JP2006229338A - Routing method and router of wireless network - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a routing method and a router for wireless network in which routing can be converged by transmitting data signal surely to a destination wireless station through a simple arrangement upon congestion of data communication. <P>SOLUTION: When a packet signal including initial path length L predetermined at a source wireless station, already propagating hop length H of a packet signal and data is transmitted from the source wireless station to a destination wireless station, a management control section 151 for a router selects a shortest path by using a routing table in the source wireless station and a relay wireless station, stores a packet signal to be transmitted in a queue memory and transmits it toward a next wireless station by radio. Furthermore, the management control section 151 selects next shortest path by using the routing table excepting a shortest path which has been selected already upon the occurrence of packet drop in the network layer at the relay wireless station when the already propagating hop length H is not longer than the initial path length L, stores a packet signal to be transmitted in a queue memory and transmits it toward a next wireless station by radio. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wireless network routing method and a router apparatus for a wireless network such as an ad hoc wireless network that performs packet communication in a wireless network such as a wireless LAN provided with a plurality of wireless stations.

  The ad hoc wireless network is assumed as a network without infrastructure capable of high-speed deployment in which each node wireless station functions as a mobile router including a wireless transceiver (or a wireless transceiver or a wireless communication device). Ad hoc wireless networks have attracted a great deal of attention over the past few years. Several protocols have been proposed in this context, and their communication performance has been evaluated using standard simulators such as ns-2, QualNet. However, there are quite a few studies that confirm the adequacy of ad hoc wireless network communication performance in real situations.

Japanese Patent Laid-Open No. 2003-043126. JP 2001-024431A. Japanese Patent Laid-Open No. 2001-244983. Tetsuro Ueda et al., “A Rotational Sector-based, Receiver-Oriented mechanism for Location Tracking and Medium Access Control in Ad Hoc Networks using Directional Antenna”, IFIP conference on Personal Wireless Communications (PWC) 2003, Venice, ITALY, September 23 -25, 2003. A. Nasipuri et al., “A MAC protocol for mobile ad hoc networks using directional antennas”, in Proceedings of IEEE Wireless Communication and Networking Conference, Vol.3, pp.1214-1219, September 2000. R. Roy Choudhury et al., “Using directional antennas for medium access control in ad hoc networks”, in Proceedings of ACM MOBICOM, September 2002. K. Gyoda et al., “Beam and null steering capability of espar antennas,” in Proceedings of IEEE AP-S International Symposium, July 2000. R. Ramanathan et al., “Ad hoc networking with directional antennas: A complete system solution”, Journal of Selected Areas in Communications, January 2005. D. Maltz et al., “Quantitative lessons from a full-scale multi-hop wireless ad hoc network testbed”, in Proceedings of Wireless Communications and Networking Conference (WCNC), September 2000. David A. Maltz et al., “Experiences designing and building a multi-hop wireless ad hoc network testbed”, Technical Report, Carnegie Mellon University, School of Computer Science, March 1999. K. Chin et al., “Implementation experience with manet outing protocols”, in Proceedings of ACM SigComm Computer Communications Review, November, 2002. Y. Hu et al., “Design and demonstration of live audio and video over multihop wireless ad hoc networks”, in Proceedings of IEEE Military Communications Conference (MILCOM), October 2002. H. Lundergren et al., “A large-scale testbed for reproducible ad hoc protocol evaluations”, in Proceedings of Wireless Communications and Networking Conference (WCNC), March 2002. S. Douglas et al., “Effects of loss rate on ad hoc wireless routing”, in MIT Laboratory of Computer Science Technical Report, MIT-LCS-TR-836, March 2002. C. Toh et al., “Experimenting with ad hoc wireless network on campus: Insights and experiences”, ACM Sigmetrics Performance Evaluation Review, December 2000. G. Pei et al., “Fisheye State Routing in Mobile Ad Hoc Networks,” in ICDCS Workshop on Wireless Networks and Mobile Computing, Taipei, Taiwan, April 10 2000. S. Roy et al., “A network-aware MAC and routing protocol for effective load balancing in ad hoc wireless networks with directional antenna”, in Proceedings of ACM MobiHoc, pp.88-89, June 2003.

  In real life, the performance of a wireless network is subject to problems such as terrain, weather, obstacles, mobility of node radio stations and the presence of electromagnetic radiation emitters, distance-based attenuation, multipath fading, shadowing and interference. It can be affected by several factors that result. Simulation usually does not reveal all of them. In other words, real-world systems face problems that do not occur in simulation. When building a realistic system, the simulation model is approximate and must handle the case of not capturing accurate details. Therefore, the development of realistic protocols for ad hoc wireless networks is a very difficult task that needs to be adequately addressed to assess the practicality and performance achievable in such networks. This is the core motivation of the present invention. Unlike simulator experiments, it is true that test bed experiments cannot be completely reproducible. Interference and radio propagation conditions are different for each experiment and are uncontrollable by the experimenter for all practical purposes. However, running the same experiment several times gives consistent results.

  Usually, a user terminal in an ad hoc wireless network uses an omnidirectional antenna. However, the use of a directional antenna can significantly reduce radio interference, and it has been proved that the use of a radio medium and thus the throughput of a network is improved (for example, Non-Patent Document 1, 2 and 3). In order to achieve this, the inventors have found in patent applicants a small, low-cost directional antenna whose user terminal is known as an electronically steerable passive array radiator array antenna apparatus. A wireless ad hoc wireless network testbed provided was developed (for example, see Non-Patent Document 4).

  Over the last few years, several efforts have been made to implement test beds for ad hoc wireless networks that use omnidirectional antennas. However, for ad hoc wireless networks using directional antennas, the fact that directional antennas have several advantages over omnidirectional antennas, such as spatial reuse, increased transmission area and better network connectivity. Nevertheless, only one testbed project has been reported (for example, see Non-Patent Document 5).

  For example, in the case of the testbed project described in Non-Patent Documents 6 and 7, the main purpose is to actually implement a protocol for an ad hoc wireless network that operates using a node wireless station that is truly mobile in an outdoor environment. Was to build a platform that would allow basic research on the implementation behavior of Each node radio station in the test bed uses a DSR (Dynamic Source Routing) routing protocol. Here, significant packet loss due to link quality variations during multi-hop communication was observed. Environmental variability sometimes creates direct but transient links between the source and destination, and loss rates increase significantly if these transient links are selected during routing It has been pointed out to do. Researchers argue that better throughput can be achieved if a multi-hop route can be guaranteed through the entire communication process between two remote node radio stations.

  In Non-Patent Document 8, a similar action is reported by building a MANET (Mobile Ad-hoc Network) test bed. The authors found that a packet sent on the fading channel could provide a new one that could provide a lower count (hop count) route to even more distant node radio stations with routing protocols. It is reported that if there is a hop neighbor wireless station, it will be erroneously concluded. This can occur even when the node radio station is stationary, resulting in lower route stability in mobility. They implemented a simple signal strength-based neighborhood node selection procedure called “powerwave” and claimed that fading channels and unreliable network links are responsible for routing protocol failures. Tested. The results show that the filtering of reliable (stable) neighboring node radio stations for the purpose of discovery and routing of neighboring node radio stations enables the generation of reliable multi-hop routes .

  Also from Maltz, a MAC filter that adopts a technique similar to power wave (see, for example, Non-Patent Document 6) and filters out traffic from an undesirable MAC (Media Access Control) address. Developed a program called A new use of the MAC filter is MANET emulation, where a plurality of node radio stations can be placed close together and signals from neighboring node radio stations can be appropriately filtered to give different topologies. The main difference between the MAC filter and the power wave is that the power wave dynamically determines which IP address to filter out based on the signal-to-noise ratio (hereinafter referred to as SNR). The MAC filter is statically configured according to the topology in question. Therefore, in general, the test bed network prevents a packet from being directly transmitted from one terminal node radio station to another terminal node radio station, for example, a MAC filter (see, for example, Non-Patent Document 6) or a power wave (for example, non-patent). Packet filtering software such as Reference 8) was included.

  Further, in Non-Patent Document 9, a test bed of 8 node radio stations using a DSR routing protocol is developed in which each node radio station uses a 2 Mbps Lucent Wave LAN-II wireless LAN. . Its purpose was to show the performance of ad hoc wireless networks in some applications such as video conferencing and remote site monitoring. If the authors know that the SNR value of a packet received from a node radio station A by a node radio station, eg, node radio station B, falls below a predetermined threshold over a considerable period of time, the authors The station A-B link suggests that it will probably break soon. Therefore, before the link breakage actually occurs, node radio station A must send a warning to the source node radio station, eg, S, to find a new route that avoids the link. This reliably reduces the waiting time for route maintenance.

  Furthermore, in Non-Patent Document 10, a number of node radio stations (37 in this case) are used to investigate scalability and to perform experiments comparing different routing protocols proposed for ad hoc wireless networks. An ad hoc protocol evaluation test bed (APE) has been developed. The method is strictly configured and after the first “ready-set-go”, the testbed participants simply follow the instructions on the screen as to when and where to go. . The node radio station moves at a normal walking speed (about 1 m / sec). A log-driven animation tool called an APE view is written that enables the communication method by placing node radio stations on the screen based on signal quality by log communication between pairs of node radio stations.

  Furthermore, the authors in Non-Patent Document 11 have demonstrated that the radio link between most node radio stations has a significant loss rate. These loss rates are sufficient to reduce forwarding performance, but not so much as to prevent the use of the link by existing ad hoc routing protocols. Link-level retransmission can mask high loss rates at the expense of substantial throughput degradation. In many cases, there is a longer but higher quality path that provides substantially better end-to-end throughput and higher total system capacity. The implementation was done at Click, a modular software router that runs at the user level on the testbed node radio station.

  Furthermore, in Non-Patent Document 12, the authors provide local information for route reconfiguration / repair when any intermediate node radio station is unavailable due to mobility during a routing session or any other reason. It proposes the use of structured query / response packets.

  In Non-Patent Document 5, the authors implement a test bed using a directional antenna, the directional power control MAC on this test bed, the discovery of nearby node radio stations by beam forming, the link characteristics of the directional antenna And proactive routing and forwarding. The simulation results of UDAN (Utilizing Directional Antennas for Ad Hoc Networking) show the effectiveness of directional antennas over omnidirectional antennas, but the results showing the accuracy and routing performance of the neighboring node radio station discovery process are quoted. It has not been. Furthermore, their directional proximity radio station discovery method basically relies on a common clock synchronization method using GPS (Global Positioning System).

  Furthermore, in Patent Document 1, using a table such as an active node list table (hereinafter referred to as an ANL table) including a list of adjacent node radio stations that are participating in an ad hoc wireless network and are active (operating state), A routing method for effectively balancing the load using a route selection process that maximizes the degree of "inter-zone non-coupling" indicating the degree of non-interference between data communications on two paths is disclosed. However, since the ANL table is used, there is a problem that the configuration of the radio station is complicated.

  The object of the present invention is to solve the above-mentioned problems, without using a prior art ANL table indicating a congestion state, and to have a simpler configuration compared to the prior art, and to ensure that a data signal is transmitted at the time of data communication congestion. It is an object of the present invention to provide a routing method and a router device for a wireless network that can be transmitted to a destination wireless station to converge the routing.

A routing method for a wireless network according to a first invention is a routing method for a wireless network that includes a plurality of wireless stations and performs wireless communication between the wireless stations.
When transmitting a packet signal including a predetermined initial path length L, a hop length H of already propagated packet signal, and data from the source radio station to the destination radio station at the source radio station, In the radio station and relay radio station, a shortest path is selected using a predetermined routing table, and the packet signal to be transmitted is stored in a queue memory and transmitted to the next radio station by radio transmission. Steps,
In the source radio station and the relay radio station when the already propagated hop length H included in the packet signal is equal to or shorter than the initial path length L, it is determined whether or not the packet is dropped in the network layer, and the drop When the next shortest path is selected using the routing table except for the shortest path that has already been selected, the packet signal to be transmitted is stored in the queue memory for transmission. And a first control step of wirelessly transmitting to the next wireless station.

  In the routing method for the wireless network, in the relay radio station when the already propagated hop length H included in the packet signal exceeds the initial path length L, the shortest path is selected using the routing table, and the transmission In order to transmit the packet signal to be transmitted, it is further characterized by further including a second control step of storing the packet signal in a queue memory and wirelessly transmitting the packet signal to the next wireless station.

A router device for a wireless network according to a second aspect of the invention is a router device for a wireless network that includes a plurality of wireless stations and performs wireless communication between the wireless stations.
When transmitting a packet signal including a predetermined initial path length L, a hop length H of already propagated packet signal, and data from the source radio station to the destination radio station at the source radio station, In the radio station and relay radio station, a shortest path is selected using a predetermined routing table, and the packet signal to be transmitted is stored in a queue memory and transmitted to the next radio station by radio transmission. Means,
In the source radio station and the relay radio station when the already propagated hop length H included in the packet signal is equal to or shorter than the initial path length L, it is determined whether or not the packet is dropped in the network layer, and the drop When the next shortest path is selected using the routing table except for the shortest path that has already been selected, the packet signal to be transmitted is stored in the queue memory for transmission. And a first control means for wirelessly transmitting to the next radio station.

  In the router device for the wireless network, the relay wireless station when the already propagated hop length H included in the packet signal exceeds the initial path length L selects the shortest path using the routing table, and transmits the transmission In order to transmit a packet signal to be transmitted, second control means for storing the packet signal in a queue memory and wirelessly transmitting it to the next wireless station is further provided.

  Therefore, according to the present invention, in the source radio station and the relay radio station when the already propagated hop length H included in the packet signal is equal to or shorter than the initial path length L, has packet drop occurred in the network layer? By determining whether or not the local packet signal congestion is detected, when the congestion is detected, the next shortest path is selected using the above routing table except the shortest path already selected. In order to transmit the packet signal to be transmitted, the packet signal is stored in a queue memory and wirelessly transmitted to the next wireless station. As a result, the configuration is simpler than the prior art without using the ANL table of the prior art indicating the congestion state, and the data signal is reliably transmitted to the destination radio station when the data communication is congested, and the routing is converged. Can be made.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In addition, in each following embodiment, the same code | symbol is attached | subjected about the same component.

  It is an object of the present invention to develop an environment for monitoring and controlling the performance of multi-hop ad hoc wireless networks that use directional electronically controlled waveguide array antenna devices. Several researchers have tried to develop an environment for ad hoc wireless networks using omnidirectional antennas, but examples of environment construction for ad hoc wireless networks using directional antennas are extremely limited ( For example, refer nonpatent literature 5.). In this embodiment, which is based on research by the present inventors, a test bed of an ad hoc wireless network using a directional electronically controlled waveguide array antenna device is realized, and a direction tracking mechanism that does not require any common clock synchronization is implemented. It is characterized by that.

  FIG. 1 is a plan layout diagram of a plurality of radio stations 1-1 to 1-9 (generally referred to by reference numeral 1) showing the configuration of an ad hoc radio network according to an embodiment of the present invention. These are block diagrams which show the structure of each radio station 1 of FIG.

  In the wireless communication system of this embodiment, as shown in FIG. 1, a plurality of wireless stations 1 are present in a plane and each wireless station 1 has a gain, transmission power, and reception sensitivity of the variable beam antenna 101. A predetermined service area determined by parameters such as, and can perform packet communication within the service area. When performing packet communication with the wireless station 1 outside the service area, the wireless station 1 within the service area Is used as a relay station to relay packet data, thereby transmitting the packet data to a desired destination wireless station 1. That is, each wireless station 1 has a router function for routing packets and operates as a source wireless station, a relay station, or a destination wireless station.

  The wireless communication system of this embodiment is applied to a packet communication system of an ad hoc wireless network such as a wireless LAN, for example, and includes an omni pattern that is an omnidirectional radiation pattern and a predetermined plane in a horizontal plane centered on the own station. A variable beam antenna 101 capable of selectively switching between a sector beam pattern capable of selectively changing a sector-shaped main beam for each azimuth angle and an exclusive sector pattern capable of forming a null point for each azimuth angle. The following tables (a) to (c) are stored in the database memory 154, and packet signals are routed while controlling the radiation pattern of the variable beam antenna 101 based on these tables. .

(A) Adjacent node wireless station that can be measured when receiving a radio signal from an adjacent node radio station (a node radio station capable of radio communication from the own station) 1 in a service area centered on the own station An azimuth and signal strength level table (hereinafter referred to as an AS table) that stores an azimuth angle and a signal strength level with respect to the radio station 1.
(B) In a horizontal plane centered on the own station, acquired in advance based on the radio signal from the adjacent node radio station including the measured value of SINR when the adjacent node radio station receives the radio signal from the own station. Based on the SINR viewed from the radio station 1 in the service area for each predetermined azimuth angle, the maximum SINR is selected for each adjacent node radio station and set as the affinity with each adjacent node radio station. An adjacent link state table (Neighbor Link-State Table) including the corresponding azimuth angle and the update time of the data (hereinafter referred to as an NLS table).
(C) By exchanging topology information (referring to path information indicating the link state between all radio stations in the ad hoc radio network in the ad hoc radio network, the same shall apply hereinafter) in the NLS table between the radio stations, the ad hoc radio network NLS table topology information related to all wireless stations 1 in the network is collected, this topology information (including the link state between each wireless station 1), and the number of updates (version version) of the topology information for each wireless station in this topology information And a communication state flag value indicating the wireless station 1 involved in an arbitrary communication process at that time (Global Link State Table) (hereinafter referred to as a GLS table).

The node radio station apparatus according to this embodiment has a router apparatus function for a radio network that performs radio communication between radio stations, and the management control unit 151 in FIG.
(A) When transmitting a packet signal including an initial path length L determined in advance at the source radio station, a hop length H of the packet signal already propagated, and data from the source radio station to the destination radio station In addition, in the source radio station and the relay radio station, a shortest path is selected using a predetermined routing table, and the packet signal to be transmitted is stored in a queue memory for transmission to the next radio station. Wirelessly transmit,
(B) In the source radio station and the relay radio station when the already propagated hop length H included in the packet signal is equal to or shorter than the initial path length L, it is determined whether or not a packet drop has occurred in the network layer. When it is determined that the drop has occurred, the queue memory is used to select the next shortest path using the routing table except for the shortest path that has already been selected, and to transmit the packet signal to be transmitted. It is characterized in that it is stored in and transmitted to the next radio station.

In addition, the management control unit 151
(C) In the relay radio station when the already propagated hop length H included in the packet signal exceeds the initial path length L, the shortest path is selected using the routing table, and the packet signal to be transmitted is transmitted. Therefore, it is characterized in that it is stored in a queue memory and wirelessly transmitted to the next wireless station.

  In order to successfully generate directional communication between two node radio stations in an ad hoc radio network equipped with a directional antenna, a direction or antenna pattern in which each node radio station can communicate best with its neighboring node radio stations. Need to recognize. Therefore, the present inventors have considered proactive (a periodic neighborhood with proactive measures in anticipation of the antenna pattern that a certain node radio station should use for communication with its neighboring node radio stations. We propose a node radio station discovery method, and then we propose a periodic broadcast and update mechanism of neighbor information to gain a global awareness of the network that can be used for proactive routing protocols.

  First, in the formation of the NLS table, in the first step of the method for the discovery and direction estimation of neighboring node radio stations, the node radio stations are able to create all 12 directional beacons that are tagged with a beam index. Broadcasts sequentially and periodically using a beam pattern. The neighboring node radio station of the node radio station receiving the beacon stores the signal strength of each received beacon when the packet arrives. In order to transmit the beam index of the transmission along with the beacon, the node radio station records the signal strength of the beacon received in each direction of each of its neighboring node radio stations. Thus, this forms an NLS table.

  Next, in forming the AS table, in the second step, after receiving the 12 broadcast beacons, the node radio station transmits the beam pattern having the received maximum signal strength in all directions and returns it. To do. Therefore, the node radio station that has received and received this information forms its AS table. Thereby, the node radio station knows the best beam pattern to reach its neighboring node radio stations. Since the beacon signal is transmitted periodically, the neighborhood information is also periodically updated. If the node radio station does not receive any beacon from the neighboring node radio station for a considerable time, the node radio station deletes the neighboring node radio station from its AS table.

  Furthermore, in the formation of the GLS table, finally, each node radio station holds a GLS table for capturing the connectivity information of the global network. In each node radio station, the GLS table is first updated with the AS table of that node radio station. Thus, when the network is first started, all the node radio stations are only aware of their own neighboring node radio stations and are not aware of any other node radio stations in the radio system. Each node radio station periodically broadcasts its GLS table as an update to its neighboring node radio stations. With this periodic update message regarding the neighboring node radio stations from the neighboring node radio stations, the node radio station gradually accumulates information about other node radio stations and those neighboring node radio stations. Accordingly, each node radio station updates its own GLS table on the basis of an update message received from another node radio station. It should be noted here that this mechanism does not guarantee that each node radio station knows the exact state of the network. This is only a recognition that helps each node radio station understand the approximate status of the network. This is similar to the fish-eye method (for example, see Non-Patent Document 13) in which the accuracy of details gradually decreases as the distance increases. .

  Next, an outline of the congestion recognition zone non-coupled routing method according to the present embodiment will be described below.

  In order to improve wireless medium utilization via an increased number of simultaneous communications, several directional MAC protocols have been proposed in the technical field of ad hoc wireless networks. However, if two routes that are physically positioned at a short distance that two independent communications in an ad hoc wireless network can interfere with each other are selected, even if a directional antenna is used in each node radio station, these two Simultaneous communication along the route becomes impossible. Thus, to achieve a greater number of simultaneous communications, an effective directional MAC protocol is not sufficient unless a zone-non-coupled route with no interference is discovered for each communication. In our initial work (see, for example, Non-Patent Document 14), a table-driven adaptive approach that exploits the true value of directional antenna advantages in ad hoc wireless networks through selection of the maximum zone non-join shortest route. Proposed a routing method. These two routes are said to be “maximum zone uncoupled” if the interference of data communication on one route to data communication along other routes is minimized. According to our initial proposal, each node radio station can approximate the global network topology and network through periodic penetration of the current network state information held by each node radio station in the network. The communication event information currently in progress is recognized. Thus, depending on this state information, the node radio station calculates a non-zoned path that avoids as much as possible the node radio station currently in use for some other communication. This method relies on periodic propagation of network and state information into the network, but incurs some control overhead.

  Regarding the implementation in the embodiment, the inventors have proposed a simpler method based on the detection of local congestion. Thus, during route selection, the node radio station must detect local congestion and select an appropriate next hop to avoid the congestion zone towards the destination. The node radio station is local when the packet drop is repeated in the MAC layer in the upper layer and the network layer overflows in a queue (for example, the queue memory of the transmission buffer memory 142) and the packet is dropped. Detect congestion. However, if traffic congestion occurs throughout the network, the packet may eventually traverse the entire network looking for non-zone-bound routes that avoid congested node radio stations.

  In order to avoid this problem, in the present embodiment, the present inventors set the “initial path length” L and the “propagation hop length (count value of the number of hops)” H selected by the source radio station. It proposes to use two measured values. This information is attached to each packet signal for data communication. The initial path length L is set by the source radio station depending on the route selected by the source radio station, and is held constant throughout the transmission period of the packet signal. Here, the initial path length L depends on the size of the wireless network, but is set to 10, for example. Further, the already propagated hop length H increases after each hop. If the packet signal does not reach its destination within L hops using a congestion aware zone non-join routing method, this selects the shortest path available to the destination radio station D. This enables convergence of the routing protocol according to the present embodiment. Accordingly, unnecessary propagation of packet signals that search for an appropriate route in the wireless network is limited. This protocol thus guarantees convergence and local congestion detection without any additional overhead. It should be noted that this method also resolves link failures for reasons other than congestion.

  Next, the device configuration of each radio station 1 will be described with reference to FIG. In FIG. 2, a radio station 1 includes a variable beam antenna 101, a directivity control unit 103 for controlling the directivity thereof, a circulator 102, a data packet transmission / reception unit having a data packet transmission unit 140 and a data packet reception unit 130. 104, a traffic monitor unit 105, a line control unit 106, and an upper layer processing apparatus 107.

  Transmission signal data for communication in packet format generated by the upper layer processing apparatus 107 that processes data to be transmitted / received is input to the modulator 143 via the transmission buffer memory 142 which is a queue memory in the network layer, and the modulator 143 Modulates a carrier wave signal of a predetermined radio frequency using a predetermined communication channel spread code generated by the spread code generator 160 by the CDMA method according to the input transmission signal data for communication, The subsequent transmission signal is output to the high frequency transmitter 144. The high-frequency transmitter 144 performs processing such as amplification on the input transmission signal, and then transmits the variable signal from the variable beam antenna 101 to another wireless station 1 via the circulator 102. On the other hand, the communication signal received in the packet format received by the variable beam antenna 101 is input to the high-frequency receiver 131 via the circulator 102, and the high-frequency receiver 131 performs low noise amplification on the input received signal. After executing the above process, the data is output to the demodulator 132. The demodulator 132 demodulates the input received signal by spectrum despreading using the communication channel spreading code generated by the spread code generator 160 by the CDMA method, and receives the demodulated received signal data as a reception buffer. The data is output to the upper layer processing apparatus 107 via the memory 133 and also output to the traffic monitor unit 105 for traffic monitoring.

In the present embodiment, the variable beam antenna 101 that is a directional antenna is connected to a plurality of antenna elements and a control unit 103 that controls the directivity,
(A) an omni pattern which is an omnidirectional radiation pattern;
(B) For example, as shown in FIG. 3, a sector beam pattern capable of selectively changing a sector-shaped main beam for each predetermined azimuth angle in a horizontal plane centered on the own station;
(C) An antenna capable of selectively switching an exclusive sector pattern capable of forming a null point for each azimuth angle by electrical control. The variable beam antenna 101 may be, for example, a known phased array antenna device, or an electronically controlled waveguide array antenna device disclosed in Patent Documents 2 and 3 and Non-Patent Document 4. A certain variable beam antenna may be used.

  The traffic monitor unit 105 includes a search engine 152, an update engine 153, a database memory 154, and a clock circuit 155, and performs routing and communication processing described later, and the wireless station 1 communicates with other wireless stations 1. The communication channel to be used in the packet communication is determined, and the spread code generator 160 sends the spread code designation data corresponding to the determined communication channel to the spread code generator 160 via the line control unit 106. The transmission timing control unit is controlled by generating a spreading code corresponding to the designated data and sending the designated data of the time slot corresponding to the determined communication channel to the transmission timing control unit 141 via the line control unit 106. 141 is a communication channel by the transmission buffer memory 142 Controls to transmit signals for a communication channel by controlling the writing and reading of signal signal data is transmitted in the corresponding time slot. The clock circuit 155 counts the current date and time and outputs the information to the management control unit 151 as necessary.

  The search engine 152 of the traffic monitor unit 105 searches the data in the database memory 154 under the control of the management control unit 151 and returns the searched data to the management control unit 151. The update engine 153 updates data in the database memory 154 under the control of the management control unit 151. Further, the database memory 154 stores an AS table, an NLS table, and a GLS table that is a table for routing.

  In this embodiment, the effective transmission beam width of the sector beam pattern for changing the directivity so that the gain in the direction of a single communication partner is maximized is set to 30 °, and the variable beam antenna 101 is used. The azimuth angle can be selectively changed every 30 °. The beam width and azimuthal angle of change may be 60 ° or other angles. Further, the packet data used in the packet communication system of the present embodiment has a format of the format shown in FIG. That is, as shown in FIG. 4A, the packet data other than for data communication includes the destination wireless station ID, packet type (tone, GLS table, RTS (Request To Send), CTS (Clear To Send), DATA, etc.), the ID of the own station, and data (including data in an upper layer). Further, as shown in FIG. 4B, the packet data for data communication includes the destination wireless station ID, packet type (tone, GLS table, RTS (Request To Send), CTS (Clear To Send), DATA. ), The ID of the local station, the initial path length L, the hop length (or hop count value) of the already propagated data, and the data (including data in the higher layer).

  Further, as shown in FIG. 6, the AS table stored in the database memory 154 stores azimuth and signal strength level information for each adjacent node radio station in the service area of the own station. It is created and updated by the packet transmission / reception control processing of 11 to 14. Further, as shown in FIG. 8, the GLS table stored in the database memory 154 includes, for each node radio station in the ad hoc radio network, an adjacent node radio station, its azimuth angle data, and the update count (version) of the data. Are created and updated by packet transmission / reception control processing described later.

  Next, the MAC communication protocol used in this embodiment will be described below. In the wireless communication network according to the present embodiment, it is assumed that a set of wireless stations 1 that perform wireless communication with each other move around in a two-dimensional enclosed space and share a common wireless communication channel. Each radio station 1 includes a variable beam antenna 101 having the above-described four radiation patterns, for example, an electronically controlled waveguide array antenna device. Each radio station 1 can execute transmission or reception at a time, but a single radio station 1 cannot perform a plurality of transmissions / receptions.

  According to the IEEE802.11 MAC protocol standard, high-reliability data communication is guaranteed using the RTS / CTS / DATA / ACK access control method. However, in the method of this embodiment, the access control method is used as a base. As will be described in detail later with reference to FIG. 9, a packet signal including a GLS table and other data is transmitted / received using a control signal using a tone signal + packet signal. Thus, data communication is performed periodically between GLS table generation and update phases. In addition, a training sequence is added to each frame to enable control of the beam and null by the transmission / reception antenna and transition to the adaptive control mode.

  Next, details of a wireless communication system for an ad hoc wireless network using the wireless station 1 of FIG. 1 will be described below.

  As described above, as the variable beam antenna 101 shown in FIG. 1, an electronically controlled waveguide array antenna device is preferably used. A typical adaptive array antenna is usually a digital beamforming antenna. In contrast, electronically controlled waveguide array antenna devices rely on high-frequency beamforming, which significantly reduces circuit complexity. An electronically controlled waveguide array antenna device includes a central excitation element connected to a radio transmitter / receiver of a transmission source radio station, and a plurality of non-circular elements provided on a predetermined radius around the excitation element and surrounded by a circular shape. And an excitation element (typically 4 to 6). A variable reactance element is connected to each non-excitation element, and by adjusting its reactance value, each non-excitation element forms the radiation pattern of the array antenna device in a different shape. The electronically controlled waveguide array antenna device is characterized by the control of the beam direction, the formation of multiple beams with the same frequency, the control of a movable beam (capable of 360-degree sweep scanning) and null steering. The advantage of using the electronically controlled waveguide array antenna device as a generalized switching beam antenna is that it can be continuously tracked with a small number of antenna elements and can have a variable number of beam patterns. It is in. Since the electronically controlled waveguide array antenna device becomes a low-cost, low-power small antenna, reduction of power consumption of the node radio station as a user terminal is promoted, and all advantages of the switching beam antenna are derived. Is possible.

In the present embodiment, each node wireless station 1 includes a variable beam antenna 101 that is a directional antenna, and an ad hoc wireless network including a plurality of N node wireless stations 1 distributed in a two-dimensional area space A is assumed. Each node radio station 1-n (hereinafter, the sign of the node radio station 1-n is abbreviated as n, where nεN) has a unique identifier of the node radio station n. Each node radio station n has a transmission reach distance (distance (radius) of a range where a transmission signal reaches) R and a beam width β assumed to be the same for all the node radio stations n in this embodiment. Have. If the beam width β is set to 360 degrees, it operates in an omnidirectional mode. In the simulation environment of the present inventors, it is assumed that the beam width β related to directivity is 45 degrees. A random way point model was set as the mobile node radio station model. That is, the node radio station n randomly selects a point of the destination radio station, and moves to the destination point at a constant speed v that is uniformly selected from the set of speeds between the specified v _{max to} v _min . When the destination is reached, the node radio station stops for a certain time called the pause time, and then the process is repeated.

Further, when the node radio station n forms a transmission beam having an azimuth angle α and a beam width β at the transmission reach distance R, its effective range from the node radio station n at the azimuth angle α is as shown in FIG. It is defined as a transmission zone B _n (α, β, R) of the wireless station n. This is because if the node radio station m (mεN) is in the transmission zone B _n (α, β, R) and the node radio station m is in the reception mode, the node radio station n is associated with the node radio station n. This means that every time a radio signal of a message is transmitted at a transmission azimuth angle α, a beam width β and a transmission reach distance R, the radio signal of the message is always received by the node radio station m. When the node radio station m moves out of the transmission zone B _n (α, β, R), the connectivity between the node radio station n and the node radio station m is lost. In the present embodiment, since the transmission beam width β and the transmission reach distance R are constant, the transmission zone B _n (α, β, R) is referred to as a transmission zone B _n (α) in the following description.

  Next, “network recognition” in each node radio station 1 in the radio communication system according to the present embodiment will be described in detail below.

  In the present embodiment, a radio communication system is proposed that has a mechanism in which each node radio station recognizes not only the adjacent node radio station but also the network recognition of the entire ad hoc radio network. This “network recognition” is useful when implementing a positive (actively active) routing method described later. Each node radio station n in the ad hoc radio network has five tables indicating the following network state information, and these tables are stored in the database memory 154 in each radio station in FIG. Details of these three tables will be described below.

(1) AS table: As shown in FIG. 6, the AS table stores information on the azimuth angle and the signal strength level for each adjacent node radio station in the service area of its own station. It is created and updated by the packet transmission / reception control processing of 11 to 14.

(2) NLS table (NLS table in node radio station n is described as NLSTn): Each node radio station n periodically records its neighbor information in order to track the direction of its neighbor node radio station. Collect "to form an NLS table. The NLS table (NLSTn (t)) of the node radio station n at time t is the maximum signal of the radio coupling detected by the node radio station n in a certain specific direction for each of the adjacent node radio stations m (mεG ⁿ ). The intensity SIGNAL ^θ _{n, m} (t) can be specified. Accordingly, the maximum signal strength SIGNAL ^θ _{n, m} (t) is received at the node radio station n from the adjacent node radio station m at the azimuth angle θ with respect to the node radio station n and detected by the node radio station n at an arbitrary time. It is the maximum signal strength when The NLS table of node radio station n helps in determining the most likely communication direction with any adjacent node radio station. Here, each node radio station selects an azimuth angle that maximizes the SINR value for each adjacent node radio station acquired in advance, and uses this SINR value as the affinity with the adjacent node radio station. Each node radio station extracts the azimuth angle and affinity value for each adjacent node radio station, and generates and updates the NLS table with the current date and time as the update date and time. In the NLS table, as shown in FIG. 7, an azimuth corresponding to the maximum SINR value, the affinity that is the maximum SINR value, and the update date and time are stored for each adjacent node radio station. .

(3) GLS table (GLS table in node radio station n is described as GLSn): The GLS table includes topology information in the ad hoc radio network that can be detected by node radio station n at time t. Specifically, as shown in FIG. 8, the GLS table stores, for each node radio station, the adjacent node radio station, its azimuth data, and the number of updates (indicating the version) of the data. To do.

In the present embodiment, each node radio station broadcasts a packet signal including the above-described GLS table (hereinafter referred to as a GLS packet signal) at a predetermined cycle interval, and performs GLS table generation and update processing. That is, each node radio station n broadcasts its GLS packet signal at a certain periodic interval (GLS packet signal transmission cycle) _TG . Here, when a certain node radio station n receives a GLS packet signal from its adjacent node radio station, it updates its own GLS table.

  FIG. 9 is a timing chart showing tone signal and packet signal transmission / reception processing used in the ad hoc wireless network of FIG. In the MAC protocol method, it is necessary to periodically transmit two packet signals of a beacon signal and a GLS packet signal, and there is a problem that the occupation time is relatively long and the throughput is lowered. In order to solve this problem, in the MAC protocol according to the present embodiment, as shown in FIG. 9, the transmitting-side radio station follows a tone signal that is an unmodulated carrier wave, a GLS table, an RTS or a CTS, Alternatively, a packet signal including data to be transmitted is transmitted. On the other hand, after receiving the tone signal, the receiving radio station decodes the packet signal, takes in the decoded data, and executes data processing. The transmission of the GLS packet signal including the GLS table is periodically executed as described above.

  FIG. 10 is a timing chart showing the types of radiation patterns and radio communication protocols at each radio station used in the ad hoc radio network of FIG. In FIG. 10, the usage example of the antenna mode of the four-way handshake which concerns on this embodiment is shown. Although adaptive control patterns can track moving node radio stations, beams and nulls cannot be formed unless a packet signal is received. Therefore, the omni pattern is used in the transmission of the tone signal + RTS and the transmission of the tone signal + CTS from the transmitting node radio station. On the other hand, in the reception of the tone signal + RTS and the reception of the tone signal + CTS at the receiving node radio station, the sector pattern directed to the azimuth angle based on the AS table is used after the rotating sector pattern is used at the start. Is used to execute a preparation process for adaptive control during communication using the sector pattern, and finally shift to a radiation pattern for adaptive control.

  Next, a method for forming the GLS table will be described below.

  Each node radio station holds a GLS table for capturing network connection information. In each node radio station, the GLS table is first updated with the NLS table of that node radio station. Thus, in the initial state, at the start of an ad hoc radio network, all node radio stations are only aware of their neighbor node radio stations, and with respect to other node radio stations in the radio communication system. "I don't know anything". Each node radio station periodically updates its GLS table, and broadcasts the updated GLS packet signal to its adjacent node radio station at a predetermined transmission cycle. With this periodic update message (GLS packet signal) for each of those neighboring node radio stations from that neighboring node radio station, the node radio stations gradually become GLS tables for other node radio stations and their respective neighboring node radio stations. Get information. In this way, each node radio station updates its own GLS table on the basis of an update message (GLS packet signal) received from another node radio station.

  When the node radio station n receives a GLS packet signal from another node radio station, the node radio station n updates its own GLS table. To do this, all node radio stations' freshness token values (number of updates) stored in the GLS table of the node radio station n and all recently stored GLS packet signals for updates are stored. The node token is compared with the freshness token value (update count) of the node radio station. If it is known that the freshness token (update count) of an arbitrary node radio station in the GLS table of the node radio station n, for example, the node radio station X is less than that in the GLS packet signal to be updated, the GLS packet signal to be updated It is clear that the latest information regarding the node radio station X is transmitted. Accordingly, the entire information regarding the node wireless station X in the GLS table of the node wireless station n is overwritten by the information of the node wireless station X in the received updated GLS packet signal. This step is performed asynchronously for all updated GLS packet signals with their arrival at the host node radio station n. This step facilitates the acquisition by the node radio station n of all the latest information that can be collected from the updated GLS packet signal.

  It has to be noted here that this mechanism does not guarantee that each node radio station recognizes the exact state of the ad hoc radio network. It is only "recognition" that helps each node radio station to elucidate the approximate state of the ad hoc radio network. This promotes the maintenance of more accurate status information in neighboring node radio stations close to the node radio station, but the accuracy of the details of the network information gradually decreases as the distance increases. It is similar to “approach” (for example, see Non-Patent Document 13).

9 showing the structure of a GLS table in any node radio station n, R _i is a recency token value of the node radio station n _i in the ad hoc wireless network consisting of N nodes radio station (update count), < _{n j, α (n i,} n j)> indicates that the node radio station _{n j} is adjacent node radio station node radio station _{n i. Here, α (n i, n j} ) shows the transmit beam azimuth alpha node radio station n _i can best communicate with the node radio station n _j.

  Next, the tracking of the position of each node radio station and the MAC protocol will be described below.

  Usually, in an ad hoc wireless network, all node wireless stations are equipped with an omni antenna. However, ad hoc wireless networks using omni antennas use RTS / CTS-based floor reservation methods that waste most of the network capacity in maintaining wireless media over a wide area. Therefore, many node radio stations adjacent to the transmitter and the receiver are forced to exist after waiting for the data communication between the transmitter and the receiver to end. To alleviate this problem, researchers in the art have proposed the use of directional antennas that significantly reduce radio interference, thereby increasing the use of the radio medium and inevitably increasing network throughput. (For example, refer nonpatent literature 4 etc.).

  In order to fully utilize the capabilities of the directional antenna, all the neighboring node radio stations of the source radio station and the destination radio station can start a new communication in the other direction, and the source radio station and the destination radio station The direction of communication must be known so that interference with data communication currently being performed with a radio station can be prevented. Thus, it is essential for each node radio station to have a mechanism for tracking the direction of its neighboring node radio stations.

  However, this direction tracking mechanism in wireless ad hoc wireless networks using directional antennas is a serious problem because it incurs significant control overhead.

  In one prior art, direction tracking is performed by using a set of tone signals and maintaining extensive network state information at each node radio station in the ad hoc radio network. Here, in the case of a dynamic state in which each node radio station moves, this is impractical. Further, in Non-Patent Document 2, the proposed MAC protocol does not need to recognize location information, and the source radio station and the destination radio station change their directions on an on-demand basis during an omnidirectional RTS-CTS exchange. To identify. All neighboring node radio stations of the source radio station s and the destination radio station d listening to this RTS-CTS dialogue communication are assumed to use this information to prevent interference with the ongoing data transmission. Has been. However, due to the omnidirectional transmission of RTS and CTS packets, this protocol does not offer the benefit of spatial reuse of the radio channel.

  In addition, another prior art suggests using the Global Positioning System (GPS) to track the location of each node radio station, but does not discuss the exact mechanism of information exchange and the resulting overhead. . Further, for example, in Non-Patent Document 3, it is assumed that the node radio station recognizes the transmission direction in order to directionally access the adjacent node radio station, but the position tracking mechanism is not shown. . Furthermore, both the methods of Non-Patent Documents 2 and 3 require the addition of hardware in each user terminal. In previous research results by one of the inventors, etc., a MAC protocol has been proposed in which each node radio station dynamically maintains neighbor information through maintenance of an azimuth pair SINR table (AS table). In this method, in order to create an AS table, each node radio station sequentially transmits directional beacon signals in 30-degree intervals in all directions in the form of directional broadcasts, covering the entire 360-degree space. To do. Here, with this prior art method, the overhead due to the control packet is extremely high.

  The MAC protocol invented by the present inventors in this embodiment is basically a “director-based, rotating sector-based directional MAC protocol by receiver”, which also functions as a position tracking mechanism. In this case, each node radio station stands by in an omnidirectional detection mode while idling. This enters “Rotating Sector Receive Mode” whenever it detects any signal that exceeds the threshold. In the “rotating sector reception mode”, the node radio station n sequentially rotates its directional antennas at 45 degree intervals in all directions to cover the entire 360 degree space in the form of sequential directional reception in each direction, Detect the signal received in the direction. After one revolution, this determines what may be the best signal reception direction by the maximum received signal strength. The beam is then set in that direction and a signal is received.

  Here, in order to enable the receiver to decode the received signal, each control packet has a time to rotate the receiver's rotating receive beam by 360 degrees, the duration of the tone signal (in our simulation). In this case, it is transmitted with a preceding tone signal having a duration slightly shorter than 200 microseconds). The purpose of transmitting this tone signal prior to any control packet signal is to allow the receiver to track what may be the best receiving direction of the signal. When this sets the beam in that direction, the purpose of the tone signal is fulfilled and a control packet signal is subsequently transmitted.

The framework according to the present embodiment proposed by the present inventors uses the following three types of broadcast (omnidirectional) control packets for medium access control.
(1) a packet signal including a GLS table (GLS packet signal),
(2) a packet signal including an RTS (transmission request) signal, and (3) a packet signal including a CTS (transmission ready) signal.

  In addition, the control packet ACK signal is also a directivity control packet. The packet signal including data is transmitted after the direction is determined after the RTS / CTS handshake is performed. As described above, the GLS packet signal is a periodic signal, and is transmitted from each node radio station at a predetermined transmission cycle (transmission interval). At each periodic interval, for example, each node radio station m broadcasts an ANL packet to its adjacent node radio station if its radio medium (wireless channel) is idle. Each receiver then sets its beam in that direction and receives and decodes the packet (see FIG. 9).

  Further, the node radio station n checks the radio medium (radio channel) every time it wishes to start data communication with the node radio station j, for example, and issues an omnidirectional RTS signal if the radio medium is free. Then send. Upon receiving the RTS signal, the destination radio station j issues and transmits an omnidirectional CTS signal. The purpose of RTS / CTS in this case is not to prohibit transmission or reception by the adjacent node radio stations of the node radio stations n and j (as in the case of using an omni antenna). This is to inform the adjacent node radio station that the adjacent node radio station j is about to receive a data packet from the node radio station n. This also specifies the approximate duration of the communication. All the adjacent node radio stations of the node radio stations n and j set their directional network allocation vector (Directional Network Allocation Vector (DNAV)) in the direction of the node radio stations n and j, so that the node radio station n Track communication between j and j. Therefore, the node radio station existing adjacent to the node radio stations n and j can communicate in the other direction “without interfering with the communication performed between the node radio station n and the node radio station j”. Can start. The source radio station and the destination radio station wait for an acknowledgment signal and a data packet signal, respectively, in a directional reception mode.

  Details of the above processing will be described below with reference to the flowcharts of FIGS. FIG. 11 is a flowchart showing packet transmission / reception control processing executed by the management control unit 105 of the wireless station 1 of FIG. 2, and FIGS. 12 to 14 are processing of routing and communication processing (step S12) which is a subroutine of FIG. It is a flowchart which shows.

In FIG. 11, first, in step S1, the variable beam antenna 101 is controlled so as to be rotated at every predetermined azimuth angle (for example, 30 degrees) with a rotating sector pattern, and a received signal is received. It is determined whether or not a received signal having a signal strength level equal to or higher than a predetermined threshold value is received. If YES, the process proceeds to step S3. If NO, the process proceeds to step S9. In step S9, it is determined whether there is a packet signal to be transmitted. If YES, the process proceeds to step S10. If NO, the process returns to step S1. In step S10, it is determined whether the packet signal to be transmitted is a GLS packet. If YES, the process proceeds to step S11. If NO, the process proceeds to step S12. Here, the GLS packet has its event periodically generated in a predetermined cycle period _TG . At this time, if YES in step S10, after transmitting a packet signal including the table in an omni pattern in step S11, Return to step S1. On the other hand, after executing the routing and communication process, which is the subroutine of FIGS. 12 to 14, in step S12, the process returns to step S1.

  In step S3, the rotating sector pattern is stopped, and the radiation pattern of the variable beam antenna 101 is set to a sector pattern directed to the predetermined azimuth angle stopped. Next, in step S4, the received signal is received with the adaptive control pattern, the packet information is decoded, the signal strength level of the received signal is measured, the received signal RS is determined in step S5, and the process branches to step S6 or S8 as follows. To do. If the received signal RS = GLS packet signal, the GLS table update process is executed in step S6, and the process returns to step S1. In this GLS table update process, the currently stored GLS table is compared with the GLS table included in the received signal, and the GLS table is updated using only the newer data that has a higher update count. If it is a new node radio station, information about the node radio station is added. Further, when the received signal RS is other signal in step S5, the other signal reception process is executed in step S8, and then the process returns to step S1.

  In the control flow of FIG. 11, in steps S1 and S2, when the variable beam antenna 101 is rotationally scanned and a reception signal having a signal intensity level equal to or higher than a predetermined threshold is received, the reception signal is detected. However, the present invention is not limited to this, and the variable beam antenna 101 is rotationally scanned over 360 degrees to receive a received signal having a signal intensity level equal to or higher than a predetermined threshold value, and the maximum received signal is detected. It may be a received signal.

In the routing and communication process (step S12) of FIG. 12, first, in step S21, it is determined whether or not it is a source wireless station of the transmission packet. If YES, the process proceeds to step S22. If NO, Proceed to step S31 in FIG. The following processing from step S22 to step S28 shows processing when the transmission packet is a transmission source radio station. In step S22, the already propagated hop length H is initialized to 0, and in step S23, based on the GLS table. In step S24, it is determined whether or not the shortest path is searched and selected. If YES in step S24, the process proceeds to step S25. If NO, the process proceeds to step S28. As an initial path length L in step S25, for example, preferably set the value L ₀ which predetermined 10, radio transmits a transmission packet to the next node radio station of the path of the shortest is the selected at step S26 For example, the data is stored in a queue memory which is the transmission buffer memory 142, for example, and the process proceeds to step S27. Here, the transmission packets stored in the queue memory are sequentially transmitted to the next radio station. In step S27, whether or not a packet drop (or loss) has occurred in the queue memory in the network layer (that is, the packet drop is repeated in the MAC layer in the upper layer and a queue (for example, In the queue memory of the transmission buffer memory 142), it is determined whether or not an overflow has occurred and a packet has been dropped. If NO, the process returns to the original main routine. After selecting the next shortest path based on the GLS table except for the selected shortest path, the process returns to step S24.

  Next, FIG. 13 and FIG. 14 show the processing when the relay packet is a relay radio station other than the transmission source radio station of the transmission packet. In step S31 of FIG. 13, the already propagated hop length H is incremented by 1, In step S32, it is determined whether or not H> L. If YES, the process proceeds to step S33. If NO, the process proceeds to step S41 in FIG. In step S33, the shortest path is searched and selected based on the GLS table table. In step S34, it is determined whether or not the search has been completed. If YES, the process proceeds to step S35. Return to the main routine. In step S35, the transmission packet is stored in, for example, a queue memory, which is the transmission buffer memory 142, for wireless transmission to the next node wireless station on the selected shortest path, and the process returns to the original main routine. Here, the transmission packets stored in the queue memory are sequentially transmitted to the next radio station.

  Further, in step S41 of FIG. 14, the shortest path is searched and selected based on the GLS table, and it is determined whether or not the search is successful in step S42. If YES, the process proceeds to step S43, while NO. When it returns to the original main routine. In step S43, the transmission packet is stored in, for example, a queue memory that is the transmission buffer memory 142 in order to wirelessly transmit the packet to the next node wireless station on the selected shortest path, and the process proceeds to step S44. Here, the transmission packets stored in the queue memory are sequentially transmitted to the next radio station. On the other hand, in step S44, as in step S27, it is determined whether or not a packet drop (or loss) has occurred in the queue memory in the network layer. If YES, the process proceeds to step S45, while NO. When it returns to the original main routine. In step S45, the next shortest path is selected based on the GLS table, except for the already selected shortest path, and then the process returns to step S42.

  In the above embodiment, routing is performed using the GLS table, but the present invention is not limited to this, and other routing control protocols such as known DSR may be used.

  As described above, according to the present invention, in the transmission source radio station and the relay radio station when the already propagated hop length H included in the packet signal is equal to or shorter than the initial path length L, the packet is dropped at the network layer. When the congestion of the local packet signal is detected by detecting whether or not the congestion has occurred and the congestion is detected, the next shortest path is excluded using the above routing table. In order to transmit the packet signal to be transmitted, the path is stored in a queue memory and wirelessly transmitted to the next wireless station. As a result, the configuration is simpler than the prior art without using the ANL table of the prior art indicating the congestion state, and the data signal is reliably transmitted to the destination radio station when the data communication is congested, and the routing is converged. Can be made.

It is a plane layout view of a plurality of radio stations 1-1 to 1-9 constituting an ad hoc radio network which is an embodiment according to the present invention. FIG. 2 is a block diagram showing an internal configuration of each wireless station 1 in FIG. 1. It is a figure which shows an example of the sector beam pattern of the variable beam antenna 101 of FIG. 4 is a diagram showing a format of packet data used in the ad hoc wireless network of FIG. 1, FIG. 4 (a) is a diagram showing a format of packet data other than for data communication, and FIG. 4 (b) is a diagram for data communication. It is a figure which shows the format of packet data. It is a top view which shows transmission zone Bn ((alpha), (beta), R) which is a transmission sector radiation pattern from each node radio station used in description of the radio | wireless communications system which concerns on this embodiment. 3 is a table showing an example of an azimuth and signal intensity level table (AS table) stored in the database memory 154 of FIG. 2. It is a figure which shows an example of the adjacent link state table (NLS table) stored in the database memory 154 of FIG. It is a figure which shows an example of the global link state table (GLS table) stored in the database memory 154 of FIG. 2 is a timing chart showing transmission / reception processing of tone signals and packet signals used in the ad hoc wireless network of FIG. 1. FIG. 2 is a timing chart showing types of radiation patterns and wireless communication protocols at each wireless station used in the ad hoc wireless network of FIG. 1. FIG. 3 is a flowchart showing packet transmission / reception control processing executed by the management control unit 105 of the wireless station 1 of FIG. It is a flowchart which shows the 1st part of the routing and communication process (step S12) which is a subroutine of FIG. It is a flowchart which shows the 2nd part of the routing and communication process (step S12) which is a subroutine of FIG. 12 is a flowchart showing a third part of the routing and communication process (step S12) which is a subroutine of FIG.

Explanation of symbols

1, 1-1 to 1-9, 1-i, 1-j, 1-k, ... node radio station,
101 ... Variable beam antenna,
102 ... circulator,
103 ... Direction control unit,
104 ... packet transmission / reception unit,
105 ... Traffic monitor section,
106 ... line control unit,
107 ... upper layer processing apparatus,
130: Packet receiver,
131 ... high frequency receiver,
132: demodulator,
133: Receive buffer memory,
140 ... packet transmitter,
141. Transmission timing control unit,
142 ... transmission buffer memory,
143 ... modulator,
144 ... high frequency transmitter,
151... Management control unit,
152 ... Search engine,
153 ... Update engine,
154 ... Database memory,
155 ... Clock circuit,
160. Spread code generator.

Claims (4)

In a routing method for a wireless network comprising a plurality of wireless stations and performing wireless communication between the wireless stations,
When a packet signal including a predetermined initial path length L, a hop length H of a packet signal already propagated, and data is transmitted from the source radio station to the destination radio station at the source radio station In the original radio station and the relay radio station, the shortest path is selected using a predetermined routing table, and the packet signal to be transmitted is stored in the queue memory and transmitted to the next radio station for transmission. Sending step;
In the source radio station and the relay radio station when the already propagated hop length H included in the packet signal is equal to or shorter than the initial path length L, it is determined whether or not the packet is dropped in the network layer, and the drop When the next shortest path is selected using the routing table except for the shortest path that has already been selected, the packet signal to be transmitted is stored in the queue memory for transmission. And a first control step of wirelessly transmitting to the next wireless station.   In the relay radio station when the already propagated hop length H included in the packet signal exceeds the initial path length L, a queue is selected to select the shortest path using the routing table and transmit the packet signal to be transmitted. The routing method for a wireless network according to claim 1, further comprising a second control step of storing in a memory and wirelessly transmitting to a next wireless station. In a router device for a wireless network that includes a plurality of wireless stations and performs wireless communication between wireless stations,
When a packet signal including a predetermined initial path length L, a hop length H of a packet signal already propagated, and data is transmitted from the source radio station to the destination radio station at the source radio station In the original radio station and the relay radio station, the shortest path is selected using a predetermined routing table, and the packet signal to be transmitted is stored in the queue memory and transmitted to the next radio station for transmission. A transmission means;
In the source radio station and the relay radio station when the already propagated hop length H included in the packet signal is equal to or shorter than the initial path length L, it is determined whether or not the packet is dropped in the network layer, and the drop When the next shortest path is selected using the routing table except for the shortest path that has already been selected, the packet signal to be transmitted is stored in the queue memory for transmission. And a first control means for wirelessly transmitting to the next wireless station. A router device for a wireless network, comprising: In the relay radio station when the already propagated hop length H included in the packet signal exceeds the initial path length L, a queue is selected to select the shortest path using the routing table and transmit the packet signal to be transmitted. 4. The router device for a wireless network according to claim 3, further comprising second control means for storing in a memory and wirelessly transmitting to the next wireless station.

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