JP2007235871A - Wireless device and wireless network system using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless device possible to reduce an increase of delay time and packet error rate. <P>SOLUTION: The wireless device 36 detects an own packet transmission volume W per unit time when relaying the wireless communications between the wireless devices 32 and 39, the wireless devices 35 and 41, and the wireless devices 38 and 37; and, if the detected packet transmission volume W becomes equal to or greater than a threshold value Wth, the wireless device 36 directs the wireless devices 33, 38, and 42 to change a packet size and a packet transmission interval, so that the packet transmission volume W becomes smaller than the threshold value Wth. The wireless devices 33, 38, and 42 change the packet size and packet transmission interval in response to the direction for changing and transmit the packets. The threshold value Wth is the maximum packet transmission volume per unit time without increasing the delay time and packet error rate in the wireless device 36. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radio apparatus and a radio network system using the radio apparatus, and more particularly to a radio apparatus constituting a radio network in which radio communication is performed between a transmission source and a transmission destination by multi-hop communication, and a radio network including the same It is about the system.

  An ad hoc network is a network that is autonomously and instantaneously constructed by a plurality of wireless devices communicating with each other. In an ad hoc network, when two wireless devices that communicate with each other do not exist in the communication area, a wireless device located between the two wireless devices functions as a router and relays a data packet. Can be formed.

  Dynamic routing protocols that support multi-hop communication include table-driven protocols and on-demand protocols. The table-driven protocol periodically exchanges control information related to a route and constructs a route table in advance, and includes FSR (Fish-eye State Routing), OLSR (Optimized Link State Routing), and TBRPF (Topology). (Dissociation Based on Reverse-Path Forwarding) and the like are known.

  In addition, the on-demand protocol is a method for constructing a route to a destination for the first time when a data transmission request occurs, and includes DSR (Dynamic Source Routing) and AODV (Ad Hoc On-Demand Distance Vector Routing). Are known.

In a conventional ad hoc network, when data communication is performed from a transmission source to a transmission destination, a communication path is determined so that the number of hops from the transmission source to the transmission destination is as small as possible (Non-Patent Document 1).
Guangyu Pei, at al, “Fisheye state routing: a routing scheme for ad hoc wireless networks”, ICC2000. Commun., Volume 1, pp70-74, LA, June 2000.

  However, in an ad hoc network, a plurality of wireless communications between a transmission source and a transmission destination may be performed via the same repeater, and a plurality of traffics may be concentrated on one repeater.

  Therefore, consider the problem when a plurality of traffics are concentrated on one repeater. FIG. 18 is a layout diagram of radio apparatuses in an experiment for examining the influence when a plurality of traffics are concentrated on one repeater. In FIG. 18, the wireless devices (1) to (5) are installed in a room in a building, and the repeater R is installed in a hallway in the building.

  In FIG. 18, the wireless device (1) installed in the left room performs bidirectional wireless communication with the wireless device (1) installed in the right room via the repeater R. The same applies to the wireless devices (2) to (5). Thus, the wireless devices (1) to (5) perform bidirectional wireless communication with the wireless device having the same number via the relay R. In this case, VoIP (Voice over Internet Protocol) was used as an application.

  Since the wireless devices (1) to (5) and R are installed in a room or a hallway, wireless communication by VoIP is performed via a static route. And the wireless communication of the same numbers (for example, wireless device (1) -wireless device (1)) was made into 1 session, and the change of the communication characteristic when the number of sessions was increased to 1-5 was investigated.

  FIG. 19 is a diagram illustrating the relationship between the average packet error rate, the average delay time, and the number of sessions. In FIG. 19, the vertical axis represents the average packet error rate and average delay time in the repeater R, and the horizontal axis represents the number of sessions relayed by the repeater R. In FIG. 19, the bar graph represents the average packet error rate, and the line graph represents the average delay time.

  From the results shown in FIG. 19, when the number of sessions relayed by the repeater R exceeds “3”, the average packet error rate and the average delay time start to increase. This is because buffering of transmission data is started in the repeater R when traffic for three sessions is concentrated in the repeater R due to 802.11 MAC protocol CSMA / CA (Carrier Sense Multiple Access Collision Avidance). is there.

  More specifically, it is assumed that there are N interactive sessions in which the source wireless device (any one of wireless devices (1) to (5)) generates M packets per second in one direction. When all these traffics are concentrated on one repeater R, the number of packets that the repeater R must transfer per second is N (session) × 2 (bidirectional) × M (pieces / second). )

  FIG. 20 is a diagram illustrating the relationship between the maximum waiting time and transfer time interval and the number of sessions. In FIG. 20, the vertical axis represents the maximum waiting time and the transfer time interval in the repeater R, and the horizontal axis represents the number of sessions relayed by the repeater R. In FIG. 20, the solid line represents the maximum waiting time, and the dotted line represents the transfer time interval.

  When the repeater R transfers 2NM packets per second, the time interval at which the repeater R transmits packets is the reciprocal of this value (= 2NM) (dotted line in FIG. 20).

  However, since a plurality of wireless devices within the same radio wave range cannot communicate at the same time due to the CSMA / CA mechanism, assuming that a typical communication time per packet is T, the repeater R is required to transmit a relay packet. The maximum waiting time that must be waited is T × 2N (solid line in FIG. 20).

  Therefore, there is a possibility that transfer data is buffered in the repeater R where the two lines shown in FIG. 20 intersect, which increases the delay time and packet loss in the repeater R. That is, when one relay R relays a plurality of traffics, there is a problem that the packet loss and the delay time are increased in the relay R.

  Therefore, the present invention has been made to solve such a problem, and an object of the present invention is to provide a radio apparatus capable of suppressing an increase in delay time and packet error rate.

  Another object of the present invention is to provide a wireless network system including a wireless device capable of suppressing increases in delay time and packet error rate.

  According to the present invention, the wireless device is a wireless device that relays wireless communication between a transmission source and a transmission destination, and includes a detection unit and a control unit. The detecting means detects a communication load of wireless communication. The control means controls the data transmission interval and the data length to be transmitted at a time so that the communication load becomes smaller than the threshold when the communication load detected by the detection means reaches or exceeds the threshold. The threshold value is the maximum communication load per unit time at which the delay time and the packet error rate in the wireless device do not increase.

  Preferably, the control unit controls the packet transmission interval and the packet size so that the communication load becomes smaller than the threshold when the communication load detected by the detection unit reaches or exceeds the threshold.

  Preferably, the wireless device further includes a relay unit. The relay means relays data at the data transmission interval and data length controlled by the control means.

  Preferably, the control means includes a determination means and an instruction means. When the communication load detected by the detection unit reaches a threshold value or more, the determination unit determines a suitable data transmission interval and a suitable data length that make the communication load smaller than the threshold value. The instructing unit instructs the transmission source to change the data transmission interval and the data length at the transmission source to a suitable data transmission interval and a suitable data length, respectively.

  According to the present invention, the wireless device is a wireless device that relays wireless communication between a transmission source and a transmission destination, and includes a detection unit and a relay unit. The detecting means detects a communication load of wireless communication. When the communication load detected by the detection unit reaches a threshold value or more, the relay unit relays data at a suitable data transmission interval and a suitable data length that make the communication load smaller than the threshold value. The threshold value is the maximum communication load per unit time at which the delay time and the packet error rate in the wireless device do not increase.

  Preferably, the relay unit bundles a plurality of packets from the transmission source and relays them to the transmission destination so that the communication load becomes smaller than the threshold when the communication load detected by the detection unit exceeds the threshold value. To do.

  Furthermore, according to the present invention, the wireless network system is a wireless network system in which wireless communication is performed between a transmission source and a transmission destination by multi-hop communication, and includes first to third wireless devices. The first wireless device is a transmission source. The second wireless device is a transmission destination. The third wireless device relays wireless communication between the first wireless device and the second wireless device. Then, when the communication load in the third wireless device reaches or exceeds the threshold value, the data transmission interval and the data length to be transmitted at a time are controlled so that the communication load becomes smaller than the threshold value. The threshold value is the maximum communication load per unit time at which the delay time and the packet error rate in the third wireless device do not increase.

  Preferably, when the communication load reaches or exceeds a threshold value, the third wireless device instructs the first wireless device to change the packet size and the packet transmission interval. The first wireless device changes the packet size and the packet transmission interval so that the communication load becomes smaller than the threshold value in response to an instruction from the third wireless device.

  In the present invention, when the communication load in the wireless device that relays wireless communication between the transmission source and the transmission destination reaches a threshold value or more, the data transmission interval and once are set so that the communication load becomes smaller than the threshold value. The data length to be transmitted is controlled.

  Therefore, according to the present invention, it is possible to suppress an increase in delay time and packet error rate in a wireless device that relays wireless communication.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a schematic diagram of a wireless network system 100 using a wireless device according to an embodiment of the present invention. The wireless network system 100 includes wireless devices 31 to 43. The wireless devices 31 to 43 are arranged in a wireless communication space. The antennas 51 to 63 are attached to the wireless devices 31 to 43, respectively.

  For example, when transmitting data from the wireless device 31 to the wireless device 42, the wireless devices 32 and 35 to 41 relay the data from the wireless device 31 and deliver the data to the wireless device 42.

  In this case, the wireless device 31 can perform wireless communication with the wireless device 42 via various routes. That is, the wireless device 31 can perform wireless communication with the wireless device 42 via the wireless devices 37 and 41, and perform wireless communication with the wireless device 42 via the wireless devices 32, 36, and 39. It is also possible to perform wireless communication with the wireless device 42 via the wireless devices 32, 35, 38, and 40.

  That is, the wireless device 31 performs wireless communication with the wireless device 42 using the wireless devices 37, 41 or the wireless devices 32, 36, 39 or the wireless devices 32, 35, 38, 40 as relays.

  Therefore, the wireless network system 100 is a multi-hop network system that performs wireless communication between a transmission source and a transmission destination by multi-hop communication.

  In such a multi-hop network system, a plurality of traffics may be concentrated on one repeater. For example, the wireless device 31 performs bidirectional wireless communication with the wireless device 42 via the wireless devices 32, 36, 39, and the wireless device 33 communicates with the wireless device 43 via the wireless devices 35, 36, 41. When communication is performed, four traffics are concentrated on the wireless device 36 as a repeater.

  Therefore, in the following, when a plurality of wireless communications are performed in the wireless network system 100, a method of performing wireless communications between a transmission source and a transmission destination by reducing the delay time and the packet error rate in the repeater Will be described.

  The OLSR protocol is used as a protocol for establishing a communication path between the transmission source and the transmission destination. The OLSR protocol is a table-driven routing protocol, and is a protocol for exchanging route information by using a Hello message and a TC (Topology Control) message to create a routing table.

[Embodiment 1]
FIG. 2 is a schematic block diagram in the first embodiment showing the configuration of radio apparatus 31 shown in FIG. The wireless device 31 includes an antenna 11, an input unit 12, an output unit 13, a user application 14, and a communication control unit 15.

  The antenna 11 constitutes each of the antennas 51 to 63 shown in FIG. The antenna 11 receives data from other wireless devices via the wireless communication space, outputs the received data to the communication control unit 15, and transmits the data from the communication control unit 15 via the wireless communication space. Send to other wireless device.

  The input unit 12 accepts a message and data destination input by the operator of the wireless device 1 and outputs the accepted message and destination to the user application 14. The output unit 13 displays a message according to control from the user application 14.

  The user application 14 generates data based on the message and destination from the input unit 12 and outputs the data to the communication control unit 15. In this case, upon receiving an instruction to change the packet size and packet transmission interval from the communication control unit 15, the user application 14 changes the packet size and packet transmission interval by a method described later, and generates a packet with the changed packet size. At the same time, the generated packet is output to the communication control unit 15 at the changed packet transmission interval.

  The communication control unit 15 includes a plurality of modules that perform communication control in accordance with an ARPA (Advanced Research Projects Agency) Internet hierarchical structure. That is, the communication control unit 15 includes a radio interface module 16, a MAC (Media Access Control) module 17, a buffer 18, an LLC (Logical Link Control) module 19, an IP (Internet Protocol) module 20, and a routing table 21. And a TCP module 22, a UDP module 23, and a routing daemon 24.

  The wireless interface module 16 belongs to the physical layer, modulates / demodulates a transmission signal or a reception signal according to a predetermined rule, and transmits / receives a signal via the antenna 11.

  The MAC module 17 belongs to the MAC layer, executes the MAC protocol, and executes various functions described below.

  That is, the MAC module 17 broadcasts the Hello packet received from the routing daemon 24 via the wireless interface module 16.

  The MAC module 17 performs retransmission control of data (packets).

  The buffer 18 belongs to the data link layer and temporarily stores packets.

  The LLC module 19 belongs to the data link layer and executes the LLC protocol to connect and release a link with an adjacent wireless device.

  The IP module 20 belongs to the Internet layer and generates an IP packet. The IP packet includes an IP header and an IP data portion for storing a packet of a higher protocol. When the IP module 20 receives data from the TCP module 22 or the UDP module 23, the IP module 20 stores the received data in the IP data portion and generates an IP packet.

  Then, the IP module 20 searches the routing table 21 and determines a route for transmitting the generated IP packet. Then, the IP module 20 transmits the IP packet to the LLC module 19 and transmits the IP packet to the transmission destination along the determined path.

  In addition, when wireless communication is performed using a certain route among the routes stored in the routing table 21, the IP module 20 creates a cache of the routing table 21 that is a copy of the wireless communication and creates the cache. A cache is held in a memory (not shown).

  The routing table 21 belongs to the Internet layer and stores path information in association with each transmission destination, as will be described later.

  The routing daemon 24 belongs to the process / application layer, monitors the execution state of other communication control modules, and processes requests from other communication control modules.

  Further, the routing daemon 24 is mounted by referring to the cache of the routing table 21 which is a copy of the wireless communication when the wireless communication is performed using a certain route among the routes stored in the routing table 21. The packet transmission amount per unit time in the wireless device 31 is calculated. The calculated packet transmission amount is calculated from the sum of the number of packets per unit time that the wireless device 31 receives and transfers from other wireless devices and the number of packets per unit time that the wireless device 31 starts transmission. Become.

  When the wireless device 31 is a repeater that relays wireless communication, when the calculated packet transmission amount per unit time reaches a threshold value or more, the routing daemon 24 sets the threshold for the packet transmission amount per unit time. A change instruction for changing the packet size and the packet transmission interval so as to be smaller than the value is generated, and the generated change instruction is transmitted to the transmission source radio apparatus.

  When the routing daemon 24 receives a change instruction from a repeater that relays wireless communication when the wireless device 31 is a transmission source wireless device, the packet transmission amount per unit time is set to a threshold value by a method described later. And a change instruction for changing the packet size and the packet transmission interval to the determined preferable packet size and the preferable packet transmission interval, respectively. Output to.

  Furthermore, the routing daemon 24 calculates the optimum route and dynamically creates the routing table 21 in the Internet layer.

  Note that each of the wireless devices 32 to 43 illustrated in FIG. 1 has the same configuration as the configuration of the wireless device 31 illustrated in FIG. 2.

  FIG. 3 is a configuration diagram of a packet PKT in the OLSR protocol. The packet PKT includes a packet header PHD and message headers MHD1, MHD2,. Note that the packet PKT is transmitted and received using the port number 698 of the UDP module 23.

  The packet header PHD includes a packet length and a packet sequence number. The packet length consists of 16-bit data and represents the number of bytes of the packet. The packet sequence number consists of 16-bit data and is used to distinguish which packet is new. The packet sequence number is incremented by “1” every time a new packet is generated. Therefore, the larger the packet sequence number, the newer the packet PKT.

  Each of the message headers MHD1, MHD2,... Includes a message type, a valid time, a message size, a source address, a TTL, a hop count, a message sequence number, and a message.

  The message type is composed of 8-bit data and represents the type of message written in the message body, and 0 to 127 are reserved. The valid time consists of 8-bit data, and represents the time when this message must be managed after reception. The valid time is composed of a mantissa part and an exponent part.

  The message size consists of 16-bit data and represents the length of the message. The source address is made up of 32-bit data and represents the wireless device that generated the message. The TTL is composed of 8-bit data and specifies the maximum number of hops to which a message is transferred. The TTL is decremented by “1” when the message is transferred. If the TTL is “0” or “1”, the message is not transferred. The number of hops consists of 8-bit data and represents the number of hops from the message generation source. The number of hops is initially set to “0” and is incremented by “1” every time it is transferred. The message sequence number consists of 16-bit data and represents an identification number assigned to each message. The message sequence number is incremented by “1” every time a message is created. The message is a message to be transmitted.

  In the OLSR protocol, various messages are transmitted and received using the packet PKT having the configuration shown in FIG.

  FIG. 4 is a configuration diagram of the routing table 21 shown in FIG. The routing table 21 includes a transmission destination, a next wireless device, and the number of hops. The transmission destination, the next wireless device, and the number of hops are associated with each other. “Destination” represents the IP address of the destination wireless device. “Next wireless device” represents the IP address of the wireless device to be transmitted next when transmitting the packet PKT to the transmission destination. “Hop number” represents the number of hops to the destination. For example, in FIG. 1, when wireless communication is performed between the wireless device 31 and the wireless device 42 through the route of the wireless device 31 -the wireless device 32 -the wireless device 36 -the wireless device 39 -the wireless device 42, the wireless device 31 In the hop count of the routing table 21, “4” is stored.

  The creation of the routing table 21 according to the OLSR protocol will be described in detail. When creating the routing table 21, the wireless devices 31 to 43 transmit and receive a Hello message and a TC message.

  The Hello message is periodically transmitted for the purpose of distributing information included in each of the wireless devices 31 to 43. By receiving this Hello message, each of the wireless devices 31 to 43 can collect information on peripheral wireless devices, and recognizes what wireless devices exist in the vicinity of the wireless devices.

  In the OLSR protocol, each of the wireless devices 31 to 43 manages local link information. The Hello message is a message for constructing and transmitting the local link information. The local link information includes “link set”, “adjacent radio device set”, “two-hop adjacent radio device set and link set to those radio devices”, “MPR (Multipoint Relay) set”, and “MPR selector set”. including.

  A link set is a link to a set of wireless devices (adjacent wireless devices) through which radio waves directly reach, and each link is expressed by an effective time of a set of addresses between two wireless devices. The valid time is also used to indicate whether the link is unidirectional or bidirectional.

  The neighboring wireless device set is configured by the address of each neighboring wireless device, the retransmitting degree (Willingness) of the wireless device, and the like. The 2-hop adjacent wireless device set represents a set of wireless devices adjacent to the adjacent wireless device.

  The MPR set is a set of wireless devices selected as MPRs. Note that MPR means that when each packet PKT is transmitted to all the wireless devices 31 to 43 of the wireless network system 100, each wireless device 31 to 43 transmits and receives all the packets PKT by transmitting and receiving one packet PKT only once. The relay wireless device is selected so that it can be transmitted to the wireless devices 31-43.

  The MPR selector set represents a set of wireless devices that have selected themselves as MPRs.

  The process of establishing local link information is generally as follows. In the initial stage of the Hello message, each wireless device 31 to 43 transmits a Hello message containing its own address to an adjacent wireless device in order to notify its existence. All of the wireless devices 31 to 43 perform this operation, and each of the wireless devices 31 to 43 grasps what address the wireless device has around itself. In this way, a link set and an adjacent wireless device set are constructed.

  The constructed local link information is continuously sent again by a Hello message again. By repeating this, it is gradually clarified whether each link is bidirectional or what kind of wireless device exists ahead of the adjacent wireless device. Each of the wireless devices 31 to 43 stores the local link information that is gradually constructed in this way.

  Further, information regarding MPR is also periodically transmitted by a Hello message and notified to each of the wireless devices 31 to 43. Each of the wireless devices 31 to 43 selects several wireless devices from among neighboring wireless devices as a set of MPRs as wireless devices that request retransmission of the packet PKT transmitted by itself. Then, since the information regarding this MPR set is transmitted to the adjacent radio apparatus by the Hello message, the radio apparatus that has received this Hello message sets the set of radio apparatuses that it has selected as the MPR as the “MPR selector set”. to manage. By doing in this way, each radio | wireless apparatus 31-43 can recognize immediately which packet apparatus PKT received should be retransmitted.

  When a local link set is established in each of the wireless devices 31 to 43 by transmission / reception of the Hello message, a TC message for notifying the topology of the entire wireless network system 100 is transmitted to the wireless devices 31 to 43. This TC message is periodically transmitted by all wireless devices selected as MPRs. Since the TC message includes a link between each wireless device and the MPR selector set, all the wireless devices 31 to 43 of the wireless network system 100 know all the MPR sets and all the MPR selector sets. Based on all the MPR sets and all the MPR selector sets, the topology of the entire wireless network system 100 can be known. Each of the wireless devices 31 to 43 calculates the shortest path using the topology of the entire wireless network system 100 and creates a route table based on the calculated shortest path.

  In addition, each radio | wireless apparatus 31-43 exchanges a TC message frequently separately from a Hello message. MPR is also used for exchanging TC messages.

  The UDP module 23 of each of the wireless devices 31 to 43 transmits and receives the above-described Hello message and TC message, and the routing daemon 24 determines the topology of the entire wireless network system 100 based on the Hello message and TC message received by the UDP module 23. The shortest path is calculated based on the overall topology of the wireless network system 100, and the routing table 21 shown in FIG. 4 is dynamically created based on the calculated shortest path.

  In the wireless network system 100, when the transmission amount of packets (transmission amount per unit time) in a wireless device that relays wireless communication between a transmission source and a transmission destination reaches or exceeds a threshold value, the wireless network system 100 functions as a relay. In order to reduce the delay time and the packet error rate in the wireless device, the packet size and the packet transmission interval are changed.

  Therefore, the change of the packet size and the packet transmission interval will be described. In this case, the wireless device 33 performs wireless communication with the wireless device 43 using a path including the wireless device 33 -the wireless device 35 -the wireless device 36 -the wireless device 41 -the wireless device 43, and the wireless device 38 is the wireless device 38. -Wireless device 36-Wireless communication is performed with the wireless device 37 using a route including the wireless device 37, and the wireless device 42 includes a wireless device 42-a wireless device 39-a wireless device 36-a wireless device 32-a wireless device 31. In the case where wireless communication is performed with the wireless device 31 using a route, the change of the packet size and the packet transmission interval will be described focusing on the operation of the wireless device 36 serving as a relay device for three wireless communication.

  It is assumed that the three wireless communications are voice communications based on VoIP (Voice over Internet Protocol).

  FIG. 5 is a diagram illustrating an example of the cache of the routing table 21. Note that the cache CACHE shown in FIG. 5 includes only the items related to the present invention among the items constituting the actual cache of the routing table 21.

  The cache CACHE of the routing table 21 includes an Face, a Destination, a Use, and a Source. “Interface” represents an interface, “Destination” represents a transmission destination, “Use” represents a packet transmission amount per unit time, and “Source” represents a transmission source.

  The cache CACHE is a cache of the routing table 21 in the wireless device 36, eth1 represents Ethernet (“Ethernet” is a registered trademark), the address “4009000A” represents the wireless device 31, and the address “ 3E090C0A ”represents the wireless device 42, the address“ 9F090C0A ”represents the wireless device 43, the address“ 99090D0A ”represents the wireless device 33, the address“ 99090C0B ”represents the wireless device 37, and the address“ 99090C0A ”. Represents the wireless device 38.

  FIG. 6 is a conceptual diagram of changing the packet size and the packet transmission interval in the wireless network system 100. FIG. 7 is a diagram showing a routing table 21A held by the wireless device 36 shown in FIG. 6, and FIG. 8 is a diagram showing packet sizes and packet transmission intervals.

  In FIG. 6, a dotted line having an arrow represents a packet transmission interval by the interval between the dotted lines, and a packet size by the length of one line in the dotted line.

  Before the packet size and the packet transmission interval are changed in the wireless network system 100, the wireless device 36 relays a 160-byte packet from the wireless device 39 to the wireless device 32 at a packet transmission interval of 20 msec. A 160-byte packet is relayed to the device 41 at a packet transmission interval of 20 msec, and a 160-byte packet is relayed from the wireless device 38 to the wireless device 37 at a packet transmission interval of 20 msec (see FIG. 6A). Further, the wireless device 36 holds a routing table 21A (see FIG. 7).

  In such a situation, the routing daemon 24 of the wireless device 36 refers to the cache CACHE (see FIG. 5) of the routing table 21A and the packet relayed by the wireless device 36 in the wireless communication between the wireless device 42 and the wireless device 31. Transmission amount (= 20823 / second), packet transmission amount (= 7122 / second) relayed by the wireless device 36 in wireless communication between the wireless device 33 and the wireless device 43, and between the wireless device 38 and the wireless device 37 The sum W (= 28585 / second) with the packet transmission amount (= 640 / second) relayed by the wireless device 36 in wireless communication is calculated. In this case, the packet transmission amount (= 20823 / second) in the wireless communication between the wireless device 42 and the wireless device 31, and the packet transmission amount (= 7122 / second) in the wireless communication between the wireless device 33 and the wireless device 43. The sum (= 28585 / second) of the packet transmission amount (= 640 / second) in the wireless communication between the wireless device 38 and the wireless device 37 is the maximum that the delay time and the packet error rate in the wireless device 36 do not increase. It is assumed that the threshold value Wth, which is the packet transmission amount per unit time (number / second), is reached.

  Then, the routing daemon 24 of the wireless device 36 determines whether or not the calculated packet transmission amount W per unit time has reached the threshold value Wth or more, and the packet transmission amount W per unit time is the threshold value. When it is determined that it has reached Wth or more, a dedicated packet including a change instruction for changing the packet size and the packet transmission interval is generated so that the packet transmission amount W per unit time is smaller than the threshold value Wth, The generated dedicated packet is transmitted to the wireless devices 33, 38, and 42 as the transmission source (see (b) of FIG. 6).

  In each of the wireless devices 33, 38, and 42 that are transmission sources, the wireless interface module 16 receives a dedicated packet including a change instruction from the wireless device 36 via the antenna 11, and sends the received dedicated packet to the routing daemon. 24.

  FIG. 9 is a table showing the relationship between the packet size and the packet transmission interval. FIG. 9 shows the relationship between the packet size and the packet transmission interval for realizing the codec method G711 and realizing uncompressed audio of 64 Kbps.

  The table TBL includes packet transmission intervals and packet sizes. Packet transmission intervals of 10 msec, 20 msec, 30 msec, 40 msec, and 50 msec are set corresponding to packet sizes of 80 bytes, 160 bytes, 240 bytes, 320 bytes, and 400 bytes, respectively. That is, when the packet size is 80 bytes, the packet transmission interval is set to 10 msec, and when the packet size is 160 bytes, the packet transmission interval is set to 20 msec. Similarly, when the packet size is 240 bytes, 320 bytes, and 400 bytes, the packet transmission intervals are set to 30 msec, 40 msec, and 50 msec, respectively.

  When the routing daemon 24 of the wireless devices 33, 38, and 42 as the transmission source receives a dedicated packet including an instruction to change the packet size and the packet transmission interval from the wireless device 36 as the repeater, it changes the packet size and the packet transmission interval. To the user application 14 is output.

  The user application 14 of the wireless devices 33, 38, and 42 holds the table TBL shown in FIG. 9, and when receiving a change instruction from the routing daemon 24, the packet size increases with reference to the table TBL, and The packet size and the packet transmission interval are changed so that the packet transmission interval becomes longer.

  More specifically, since the current packet size is 160 bytes and the current packet transmission interval is 20 msec, the user application 14 of the wireless devices 33, 38, and 42 has a packet size larger than 160 bytes. The packet size and the packet transmission interval are changed so that the transmission interval is longer than 20 msec. For example, the user application 14 of the wireless devices 33, 38, 42 changes the current packet size and the current packet transmission interval to a packet size of 400 bytes and a packet transmission interval of 50 msec, respectively ((a), ( b)).

  Then, the user application 14 of the wireless devices 33, 38, and 42 generates a packet with a packet size of 400 bytes, and outputs the generated packet to the communication control unit 15 at a packet transmission interval of 50 msec. And the communication control part 15 of the radio | wireless apparatuses 33,38,42 transmits the packet of 400 bytes from the user application 14 to a transmission destination at a packet transmission interval of 50 msec.

  In the wireless device 36 that is a repeater, the wireless interface module 16 receives the packet transmitted by the wireless device 33 from the wireless device 35 via the antenna 11 and transmits the received packet to the routing daemon 24. The routing daemon 24 of the wireless device 36 receives the packet from the wireless interface module 16 and detects that the destination of the received packet is not the wireless device 36.

  Then, the routing daemon 24 of the wireless device 36 outputs the packet to the IP module 20, and the IP module 20 relays the packet received from the routing daemon 24 to the wireless device 43 that is the transmission destination with reference to the routing table 21A. .

  The wireless device 36 relays the packet transmitted from the wireless device 42 to the wireless device 31 and relays the packet transmitted from the wireless device 38 to the wireless device 37 by the above-described operation.

  As described above, each of the wireless devices 33, 38, and 42 as the transmission source transmits a packet to the transmission destination with a packet size of 400 bytes and a packet transmission interval of 50 msec. The routing daemon 24 relays the packet to the transmission destination with a packet size of 400 bytes and a packet transmission interval of 50 msec (see (c) of FIG. 6).

  FIG. 10 is a diagram showing the relationship between the maximum waiting time and transfer time interval and the number of sessions. In FIG. 10, the vertical axis represents the maximum waiting time and the transfer time interval (= packet transmission interval, hereinafter the same), and the horizontal axis represents the number of sessions. The straight line k1 indicates the relationship between the maximum waiting time and the number of sessions when the packet size is 160 bytes and the packet transmission interval is 20 msec, and the curve k2 indicates that the packet size is 160 bytes and the packet transmission interval. The relationship between the transfer time interval and the number of sessions in the case where is 20 msec is shown.

  Further, a straight line k3 indicates the relationship between the maximum waiting time and the number of sessions when the packet size is 400 bytes and the packet transmission interval is 50 msec, and the curve k4 indicates that the packet size is 400 bytes and the packet transmission interval. Shows the relationship between the transfer time interval and the number of sessions in the case where is 50 msec.

  In both cases where the packet size is 160 bytes and the packet transmission interval is 20 msec and the packet size is 400 bytes and the packet transmission interval is 50 msec, the maximum waiting time is the number of sessions. As it increases, it becomes longer monotonously. For the same number of sessions, the maximum waiting time is longer when the packet size is 400 bytes and the packet transmission interval is 50 msec. In addition, the difference in maximum waiting time for the same number of sessions increases as the number of sessions increases (see straight lines k1 and k3).

  On the other hand, the transfer time interval is a session both in the case where the packet size is 160 bytes and the packet transmission interval is 20 msec and in the case where the packet size is 400 bytes and the packet transmission interval is 50 msec. Decreases with increasing number. For the same number of sessions, the transfer time interval is longer when the packet size is 400 bytes and the packet transmission interval is 50 msec. Further, the difference in the transfer time interval for the same number of sessions decreases as the number of sessions increases (see curves k2 and k4).

  When the packet size is 160 bytes and the packet transmission interval is 20 msec, the curve k2 indicating the transfer time interval intersects the straight line k1 indicating the maximum waiting time at the point P1, and the packet size is 400 bytes. When the packet transmission interval is 50 msec, the curve k4 indicating the transfer time interval intersects with the straight line k2 indicating the maximum waiting time at the point P2.

  When the packet size is 160 bytes and the packet transmission interval is 20 msec, if the number of sessions exceeds the point P1, buffering of transfer data may occur, increasing the delay time and packet loss in the repeater Let That is, when the packet size is 160 bytes and the packet transmission interval is 20 msec, the delay time and the packet loss increase when the number of sessions becomes three or more.

  However, when the packet size is 400 bytes and the packet transmission interval is 50 msec, the delay time and the packet loss do not increase until the number of sessions is three.

  Therefore, the wireless device 36 relaying three sessions of wireless communication between the wireless device 33 and the wireless device 43, wireless communication between the wireless device 38 and the wireless device 37, and wireless communication between the wireless device 42 and the wireless device 31 is When the packet transmission amount W per unit time reaches the threshold value Wth or more, the current packet size and the current packet transmission interval are set to a packet size of 400 bytes and a packet transmission interval of 50 msec (= delay time and packet up to 3 sessions, respectively). Changing to packet size and packet transmission interval that does not increase loss has an effect of making the packet transmission amount W per unit time smaller than the threshold value Wth.

  When the packet size is 240 bytes and the packet transmission interval is 30 msec, and when the packet size is 320 bytes and the packet transmission interval is 40 msec, the maximum waiting time is between the straight line k1 and the straight line k3. The transfer time interval exists between the curve k2 and the curve k4.

  As a result, when the packet size is 240 bytes and the packet transmission interval is 30 msec, and when the packet size is 320 bytes and the packet transmission interval is 40 msec, a straight line indicating the relationship between the maximum waiting time and the number of sessions Intersects between the curve indicating the relationship between the transfer time interval and the number of sessions and the point P1 and the point P2, and the intersecting point is when the packet size is 240 bytes and the packet transmission interval is 30 msec. When the packet size is 320 bytes and the packet transmission interval is 40 msec, the packet size increases and when the packet transmission interval increases, the shift from the point P1 to the point P2 occurs.

  That is, as the packet size increases and the packet transmission interval increases, the number of sessions in which the delay time and the packet loss do not increase relatively increases.

  Therefore, the wireless device 36 relaying three sessions of wireless communication between the wireless device 33 and the wireless device 43, wireless communication between the wireless device 38 and the wireless device 37, and wireless communication between the wireless device 42 and the wireless device 31 is When the packet transmission amount W per unit time reaches the threshold value Wth or more, the packet size is made larger than the current packet size of 160 bytes, and the packet transmission interval is made larger than the current packet transmission interval of 20 msec. Increasing the length is effective in making the packet transmission amount W smaller than the threshold value Wth.

  That is, the current packet size is gradually changed without changing the current packet size and the current packet transmission interval to the packet size and the packet transmission interval at which the packet transmission amount W per unit time is smaller than the threshold value Wth. And the current packet transmission interval is gradually lengthened to finally reduce the current packet size and the current packet transmission interval so that the packet transmission amount W per unit time is smaller than the threshold value Wth. The packet size and the packet transmission interval can be changed.

  The packet size and the packet transmission interval are [packet size = 80 bytes, packet transmission interval = 10 msec], [packet size = 160 bytes, packet transmission interval = 20 msec], [packet size = 240 bytes, packet transmission interval = 30 msec. ], [Packet size = 320 bytes, packet transmission interval = 40 msec] and [Packet size = 400 bytes, packet transmission interval = 50 msec] to perform wireless communication at a transfer rate of 64 Kbps per second ( This corresponds to performing wireless communication by sequentially changing the packet transmission amount W per unit time) to 100/50, 33 / second, 25 / second, and 20 / second.

  Therefore, increasing the packet size and increasing the packet transmission interval to perform wireless communication corresponds to performing wireless communication with a reduced packet transmission amount W per unit time.

  When the packet transmission interval is increased from 20 msec to 50 msec, there is a concern about voice delay, but it is considered that the problem of voice delay does not occur for the following reason.

  That is, when IEEE802.11b, which is a wireless communication standard, is used, the typical communication time per packet is 1 byte when the packet size is 160 bytes even if an ACK (Acknowledge) packet at the MAC level is included. If it is .22 msec and the packet size is 400 bytes, it is 1.44 msec.

  As a result, the typical difference in communication time between the two packet sizes is theoretically about 0.2 msec, which is considered to be an error range in consideration of the processing time of the system. That is, the typical communication time per packet is almost the same for each packet size.

  Therefore, when the packet size is increased to 400 bytes, even if the packet transmission interval is increased from 20 msec to 50 msec, it is considered that the problem of voice delay does not occur. This is the same when the packet size is 240 bytes and the packet transmission interval is 30 msec, and when the packet size is 320 bytes and the packet transmission interval is 40 msec.

  In order to confirm this, an experiment was performed by changing the packet size and the packet transmission interval in the environment shown in FIG. FIG. 11 is a diagram showing the relationship between the average packet error rate and average delay time and the number of sessions. In addition, the experimental result shown in FIG. 11 is an average when performing one experiment by transmitting 5000 packets 10 times.

  In FIG. 11, the vertical axis represents the average packet error rate and the average delay time, and the horizontal axis represents the number of sessions. A broken line k5 indicates an average delay time when the packet size is 160 bytes and the packet transmission interval is 20 msec. A broken line k6 indicates a case where the packet size is 400 bytes and the packet transmission interval is 50 msec. Indicates the average delay time. The bar graph BG1 indicates an average packet error rate when the packet size is 160 bytes and the packet transmission interval is 20 msec, and the bar graph BG2 indicates that the packet size is 400 bytes and the packet transmission interval is 50 msec. Represents the average packet error rate.

  When the packet size is 160 bytes and the packet transmission interval is 20 msec, when the number of sessions exceeds 3, the average packet error rate increases rapidly (see bar graph BG1), and the average delay time increases dramatically. (Refer to the broken line k5).

  On the other hand, if the packet size is 400 bytes and the packet transmission interval is 50 msec, the average packet error rate is almost constant at less than 0.01% even if the number of sessions increases to 5. (See bar graph BG2), the average delay time hardly occurs (see line k6).

  Therefore, it was experimentally confirmed that changing the packet size and packet transmission interval from 160 bytes and 20 msec to 400 bytes and 50 msec, respectively, has the effect of not increasing the delay time and packet loss. .

  Next, an operation for changing the packet size and the packet transmission interval in the wireless network system 100 will be described. FIG. 12 is a flowchart of the operation in the first embodiment. In FIG. 12, the wireless device 36 is described as a relay wireless device, and the wireless devices 33, 38, and 42 are described as transmitting wireless devices.

  When a series of operations is started, the wireless device 36 (= relay wireless device) detects the packet transmission amount W per unit time based on the cache CACHE of the routing table 21 by the method described above (step S1). .

  Then, the wireless device 36 (= relay wireless device) determines whether or not the detected packet transmission amount W per unit time has reached or exceeded the threshold value Wth (step S2), and packet transmission per unit time. When the amount W reaches the threshold value Wth or more, an instruction to change the packet size and the packet transmission interval is transmitted to the wireless devices 33, 38, and 42 (= transmitting wireless device) (step S3).

  The wireless devices 33, 38, and 42 (= transmitting wireless device) receive the change instruction from the wireless device 36 (= relay wireless device) (step S4), and set the packet size to the current size according to the received change instruction. And the packet transmission interval is made longer than the current packet transmission interval, and the packet is transmitted to the transmission destination (step S5).

  More specifically, when the current packet size is 160 bytes and the current packet transmission interval is 20 msec, the wireless devices 33, 38, and 42 (= transmission source wireless device) have [packet size = 240 bytes. , Packet transmission interval = 30 msec], [packet size = 320 bytes, packet transmission interval = 40 msec] and [packet size = 400 bytes, packet transmission interval = 50 msec].

  Then, the wireless device 36 (= relay wireless device) relays packets from the wireless devices 33, 38, and 42 (= transmission source wireless device) (step S6). Thereafter, the series of operations proceeds to step S1, and in step S2, the above-described steps S1 to S6 are repeatedly executed until the packet transmission amount W per unit time becomes smaller than the threshold value Wth.

  In step S2, when the packet transmission amount W per unit time becomes smaller than the threshold value Wth, the wireless devices 33, 38, and 42 (= transmission source wireless device) have a packet transmission amount W per unit time of The packet is transmitted to the transmission destination with a packet size and packet transmission interval smaller than the threshold value Wth (step S7), and the wireless device 36 (= relay wireless device) wirelessly transmits a packet transmission amount W smaller than the threshold value Wth. Packets from the devices 33, 38, and 42 (= transmission source wireless device) are relayed (step S8). As a result, the series of operations ends.

  In this way, in the flowchart shown in FIG. 12, the wireless devices 33, 38, and 42 (= transmission source wireless device) change the packet size to the current size according to the change instruction from the wireless device 36 (= relay wireless device). And the packet transmission interval is set longer than the current packet transmission interval, and the packet is transmitted to the transmission destination (see steps S4 and S5). When the wireless devices 33, 38, and 42 (= the transmitting wireless device) increase the packet size and increase the packet transmission interval in step S5, they are larger than the current packet size (= 160 bytes) Also, longer than the current packet transmission interval (= 20 msec) [packet size = 240 bytes, packet transmission interval = 30 msec], [packet size = 320 bytes, packet transmission interval = 40 msec] and [packet size = 400 bytes, packet An arbitrary packet size and packet transmission interval are selected from [transmission interval = 50 msec], and the packet is transmitted to the transmission destination.

  Accordingly, there is a case where the packet transmission amount W per unit time becomes smaller than the threshold value Wth by one change of the packet size and the packet transmission interval, and the packet size and the packet transmission interval are changed to two times and three times. As a result, the packet transmission amount W per unit time may be smaller than the threshold value Wth.

  That is, if the current packet size and the current packet transmission interval [packet size = 160 bytes, packet transmission interval = 20 msec] are changed to [packet size = 400 bytes, packet transmission interval = 50 msec], the unit per unit time If the packet transmission amount W may be smaller than the threshold value Wth, [packet size = 160 bytes, packet transmission interval = 20 msec] to [packet size = 240 bytes, packet transmission interval = 30 msec] and [packet size = Even if sequentially changed to 320 bytes, packet transmission interval = 40 msec], the packet transmission amount W per unit time does not become smaller than the threshold value Wth, and finally [packet size = 400 bytes, packet transmission interval = 50 msec]. By changing to Position packet transmission amount W per time may be smaller than the threshold value Wth.

  However, according to the flowchart shown in FIG. 12, the packet size and the packet transmission interval are finally set to a suitable packet size and a suitable packet transmission interval at which the packet transmission amount W per unit time is smaller than the threshold value Wth. Changed to

  Therefore, in the wireless network system 100, the delay time and the packet error rate when performing wireless communication by multi-hop can be suppressed.

  FIG. 13 is another flowchart in the first embodiment for explaining the operation of changing the packet size and the packet transmission interval in the radio network system 100. In FIG. 13, the wireless device 36 is described as a relay wireless device, and the wireless devices 33, 38, and 42 are described as transmission source wireless devices.

  In the flowchart shown in FIG. 13, step S3 in the flowchart shown in FIG. 12 is replaced with steps S3A and S3B, step S5 is replaced with step S5A, and steps S6 and S7 are deleted. Is the same.

  Steps S1 and S2 described above are executed, and if it is determined in step S2 that the packet transmission amount W per unit time is smaller than the threshold value Wth, the series of operations proceeds to step S1.

  When it is determined in step S2 that the packet transmission amount W per unit time is equal to or greater than the threshold value Wth, the wireless device 36 (= relay wireless device) has a threshold for the packet transmission amount W per unit time. A suitable packet size smaller than the value Wth and a suitable packet transmission interval are determined (step S3A).

  In this case, the routing daemon 24 of the wireless device 36 (= relay wireless device) maintains the relationship between the maximum waiting time and transfer time interval and the number of sessions shown in FIG. 10, and the wireless device 36 (= relay wireless device). Recognizes the number of sessions to be relayed, so that the delay time and the packet error rate do not increase, that is, the packet size and the packet transmission interval at which the packet transmission amount W per unit time becomes smaller than the threshold value Wth. Can be determined.

  For example, when the wireless device 36 (= relay wireless device) relays wireless communication of 3 sessions with a packet size of 160 bytes and a packet transmission interval of 20 msec, the packet transmission amount W per unit time is equal to or greater than the threshold value Wth. If the packet size and the packet transmission interval are changed to a packet size of 400 bytes and a packet transmission interval of 50 msec, the delay time and the packet error rate do not increase in three sessions, that is, per unit time It can be seen that the packet transmission amount W can be made smaller than the threshold value Wth. Therefore, the routing daemon 24 of the wireless device 36 (= relay wireless device) refers to the relationship between the maximum waiting time and the transfer time interval and the number of sessions shown in FIG. A packet size and a packet transmission interval that are smaller than the value Wth are determined.

  When the wireless device 36 (= relay wireless device) determines a suitable packet size and a suitable packet transmission interval at which the packet transmission amount W per unit time is smaller than the threshold value Wth, the wireless device 36 (= relay wireless device) sets the packet size and the packet transmission interval, respectively. A dedicated packet including a change instruction for changing to a suitable packet size and a suitable packet transmission interval is transmitted to the wireless devices 33, 38, and 42 (= transmitting wireless device) (step S3B).

  After that, when step S4 described above is executed, the wireless devices 33, 38, and 42 (= the transmitting wireless device) set the packet transmission amount W per unit time from the threshold value Wth. The packet is changed to a suitable packet size and a suitable packet transmission interval that are also reduced, and the packet is transmitted to the destination (step S5A).

  And step S7 mentioned above is performed and a series of operation | movement is complete | finished.

  As described above, the flowchart shown in FIG. 13 indicates that the wireless device 36 as the relay wireless device indicates the packet size and the packet transmission interval at which the packet transmission amount W per unit time becomes smaller than the threshold value Wth. 10 is a flowchart in a case where wireless communication is performed with a packet size and a packet transmission interval in which the packet transmission amount W per time is smaller than a threshold value Wth.

  Then, according to the flowchart shown in FIG. 13, the packet transmission amount W per unit time becomes smaller than the threshold value Wth by changing the packet size and the packet transmission interval once, so that the delay time and the packet error rate increase. Can be quickly suppressed.

  As described above, the wireless device 36 (= relay wireless device) is wireless between a plurality of transmission sources (= wireless devices 33, 38, 42) and a plurality of transmission destinations (= wireless devices 43, 37, 31). When the communication is relayed and the packet transmission amount W per unit time in the self reaches a threshold value Wth or more, an instruction to change the packet size and the packet transmission interval is sent to a plurality of transmission sources (= wireless devices 33, 38, 42). Send.

  Note that the packet size and the packet transmission interval shown in FIG. 9 are examples, and in the present invention, the present invention is not limited to this, and the packet transmission interval and the packet size may be determined within a range that does not cause a problem of voice delay. .

  In the case of voice, since 100 msec to 150 msec is a delay time at which a delay starts to be felt by human hearing, a packet transmission interval is determined in a range shorter than 100 msec to 150 msec, and a predetermined transfer rate is determined using the determined packet transmission interval. The packet size may be determined so that can be realized.

  Audio is an application that requires real-time performance, but games other than audio are applications that also require real-time performance. Therefore, even when the application is a game, the packet size and the packet transmission interval are changed by the above-described operation so that the packet transmission amount W per unit time becomes smaller than the threshold value Wth.

  As described above, in Embodiment 1, when the packet transmission amount W per unit time in the wireless device 36 (= relay wireless device) reaches the threshold value Wth or more, the wireless device 36 (= relay wireless device). The wireless device 33, 38, 42 (= transmission source wireless device) issues a change instruction for changing the packet size and the packet transmission interval so that the packet transmission amount W per unit time is smaller than the threshold value Wth. Send to.

  That is, when the packet transmission amount W per unit time in the relay radio apparatus reaches the threshold value Wth or more, the relay radio apparatus has a packet size and a packet so that the packet transmission amount W per unit time becomes smaller than the threshold value Wth. Instructs the sender to change the transmission interval.

  Therefore, according to the first embodiment, when multihop communication is performed in the radio network system 100, when the packet transmission amount W per unit time in the relay radio apparatus reaches the threshold value Wth or more, the unit time The packet size and the packet transmission interval are controlled so that the per-packet transmission amount W is smaller than the threshold value Wth.

  In the above description, a case where the wireless device 36 (= relay wireless device) relays three sessions, that is, a case where wireless communication is relayed between a plurality of transmission sources and a plurality of transmission destinations has been described. The device 36 (= relay wireless device) may relay wireless communication between one transmission source and one transmission destination. In this case, the packet transmission amount W per unit time is a threshold. When the value Wth or more is reached, a packet size and packet transmission interval change instruction is transmitted to one transmission source.

  In the above, when the packet transmission amount W per unit time in the wireless device 36 (= relay wireless device) reaches the threshold value Wth or more, the packet transmission amount W per unit time is smaller than the threshold value Wth. In the present invention, the packet transmission amount W per unit time in the wireless device 36 (= relay wireless device) is set to the threshold value Wth. When the above is reached, the codec method itself in the wireless devices 33, 38, and 42 of the transmission source may be changed so that the packet transmission amount W per unit time becomes smaller than the threshold value Wth.

[Embodiment 2]
FIG. 14 is a schematic block diagram in the second embodiment showing the configuration of radio apparatuses 31 to 43 shown in FIG. In the second embodiment, the wireless devices 31 to 43 include the wireless device 31A illustrated in FIG.

  The wireless device 31A is the same as the wireless device 31 except that the communication control unit 15 of the wireless device 31 shown in FIG. The communication control unit 15A is the same as the communication control unit 15 except that the routing daemon 24 of the communication control unit 15 shown in FIG.

  When the wireless device 31A is a repeater, the routing daemon 24A, when the packet transmission amount W per unit time reaches a threshold value Wth or more, transmits a plurality of packets transmitted from the transmission source wireless device for each transmission destination. Bundle and send to destination. The routing daemon 24A performs the same functions as the routing daemon 24.

  FIG. 15 is another conceptual diagram of changing the packet size and the packet transmission interval in the wireless network system 100. FIG. 16 is a conceptual diagram showing a packet transmission method.

  In FIG. 15, a dotted line having an arrow represents a packet transmission interval by the interval between the dotted lines, and represents a packet length by the length of one line in the dotted line.

  Before the packet length and the packet transmission interval are changed in the wireless network system 100, the wireless device 36 relays three sessions with a packet size of 160 bytes and a packet transmission interval of 20 msec as in the first embodiment ( (See (a) of FIG. 15). Further, the wireless device 36 holds a routing table 21A (see FIG. 7).

  In such a situation, the routing daemon 24A of the wireless device 36 refers to the cache CACHE (see FIG. 5) of the routing table 21A and calculates the packet transmission amount W per unit time by the above-described operation. It is determined whether or not the packet transmission amount W has reached or exceeded the threshold value Wth.

  When the routing daemon 24A of the wireless device 36 determines that the packet transmission amount W per unit time has reached the threshold value Wth or more, the packet transmission amount W per unit time is smaller than the threshold value Wth. In this way, a plurality of packets are bundled and transmitted to the transmission destination (see FIG. 15B).

  In this case, each of the wireless devices 35, 39 that relay wireless communication on the transmission side from the wireless devices 33, 38, 42 and the wireless device 36 that is the transmission source has a packet size of 160 bytes and a packet transmission interval of 20 msec. The packet is transmitted (see (b) of FIG. 15 and (a) of FIG. 16), and the routing daemon 24A of the wireless device 36 is received from the wireless device that relays wireless communication on the transmission side or on the transmission side. Two packets are bundled for each destination, and the two bundled packets are transmitted to each destination at a transmission interval of 40 msec (see FIG. 15B and FIG. 16B). That is, the routing daemon 24A of the wireless device 36 bundles two packets without changing the packet size of each of the plurality of received packets, and transmits the packets to each destination with a longer transmission interval.

  By bundling two 160-byte packets and transmitting the two bundled packets at a transmission interval of 40 msec, the packet transmission amount W per unit time is reduced from 50 / sec to 25 / sec. As a result, the delay time and the packet error rate can be suppressed.

  The number of packets to be bundled is not limited to two, but may be three or more. If the transmission interval is determined so as to realize a predetermined transfer rate according to the number of packets bundled. Good. For example, if three 160-byte packets are bundled, the transmission interval is set to 60 msec in order to realize a transfer rate of 64 Kbps, and if four 160-byte packets are bundled, a transfer rate of 64 Kbps. In order to realize the above, the transmission interval is set to 80 msec. The same applies when bundling other numbers of packets.

  FIG. 17 is a flowchart in the second embodiment for explaining the operation of changing the packet length and the packet transmission interval in the radio network system 100.

  When a series of operations is started, the wireless device 36 (= relay wireless device) detects the packet transmission amount W per unit time based on the cache CACHE of the routing table 21 by the method described above (step S1). .

  Then, the wireless device 36 (= relay wireless device) determines whether or not the detected packet transmission amount W per unit time has reached or exceeded the threshold value Wth (step S2), and packet transmission per unit time. When the amount W is smaller than the threshold value Wth, step S1 is repeatedly executed.

  When it is determined in step S2 that the packet transmission amount W per unit time has reached the threshold value Wth or more, the wireless device 36 (= relay wireless device) has a threshold for the packet transmission amount W per unit time. A plurality of packets from the wireless devices 33, 38, and 42 (= transmission source wireless device) are bundled so as to be smaller than the value Wth, and the plurality of bundled packets are relayed to a transmission destination with a longer transmission interval. (Step S3B). As a result, a series of operations is completed.

  Thus, in the wireless device 36 (= relay wireless device), when the packet transmission amount W per unit time reaches the threshold value Wth or more, the packet transmission amount W per unit time becomes smaller than the threshold value Wth. As described above, a plurality of packets to be relayed to the transmission destination are bundled, and the plurality of bundled packets are relayed to the transmission destination with a transmission interval longer than the current transmission interval. Therefore, increase in delay time and packet error rate can be suppressed.

  As described above, in the second embodiment, the wireless device 36 (= relay wireless device), when the packet transmission amount W per unit time in itself reaches the threshold value Wth or more, the packet transmission amount per unit time. A plurality of packets are bundled so that W is smaller than the threshold value Wth, and control is performed to increase the transmission interval of the bundled packets.

  The wireless device 36 (= relay wireless device) relays wireless communication between a plurality of transmission sources (= wireless devices 33, 38, 42) and a plurality of transmission destinations (= wireless devices 43, 37, 31). When the packet transmission amount W per unit time in the self reaches a threshold value Wth or more, a plurality of packets are bundled for each transmission destination, and the transmission intervals of the bundled packets are increased to each transmission destination. Send to.

  Therefore, according to the second embodiment, when multihop communication is performed in the radio network system 100, when the packet transmission amount W per unit time in the relay radio apparatus reaches the threshold value Wth or more, the unit time Control is performed to bundle a plurality of packets so that the per-packet transmission amount W is smaller than the threshold value Wth and to increase the transmission interval of the bundled packets.

  In the above description, a case where the wireless device 36 (= relay wireless device) relays three sessions, that is, a case where wireless communication is relayed between a plurality of transmission sources and a plurality of transmission destinations has been described. The device 36 (= relay wireless device) may relay wireless communication between one transmission source and one transmission destination. In this case, the packet transmission amount W per unit time is a threshold. When the value reaches or exceeds the value Wth, a plurality of packets to be transmitted to one transmission destination are bundled, and the plurality of bundled packets are transmitted to one transmission destination with a longer transmission interval.

  In the first embodiment, when the packet transmission amount W per unit time in the relay radio apparatus (= radio apparatus 36) reaches the threshold value Wth or more, the relay radio apparatus (= radio apparatus 36) Control is performed so that the packet size is larger than the current packet size and the packet transmission interval is longer than the current packet transmission interval so that the packet transmission amount W is smaller than the threshold value Wth.

  In the second embodiment, when the packet transmission amount W per unit time in the relay radio apparatus (= radio apparatus 36) reaches the threshold value Wth or more, the relay radio apparatus (= radio apparatus 36) A plurality of packets are bundled so that the per-packet transmission amount W is smaller than the threshold value Wth, and control is performed to increase the transmission interval of the bundled packets.

  Increasing the packet size and bundling a plurality of packets are equivalent to increasing the length of data transmitted at one time, and increasing the packet transmission interval is equivalent to increasing the data transmission interval. Therefore, the relay radio apparatus according to the present invention is configured such that when the packet transmission amount W per unit time in itself reaches the threshold value Wth or more, the packet transmission amount per unit time becomes smaller than the threshold value Wth. What is necessary is just to control the data transmission interval and the data length to be transmitted at a time.

  In addition, the wireless network system according to the present invention is configured such that when the packet transmission amount W per unit time in the relay radio apparatus reaches or exceeds the threshold value Wth, the packet transmission amount per unit time becomes smaller than the threshold value Wth. As long as the data transmission interval and the data length to be transmitted at one time are controlled.

  Furthermore, according to the present invention, when the wireless device 36 (= relay wireless device) has information on the congestion state of the wireless device one hop ahead in the direction of the transmission destination by the function of the application, one hop before the transmission side The wireless device may control the data transmission interval and the data length transmitted at a time.

  In Embodiments 1 and 2 described above, the object of wireless communication has been described as audio data. However, the present invention is not limited to this, and image data may be the object of wireless communication.

  In the first and second embodiments described above, the packet transmission amount per unit time when the packet transmission amount W per unit time in the relay radio apparatus (= radio apparatus 36) reaches or exceeds the threshold value Wth. In the present invention, the data transmission interval and the data length to be transmitted at a time are controlled so as to be smaller than the threshold value Wth. However, the present invention is not limited to this, and the relay wireless device (= wireless device 36). The data transmission interval and the data length to be transmitted at one time are controlled so that the packet transmission amount per unit time becomes smaller than the threshold value Wth when the data transmission interval at the time becomes less than the threshold value. In general, when the communication load in the relay wireless device (= wireless device 36) exceeds a threshold value, the packet transmission amount per unit time is the threshold. To be smaller than Wth, the data transmission interval may be controlled and the data length to be transmitted at one time. Therefore, in the present invention, the packet transmission amount W per unit time equal to or greater than the threshold value Wth and the packet transmission interval equal to or less than the threshold value constitute a “communication load”.

  The threshold value is generally defined as “the maximum communication load per unit time at which the delay time and the packet error rate in the relay radio apparatus do not increase”.

  The packet transmission interval is used as a criterion for determining whether or not to perform processing for controlling the data transmission interval and the data length to be transmitted at a time so that the packet transmission amount W per unit time is smaller than the threshold value Wth. Is used, the routing daemons 24 and 24A calculate the packet transmission interval by calculating the reciprocal of the packet transmission amount W calculated by the above-described method.

  Further, the routing daemons 24 and 24A that determine that the packet transmission amount W per unit time has reached the threshold value Wth or more, or the routing daemons 24 and 24A that determine that the packet transmission interval has reached the threshold value or less, "Detecting means" is configured.

  Further, the routing daemon 24 of the wireless device 36 (= relay wireless device) that transmits an instruction to change the packet size and the packet transmission interval to the wireless devices 33, 38, 42 (= transmitting wireless device) is provided with “control means”. Constitute.

  Further, the routing daemon 24 and the IP module 20 of the wireless device 36 that relays a packet transmitted from the transmission source constitute a “relay unit”.

  Further, when the packet transmission amount W per unit time reaches the threshold value Wth or more, the wireless device 36 determines a packet size and a packet transmission interval at which the packet transmission amount W per unit time becomes smaller than the threshold value Wth. The routing daemon 24 constitutes “determination means”.

  Further, the routing daemon 24 of the wireless device 36 (= relay wireless device) that instructs the wireless devices 33, 38, 42 (= transmitting wireless device) to change the packet size and packet transmission interval constitutes “instruction means”. To do.

  Further, when the packet transmission amount W per unit time reaches the threshold value Wth or more, the routing daemon 24A of the wireless device 36 that bundles a plurality of packets for each transmission destination and transmits the packets to each transmission destination sets the “relay means”. Constitute.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention is applied to a radio apparatus capable of suppressing increases in delay time and packet error rate. The present invention is also applied to a wireless network system including a wireless device capable of suppressing increases in delay time and packet error rate.

1 is a schematic diagram of a wireless network system using a wireless device according to an embodiment of the present invention. FIG. 2 is a schematic block diagram in the first embodiment showing the configuration of the wireless device shown in FIG. 1. It is a block diagram of the packet PKT in OLSR protocol. It is a block diagram of the routing table shown in FIG. It is a figure which shows an example of the cache of a routing table. It is a conceptual diagram of the change of the packet size and packet transmission interval in a wireless network system. It is a figure which shows the routing table which the radio | wireless apparatus shown in FIG. 6 hold | maintains. It is a figure which shows a packet size and a packet transmission interval. It is a table figure which shows the relationship between a packet size and a packet transmission interval. It is a figure which shows the relationship between the maximum waiting time and transfer time interval, and the number of sessions. It is a figure which shows the relationship between an average packet error rate and average delay time, and the number of sessions. 3 is a flowchart of the operation in the first embodiment. 10 is another flowchart in the first embodiment for explaining an operation of changing the packet size and the packet transmission interval in the wireless network system. FIG. 3 is a schematic block diagram in Embodiment 2 showing the configuration of the wireless device shown in FIG. 1. It is another conceptual diagram of the change of the packet size and packet transmission interval in the wireless network system. It is a conceptual diagram which shows the transmission method of a packet. 9 is a flowchart in Embodiment 2 for explaining an operation of changing a packet length and a packet transmission interval in a wireless network system. It is the layout of the radio | wireless apparatus in the experiment for investigating the influence when a some traffic concentrates on one repeater. It is a figure which shows the relationship between an average packet error rate and average delay time, and the number of sessions. It is a figure which shows the relationship between the maximum waiting time and transfer time interval, and the number of sessions.

Explanation of symbols

  11 antenna, 12 input unit, 13 output unit, 14 user application, 15, 15A communication control unit, 16 wireless interface module, 17 MAC module, 18 buffer, 19 LLC module, 20 IP module, 21, 21A routing table, 22 TCP Module, 23 UDP module, 24, 24A routing daemon, 31-43, 31A wireless device, 51-63 antenna, 100 wireless network system.

Claims (8)

A wireless device that relays wireless communication between a transmission source and a transmission destination,
Detecting means for detecting a communication load of the wireless communication;
Control means for controlling a data transmission interval and a data length to be transmitted at a time so that the communication load becomes smaller than the threshold when the detected communication load exceeds a threshold value;
The threshold is the maximum communication load per unit time at which the delay time and the packet error rate in the wireless device do not increase.   2. The control unit according to claim 1, wherein, when the detected communication load reaches or exceeds the threshold value, the control unit controls a packet transmission interval and a packet size so that the communication load becomes smaller than the threshold value. Wireless devices.   The radio apparatus according to claim 1, further comprising a relay unit that relays data at a data transmission interval and a data length controlled by the control unit. The control means includes
Determining means for determining a suitable data transmission interval and a suitable data length when the detected communication load reaches or exceeds the threshold, the communication load being smaller than the threshold;
4. An instruction unit that instructs the transmission source to change a data transmission interval and a data length at the transmission source to the suitable data transmission interval and the suitable data length, respectively. A wireless device according to claim 1. A wireless device that relays wireless communication between a transmission source and a transmission destination,
Detecting means for detecting a communication load of the wireless communication;
A relay means for relaying data at a suitable data transmission interval and a suitable data length when the detected communication load exceeds a threshold value, the communication load being smaller than the threshold value;
The threshold is the maximum communication load per unit time at which the delay time and the packet error rate in the wireless device do not increase.   The relay means bundles a plurality of packets from the transmission source to the transmission destination so that the communication load becomes smaller than the threshold when the detected communication load reaches or exceeds the threshold value. 6. The wireless device according to claim 5, which relays. A wireless network system in which wireless communication is performed between a transmission source and a transmission destination by multi-hop communication,
A first wireless device that is the source;
A second wireless device that is the destination;
A third wireless device that relays the wireless communication between the first wireless device and the second wireless device;
When the communication load in the third wireless device reaches a threshold value or more, the data transmission interval and the data length to be transmitted at a time are controlled so that the communication load is smaller than the threshold value,
The wireless network system, wherein the threshold value is a maximum communication load per unit time at which a delay time and a packet error rate in the third wireless device do not increase. When the communication load reaches or exceeds the threshold, the third wireless device instructs the first wireless device to change a packet size and a packet transmission interval.
The first wireless device changes a packet size and a packet transmission interval so that the communication load becomes smaller than the threshold value according to an instruction from the third wireless device. Wireless network system.

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