JP2010056942A - Wireless communication apparatus and wireless communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a channel from being disconnected at a non-communication condition during a set of operations for packet resending for the purpose of implementing efficient wireless communication. <P>SOLUTION: A typical configuration refers to a wireless communication apparatus connected to a base station 130, and includes a packet receiver 212 for receiving packet sent from the base station 130, a retransmission tracking part 214 for detecting a missing number in sequence numbers given to the received packets, a non-communication detection part 220 for detecting the non-communication condition, and a dummy transmitter 216 for sending dummy data to the base station 130 when the non-communication condition is detected by the non-communication detection part 220 after the retransmission tracking part 214 has detected the missing number in the sequence numbers. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless communication apparatus and a wireless communication method for connecting to an access point.

  In recent years, communication networks such as the Internet have become broadband, and wireless broadband systems through wireless communication represented by Bluetooth (registered trademark), ZigBee, and the like are also in an expanding trend. As a means for executing such wireless communication, CDMA (Code Division Multiple Access), iBurst (registered trademark), WiMAX (Worldwide Interoperability for Microwave Access), etc., which are also used for mobile phone networks, can be used. .

  CDMA is a scheme in which a plurality of signals are multiplied by different codes, and all signals are combined and transmitted using one frequency. On the other hand, iBurst (registered trademark) uses adaptive modulation technology that selects an optimal code modulation method according to the communication environment, an adaptive array antenna that imparts directivity to radio waves, and the like to increase the effective communication speed. is there. WiMAX is one of communication methods using an OFDMA (Orthogonal Frequency Division Multiple Access) method. The OFDMA method is classified as one of data multiplexing methods, and has a unit time axis. In this method, a large number of carrier waves are used, and the frequency bands are effectively used by partially overlapping the carrier band so that the phase of the signal wave to be modulated is orthogonal between adjacent carriers.

  When a user uses such wireless communication to execute data transmission / reception with an information processing device such as his / her personal computer, the user connects a relay device such as a PC card corresponding to the wireless communication to the information processing device. Must-have. In such a relay device, the packet transmitted from the information processing device is transmitted as a radio signal to the access point, and the radio signal received from the access point is converted into a packet and transmitted to the information processing device. Thus, the information processing apparatus can use wireless communication.

However, in wireless communication, the occupying bandwidth is narrow and resources such as connected channels are limited. Therefore, a plurality of information processing devices and mobile phones are communicating with one access point at the same time, and a terminal such as an information processing device newly tries to connect via a relay device when there is no available channel May fail. Therefore, when a channel is not available for a communication request from a terminal, a control station such as an access point temporarily holds the request in a queue and permits connection when the channel is available. A control technique is disclosed (for example, Patent Document 1).
JP-A-8-186567

  Through the communication as described above, the user can receive various services by a Web server connected to the Internet, for example. TCP / IP (Transmission Control Protocol / Internet Protocol) is widely used as the Internet standard protocol. In TCP / IP, a transmission side (for example, a server) confirms that a transmitted packet is correctly received by an acknowledgment (ACK: ACKnowledgement) sent back from the reception side (for example, an information processing apparatus). When the ACK is not sent back for a predetermined time or when there is a retransmission request, the transmitting side determines that the transmitted packet is lost for some reason during the communication, and transmits (resends) the same packet again. .

  In TCP / IP, when a server sends a packet to an information processing device through an access point and a relay device, the server sends a new packet until a confirmation response is received after sending a packet for which a retransmission request has been sent. do not do. During this time, if the access point has completely transmitted packets accumulated in its own buffer, the flow of data from the access point to the relay device is temporarily stopped. Further, when the information processing apparatus sends an acknowledgment to the packet for which a retransmission request has been made, thereafter, the information processing apparatus does not make an acknowledgment until the next packet is received from the server. That is, the data flow from the relay device to the access point is also stopped. Accordingly, a non-communication state in which data is not exchanged between the access point and the relay device occurs until a new packet is transmitted from the server.

  When such a no-communication state elapses for a predetermined period, the access point forcibly releases (disconnects) the channel that it has determined that communication is not taking place in order to make effective use of resources, and there is a communication request. Assign to other terminals.

  The information processing apparatus that has been disconnected must make a communication request to the access point again in order to continue receiving data. In such a communication request, there is a possibility that the channel may be blocked by another communication request, and even if the channel is free, a re-registration process for establishing wireless communication occurs, and wasteful time is spent. End up. In particular, when using the technique of Patent Document 1 or the like, when connection requests are accumulated in the queue, the previous connection request is executed at the end of the queue to reconnect, and the channel is not available. When it is possible to wait, the data throughput is significantly reduced.

  In view of such a problem, the present invention prevents a situation in which a channel is disconnected in a no-communication state caused by a series of packet retransmission processes, and can perform efficient wireless communication. It is an object of the present invention to provide a wireless communication method.

  In order to solve the above-described problem, a typical configuration of the present invention is a wireless communication apparatus connected to an access point, which is attached to a packet reception unit that receives a packet transmitted from the access point and the received packet. When the non-communication detecting unit detects a non-communication state after the retransmission grasping unit detects a sequence number missing number, And a dummy transmitter for transmitting dummy data to the access point.

  In the present invention, a packet is lost during communication, and the wireless communication apparatus detects the missing missing packet, receives the missing packet, and then receives a normal packet that is not a missing packet. In this case, the dummy transmission unit transmits so-called dummy data that does not include significant information to the access point. With this configuration, communication is continued from the wireless communication apparatus to the access point by at least transmission of dummy data, and the channel is not forcibly disconnected by the access point.

  In the retransmission status until the retransmission grasp unit detects the missing packet and receives the missing packet, the retransmission release waiting state after receiving the missing packet and receiving the normal packet that is not the missing packet, A normal state where a normal packet is received, and a state transition control unit that performs state transition, respectively, a dummy transmission unit is in a retransmission state or a retransmission release waiting state, and a no-communication detection unit is in a no-communication state While detecting, dummy data may be transmitted.

  The non-communication state between the access point and the wireless communication device may repeatedly occur for reasons such as deterioration of the communication environment. However, a temporary no-communication state that causes unnecessary disconnection of the channel by the access point occurs during a series of processes of retransmission of missing packets. That is, it occurs from when the wireless communication apparatus transmits a missing packet retransmission request until it receives the missing packet, returns its ACK, and receives a normal packet that is not a missing packet. Therefore, of the series of retransmission processes, the first half is set as the retransmission state, the second half is set as the retransmission release waiting state, and the other period is distinguished as the normal state at the time when the ACK of the missing packet is returned. Then, the dummy data is transmitted only when there is no communication in the retransmission state and the retransmission release waiting state. With this configuration, the wireless communication apparatus can avoid a decrease in throughput due to channel disconnection without causing a no-communication state even if transmission of dummy data is limited to a retransmission state and a retransmission release waiting state.

  The state transition control unit sets the retransmission state or the retransmission release waiting state when any of the retransmission state period, the retransmission release waiting period, or the combined retransmission state and retransmission release waiting state continues for a predetermined time. It may be canceled and transition to the normal state.

  A time limit is set for the retransmission state in which dummy data is transmitted, the retransmission release waiting state, or the retransmission state and the retransmission release waiting state, and the wireless communication device returns to the normal state after a predetermined time and stops transmitting dummy data. To do. For example, due to reasons such as deterioration of the communication environment, missing packets or normal packets that are not missing packets will not reach the wireless communication device indefinitely, and will not transition from the retransmission state or the retransmission release waiting state to the normal state, and transmission of dummy data is limited. May continue without. At this time, if the channel used for communication is occupied indefinitely without disconnecting, the other terminals cannot use the channel and the communication efficiency of the entire system is lowered. With this configuration, it is possible to avoid a situation in which the wireless communication apparatus occupies the communication channel for a predetermined time or longer without performing significant data transmission and reception, and more efficiently use a channel using a finite bandwidth. .

  When there are a plurality of channels connected to the access point and the wireless communication device, the dummy transmission unit may identify the channel in which the non-communication detection unit detects the non-communication state and transmit the dummy data through the channel. .

  Currently, a technique is used in which a terminal communicates with an access point by using a plurality of channels in combination to improve the data communication speed. When communication is performed using a plurality of channels, the data transmission / reception of the plurality of channels may be biased to a specific channel, and a non-communication state may occur for another channel for a longer time. Therefore, the dummy transmission unit can avoid channel disconnection more reliably by specifying a channel in a non-communication state and transmitting dummy data from the channel.

  Another exemplary configuration of the present invention is a wireless communication method of a wireless communication apparatus connected to an access point, which receives a packet transmitted from the access point and is a missing sequence number assigned to the received packet. , Detecting a no-communication state, detecting a missing sequence number, and detecting a no-communication state, dummy data is transmitted to the access point.

  The above-described components based on the technical idea of the wireless communication device and the description thereof can be applied to the wireless communication method.

  As described above, according to the present invention, it is possible to prevent a situation in which a channel is disconnected during a no-communication state caused by a series of packet retransmission processes, and to perform efficient wireless communication.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

(Wireless communication system 100)
FIG. 1 is an explanatory diagram showing a schematic connection relationship of the wireless communication system 100 in the present embodiment. Such a wireless communication system 100 includes a wireless communication device including an information processing device 110 and a relay device 120, a base station 130 as an access point, an ISDN (Integrated Services Digital Network) line, the Internet, a dedicated line, and the like. The communication network 140, the management server 150, and the external server 160 are configured. In the present embodiment, an example in which the information processing apparatus 110 and the external server 160 perform TCP / IP communication through the relay apparatus 120, the base station 130, and the communication network 140 is shown.

  The information processing apparatus 110 includes a personal computer, a notebook personal computer, an in-vehicle module, a car navigation system, a PDA (Personal Digital Assistant), a digital camera, a music player, a portable TV, a game device, a DVD player, a remote controller, a mobile phone, and a PHS (PHS). It is composed of various electronic devices such as Personal Handy phone System) terminals and functions as an input / output interface for users.

  The relay device 120 has a wireless function and is electrically connected to a PCMCIA (Personal Computer Memory Card International Association) slot or a USB (Universal Serial Bus) slot provided in the information processing device 110 to connect the information processing device 110 and the base station. 130 is relayed. In the present embodiment, an example is given in which the relay device 120 performs wireless communication with the base station 130 as an access point. However, the relay devices 120 do not go through other access points or access points like an ad hoc network. This embodiment also includes a form of direct communication connection.

  The base station 130 establishes wireless communication with a relay terminal 120, a mobile terminal such as a mobile phone or a PHS terminal, and provides a call function, a Web browsing function, a mail transmission / reception function, and the like.

  The management server 150 uses the information processing apparatus 110 of the user to access the external server 160 or the like through the relay apparatus 120, and between the relay apparatus 120 and the base station 130 and between the base station 130 and the external A communication path with the server 160 is established, and a connection between the information processing apparatus 110 and the external server 160 is ensured.

  The external server 160 is various servers connected to the communication network 140 such as an FTP server provided by a service provider, and performs uploading of packets from the information processing apparatus 110 and downloading of packets to the information processing apparatus 110. .

  In the wireless communication system 100, a communication line from the information processing apparatus 110 of the wireless communication system 100 to an external server 160 having data for high speed communication of data such as Web browsing and video distribution as a communication partner in response to a user operation input. When the connection is made, the relay device 120 makes a wireless connection request to the base station 130 within the communicable range. Receiving the wireless connection request, the base station 130 establishes communication with the external server 160 via the communication network 140 or requests the management server 150 for communication connection with the communication partner via the communication network 140 for management. The server 150 establishes a communication path with the external server 160, and establishes communication between the information processing apparatus 110 and the external server 160.

  In such a wireless communication system 100, various techniques are employed to improve the communication speed and communication quality between the relay device 120 and the base station 130. In this embodiment, for example, iBurst (registered trademark) is adopted. iBurst (registered trademark) has a wide communication distance of about several kilometers, and performs high-speed digital communication with a maximum communication speed of about 2 Mbps in downlink (transmission from the base station 130 to a communication terminal including the relay device 120). Is possible.

  Therefore, in the wireless communication system 100 using iBurst (registered trademark), the information processing device 110 including the relay device 120 has mobility and portability like a PHS and a mobile phone, and also has e-mail, Web browsing, Data such as IP phone and video distribution can be communicated at high speed. Further, wireless communication based on a TDMA (Time Division Multiple Access) -TDD (Time Division Duplex) method is performed between the relay device 120 and the base station 130.

  FIG. 2 is an explanatory diagram for explaining the occurrence of a no-communication state in the wireless communication system 100. In TCP / IP, the external server 160 transmits a packet to the information processing apparatus 110 through the base station 130 and the relay apparatus 120. The sequence number of the transmitted packet is indicated by a numerical value after “seq =” on the transition line of the information processing apparatus 110.

  At this time, if a packet is lost during transmission (indicated by x in the figure), the information processing apparatus 110 sends an ACK that describes the maximum value of consecutive sequence numbers among the received packets without any missing number. Send to. In FIG. 2, the information processing apparatus 110 receives the packet of seq = 73 after the packet of seq = 72 is lost, and the sequence number of the packet received up to that time and the packet of seq = 73 are consecutive. Can be grasped (72 is a missing number). Therefore, ACK = 71 in which 71, which is the maximum value of consecutive sequence numbers without missing numbers, is transmitted among the received packets is transmitted.

  Since the received ACK number is not the expected number (ACK = 72) but ACK = 71, the external server 160 determines that the packet of seq = 72 obtained by adding 1 to the number 71 is lost (seq = 72 packet) and a missing packet (seq = 72) is transmitted (retransmitted).

  Thereafter, even if the external server 160 receives an ACK with a number smaller than 72 until it receives an ACK (ACK = 72) of the missing packet (seq = 72) (assuming that ACK = 71 is received a plurality of times in the figure). Also, do not send the same missing packet repeatedly. Therefore, the external server 160 transmits a missing packet (seq = 72) only once in response to successive retransmission requests (ACK = 71). During this time, if the base station 130 has completely transmitted packets stored in its own buffer, the data flow from the base station 130 to the relay device 120 is temporarily stopped.

  Further, when the information processing apparatus 110 normally receives the missing packet (seq = 72), the information processing apparatus 110 transmits an ACK (ACK = 80 in the figure) in which the maximum value of the sequence number of the packet that is received at that time is not lost. To do. The ACK = 80 indicates that the information processing apparatus 110 has normally received at least packets up to at least seq = 80. At this time, the information processing apparatus 110 does not transmit the next ACK until receiving a normal packet that is not a missing packet from the external server 160. That is, the data flow from the relay apparatus 120 to the base station 130 is temporarily stopped.

  Accordingly, the temporary non-communication in which data is not exchanged between the base station 130 and the relay device 120 during the period indicated by “no communication” in the figure until a new packet is transmitted from the external server 160. A situation will occur.

  When such a temporary no-communication state occurs, the base station 130 forcibly releases (disconnects) the channel that is determined not to be in communication in order to effectively use resources, It may be assigned to another terminal. In particular, in iBurst (registered trademark), the base station 130 releases the channel when it is in a no-communication state for a short time of about 20 ms.

  The information processing apparatus 110 that has been disconnected must make a communication request to the base station 130 again in order to continue receiving data. In such a communication request, re-registration processing for establishing wireless communication occurs, and a wasteful time is consumed.

  An object of the present embodiment is to perform efficient wireless communication by preventing a situation in which a channel is disconnected in a no-communication state caused by a series of packet retransmission processes. Hereinafter, the relay apparatus 120 that exhibits such an effect will be described in detail.

(Relay device 120)
FIG. 3 is a functional block diagram illustrating a hardware configuration of the relay device 120 according to the present embodiment. The relay device 120 includes a transmission / reception unit 200, a state transition control unit 202, and a resource management unit 204.

  The transmission / reception unit 200 includes an antenna unit 210, a packet reception unit 212, a retransmission grasp unit 214, and a dummy transmission unit 216. The transmission / reception unit 200 receives an ACK for an received packet transmitted from the information processing apparatus 110, information processing A packet including transmission data transmitted from the device 110 is transmitted.

  The antenna unit 210 converts an electromagnetic wave from the base station 130 into an electric signal and transmits the electric signal to the packet receiving unit 212, and converts an electric signal from the retransmission grasping unit 214 and the dummy transmission unit 216 into an electromagnetic wave and transmits the electromagnetic wave to the base station 130. . The packet receiving unit 212 receives a packet transmitted from the base station 130 and transmits the packet to the state transition control unit 202 described later.

  Retransmission grasping unit 214 detects a missing sequence number assigned to a packet received by state transition control unit 202 described later. It can be ascertained whether or not retransmission occurs between the external server 160 and the information processing apparatus 110. In this embodiment, the retransmission request is implemented by transmitting an ACK to which a number one prior to the missing sequence number for which a retransmission request is made.

  When the dummy transmission unit 216 is in a retransmission state to be described later or in a retransmission release waiting state, and a non-communication detection unit 220 (to be described later) detects a non-communication state, the resource management unit 204 instructs to transmit dummy data. Dummy data is transmitted to the base station 130. The dummy data is data that does not include significant information that affects communication, and is configured to be ignored or discarded by the base station 130. Although the base station 130 does not react to the dummy data, the base station 130 determines that communication is continued according to the reception operation itself, and therefore, avoids disconnection of a channel in a temporary non-communication state and maintains the connection. Can do. In addition, when there are a plurality of channels to which the access point and the relay device 120 are connected, the dummy transmission unit 216 determines the channel in which the non-communication detection unit 220 (to be described later) detects the non-communication state by the resource management unit 204 (to be described later). The dummy data is transmitted through the channel specified by the instruction.

  Currently, a technique is used in which the relay apparatus 120 communicates with the base station 130 using a plurality of channels in combination to improve the data communication speed. When communication is performed using a plurality of channels, the data transmission / reception of the plurality of channels may be biased to a specific channel, and a non-communication state may occur for another channel for a longer time. Therefore, the dummy transmission unit 216 can avoid channel disconnection more reliably by specifying a channel in a non-communication state and transmitting dummy data from the channel.

  The state transition control unit 202 detects the missing packet by the retransmission grasping unit 214 and recognizes that retransmission occurs, and then the retransmission state until the missing packet is received, and the missing packet after receiving the missing packet. State transition is performed between a retransmission cancellation waiting state until a normal packet is received and a normal state where a normal packet that is not a missing packet is received. The state transition is determined based on the sequence number of the packet transmitted from the packet receiving unit 212. Therefore, after obtaining the sequence number from the packet, the state transition control unit 202 transmits (transfers) the packet to the information processing apparatus 110. The state transition and processing determination will be described in detail later with reference to FIG.

  In addition, the state transition control unit 202 has a retransmission cancellation timer, and monitors the elapsed time after entering the retransmission cancellation waiting state. When any one of the retransmission state period, the retransmission cancellation waiting period, or the combined retransmission period and retransmission cancellation waiting period continues for a predetermined time, the state transition control unit 202 determines whether the retransmission state or the retransmission cancellation The waiting state is released and the normal state is entered. When the elapsed time from the normal state becomes a predetermined value or more, the communication disconnection unit 220 described later disconnects the channel.

FIG. 4 is a flowchart showing the flow of processing when a packet is received when the present embodiment as a comparative example is not applied. When the state is not determined as in the comparative example, when the packet receiving unit 212 receives the packet (S500 YES), the sequence number given to the packet is larger than the expected number (S502 YES), or
When the sequence number given to the received packet is equal to the expected number (S506 YES), the received packet is transmitted to the information processing apparatus 110 (S504, S508). Furthermore, when the sequence number given to the received packet is smaller than the expected number (NO in S506), the received packet is discarded (S510).

  Here, the expected number is a number obtained by adding a predetermined value (packet reception unit) to the sequence number given to the ACK received from the information processing apparatus 110 immediately before. When transitioning to the retransmission state, the sequence number given to the ACK received immediately before this is fixed as the expected number during the retransmission state. Such a predetermined value is equal to the number of packets received until the relay apparatus 120 transmits an ACK.

  FIG. 5 is a flowchart showing the flow of processing when a packet is received in this embodiment. Unlike the comparative example of FIG. 4, the state is changed according to the received packet. Here, the same processes as those in FIG. 4 are denoted by the same reference numerals, description thereof is omitted, and different processes are described in detail.

  If the sequence number given to the received packet is larger than the expected number (YES in S502), the retransmission state is set, and if the previous state is not the retransmission state, the state is changed to the retransmission state (S600). Further, when the retransmission cancellation timer is stopped, the timer is started (S602), and the received packet is transmitted to the information processing apparatus 110 (S504). Packets received after the missing packet are sequentially transmitted to the information processing apparatus 110.

  If the sequence number given to the received packet is equal to the expected number (S506 YES) and the previous state is the retransmission state (S604 YES), the retransmission release waiting state is entered, and the state is set to the retransmission release waiting state. A transition is made (S606). Further, if the immediately preceding state is not the retransmission state (NO in S604), the normal state is set. If the immediately preceding state is not the normal state, the state is changed to the normal state (S608). If the retransmission cancellation timer has been started, it is stopped (S610).

  If the sequence number assigned to the received packet is not equal to the expected number (NO in S506), the received packet is discarded (S510). This is because such a packet is judged to have been received through a long communication path simply because the communication environment is bad. At this time, the previous state is maintained without changing the state.

  As described above, compared to the comparative example, in this embodiment, dummy data is transmitted in a non-communication state by performing a state transition to each of a retransmission state, a retransmission release waiting state, and a normal state according to a received packet. It is possible to specify the power period.

  FIG. 6 is a flowchart showing a flow of processing of the retransmission cancellation timer in the present embodiment. The state transition control unit 202 measures a retransmission cancellation timer in parallel with the processing flow described in FIG. The retransmission cancellation timer is started and stopped in the processing flow shown in FIG. 5 (S602 and S610 in FIG. 5).

  The retransmission cancellation timer waits until the retransmission cancellation timer is activated (NO in S700). When the retransmission cancellation timer is activated (S700 YES), it is determined whether or not an elapsed time K1 after the activation of the retransmission cancellation timer exceeds a predetermined time T (S702). When the predetermined time T is exceeded (YES in S702), the state transits to the normal state. When the time is equal to or shorter than the predetermined time T (NO in S702), the process returns to the determination of whether the retransmission cancellation timer is activated (S700).

  With this processing, for example, when no packet arrives from the base station 130 in the retransmission state or the retransmission cancellation waiting state, the elapsed time K1 exceeds the predetermined time T and transitions to the normal state after starting the retransmission cancellation timer. If no further packet arrives and the no-communication state continues, the communication disconnecting unit 220 described later disconnects the channel.

  A time limit is set for transmitting the dummy data, the retransmission state period, the retransmission release waiting state period, or the combined period of the retransmission state and the retransmission release waiting state, and the relay device 120 returns to the normal state when a predetermined time elapses. The transmission of dummy data is stopped. For example, due to the deterioration of the communication environment, a missing packet or a normal packet that is not a missing packet does not reach the relay device 120 indefinitely, and does not transit from the retransmission state or the retransmission release waiting state to the normal state, and transmission of dummy data is limited. May continue without. At this time, if the channel used for communication is occupied indefinitely without disconnecting, the other terminals cannot use the channel, and the communication efficiency of the entire wireless communication system 100 decreases. With this configuration, it is possible to avoid a situation in which the relay device 120 occupies a communication channel for a predetermined time or more without performing significant data transmission / reception, and more efficiently use a channel using a finite bandwidth. .

  The resource management unit 204 manages a channel connected to the base station 130. In addition, when the connected channel is in a non-communication state and is in a retransmission state or a retransmission release waiting state, an instruction is transmitted to the dummy transmission unit 216 to transmit dummy data. The resource management unit 204 includes a no-communication detection unit 220 and a communication disconnection unit 222.

  The non-communication detection unit 220 monitors the channel connected between the relay device 120 and the base station 130 through the transmission / reception unit 200, and is in a non-communication state where transmission and reception of packets such as normal data and dummy data are not performed. Is detected. Further, when a plurality of channels are connected, a non-communication state can be detected for each channel.

  The communication disconnection unit 222 acquires channel information in a no-communication state from the no-communication detection unit 222 and acquires the current state from the state transition control unit 202. If the elapsed time after entering the no-communication state exceeds a predetermined time, all the channels in the retransmission state or the retransmission release waiting state are disconnected.

  FIG. 7 is a flowchart for disconnecting a non-communication channel when the present embodiment as a comparative example is not applied. If the channel connected to the base station 130 is not in a no-communication state (S800 NO), the resource management unit 204 stands by. In addition, even when the elapsed time K2 after entering the no-communication state does not exceed the predetermined value t (NO in S802), the process stands by. Further, when the elapsed time K2 after entering the no-communication state exceeds a predetermined value t (YES in S802), the connected channel is disconnected (S804).

  FIG. 8 is a flowchart for disconnecting a channel in a non-communication state in the present embodiment. Unlike the comparative example of FIG. 7, the process is changed according to the state controlled by the state transition control unit 202. Here, the same processes as those in FIG. 7 are denoted by the same reference numerals, description thereof is omitted, and different processes are described in detail.

  The resource management unit 204 stands by when the connected channel is not in a no-communication state (S800 NO). If the connected channel is in the no-communication state (YES in S800), the state transition control unit 202 is inquired to determine whether it is in the retransmission state or the retransmission release waiting state (S900). When it is in a retransmission state or a retransmission release waiting state (S900 YES), the dummy transmission unit 216 transmits dummy data (S902). If it is not in the retransmission state or the retransmission release waiting state, a determination process of the elapsed time K2 after the non-communication state is established (S802). The subsequent processing is the same as that of the comparative example. The process described in the flowchart is executed for each connected channel.

  In contrast to the comparative example, in the present embodiment, even if the communication is not performed, the relay device itself does not disconnect the communication channel as long as it is in the retransmission state or the retransmission release waiting state. Furthermore, it is possible to avoid a situation where the base station 130 is disconnected by transmitting dummy data.

  FIG. 9 is an explanatory diagram comparing channel disconnection timings. FIG. 9A is a comparative example when the present embodiment is not applied, and FIG. 9B shows the timing at which the channel is disconnected when dummy data is transmitted. In the comparative example, since the dummy data is not transmitted, the channel is disconnected by the communication disconnection unit 222 (disconnection timing A) when the elapsed time from the no-communication state is continued until the predetermined value t. In FIG. 9B, dummy data is transmitted when in a no-communication state and in a retransmission state or a retransmission release waiting state. When dummy data is transmitted for a predetermined time T, a transition is made to the normal state. If the elapsed time from the transition to the normal state is continued until the predetermined value t, the channel is disconnected by the communication disconnection unit 222 (disconnection timing B). As is clear from a comparison between FIG. 9A and FIG. 9B, the cutting timing B is cut later than the cutting timing A by a predetermined time T during which dummy data transmission was performed, and temporarily. Can avoid unnecessary disconnection in a typical no-communication state.

Although not explicitly shown in FIG. 9, the channel to which the base station 130 is connected is also monitored, and the channel that has been in the no-communication state for a predetermined time or longer is disconnected. However, in FIG. 9B, since no communication state is not established for a predetermined time T during which dummy data transmission is performed, unnecessary disconnection in a temporary no communication state can also be avoided.
(Wireless communication method)

  FIG. 10 is an explanatory diagram illustrating a packet wireless communication method among the external server 160, the base station 130, the relay device 120, and the information processing device 110 according to the present embodiment with a specific example. Since the packet transmitted from the external server 160 is lost, the information processing apparatus 110 makes a retransmission request for the missing packet and receives the missing packet (seq = 72), the description is omitted because it overlaps with the description in FIG.

  When the state transition control unit 202 receives the missing packet (seq = 72) from the base station 130, the state transition control unit 202 determines that it is in a retransmission release waiting state. Then, relay device 120 receives the missing packet retransmitted from base station 130 and transmits it to information processing device 110, and then information processing device 110 transmits the ACK. When relay apparatus 120 transmits the received ACK to base station 130, relay apparatus 120 enters a no-communication state with base station 130. When determining that the resource management unit 204 is in the no-communication state, the resource management unit 204 notifies the dummy transmission unit 216. The dummy transmission unit 216 continues to transmit dummy data from a channel in a no-communication state (one-dot chain line), and keeps the channel being communicated from being disconnected by the base station 130.

  The no-communication state between the base station 130 and the relay device 120 may repeatedly occur for reasons such as deterioration of the communication environment. However, a temporary no-communication state that causes unnecessary disconnection of the channel by the base station 130 occurs during a series of processes of retransmission of missing packets. In other words, there is a high possibility that the information processing apparatus 110 will transmit the missing packet retransmission request, receive the missing packet, return the ACK, and receive a normal packet that is not the missing packet. Therefore, in the series of retransmission processes, the first half is set as the retransmission state, the second half is set as the retransmission release waiting state, and the other period is distinguished as the normal state at the time when the ACK indicating that the missing packet has been received is returned. Then, the dummy data is transmitted only when there is no communication in the retransmission state and the retransmission release waiting state. With this configuration, even if the relay apparatus 120 limits the transmission of dummy data to the retransmission state and the retransmission release waiting state, it is possible to avoid a decrease in throughput due to channel disconnection without causing a no-communication state.

  Then, when the ACK (ACK = 80) for the retransmitted packet reaches the external server 160 and the relay device 120 receives the newly transmitted packet (seq = 81) instead of the retransmission, the state transition control unit 202 The resource management unit 204 detects that the state has changed to the normal state, and instructs the dummy transmission unit 216 to stop transmission of dummy data. Thereafter, normal communication is executed.

  FIG. 11 is an explanatory diagram illustrating a packet wireless communication method among the external server 160, the base station 130, the relay device 120, and the information processing device 110 according to another embodiment, according to another specific example. In FIG. 10, a plurality of packets remain in the buffer of the base station 130 when the packet is lost, but FIG. 11 shows an example in which no packets remain in the buffer of the base station 130.

  If a packet is lost during transmission of a packet from the base station 130 to the relay device 120 (illustrated by x), then the state transition control unit 202 receives a packet of seq = 73 and has received it by that time. It can be understood that the sequence number of the packet that has been seq and the packet of seq = 73 are not consecutive (72 is a missing number). After that, the information processing apparatus 110 that has received the packet of seq = 73 instructs to transmit ACK = 71 in which 71, which is the maximum value of the consecutive sequence numbers without missing numbers, among the received packets, Relay device 120 transmits ACK = 71 to base station 130.

  The external server 160 determines that the received ACK is an ACK = 72, which is an expected number, but ACK = 71, so that seq = 72 obtained by adding 1 to the number 71 is a missing packet (seq = 72), a packet of seq = 72 for which a retransmission request has been made is transmitted (retransmitted).

  However, since the base station 130 has completely transmitted all the packets that need to be transmitted and no packets remain in the buffer, no new packets are transmitted. Also, after transmitting ACK = 71, the relay apparatus 120 cannot transmit a packet until it receives a missing packet (ACK = 71) and transmits an ACK received from the information processing apparatus 110. A condition can occur.

  At this time, if the resource management unit 204 determines that this channel is in a retransmission state and is in a no-communication state, the resource management unit 204 sends an instruction to the dummy transmission unit 216 to transmit dummy data. Since the dummy transmission unit 216 transmits dummy data (a one-dot chain line in a retransmission state), disconnection of a channel due to a no-communication state can be avoided.

  Further, after transmitting ACK = 73, the base station 130 similarly does not accumulate buffers, and the relay apparatus 120 cannot transmit the ACK from the information processing apparatus 110 to the base station 130 until the next packet is received. Although a non-communication state occurs, it is determined that the state is in a retransmission release waiting state, and transmission of dummy data (a one-dot chain line in the retransmission release waiting state) can avoid disconnection of the channel due to the no communication state.

  As described with reference to FIGS. 10 and 11, the relay device 120 receives a missing packet after the packet is lost during communication, and the relay device 120 transmits a retransmission request for the missing missing packet. When a non-communication state is reached before receiving a normal packet that is not a packet, the dummy transmission unit 216 transmits dummy data that does not include significant information to the base station 130. With this configuration, communication is continued from the relay apparatus 120 to the base station 130 by at least transmission of dummy data, and the channel is not forcibly disconnected by the base station 130.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  Note that each step in the wireless communication method of the present specification does not necessarily have to be processed in time series in the order described as a flowchart or a sequence diagram, and may include processing in parallel or by a subroutine.

  The present invention can be used for a wireless communication apparatus and a wireless communication method connected to an access point.

It is explanatory drawing which showed the rough connection relation of the radio | wireless communications system in this embodiment. It is explanatory drawing explaining generation | occurrence | production of the no-communication state in a radio | wireless communications system. It is the functional block diagram which showed the hardware constitutions of the relay apparatus in this embodiment. It is the flowchart which showed the flow of the process at the time of receiving the packet when not applying this embodiment as a comparative example. It is the flowchart which showed the flow of the process at the time of receiving the packet in this embodiment. It is the flowchart which showed the flow of the process of the resending cancellation | release timer in this embodiment. It is a flowchart of the disconnection of the channel of a non-communication state when not applying this embodiment as a comparative example. It is a flowchart of the disconnection of the channel of a non-communication state in this embodiment. It is explanatory drawing which compared the timing of channel cutting | disconnection. It is explanatory drawing explaining the radio | wireless communication method of the packet between the external server in this embodiment, a base station, a relay apparatus, and information processing apparatus by the specific example. It is explanatory drawing explaining the radio | wireless communication method of the packet between the external server in this embodiment, a base station, a relay apparatus, and information processing apparatus by another specific example.

Explanation of symbols

110 ... Information processing device 120 ... Relay device 130 ... Base station (access point)
202 ... State transition control unit 212 ... Packet reception unit 214 ... Retransmission grasping unit 216 ... Dummy transmission unit 220 ... Non-communication detection unit

Claims (5)

A wireless communication device connected to an access point,
A packet receiving unit for receiving a packet transmitted from the access point;
A retransmission grasp unit for detecting a missing number of a sequence number given to the received packet;
A no-communication detector for detecting a no-communication state;
A dummy transmitter for transmitting dummy data to the access point when the no-communication detecting unit detects a no-communication state after the retransmission grasping unit detects a missing sequence number;
A wireless communication apparatus comprising: A retransmission state until the retransmission grasping unit detects the missing packet and receives the missing packet, and a retransmission release waiting state after receiving the missing packet and receiving a normal packet that is not the missing packet; , Further comprising a state transition control unit for making a state transition to a normal state for receiving a normal packet that is not the missing packet,
The dummy transmission unit transmits the dummy data while in the retransmission state or the retransmission release waiting state and the no-communication detection unit detects a no-communication state. A wireless communication device according to 1.   The state transition control unit, when any one of the period of the retransmission state, the period of the retransmission cancellation waiting state, or the period of the retransmission state and the retransmission cancellation waiting state continues for a predetermined time, the retransmission state, or The wireless communication apparatus according to claim 1 or 2, wherein the retransmission cancellation waiting state is canceled and the state transits to the normal state.   When there are a plurality of channels to which the access point and the wireless communication device are connected, the dummy transmission unit specifies a channel in which the non-communication detection unit detects a non-communication state, and the dummy data is transmitted through the channel. The wireless communication device according to claim 1, wherein the wireless communication device transmits the wireless communication device. A wireless communication method of a wireless communication device connected to an access point,
Receiving a packet transmitted from the access point;
Detecting a missing sequence number given to the received packet,
Detect no-communication
A wireless communication method comprising: transmitting dummy data to the access point when a non-communication state is detected after detecting a missing number of the sequence number.

Images