500 ms. Each was measured. In the figure, the line graph shows the throughput, and the bar graph shows the number of ACKs.

  As shown in the figure, the number of transmitted ACKs was equal in any of the above six patterns. This indicates that the retransmission is not caused by timeout of the retransmission timer before the FDT times out. A typical value of the retransmission timer is 2 seconds, and an increase in ACK due to retransmission can be prevented by setting a value smaller than that value.

  Further, by using a 1 ms timer, it is possible to show a throughput performance (about 6.5 Mbps) that is almost equivalent to the technique of the first embodiment. Even if the FDT is set to 10 ms, it can be said that the performance degradation is about 5%. As described above, according to the method of the present embodiment, it is possible to reduce ACK and maintain the performance of the conventional TCP within an acceptable range by changing only the TCP on the receiving side as in the first embodiment. As a result, it is possible to realize a significant power saving of the Web server 1 and the mobile phone 2.

  It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

  In the above-described embodiment, TCP is used as a communication protocol. However, the protocol to which the present invention is applicable is not limited to TCP, and any protocol that performs communication using ACK, such as UDP, can be used. It is possible to apply.

  In the above-described embodiment, an example in which a mobile phone is used as a wireless terminal has been described. However, the wireless terminal is of course not limited thereto, and may be applied to any wireless terminal such as a PDA, a sensor node for data measurement, and a notebook PC. be able to.

  In the above-described embodiment, the case where the Web server and the mobile terminal communicate via a hot spot has been described. However, the configuration of the network is not limited to this mode. For example, wireless terminals such as mobile phones can communicate with each other. It is applicable also to the aspect which performs. Further, although a wireless LAN is used as the wireless communication means, for example, a short-range wireless communication standard such as Bluetooth or other standards can be used. Furthermore, it is of course possible to apply the present invention to a device connected to a network by wire, such as a desktop PC.

  Further, it is possible to combine another technique with the technique in the above-described embodiment. For example, there is a mechanism called ACK Reconstruction. In this method, the TCP on the transmission side is changed so that congestion control is performed based on the sequence number instead of the number of ACKs. In particular, in the technique of the first embodiment of the present invention, high throughput can be expected by using the ACK Reconstruction on the transmission side.

  As another method for reducing ACK, for example, when the transmission side receives an ACK for a data segment transmitted by window control within a predetermined time and the retransmission timer times out, the transmitted data is reduced. Instead of retransmitting the segment, a method of transmitting a data segment having a sequence number next to the transmitted data segment (referred to as a jump segment) is also conceivable. In this case, on the receiving side, when a jump segment is received, an ACK requesting a segment not yet received is returned. For example, when the transmission side transmits 1, 2, 3, and 4 data segments, 4 is lost, and the retransmission timer on the transmission side times out. Therefore, the transmission side transmits the data segment 5 next to the transmitted data segment. On the receiving side, 4 is returned as an ACK for the 5. Further, the transmission side receives the 4 ACK and transmits the data segment 4 and the segment 6 in which the next transmitted segment 5 is skipped. By using such a method, the amount of data segments to be retransmitted can be reduced as compared to the case where all the data segments 1 to 4 are retransmitted in the case of the conventional TCP.

  By combining this technique for reducing retransmitted data segments and the technique of the present invention for reducing data segments that are indirectly retransmitted by reducing ACK, not only power saving but also throughput can be improved. You can also.

It is the figure explaining the electric power consumed in the data communication in the node of C, D, and E which exists in the transmission node A and the receiving node B, and others nearby. It is the figure which showed the relationship between the loss rate at the time of discarding only a data segment at random, and a throughput. It is the figure which showed the relationship between the loss rate at the time of discarding only an ACK segment at random, and a throughput. It is the figure which showed the throughput in case the loss rates of ACK segment are 0.3-0.5. It is the figure which showed the throughput in case the loss rates of ACK segment are 0.5-0.7. It is the graph which plotted the sequence number of the transmission data segment in a transmission node, and a reception ACK segment in time series. It is the figure which showed a mode that ACK was transmitted with respect to the data transmitted from a transmission node in TCP communication. It is the figure which showed the result of having measured the ratio of the number of Negligible ACK and Significant ACK, changing a data loss rate. It is the figure which showed the structure of the communication system in 1st Embodiment. It is the figure which showed the hardware constitutions of the Web server. 3 is a block diagram illustrating a functional configuration example in a data transmission / reception process of the Web server 1. FIG. The operation at the time of data segment transmission of the Web server 1 will be described. FIG. 12 is a flowchart for explaining the operation. 4 is a flowchart for explaining the operation of the mobile phone 2 when receiving a data segment. It is the figure which showed the result of having measured and compared the number and throughput of ACK with the method and TCP-Reno system of 1st Embodiment. It is the figure which measured and compared the power consumption by transmission of ACK by the method by 1st Embodiment, and TCP-Reno. It is the figure which showed the result measured about the space | interval which the conventional TCP is transmitting the data segment. 4 is a flowchart for explaining the operation of the mobile phone 2 when receiving a data segment. It is the figure which showed the result of having measured the number of ACK and the throughput at the time of using the method in 2nd Embodiment by simulation, respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Web server 2 ... Mobile phone 3 ... Hot spot 4 ... Internet 14, 24 ... Communication part 31, 41 ... Data control part 32, 42 ... TCP control part 33, 43 ... TCB memory | storage part 34, 44 ... Transmission buffer 35, 45: Transmitter 36, 46 ... Receiver 37, 47 ... Receive buffer

Claims (9)

An information processing apparatus connected to another information processing apparatus via a network,
Receiving means for receiving data from the other information processing apparatus according to a predetermined protocol;
Determining means for determining whether or not it is necessary to transmit an acknowledgment for the received data;
An information processing apparatus, comprising: a transmission unit configured to transmit an acknowledgment to the other information processing apparatus for the data determined to be necessary to transmit among the received data. The information processing apparatus according to claim 1,
The information processing apparatus according to claim 1, wherein the determination unit determines that it is necessary to transmit a confirmation response to the received data when the next data is not received for a predetermined time after the data is received. The information processing apparatus according to claim 1,
The received data is provided with a flag indicating whether the confirmation response transmission is necessary by the other information processing apparatus,
The information processing apparatus, wherein the determination unit determines whether or not the confirmation response needs to be transmitted by referring to the flag. The information processing apparatus according to claim 3,
The predetermined protocol is TCP;
When the control flag is attached to the received data, the determination means transmits an acknowledgment for the received data regardless of the type of flag indicating whether the acknowledgment is required to be transmitted. An information processing apparatus characterized by determining that it is necessary. The information processing apparatus according to claim 4,
Means for recognizing a first sequence number of data to be received next to the received data each time data is received;
Means for comparing the recognized first sequence number with a second sequence number of data first received after the recognition;
If the second sequence number is larger as a result of the comparison, the determination means sets a flag type indicating whether transmission of the confirmation response given to the data of the second sequence number is necessary. Regardless, it is determined that it is necessary to retransmit the already transmitted acknowledgment for the data of the sequence number immediately before the first sequence number,
The information processing apparatus according to claim 1, wherein the transmission unit performs control so that the number of retransmissions is not more than four times. A system in which a first information processing apparatus and a second information processing apparatus are connected via a network,
The first information processing apparatus includes:
Granting means for granting a flag indicating whether or not to transmit a confirmation response to the data to data to be transmitted to the second information processing apparatus;
First transmission means for transmitting the data to which the flag has been assigned according to a predetermined protocol;
The second information processing apparatus
Receiving means for receiving data transmitted from the first information processing apparatus according to the predetermined protocol;
Determining means for determining whether or not it is necessary to transmit an acknowledgment for the received data based on the given flag;
Information including: a second transmission unit configured to transmit an acknowledgment to the first information processing apparatus for the data determined to be required to be transmitted among the received data. Processing system. The information processing system according to claim 6,
The predetermined protocol is TCP;
The first transmission means transmits a plurality of data continuously by window control,
The assigning means assigns a flag indicating that transmission of the confirmation response is required to data having the largest sequence number among the plurality of data to be transmitted, and indicates that transmission of the confirmation response is not required for other data. An information processing system characterized by providing a flag. A method in which an information processing apparatus connected to another information processing apparatus via a network processes information,
Receiving data from the other information processing apparatus according to a predetermined protocol;
Determining whether it is necessary to send an acknowledgment to the received data;
An information processing method comprising: transmitting, to the other information processing apparatus, a confirmation response to data that is determined to be required to be transmitted among the received data. To information processing devices connected to other information processing devices via a network,
Receiving data from the other information processing apparatus according to a predetermined protocol;
Determining whether it is necessary to send an acknowledgment to the received data;
A program for executing a step of transmitting an acknowledgment to the other information processing apparatus for the data determined to be necessary to be transmitted among the received data.

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