JP2006101400A - Control apparatus and control method for wireless network - Google Patents

Control apparatus and control method for wireless network Download PDF

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JP2006101400A
JP2006101400A JP2004287482A JP2004287482A JP2006101400A JP 2006101400 A JP2006101400 A JP 2006101400A JP 2004287482 A JP2004287482 A JP 2004287482A JP 2004287482 A JP2004287482 A JP 2004287482A JP 2006101400 A JP2006101400 A JP 2006101400A
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packet
priority flow
radio station
flow
high priority
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Bandyopadhyay Somprakash
Shinsuke Tanaka
Tetsuo Ueda
ソンプラカッシュ・バンディオパダイ
哲郎 植田
信介 田中
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Advanced Telecommunication Research Institute International
株式会社国際電気通信基礎技術研究所
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<P>PROBLEM TO BE SOLVED: To improve the throughput of a high-priority flow, by supporting QoS based on the priorities of flows and controlling the low-priority flow. <P>SOLUTION: A radio station of transmission source of a high-priority flow transmits a packet signal of the high-priority flow, while controlling the packet injection interval of the high-priority flow, based on a packet injection interval (PII) acquired at the transmission source radio station, a packet arrival interval (PAI) computed at the transmission source radio station and a packet injection interval (PII) and a packet arrival interval (PAI) which are reverse propagated. A radio station of transmission source of a low-priority flow transmits a packet signal of the low-priority flow, while controlling the packet injection interval of the low-priority flow based on a deviation (MDII) computed at the transmission source radio station and a deviation (MDII) propagated reversely. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device and a control method for a wireless network such as an ad hoc wireless network that performs packet communication in a wireless network such as a wireless LAN including a plurality of node wireless stations.

  Along with recent advances in wireless communication systems and personal computers, research has been conducted on ad hoc wireless networks that are composed of a plurality of node wireless stations that operate as mobile router devices and are assumed to be infrastructureless networks that can be quickly deployed. Has been. In this ad hoc wireless network, various solutions have recently been proposed for the problem of providing quality of service (QoS) in mobile ad hoc networks (see Non-Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 2001-244983. JP 2001-024431A. Kui Wu et al., "QoS Support in Mobile Ad hoc Networks", Crossing Boundaries-an interdisciplinary journal, Vol.1, No.1, Fall 2001. Satyabrata Chakrabarti et al., "QoS issues in Ad Hoc Wireless Networks", IEEE Communications Magazine, Vol.39, No.2, pp.142-148, February 2001. X. Pallot et al., "Implementing Message Priority Policies over an 802.11 Based Mobile Ad Hoc Network", Proceedings of MILCOM 2001, Washington, U.S.A., October 2001. Kolarov et al., "A control theoretic approach to the design of close loop rate based flow control for high speed ATM networks", Proceedings of IEEE INFOCOM'97, pp.293-300, April 1997. S. Keshav, "A control-theoretic approach to flow control", Proceedings of ACM SIGCOMM'91, pp.3-15, Zurich, Switzerland, September 1991. C. R. Kalmanek et al., "Rate Controlled Servers for Very High Speed Networks", Proceedings of Globecom 1990, 300.3.1-300.3.9, December 1990. L. Benmohamed et al., "Feedback Control of Congestion in Packet Switching Networks: The Case of a Single Congested Node", IEEE / ACM Transactions on Networking, Vol. 1, No. 6, pp. 693-707, 1993. Siuli Roy et al., "A Network-Aware MAC and Routing Protocol for Effective Load Balancing in Ad Hoc Wireless Networks with Directional Antenna", Proceedings of ACM MobiHoc 2003, Maryland, U.S.A., 1-3 June 2003. Thyagarajan Nandagopal et al., "Service differentiation through end-to-end rate control in low bandwidth wireless packet networks", Proceedings of the 6th International Workshop on Mobile Multimedia Communications, San Diego, California, U.S.A., November 1999. Seung-Seok Kang et al., "Provisioning Service Differentiation in Ad Hoc Networks by the Modification of Back off Algorithm", International Conference on Computer Communication and Network (ICCCN) 2001, Scottsdale, Arizona, U.S.A., October 2001. S. Mangold et al., "IEEE 802.11e Wireless LAN for Quality of Service", (invited paper), Proceedings of the European Wireless 2002, Florence, Italy, February 2002. Xue Yang et al., "Priority Scheduling in Wireless Ad Hoc Networks", ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc), June 2002. Vance J. VanDoren, "Understanding PID Control: Familiar examples show how and why proportional-integral-derivative controllers behave the way they do", Control Engineering, http://www.controleng.com, June 1, 2000. Minorsky, "Directional Stability of automatically steered bodies", Journal of American Social of Naval Engineering, Vol. 34, pp.284, 1922. G. F. Franklin et al., "Feedback Control of Dynamic Systems", Addison-Wesley, Singapore, 1988. 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", Proceedings of the IFIP conference on Personal Wireless Communications PWC 2003, Venice, Italy, September 23-25, 2003. T. Ueda et al., "Evaluating the Performance of Wireless Ad Hoc Network Testbed Smart Antenna", Fourth IEEE Conference on Mobile and Wireless Communication Networks (MWCN2002), September 2002. QualNet Simulator Version 3.1, Scalable Network Technologies, http://www.scalable-networks.com, accessible on June 11, 2004.

  However, as pointed out in Non-Patent Document 3, since the bandwidth of the mobile radio channel is limited, the same QoS cannot be given to every class of traffic flow. It is therefore necessary to implement some means for providing each class with a different QoS by assigning a class a priority over other classes. Several solutions already exist for the wired environment, but such solutions do not work well in ad hoc wireless networks due to the shared communication environment and the mobility of the host wireless station device.

  Some researchers use flow rate control in the context of wired networks to control congestion in the network, provide flow-based end-to-end QoS, and address fairness issues The concept of the control theory approach is explored (see Non-Patent Documents 4 to 7). Non-Patent Document 4 proposes a control mechanism that can be used when designing a controller that supports a service at an available bit rate, in which a plurality of users are composed of a plurality of distributed controllers. Adjust the appropriate set based on flow rate feedback to dynamically share available bandwidth in a fair manner. Non-Patent Document 5 presents a control theoretical approach that can be used to control transport connections in a reservationless network. These flow control schemes use a feedback type control mechanism that allows multiple flows that exist in the network to have available bandwidth between them depending on the state of the network at a given moment. Can be shared equally. However, these schemes do not deal with the priority-based service problem of prioritizing some flows over others. Further, these non-patent literatures are investigating wired network environments.

  The routes of two flows in an ad hoc wireless network affect each other when sharing a common node radio station or are close enough to interfere with each other, resulting in route coupling (non-patent document). 8). In this case, the plurality of node radio stations in these two routes always contend for access to the media they share. In such a situation, if the flow rate of the low priority flow is reduced, the high priority flow will have a greater opportunity to access the medium shared by multiple flows, resulting in As a result, the congestion is reduced and the throughput of the high priority flow is increased. Thus, priority-based flow control is an effective means for providing service differentiation for multiple flows of different classes.

  Some researchers have introduced end-to-end flow control in the transport layer to achieve service differentiation (see Non-Patent Document 9). However, these schemes cannot guarantee a desired rate for high priority traffic flows. The work of Non-Patent Document 9 on service differentiation using flow rate control focuses on individualized flow control. In this case, multiple flows are individually controlled using rate vectors based on end-to-end feedback, and the flow rate for high priority flows is more moderately suppressed than the flow rate for low priority flows. . Therefore, although the flow rate of the high priority flow increases, there is a possibility that a desired flow level cannot be maintained.

  Further, there are technologies disclosed in Non-Patent Documents 10 to 12 as solutions for other existing MAC layers (media access control layers) related to service differentiation. In MANET (Mobile Ad Hoc Network), the frame interval (IFS) and the size of the contention window (contention window: CW) are changed according to the priority of the traffic flow in the MAC layer, and the back-off algorithm is appropriately changed. As a result, several attempts have been made to support QoS. However, this does not guarantee that high priority packets always access the medium for data communication without contention (see Non-Patent Document 12). In these schemes, multiple high priority flows competing for the medium do not necessarily gain access to a guaranteed fair medium. Furthermore, multiple low priority traffic flows in the absence of high priority traffic flows may select a large contention window, which may lead to poor utilization of the medium.

  Another important aspect of QoS in the MAC layer that is not addressed in the above-mentioned literature is the packet transmission rate. In the intermediate node radio station MAC layer, low priority packets are often found with the increased backoff counter selected, but this counter value is unknown to the source radio station. So that the originating radio station may still inject packets at a very high rate. As a result, packets arriving at a very high rate at intermediate node radio stations handling low priority flows remain stored in the queue memory without being quickly serviced by the MAC layer. May be discarded due to memory overflow.

  The object of the present invention is to solve the above-mentioned problems, and in an ad hoc wireless network in which flows of different priorities exist, the QoS of the flow can be supported based on the priority of each flow. Provided is a control device and a control method for a wireless network capable of controlling a low priority flow so as to minimize interference of a low priority flow with respect to a high priority flow and increasing the throughput of the high priority flow. There is to do.

A control device for a wireless network according to a first invention includes a plurality of wireless stations, and for a wireless network that performs packet wireless communication using a plurality of packet flows having different priorities between the wireless stations. In the control device,
The packet signal of each packet flow includes data indicating the current packet injection interval (PII) of the packet flow to which the packet signal belongs,
When each radio station handling a high priority flow among the plurality of packet flows receives a packet signal of a high priority flow different from the high priority flow handled by each radio station, the received packet signal To obtain the packet injection interval (PII) of the different high priority flow from, and calculate the packet arrival interval (PAI) of the packet signal of the different high priority flow,
Radio stations that handle the high-priority flow and that are other than the source radio station of the high-priority flow use the acquired packet injection interval (PII) and the calculated packet arrival interval (PAI). And back-propagating toward the high-priority flow source radio station,
The source radio station of the high priority flow is back-propagated with the packet injection interval (PII) acquired at the source radio station and the packet arrival interval (PAI) calculated at the source radio station. Based on the packet injection interval (PII) and the packet arrival interval (PAI), the packet injection interval of the high priority flow is controlled and the packet signal of the high priority flow is transmitted.
When each radio station that handles a low priority flow among the plurality of packet flows receives the packet signal of the high priority flow, the radio station receives a packet injection interval (PII) of the high priority flow from the received packet signal. ) To calculate the packet arrival interval (PAI) of the packet signal of the high priority flow, and the deviation between the acquired packet injection interval (PII) and the calculated packet arrival interval (PAI) ( MDII)
A radio station that handles the low priority flow and that is other than the source radio station of the low priority flow directs the calculated deviation (MDII) to the source radio station of the low priority flow Backpropagating
Based on the deviation (MDII) calculated at the source radio station and the back-propagated deviation (MDII), the source radio station of the low priority flow determines the packet injection interval of the low priority flow. The low-priority flow packet signal is transmitted under control.

In the control device for the wireless network, the high-priority flow source wireless station is:
Calculating an average value (PAPII) of packet injection intervals that is a weighted average of the packet injection interval (PII) acquired at the source wireless station and the back-propagated packet injection interval (PII);
Calculating an average value (PAPAI) of packet arrival intervals which is a weighted average of the packet arrival interval (PAI) calculated at the source wireless station and the back-propagated packet arrival interval (PAI);
An error between the average value of the current packet injection interval (PII) of the high priority flow and the average value of the calculated packet injection intervals (PAPI) and the average value of the calculated packet arrival intervals (PAPAI) And the packet injection interval of the high priority flow is controlled using a proportional control method based on the calculated error.

Further, in the control device for the wireless network, the source wireless station of the low priority flow is:
Calculating a maximum deviation value (PMDII) which is a maximum value of the deviation (MDII) calculated in the source wireless station and the back-propagated deviation (MDII);
The low-priority flow packet injection interval is controlled using a proportional, integral and derivative (PID) control method based on the calculated maximum deviation (PMDII).

A control method for a radio network according to a second invention is provided for a radio network that includes a plurality of radio stations and performs packet radio communication using a plurality of packet flows having different priorities between the radio stations. In the control method,
The packet signal of each packet flow includes data indicating the current packet injection interval (PII) of the packet flow to which the packet signal belongs,
When each radio station handling a high priority flow among the plurality of packet flows receives a packet signal of a high priority flow different from the high priority flow handled by each radio station, the received packet signal To obtain the packet injection interval (PII) of the different high priority flow from, and calculate the packet arrival interval (PAI) of the packet signal of the different high priority flow,
Radio stations that handle the high-priority flow and that are other than the source radio station of the high-priority flow use the acquired packet injection interval (PII) and the calculated packet arrival interval (PAI). And back-propagating toward the high-priority flow source radio station,
The source radio station of the high priority flow is back-propagated with the packet injection interval (PII) acquired at the source radio station and the packet arrival interval (PAI) calculated at the source radio station. Based on the packet injection interval (PII) and the packet arrival interval (PAI), the packet injection interval of the high priority flow is controlled and the packet signal of the high priority flow is transmitted.
When each radio station that handles a low priority flow among the plurality of packet flows receives the packet signal of the high priority flow, the radio station receives a packet injection interval (PII) of the high priority flow from the received packet signal. ) To calculate the packet arrival interval (PAI) of the packet signal of the high priority flow, and the deviation between the acquired packet injection interval (PII) and the calculated packet arrival interval (PAI) ( MDII)
A radio station that handles the low priority flow and that is other than the source radio station of the low priority flow directs the calculated deviation (MDII) to the source radio station of the low priority flow Backpropagating
Based on the deviation (MDII) calculated at the source radio station and the back-propagated deviation (MDII), the source radio station of the low priority flow determines the packet injection interval of the low priority flow. The low-priority flow packet signal is transmitted under control.

Further, in the control method for the wireless network, the source wireless station of the high priority flow is:
Calculating an average value (PAPII) of packet injection intervals that is a weighted average of the packet injection interval (PII) acquired at the source wireless station and the back-propagated packet injection interval (PII);
Calculating an average value (PAPAI) of packet arrival intervals which is a weighted average of the packet arrival interval (PAI) calculated at the source wireless station and the back-propagated packet arrival interval (PAI);
An error between the average value of the current packet injection interval (PII) of the high priority flow and the average value of the calculated packet injection intervals (PAPI) and the average value of the calculated packet arrival intervals (PAPAI) And the packet injection interval of the high priority flow is controlled using a proportional control method based on the calculated error.

Furthermore, in the control method for a wireless network, the source wireless station of the low priority flow is:
Calculating a maximum deviation value (PMDII) which is a maximum value of the deviation (MDII) calculated in the source wireless station and the back-propagated deviation (MDII);
The low-priority flow packet injection interval is controlled using a proportional, integral and derivative (PID) control method based on the calculated maximum deviation (PMDII).

  Therefore, according to the present invention, in an ad hoc wireless network having a plurality of different priority flows, the QoS of the flow can be supported based on the priority of each flow. Low priority flows can be controlled to minimize low priority flow interference and increase the throughput of high priority flows.

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

  In an embodiment according to the present invention, a high-priority flow (a packet signal having a high priority is transmitted from the source in order to solve the above-mentioned problems and to achieve sufficient utilization of the wireless medium according to adaptive rate control). A flow of session connection when transmitting from a wireless station to a destination wireless station via a flow on a predetermined wireless medium route) is maintained at a desired level, and a low priority flow (higher priority than A session connection flow when a packet signal having a low priority, which is a lower priority, is transmitted from a source wireless station to a destination wireless station via a flow on a predetermined wireless medium route). A control system is provided that includes a controller for a wireless network that can be maximized. Here, in order to provide this desirable service differentiation for high priority flows, the low priority flows that cause interference with the high priority flows are considered high priority at each node radio station on the route. Detect and measure the flow rate of the flow and finally adjust the flow rate of the low priority flow using a control theory approach so that the high priority flow is held at its desired level Control and measure the flow rate of other high-priority flows at each node radio station on the route of one high-priority flow when multiple high-priority flows exist and interfere with each other However, a flow rate control algorithm for controlling the flow rate of each high priority flow so as to be held fairly is required. This detection and measurement of the flow rate needs to be performed in the MAC layer of each node radio station involved in routing from the source radio station to the destination radio station.

  FIG. 1 shows a planar arrangement of a plurality of node radio stations 1-1 to 1-9 (generally denoted by reference numeral 1) showing the configuration of an ad hoc radio network which is a radio communication system according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of each node radio station 1 of FIG.

The wireless communication system according to this embodiment is applied to a packet communication system of an ad hoc wireless network such as a wireless LAN. Each node wireless station 1 has an omnidirectional omni pattern and a predetermined azimuth angle width. The variable beam antenna 101 that executes the control of the radiation pattern using at least the sector pattern that is included and the rotating sector pattern that scans while rotating the sector pattern is provided, and the following processing is executed.
(I) A beacon signal including its own station ID is transmitted by broadcast using an omni pattern to each node radio station 1 in its service area.
(Ii) receiving the beacon signal using a rotating sector pattern, and detecting the azimuth angle, signal strength level, and node radio station ID (that is, transmitting station ID) of the beacon signal, thereby the plurality of node radio stations The azimuth angle and signal strength level for each node radio station 1 in the service area of 1 is an azimuth and signal strength level table (hereinafter referred to as an AS table. AS is an abbreviation for Angle-Signal Strength). Is stored in the database memory 154.
(Iii) When transmitting the packet signal to the destination wireless station, the packet signal is routed by transmitting the packet signal to the destination wireless station using the sector pattern of the azimuth angle indicated by the AS table.
(Iv) RTS packet signal (hereinafter referred to as RTS) having the signal format shown in FIG. 4 (a) using the basic communication procedure of RTS (Request To Send) / CTS (Clear To Send) signal according to the prior art as a base. By using the CTS packet signal (hereinafter referred to as CTS signal) having the signal format shown in FIG. The signal processing is executed.

(A) Each node radio station 1 handling a high priority flow among a plurality of packet flows is an RTS signal or a CTS signal of a high priority flow different from the high priority flow handled by each node radio station 1. When a packet signal is received, the packet injection interval (Packet Injection Interval: PII) of the different high priority flow is acquired from the received packet signal (see FIGS. 4A and 4B), and the database memory The PAI table in the database memory 154 is calculated by using the equation (5) and calculating the packet arrival interval (PAI) of the packet signal of the different high priority flow. (Step S51 in FIG. 21). The node radio stations that handle the high priority flow and other than the source radio station of the high priority flow can obtain the obtained packet injection interval (PII) and the calculated packet arrival interval (PAI). Are propagated back to the high-priority flow source radio station using the CTS signal (step S54 in FIG. 21 or step S59 in FIG. 22). The high-priority flow source radio station transmits the packet injection interval (PII) of another high-priority flow acquired by this source radio station and the packet injection interval (PII) back-propagated from other node radio stations. ) And the packet arrival interval (PAI) of other high-priority flows calculated by this source radio station, and the average value of the packet injection interval (Propagated Average Packet Injection Interval: PAPIII) The average value of the packet arrival interval (Propagated Average Packet Arrival Interval: PAPAI), which is a weighted average with the packet arrival interval (PAI) back-propagated from other node radio stations, is calculated, and this source radio of the high priority flow The average value of the current packet injection interval (PII) by the station and the average value of the calculated packet injection intervals (PAPII), and the average of the calculated packet arrival intervals. The error from the value (PAPAI) is calculated using Equation (15), and the packet injection interval of the high priority flow is controlled using the proportional control method of Equation (16) based on the calculated error. A packet signal of a priority flow is transmitted (step S53 in FIG. 21 or step S58 in FIG. 22).
(B) When each node radio station 1 that handles a low priority flow among a plurality of packet flows receives a packet signal of a high priority flow, a packet injection interval of the high priority flow from the received packet signal ( PII) (see FIGS. 4 (a) and 4 (b)) and stored in the PII table in the database memory 154, and using the equation (5), the packet of the packet signal of the high priority flow The arrival interval (PAI) is calculated and stored in the PAI table in the database memory 154 (step S36 in FIG. 20), and the deviation between the acquired packet injection interval (PII) and the calculated packet arrival interval (PAI) Calculate (MDII). A node radio station that handles a low priority flow and that is not the source radio station of the low priority flow transmits the calculated deviation (MDII) using the CTS signal. Back propagation is performed toward the original radio station (step S39 or S44 in FIG. 20). The low-priority flow source radio station has a maximum deviation that is the maximum value of the deviation (MDII) calculated by this source radio station and the deviation (MDII) back-propagated from other node radio stations. (PMDII) and control the packet injection interval of the low priority flow using the proportional, integral and derivative (PID) control method of Equation (14) based on the calculated maximum deviation (PMDII) The low priority flow packet signal is transmitted (step S38 or S43 in FIG. 20).

  In the radio communication system according to this embodiment, as shown in FIG. 1, a plurality of node radio stations 1 are present in a plane and each node radio station 1 has a gain and transmission power of the variable beam antenna 101, respectively. And a predetermined service area determined by parameters such as reception sensitivity, packet communication can be performed within this service area, and when performing packet communication with the node radio station 1 outside the service area, The packet data is transmitted to the desired destination radio station 1 by relaying the packet data using the node radio station 1 as a relay station. That is, each node radio station 1 includes a router device that performs packet routing, and operates as a transmission terminal, a relay station, or a destination terminal.

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

  Transmission signal data for communication in packet format generated according to 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, and the modulator 143 has a predetermined radio frequency. The carrier wave signal is subjected to spread spectrum modulation in accordance with the input communication transmission signal data using a predetermined communication channel spreading code generated by the spread code generator 160 by the CDMA method, and the modulated transmission signal is transmitted at a high frequency. Output to the machine 144. The high-frequency transmitter 144 performs processing such as amplification on the input transmission signal, and then transmits the signal from the variable beam antenna 101 to another node radio 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 variable directivity antenna includes a plurality of antenna elements and a radiation pattern control unit 103 that controls the directivity thereof. A feeding element to which a signal is fed, a plurality of non-feeding elements which are provided at a predetermined interval from the feeding element and to which no radio signal is fed, and a variable reactance element connected to each of the non-feeding elements It is possible to use a so-called electronically controlled waveguide array antenna device disclosed in Patent Document 2, which includes an array antenna and changes the directivity characteristic of the array antenna by changing the reactance value of each variable reactance element. it can. In the present embodiment, the variable beam antenna 101 can change the direction of the main beam having a predetermined beam width, for example, by electrical control at a predetermined scanning interval, and selectively sets the following radiation patterns. Works.

(I) Omnidirectional omni pattern.
(Ii) A sector pattern having a predetermined azimuth angle width.
(Iii) A rotating sector pattern in which the sector pattern is scanned while rotating every predetermined azimuth angle (for example, 30 degrees).
(Iv) An adaptive control pattern in which the main beam of the variable beam antenna 101 is directed toward the desired wave and the null is directed toward the interference wave using an adaptive control method such as a known steepest gradient method.

  The variable beam antenna 101 may be a known phased array antenna device, for example.

  The traffic monitor unit 105 includes a management control unit 151, a search engine 152, an update engine 153, and a database memory 154. The traffic monitor unit 105 executes packet transmission / reception control processing, which will be described later, and the node radio station 1 performs other node radio stations. 1 determines the communication channel to be used in the packet communication with 1 and sends the specified data of the spreading code corresponding to the determined communication channel to the spreading code generator 160 via the line control unit 106. 160 is controlled to generate a spreading code corresponding to the designated data, and the designated data of the time slot corresponding to the determined communication channel is sent to the transmission timing control unit 141 via the line control unit 106, so that transmission is performed. The timing control unit 141 uses the transmission buffer memory 142 to Controls to transmit signals for a communication channel by controlling the writing and reading of the transmitted signal data channel is transmitted in the corresponding time slot.

  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 azimuth and signal intensity level table (AS table), a packet arrival interval table (PAI table), and a packet injection interval table (PII table).

  As shown in FIG. 12, 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 its own station, and packet transmission / reception control described later. Created and updated by processing. Further, as shown in FIG. 13, the PAI table stored in the database memory 154 includes a plurality of different high-priority flow packet arrival intervals PAI corresponding to each of a plurality of azimuth angles defined in the wireless station 1. Is stored. As shown in FIG. 14, the PII table stored in the database memory 154 stores the packet injection interval PII of the high priority flow corresponding to each of a plurality of different high priority flow communication IDs.

  The ad hoc wireless network according to the present embodiment is a packet communication system, and packet data used in the packet communication system has a general format shown in FIG. That is, the packet data includes a destination ID, a packet type (beacon, RTS, CTS, DATA, ACK, etc.), an ID of the own station, and data (including data in an upper layer). In this embodiment, a special format RTS signal as shown in FIG. 4A and a special format CTS signal as shown in FIG. 4B are used.

  As shown in FIG. 4A, the RTS signal includes a receiving station ID field, a packet type field, a transmitting station ID field, a communication ID field, a priority level field, a PII field, and a data field to be transmitted. Here, the communication ID field is added to indicate the communication ID of the flow to which the packet belongs, and the priority level field is the priority level of the flow to which the packet belongs (ie, high priority flow or low priority). The PII field is added to indicate the current packet injection interval of the flow to which the packet belongs. The communication ID field, priority level field, and PII field in the RTS signal are required to notify the neighboring node radio stations of the priority level of the ongoing communication and the current packet injection interval.

  As shown in FIG. 4B, when the CTS signal is a high priority flow CTS signal, the receiving station ID field, the packet type field, the transmitting station ID field, the communication ID field, the priority, It includes a level field (high priority flow or low priority flow), a PII field, a PAPAI and PAPII field, and a field of data to be transmitted. The data in the receiving station ID field of the CTS signal is the same as the data in the transmitting station ID field of the RTS signal, and the data in the transmitting station ID field of the CTS signal is the same as the data in the receiving station ID field of the RTS signal. The same. As in the case of the RTS signal, the communication ID field, priority level field, and PII field in the CTS signal are necessary for notifying the neighboring node radio stations of the priority level of the ongoing communication and the current packet injection interval. It is said. The PAPAI and PAPII fields are data based on PAI and PII of packet signals belonging to other high priority flows in the vicinity of the route of the high priority flow to which the CTS signal belongs, respectively. This means that the high-priority flows are repeatedly and adaptively adjusted so that multiple high-priority flows protect each other's flow rate and maximize the medium to achieve a common flow rate. Show that you can. When the CTS signal is a low priority flow CTS signal, a PMDII field is included instead of the PAPAI and PAPII fields. The PMDII field includes a deviation of a packet arrival interval (PAI) from a packet injection interval (PII) related to a packet signal belonging to another high priority flow in the vicinity of the route of the low priority flow to which the CTS signal belongs. . This error information about the flow rate of the high priority flow sensed by the intermediate node radio station on the route of the low priority flow is back-propagated towards the source radio station of the low priority flow, Acts as feedback to the originating radio station of the low priority flow. This maximizes the opportunity for each node radio station transmitting packet signals of high priority flows to access the medium and keeps the expected packet arrival intervals of those high priority flows. The low-priority flow can repeatedly and adaptively adjust its flow rate. Details of the RTS signal and CTS signal transmission / reception processing will be described later.

  Next, the MAC communication protocol used in the ad hoc wireless network according to the present embodiment will be described below. In the ad hoc wireless network according to the present embodiment, it is assumed that a set of node wireless stations 1 that perform wireless communication with each other move around in a two-dimensional closed space and share a common wireless communication channel. Each node 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 node radio station 1 can execute transmission or reception at a time, but a single node radio station 1 cannot perform a plurality of transmissions / receptions.

  According to the IEEE802.11 MAC protocol standard, high-reliability data communication is guaranteed by using the RTS / CTS / DATA / ACK access control method, but the method according to the present embodiment is based on this access control method. As described above, a phase for forming the AS table is added together with an additional command signal and a response signal. Therefore, data communication is performed between periodic AS table generation 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.

  FIG. 17 shows a usage example of the antenna mode of the four-way handshake according to the present embodiment. An adaptive control pattern can track a moving terminal, but beams and nulls cannot be formed unless a packet signal is received. Therefore, an omni pattern and a sector pattern are used at the start of RTS transmission and RTS / CTS reception. Furthermore, since the waiting node radio station 1 does not recognize from which direction the directional RTS signal arrives, a rotating sector pattern is used. It should be noted that the transmission time of the RTS signal in the case of the AS table according to the present embodiment is twice the transmission time of the RTS signal in the SINR table used in the conventional MAC protocol disclosed in Patent Document 1. Further, the beam direction of the sector pattern in the transmission of the RTS signal and the reception of the CTS signal can be obtained from the AS table of FIG.

  Next, the control pattern of FIG. 17 which is a timing chart showing the types of radiation patterns and radio communication protocols at each node radio station used in the ad hoc radio network of FIG. 1 will be described in detail below. First, an RTS signal transmission source radio station transmits an RTS signal to the reception side radio station using a sector pattern in which a beam is directed to the RTS signal reception side radio station indicated by the AS table. When the RTS signal is received using the rotating sector pattern and the node radio station ID in the RTS signal is detected, the azimuth and signal strength level table is shown based on the node radio station ID of the source radio station. The RTS signal is received by changing to the adaptive control pattern through the sector pattern in which the beam is directed to the transmission source radio station. Next, the receiving radio station continuously transmits the CTS signal to the transmission source radio station using the adaptive control pattern, while the transmission source radio station receives the CTS signal by changing the sector pattern to the adaptive control pattern. This establishes a wireless link with the receiving wireless station. Thereafter, both the transmission source radio station and the reception side radio station perform transmission / reception of the data signal and the ACK signal using the adaptive control pattern. That is, the transmission source radio station transmits a data signal using the adaptive control pattern, while the reception-side radio station receives the transmitted data signal using the adaptive control pattern. Next, the receiving radio station transmits an ACK signal to the source radio station using an adaptive control pattern as a confirmation signal that the data signal has been received, while the source radio station adaptively controls this ACK signal. Receive using pattern.

  In the control pattern according to the present embodiment shown in FIG. 17, the radiation pattern of the antenna changed from the reception of the RTS signal to the adaptive control pattern is used in the receiving radio station and the transmission source radio station. Instead of using the adaptive control pattern, only the sector pattern may be used.

  In the MAC protocol according to the present embodiment using the AS table of FIG. 12, each node radio station 1 periodically executes the following steps.

(I) The node radio stations 1-n adjacent to the node radio stations 1-i, 1-j, 1-k always stand by in a reception mode using a rotating sector pattern. When the rotating sector pattern is used, the node radio station 1-n controls the variable beam antenna 101, changes the beam in all directions so that the beam is sequentially directed in each direction, and receives a signal every time the beam direction is changed. To detect. In this embodiment, 12 sector patterns having a beam width of 30 degrees and adjacent to each other in a horizontal plane are sequentially used to scan all azimuth angles over 360 degrees.
(Ii) Whenever a radio channel is available, each node radio station 1 transmits a beacon signal to nearby node radio stations using an omni pattern. In the method using the MAC protocol according to the present embodiment, two packet signals are sequentially transmitted as beacons as shown in FIG. The first packet signal of the beacon assists a node radio station receiving using the rotating sector pattern to detect whether a beacon signal is being transmitted. Next, the node radio station that receives the beacon receives and decodes the second packet signal of the beacon. The second packet signal of the beacon includes the node radio station ID. Here, the time for each node radio station waiting while rotating the sector pattern to rotate the sector pattern in all 12 directions needs to be set shorter than the duration of one packet signal which is a beacon signal. is there.
(Iii) In the rotating sector pattern, the first packet of a beacon from another node radio station 1-i in one sector pattern of the rotating sector pattern while the node radio station 1-n rotates its antenna pattern When the signal is detected, the node radio station 1-n stops rotating in the sector pattern when the first packet signal is detected, and receives the second packet signal of the beacon from the node radio station 1-i. When the node radio station 1-n measures the signal strength level of the second packet signal and decodes the node radio station ID of the node radio station 1-i, the sector pattern of the first packet signal is detected. Let the azimuth be the azimuth of the adjacent node radio station 1-i that transmitted the beacon signal.
(Iv) The node radio station 1-n writes the detected information in the entry of the node radio station 1-i in the AS table of the node radio station 1-n. In FIG. 12, the azimuth angle ANGLE n, i (t) is set on the node radio station 1-n when the node radio station 1-n receives a beacon signal from the node radio station 1-i at time t. Is the azimuth angle of the beam direction toward the node radio station 1-i, and SIGNAL n, i (t) is the node radio when the sector pattern is set in the node radio station 1-n. This is the signal level of the beacon signal received from the station 1-i.
(V) The node radio station 1-n sequentially receives the beacon signals from the node radio stations 1-i, 1-j, 1-k, thereby causing the node radio station 1-n in the AS table of the node radio station 1-n. The entire entries of i, 1-j, 1-k are stored cumulatively, or the contents of the entries are updated and stored.

  By the way, in the prior art protocol according to Patent Document 1, an arbitrary node radio station transmits a setup signal and starts forming an SINR table based on the setup signal. Here, the main beam azimuth of the pattern set for the variable beam antenna when the node radio station operates as a transmitter is always different from the main beam azimuth of the pattern set when operating as a receiver. For example, without previously broadcasting 12 RQ packet signals to surrounding node radio stations, by receiving the signals from the surrounding node radio stations in a rotating sector pattern, the azimuth angle at which the surrounding node radio stations are located is determined. It is not appropriate to try to predict. Therefore, it is necessary to use not only the 12 RQ packet signals based on the azimuth information but also the conversion of the azimuth information from the receiver of the setup packet signal and the 12 RQ packet signals based on the RE packet signal. Each node radio station that receives many setup packet signals and 12 RQ packet signals from all surrounding node radio stations must respond to all adjacent node radio stations via the RE packet signal. It had the problem that.

  On the other hand, in the MAC communication protocol used in the ad hoc wireless network according to the present embodiment, each AS table is created in a node wireless station that receives a beacon signal, so that a beacon signal transmitted in an omni pattern is used. By receiving the rotating sector pattern, it is possible to predict the azimuth angle at which the beacon signal arrives. The problem of the link becoming asymmetric when transmission power at each node radio station is different can be avoided by adding transmission power information to the beacon. As a result, even if there are no 12 RQ packet signals or RE packet signals, only two packet signals may be transmitted as beacon signals. Furthermore, since this beacon signal is transmitted in an omni pattern, it is sufficient for each node radio station to transmit a beacon signal only once to a nearby node radio station. In other words, each node radio station can cause all adjacent node radio stations to predict the azimuth angle at which the beacon signal is received, by transmitting only one beacon signal, and only the number of adjacent node radio stations. There is no need to transmit a beacon signal.

  Furthermore, in the proposed MAC protocol according to the present embodiment, each node radio station uses the signal strength level instead of SINR as a link quality parameter when predicting the azimuth angle of the adjacent node radio station. The MAC protocol according to the embodiment can avoid the problem of interference in the SINR table for each azimuth angle in the prior art protocol disclosed in Patent Document 1.

Each node radio station transmits a beacon signal at the same transmission interval. In this case, even if each node radio station randomly selects the transition timing of the beacon signal, if a plurality of beacon signals are transmitted at the same time, some non-directional beacon signals are generated due to a collision occurring at the receiver side. It can be lost. It should be noted that a beacon signal cannot be decoded in a reception mode with an omni pattern, but a plurality of beacon signals can be divided into sector patterns in a rotating sector pattern. Here, the probability of this collision can be further reduced by each node radio station 1 selecting a transmission interval. For example, a random timing can be selected from the window of the duration t d with respect to the reference cycle time interval t i in the wireless network system. Here, it is assumed that t d <t i holds.

  Next, a flow rate control method used in the ad hoc wireless network according to the embodiment of the present invention, that is, a method for differentiating services by controlling the packet injection rate for each different flow will be described below.

FIG. 5 is a diagram illustrating problems in the prior art. When an omni antenna is used, a low priority flow (ie, route {S 2 −N 2 −N 3 −D 2 }) is caused by route coupling. Or a flow on {S 2 -D 2 }) obstructs a high priority flow (ie, a flow on route {S 1 -N 1 -D 1 } or {S 1 -D 1 }) (or two flows). FIG. 2 is a plan view showing a case in which the wireless communication between node wireless stations is caused by using an omni antenna.

According to the embodiment of the present invention, each node radio station that transmits a low priority flow packet signal detects a high priority flow and measures its flow rate. It is necessary to perform this in the MAC layer of each node radio station involved in routing from the flow source radio station to the destination radio station. Specifically, a node radio station (for example, node radio stations S 2 , N 2 , N 3 , and D 2 in FIG. 5) that transmits a low priority flow packet signal is a node radio that transmits a high priority flow packet signal. Each of the low-priority flow packet signals is transmitted by recording the reception interval of continuous RTS signals and / or CTS signals from the stations (for example, node radio stations S 1 , N 1 , D 1 in FIG. 5). It becomes possible to measure the flow rate of the high priority flow in the vicinity of the node radio station. For example, in the example of FIG. 5, the node radio station N 3 receives the RTS signal from the node radio station N 1 that transmits the packet signal of the high priority flow, and measures the flow rate of the high priority flow at each time. be able to. Information of the measured flow rate is back propagation to node radio station S 2 is the source wireless station of the low priority flows, the node radio station S 2 is maintained the flow rate of the high priority flow to the desired level Therefore, the control amount is determined by calculation, and the packet injection rate of the low priority flow is adaptively adjusted.

When the route {S 2 -D 2 } in FIG. 5 is a route for transmitting a packet signal of a high priority flow instead of a low priority flow, the route {S 1 -D 1 which is two high priority flows. } And the competition between each flow on {S 2 -D 2 } affects the throughput and packet rate of both high priority flows. To optimally maximize both the throughput and packet transmission rate of each flow, implement a similar adaptive flow rate control technique that attempts to achieve fairness between the flows by controlling both flows. There must be.

For example, in FIG. 5, assume that there is a low priority flow on the continuous route {S 2 −N 2 −N 3 −D 2 }. When this flow operates independently, its flow rate is fixed to a predefined value. Here, the high priority flow on the route {S 1 -N 1 -D 1 } starts operation. Assume that it is desired to keep the flow rate of this high priority flow fixed at a predefined level. However, these two routes in FIG. 5 interfere with each other because they are close enough to cause route coupling, so that the flow rate of the high priority flow causes the packet signal of the low priority flow to It decreases in the node radio stations N 1 and D 1 interfering with the node radio stations N 3 and D 2 to be handled.

  The purpose of the present inventors in constructing the flow rate control method according to the present embodiment is to detect a decrease in the flow rate of the high priority flow in the node radio station handling the packet signal of the low priority flow. The information about the detected decrease in the flow rate is back-propagated back to the low-priority flow source radio station, so that the low-priority flow source radio station The rate can be adaptively reduced to keep the flow rate of the high priority flow at its predefined value.

In executing this, both the node radio stations N 3 and D 2 are based on the route {S 1 -D from the RTS signal transmitted by the node radio station N 1 and the CTS signal transmitted by the node radio station D 1 . 1 } detect high priority flows above. The presence of this high priority flow, this was far from the high-priority flows, the source wireless station S 2 of the low priority flows remains unknown. Therefore, the node radio station D 2 transmits information that the high priority flow on the route {S 1 -D 1 } is detected to the node radio station N 3 with the assistance of the CTS signal. Node radio station N 3, when to transmit a CTS signal to the node radio station N 2, and the information for the high priority flows, itself detected, information received from the node radio station D 2 (i.e., node wireless Station D 2 , combined with the information that a high-priority flow on route {S 1 -D 1 } was detected) and redundantly considering one or more information about contention in the flow This is transmitted to the node radio station N 2 using the CTS signal. Next, the node radio station N 2 transmits the information received from the node radio station N 3 and the information acquired in the node radio station N 2 back to the node radio station S 2 using the CTS signal. Finally, the originating node radio station S 2 is a source wireless station, taking into account that there conflict in the medium of each flow, make adaptively determined to reduce the packet injection rate of the low priority flows. Therefore, the information about the contention with the high priority flow in the medium is transmitted to the source radio station S 2 of the low priority flow without requiring transmission of extra packets, and this source radio station S 2 Adaptively lower the packet injection rate for low priority flows. According to the system as described above, when there is no contention in the medium, even a low priority flow can be operated at the predefined flow rate. When a high priority flow interferes with other high priority flows, the same measurement, detection, back propagation, and control techniques are employed.

  In the flow rate control method according to the present embodiment, when a high priority flow competes with a low priority flow, a specific level of service guarantee is achieved for the flow rate to the high priority flow. To this end, this embodiment proposes a flow rate control method using an omni antenna (omni-directional antenna) and a protocol with extremely low overhead, and then uses a directional antenna to increase the overall throughput. A modified embodiment of this flow rate control scheme is proposed.

  Next, a control theoretical approach used as the principle of the flow rate control method used in the ad hoc wireless network according to the present embodiment will be described. In the specification of the present application, the number of the brackets with a corner in which the mathematical expression is input and the number of the square brackets in which the mathematical expression is input are mixed, and a series of numbers in the specification is used. The formula number is assigned to the last part of the formula using the format of “formula (1)” as the formula number.

  First, a description will be given from several preparation steps regarding a proportional-integral-derivative (PID) control method, which is a control theoretical approach related to the flow rate control method used in the present embodiment.

  FIG. 6 is a block diagram showing a configuration of a basic feedback controller device. The feedback controller generates an output u of the control signal that causes the process to perform some correction so as to drive the output signal Y, which is a measurable process variable, toward a desired value known as the set value Rp. Designed to This feedback controller device uses an actuator (not shown) to affect the process and uses a sensor (not shown) to measure the result.

  In FIG. 6, the feedback controller device includes a subtracter 10, a controller 11 that is a PID controller, and a plant device 12 to be controlled. The reducer 10 subtracts the actual output signal Y output from the plant device 12 from the input desired set value signal Rp, and outputs a tracking error signal e which is a difference signal of the subtraction result to the controller 11. The controller 11 generates a control signal u for control using a predetermined control method based on the input tracking error signal e and outputs the control signal u to the plant apparatus 12. The operation of the plant apparatus 12 is controlled based on the input control signal u, and the output signal Y from the plant apparatus 12 at that time is output to the subtracter 10 and also output to an external apparatus.

  As described above, in the feedback controller device of FIG. 6, the controller 11 observes the error signal e between the set value signal (Rp) and the measured value of the output signal (Y) as a process variable, and outputs the error signal e. A control signal u is determined. The error signal e is generated when a process disturbance or load changes the process variable. The role of the feedback controller device in FIG. 6 is to automatically eliminate the error signal e to zero ( For example, refer nonpatent literature 13.).

  The initial feedback controller used the concept of operations of proportional control, integral control, and differential control (PID control) explicitly or implicitly in its control configuration. Here, PID control was strictly theoretically considered in a study on ship steering by MY NORKEY that was announced in 1922 (see Non-Patent Document 14). The PID controller is still the most widely used control configuration in modern industrial processes (see, for example, Non-Patent Document 15).

  The general form of the PID control algorithm is expressed by the following equation.

The PID controller 11 calculates both the differentiation and integration of the tracking error signal e based on the tracking error signal e calculated and input by the subtracter 10 and generates a control signal u in the form of the expression (1). Output. The control signal u immediately after being output from the controller 11 is “proportional gain constant (k p )” × “magnitude of error signal”, “integral gain constant (k i )” × “error signal Equal to the sum of integral (ie, definite or indefinite integral over a given time interval) + “differential gain constant (k d )” × “derivative of error signal (ie, derivative or derivative at a given time)” .

The proportional gain constant (k p ) has the effect of shortening the rise time and reduces, although not completely removing the steady state error. Integral gain constant (k i) is has the effect of removing the steady state error, it may worsen the transient response. The differential gain constant (k d ) has the effect of increasing system stability, reducing overshoot, and improving transient response.

  The above equation is a continuous time display of the output signal u of the controller 11, and in order to implement the feedback controller device of FIG. 6, the output signal u needs to be converted into a discrete time display. There are several ways to perform this transformation, but the simplest is to use a first-order finite difference.

When the time n expressed in the discrete time format is used, the proportional error term also includes an error e () between the reference value Rp (n) and the current measured value Y (n) of the process variable output from the plant apparatus. n). The differential term de / dt and the integral term ∫e (t) dt in the discrete time format can be replaced by the following formula, where the unit time length is Δt.

  Here, w is an integration control window. Therefore, the final form m (n) obtained by rewriting the output signal u of the equation (1) expressed in the continuous time format into the discrete time format is expressed by the following equation.

  Therefore, in order to calculate a desired output signal value, it is necessary to obtain the current error, the sum of errors, and the most recent change in error.

  Next, a flow rate control method based on priority when the PID control method described above is applied to the ad hoc wireless network of FIG. 1 will be described.

  7 to 9 are block diagrams schematically showing a flow rate control apparatus based on priority when the feedback controller of FIG. 6 is applied to the ad hoc wireless network of FIG. FIG. 7 shows a case where a single high priority flow H and a single low priority flow L exist in the ad hoc wireless network of FIG. 1 and route-couple to each other, that is, the route of these two flows is 1. Basic flow rate control in the network is schematically represented as a single flow rate control device when one or more common node radio stations are shared or are close enough to interfere with each other. It shows.

The flow rate control apparatus of FIG. 7 is configured to output a current output signal Y that is an actual flow rate of the high priority flow H obtained as a feedback signal from the set value signal Rp indicating the desired flow rate of the high priority flow H. And a subtractor 20 that outputs a tracking error signal e as a result of the subtraction, and a source radio station S L (not shown in FIG. 7) of the low-priority flow L. A low-priority flow controller (LPC) 21 that PID-controls the flow rate u of the low-priority flow L based on the input of the signal e, and a network that transmits packet signals of the high-priority flow H and the low-priority flow L And the low-priority flow L and the route coupling are respectively provided in the flow system 22 and the radio station transmitting the packet signal of the low-priority flow L. Jill measured flow rate of the high priority flow H, the flow rate, and a system 23 for back propagation toward the originating radio station S L of the low priority flows. Therefore, the flow rate of the low priority flow L controlled by the flow controller 21 corresponds to the control signal u of the controller 11 in FIG. 6, and the output signal from the flow system 22 in FIG. 7 corresponds to the output signal Y in FIG. The output signal Y is back-propagated by the system 23 and fed back to the subtracter 20.

In the case of FIG. 7, in order to keep the high priority flow H at the desired flow rate setting value Rp, the low priority flow L is set as much as possible to the output signal Y of the flow rate of the high priority flow H. as approaches rp, and a PID control method adaptively changes the control signal u is a flow rate of the low priority flows L using the originating radio station S L of the low priority flow L. Each node radio station that transmits a packet signal of the low priority flow L has the flow rate of the high priority flow H (that is, the current output signal) if the node radio stations are coupled to the high priority flow H. obtains the measured value by measuring the Y), the information of this measurement is back propagation toward the originating radio station S L for transmitting a packet signal of the low priority flows L. The means for making this measurement is conceptually shown as block M in the system 23 that backpropagates the flow rate. The backpropagation information, the source wireless station S L of the low priority flows L determines the flow rate Y of the high priority flow H, executes a control process using the PID control method. Based on the process described above, the source wireless station S L of the low priority flows L adjusts the flow rate of the low priority flows L, the process is repeated.

It should be noted that there is a significant difference between the above-described prior art PID controller and the flow rate control scheme used in the embodiments of the present invention. In the flow rate control method used in the present embodiment, when the control signal u (that is, the flow rate of the low priority flow) output from the low priority flow controller LPC is set to zero, there is no other low priority flow. If not, it can easily be seen that the flow rate Y of the high priority flow reaches the desired flow rate set value Rp. Thus, this solution does not require a controller in the conventional sense at all if only the problem of keeping the flow rate of the high priority flow at the desired value is focused. However, the purpose of the ad hoc wireless network according to the present embodiment is to maximize the flow rate setting value Rp L of the low priority flow while maintaining the flow rate setting value Rp H of the high priority flow at the desired level. There is. This is similar to the maximum-minimum (max-min) flow rate control. In this case, the flow rate control method used in this embodiment uses the flow rate setting value Rp H of the high priority flow as its value. in low priority flows in the flow rate set value Rp L as further will not be possible to increase the method without lowering than desired, by dynamically adjusting and control the value of the set value Rp L The set value Rp H is held at the desired level. This type of requirement does not exist in conventional PID control, and thus the approach according to embodiments of the present invention is novel to the prior art PID control method. This will be explained continuously.

  FIG. 8 shows a basic configuration of the ad hoc wireless network shown in FIG. 1 when a single high priority flow H and a plurality of n low priority flows L1 to Ln exist and route-couple to each other. The flow rate control is schematically shown as one flow rate control device. In the flow rate control apparatus of FIG. 8, the controller 21 is provided in each of the transmission source radio stations (not shown in FIG. 8) of the low priority flows L1 to Ln, and the tracking error input from the subtracter 20. Low-priority flow controllers LPC1 to LPCn that perform PID control of the flow rate u of the low-priority flows L1 to Ln based on the signal e are provided. In addition, the system 23 that reversely propagates the flow rate corresponds to each of the low priority flows L1 to Ln, and the high priority flow H coupled to the node radio station that transmits the packet signal of the low priority flow. Blocks M1 to Mn for measuring the flow rate are provided. In the flow rate control apparatus of FIG. 8, the other components are the same as those of the flow rate control apparatus of FIG.

  In the flow rate control device of FIG. 8, in order to maintain the flow rate of the high priority flow H at the desired flow rate setting value Rp, each of the low priority flows L1 to Ln is in its source radio station. The PID control method is used to adaptively change the flow rates of the low priority flows L1 to Ln. The node radio stations that respectively transmit the packet signals of the low priority flows L1 to Ln measure the flow rate of the high priority flow H using the blocks M1 to Mn, respectively. Back propagation is performed toward the source radio stations of the priority flows L1 to Ln. The flow rate of each low priority flow L1-Ln is adjusted based on this and the process is repeated. Each low priority flow L1 to Ln holds the flow rate of the high priority flow H using the same control method.

  FIG. 9 shows a case where a plurality of m high priority flows H1 to Hm and a plurality n low priority flows L1 to Ln exist in the ad hoc wireless network of FIG. The basic flow rate control of each low priority flow is schematically shown as one flow rate control device. In the flow rate control apparatus of FIG. 9, the system 23 for back-propagating the flow rate measures the output signals Y1 to Ym indicating the flow rates of the high-priority flows H1 to Hm, respectively, and determines the low-priority flows L1 to Ln. Back propagates toward the source radio station. Further, the flow rate control device of FIG. 9 is provided in each source radio station (not shown in FIG. 9) of the high priority flows H1 to Hm, and the high priority is based on the output signals Y1 to Ym. A high-priority flow setting value controller 24 for calculating desired setting values of the flow rates of the flows H1 to Hm is further provided. The high-priority flow controller for controlling the flow rate of each high-priority flow based on the desired setting value of the flow rate calculated by the controller 24 is transmitted from the source radio station of each high-priority flow H1 to Hm. Each has an HPC (not shown). Furthermore, in the flow rate control apparatus of FIG. 9, a predetermined initial value is initially input to the subtracter 20 as the set value signal Rp indicating the desired flow rate of the high priority flow H, and thereafter the dynamic value is dynamically changed. A set value is input, that is, a set value of the flow rate of the high priority flows H1 to Hm calculated by the set value controller 24 of the high priority flow is input. In the flow rate control device of FIG. 9, the other components are the same as those of the flow rate control device of FIG.

  When a plurality of high-priority flows exist in the network system as shown in FIG. 9, setting of a desired flow rate assigned to the high-priority flow when each of the high-priority flows exists alone The value Rp is no longer valid. This is because even when there is no low priority flow, the coupling between two or more high priority flows causes all of those high priority flows to exist alone. This is because it is not allowed to maintain the flow rate at the time of being.

  Therefore, when a plurality of high priority flows are coupled to each other, it is necessary to dynamically determine a new setting value of the flow rate for the high priority flows. For example, when a wireless communication system allows a single high priority flow to operate at a guaranteed flow rate of 50 packets per second, this same system will have two high priority routes route coupled together in the system. This same flow rate cannot be guaranteed when there is a second degree flow. In this case, the flow rate guaranteed for each high priority flow is, for example, 30 packets per second. The other low priority flows then attempt to retain this new flow rate assigned to each high priority flow at this point.

In order to dynamically change the setting value of a high priority flow in a distributed environment, each high priority flow monitors the presence of other high priority flows in its vicinity. If the high priority flow H1 detects another high priority flow H2 that is in the vicinity of it, this causes the possibility of route coupling of these two high priority flows, the flow H1 is The set value of the flow rate is changed to a newly calculated value Rnew1 . Here, R> R new1 , and the unit is the number of packets / second. Similarly, the flow H2 also detects the flow H1 and changes its set value to the value Rnew2 . If the flow H1 detects two high priority flows in the vicinity thereof, the flow H1 changes its set value to another newly calculated value Rnew3 . Here, R> R new1 > R new3 , and the unit is the number of packets / second.

  These settings may be predefined by experiment or may be calculated adaptively for optimal use of the media. In the later-described simulation according to the present embodiment, the set value is adaptively calculated by experiment.

After the set value of the flow rate of the high priority flow H1 is changed to the value Rnew1 or Rnew3 , the high priority flow H1 detects the presence of another high priority flow in the vicinity for the specified time period. Otherwise, the set value of the flow rate of the high priority flow H1 is returned to the original value R.

The low-priority flow measures the flow rate of the high-priority flow in the vicinity thereof, and acquires the set value of the flow rate of the high-priority flow. The low priority flow adjusts the flow rate of the low priority flow accordingly to protect the “weakest” high priority flow. In the present specification, the “weakest” high priority flow is a high priority having a maximum error signal value e = (R new −Y) when the setting value of the high priority flow is a value R new. Degree flow. The processing of the low priority flow described above naturally guarantees the protection of other high priority flows in the vicinity. Each low priority flow uses the same control scheme to protect the high priority flow.

  Next, implementation of the flow rate control method using the directional variable beam antenna 101 will be described.

  Up to this point, with reference to FIG. 5, the case where the neighboring node radio station of each node radio station is an omnidirectional node radio station using an omnidirectional antenna device has been considered. However, as shown in FIG. 2, in order to modify the flow rate control method according to the present embodiment so as to be adapted to an ad hoc wireless network using the directional variable beam antenna 101, the directional MAC and directivity It is necessary to consider a nearby node radio station equipped with an antenna device.

  In Non-Patent Documents 16 and 17, the present inventors have implemented a directional MAC protocol based on a rotating sector on the receiver side, and a node radio station using this protocol tracks the position of its neighboring node radio stations. Showed that it can. Accordingly, each node radio station 1-n that implements this directional MAC protocol recognizes its neighboring node radio station 1-m (m ≠ n) along with the direction in which the neighboring node radio station 1-m is located, This information is recorded in the azimuth and signal strength table (AS table) stored in the database memory 154 in each node radio station 1-n. In this conventional example, the RTS signal and the CTS signal are transmitted using an omnidirectional antenna pattern, whereas the data packet signal and the ACK packet signal are transmitted using a directional antenna pattern. The use of a directional variable beam antenna 101 in an ad hoc wireless network can significantly reduce radio interference, thus improving the utilization of the wireless medium (see Non-Patent Documents 8, 16 and 17). . This characteristic of the directional variable beam antenna 101 is used to improve the efficiency of the protocol of the flow rate control scheme according to the embodiment of the present invention.

FIG. 10 schematically shows wireless communication when the above-described directional variable beam antenna 101 is used. When the variable beam antenna 101 is used with a sector pattern set, the route {S 2 − of FIG. FIG. 6 is a plan view showing that a low priority flow on D 2 } can exist simultaneously with a high priority flow on route {S 1 -D 1 }. In the situation of FIG. 10, the variable beam antenna 101 is provided at each of the node radio stations S 1 , N 1 , D 1 , S 2 , N 2 , N 3 , D 2 , so that the route {S 1 -D 1 in FIG. } And {S 2 −D 2 } can coexist without interfering with each other without high priority flows and low priority flows. If an omni pattern is used (FIG. 5), such coexistence would not be possible. Therefore, when the directional variable beam antenna 101 is used, a low priority flow on the route {S 2 -D 2 } is present even if a high priority flow exists on the route {S 1 -D 1 }. It is not necessary to control the packet injection rate of the low priority flow.

  Using a directional variable beam antenna 101, contention of contention in the medium is meant in the sense that even if traffic flows of different priority levels exist nearby, only contention for communication in the direction of the desired flow is considered. Detection also becomes “directional” (ie, detects competition at a given azimuth). According to the directional MAC protocol, the AS table of each node wireless station is examined to detect a competition at a predetermined azimuth angle in the medium. Since the directional variable beam antenna 101 increases the efficiency of SDMA (spatial division multiple access), this increases the packet injection rate of low priority flows while minimizing interference to other flows in the medium. Thus, the throughput of high priority and low priority traffic flows is consequently increased. At the same time, the opportunity for multiple high priority flows to route couple to each other is reduced and the performance of high priority flows is improved.

  Next, a process of detecting a certain high priority flow by another flow and measuring the flow rate of the high priority flow in the flow rate control method according to the present embodiment will be described.

  When transmission of a packet signal related to a certain flow is started, the packet signal is transmitted through a plurality of hops (node radio stations) and in the MAC layer, and packet transmission in each intermediate node radio station is an RTS signal, Confirmed by exchange of CTS signal, DATA signal and ACK signal. In this embodiment, the RTS signal and the CTS signal detect information related to the high priority flow, and the information related to the high priority flow is transmitted from both the low priority flow and the high priority flow. The low-priority flow and high-priority flow source radio stations make decisions regarding packet injection rate control based on information related to the back-propagated flows. I will give you.

As shown in FIG. 10, the low priority flow interferes with the high priority flow only when the flow directions of both the low priority flow and the high priority flow overlap. In FIG. 10, the node radio stations N 1 and N 3 exist within the transmission range when the antenna pattern of the omni pattern is used, but if each node radio station uses a directional antenna pattern, the node radio stations N 1 and N 3 The flow from the radio station N 1 to the node radio station D 1 does not interfere with the flow from the node radio station N 3 to the node radio station D 2 . In order to guarantee this, each node radio station in the low-priority flow has a transmission zone formed in the direction of the low-priority flow by the variable beam antenna 101 of the node radio station. It is essential to detect whether or not a node radio station transmitting a signal is included. If the transmission zone includes such a node radio station (ie if there is interference), this implies that the low priority flow interferes with the high priority flow, and necessarily low priority. It is necessary to control the flow rate of the flow to protect the flow rate of the high priority flow.

  Hereinafter, a mechanism will be formulated in which an arbitrary node radio station 1-n detects a high priority flow and measures its flow rate. For this purpose, first, some parameters are defined.

<Definition 1> When the node radio station 1-n uses the variable beam antenna 101 to form a transmission beam having a azimuth angle α and a beam width (angle) β and a transmission range (transmission radius) Z, The effective reach in the azimuth angle α of 1-n is defined as the transmission zone TZn (α, β, Z) of the node radio station 1-n. FIG. 11 shows the transmission zone TZn (α, β, Z). This means that when the node radio station 1-m is in the transmission zone TZn (α, β, Z) and the node radio station 1-m is in the reception mode, the node radio station 1-n Whenever a message is transmitted with transmission azimuth α, beam width β and transmission range Z for station 1-n, it implies that this message is received by node radio station 1-m. When the node radio station 1-m moves out of the transmission zone TZn (α, β, Z), the connection between the node radio station 1-n and the node radio station 1-m is lost. In the following exemplary discussion, since the transmission beam width β and the transmission range Z are constant, the transmission zone TZn (α, β, Z) is expressed as a transmission zone TZn (α).

<Definition 2> The RTS signal reception time RRT Hi, α, n (t) is determined from the node wireless station 1 to the node wireless station 1-n from any node wireless station handling the high priority flow Hi at that time. It is defined as a time t at which an RTS signal is received at an azimuth angle α with respect to −n.

<Definition 3> The packet arrival interval PAI Hi, α, n (t) is measured by two consecutive RSTs from the node radio station handling the high priority flow Hi measured at the node radio station 1-n at time t. It is defined as the interval of time (RRT) when the signal is received at the azimuth angle α with respect to the node radio station 1-n. This is because the flow rate of a high priority flow in the vicinity thereof (that is, the number of packets per unit time: 1 / PAI Hi, α, n (t)) is used to measure. From this definition, the following equation holds.

[Equation 1]
PAI Hi, α, n (t)
= RRT Hi, α, n (t) −RRT Hi, α, n (t previous )
(5)

Here, the previous reception time tprevious of the RTS signal from the high priority flow Hi satisfies t−Δt < tprevious ≦ t. Δt is a constant indicating a time period introduced in order to ensure that the continuity of two RTS signals arriving at the node radio station 1-n is valid. For example, if the node radio station 1-n fails to receive the RTS signal due to random channel error, collision or mobility, the node radio station 1-n may erroneously calculate the flow rate. The constant Δt needs to be introduced in order to cope with such a situation, and when the previous reception time t previous is earlier than the time period Δt, the calculation of Expression (5) is not executed.

  In the case of a high priority flow destination radio station that does not issue an RTS signal, a node radio station in the vicinity of this destination radio station calculates the flow rate of the high priority flow in the destination radio station in the vicinity. The node radio station monitors the reception time of the CTS signal transmitted from the destination radio station.

<Definition 4> PAIT n (t) is defined as a packet arrival interval table (PAI table) at the time t in the node radio station 1-n, and this PAI table has each direction as shown in FIG. For each angle α, PAI Hi, α, n (t) of each high priority flow Hi is stored.

<Definition 5> The packet injection interval PII Hi (t) is defined as the time interval at which the source radio station of the high priority flow Hi injects a packet signal at that time. This is obtained from the PII field of the RTS signal that belongs to the high priority flow and carries information on the current packet injection interval of the high priority flow. PII Hi (t) is considered valid if this PII Hi (t) is obtained from the RTS signal received within the time interval [t, t−Δt].

<Definition 6> PIIT n (t) is defined as a packet injection interval table (PII table) at time t in the node radio station 1-n, and this PII table is a node radio as shown in FIG. A set of the current packet injection interval PII Hi (t) of the high priority flow in the vicinity of the station 1-n and the communication ID of the high priority flow is stored.

  Thus, a low priority flow or a high priority flow (eg, F) handled by the node radio station 1-n causes a conflict with another high priority flow (eg, H). Is dependent on the transmission direction or transmission zone in the node radio station 1-n of the flow F and the communication of the high priority flow H that is in progress in the transmission zone. Here, it is assumed that the flow F in the node radio station 1-n communicates with the next hop (node radio station) using the transmission zone TZn (γ) for the node radio station 1-n. In other words, the azimuth angle γ of the transmission zone TZn (γ) is the direction of the flow F at the node radio station 1-n at time t. Whether or not this flow F in the node radio station 1-n causes a conflict with an arbitrary high priority flow in the vicinity thereof is determined in the entry of the azimuth angle γ in the PAI table of the node radio station 1-n. Dependent. More precisely, if the PAI of any high priority flow having an entry of azimuth angle γ in the PAI table of the node radio station 1-n has a deviation from the PII of that high priority flow, this means that This indicates that the high priority flow is affected by the competition caused by the flow F. The PII value of the high priority flow is acquired from the PII table of the node radio station 1-n.

  Next, information related to a certain high-priority flow is detected by another high-priority flow or low-priority flow that is different from the high-priority flow, and is directed to the source radio station of those different flows. The reverse propagation process will be described. When one low priority flow is route coupled with multiple high priority flows, the low priority flow attempts to maintain the flow rate of the high priority flow. If route coupling occurs between two high priority flows, these flows will try to converge their flow rate to the new setting and keep each other's flow rate at the new setting. . As described above, the target is different between the flow rate control of the low priority flow and the flow rate control of the high priority flow. Therefore, the method of back propagation and packet injection rate control of information related to the high priority flow is different between the low priority flow and the high priority flow.

  Here, first, a method of back-propagating information related to the high priority flow detected on the low priority flow toward the source wireless station of the low priority flow will be described.

The low priority flow attempts to improve the flow rate of the high priority flow that is most affected by the competition. The high-priority flow that is most affected by competition refers to the high-priority flow that has the largest PAI deviation from its PII. Therefore, in a certain node radio station 1-n, the azimuth angle γ is the direction of the low priority flow Li, and the entry of the azimuth angle γ in the PAI table of the node radio station 1-n is {<PAI Hj1, γ, n If any PAI for a high-priority flow such as (t) >><PAI Hj2, γ, n (t)>...} Is included, the maximum deviation in injection interval at time t in the node radio station 1-n. The value MDII (n, γ, t) is calculated according to the following equation:

[Equation 2]
MDII (n, γ, t)
= MAX {<PAI Hj1, γ, n (t) −PII Hj1 (t)>
<PAI Hj2, γ, n (t) -PII Hj2 (t)> ...} (6)

Here, MAX {<a><b>...} Indicates the maximum value among the arguments <a>, <b>,. If MDII (n, γ, t) = <PAI Hjk, γ, n (t) −PII Hjk (t)>, then the flow Hjk is the highest priority flow that is most affected by competition. The value of MDII (n, γ, t) is the maximum value of the error in the flow rate of the high priority flow, and the flow rate of the high priority flow Hjk is maintained by adjusting the flow rate of the low priority flow Li. In order to do so, it needs to be propagated back toward the source radio station of the flow Li. Since the maximum of these PAI values from their corresponding PII values represents the highest priority flow that is most affected by competition, MDII (n, γ, t) is low priority. It should be noted that it assists in identifying the highest priority flow that is most affected by contention by the node radio station that transmits the packet signal of the higher flow. Thus, a low priority flow will iteratively adjust the flow rate of the low priority flow to maintain the flow rate of this high priority flow, which in turn results in other high priority flows. The flow rate of the flow is also automatically maintained.

  Next, a technique for measuring the dispersion of the flow rate of the high priority flow by the source radio station of the low priority flow will be described. FIG. 15 shows the maximum value of the high-priority flow packet injection interval in the vicinity of the low-priority flow detected in each node radio station that transmits the packet signal of the low-priority flow. It is a figure which shows roughly the process made to propagate back toward the former radio station.

If the route {S → N 1 ... → N k−1 → N k → N k + 1 →... → D} is a route from the source radio station to the destination radio station of the low priority flow, each node radio station , MDII (N k , γ k , t) is used to independently measure the maximum value of the flow rate deviation of the high priority flow. Here, the azimuth angle γ k depends on the direction of the low priority flow in each node radio station N k . The perceived maximum flow rate deviation of the high priority flow may be different for each node radio station of the low priority flow. However, in order to execute the flow rate control of the low-priority flow, the source wireless station of the low-priority flow uses the flow rate bottleneck information in the high-priority flow, that is, the node radio stations S, N 1 , .., N k−1 , N k , N k + 1 ,..., D need to be recognized for the maximum value among all deviation values related to the flow rate of the high priority flow. In other words, the source wireless station S, the total node radio station S, N 1, ..., N k-1, N k, N k + 1, ..., at D, in the direction of the low priority flows MDII (N k, It is necessary to know the maximum value of γ k , t).

  To simplify the discussion, we have considered the case where the node radio station handles only one low priority flow. However, one node radio station may be involved in multiple low priority flows. Therefore, it is necessary to associate MDII with a flow communication ID and a flow direction indicated by the communication ID, not with an absolute value of an arbitrary azimuth angle γ. Therefore, the definition of MDII is changed to the following definition 7.

<Definition 7> The maximum value DMDII (N k ) Li (t) of the deviation of the injection interval detected by the node radio station N k that transmits the packet signal of the low priority flow Li at time t is set as the node radio station N k. And defined as the maximum value of the deviation of the PAI of the high priority flow from the PII of the high priority flow detected in the direction of the low priority flow Li. Therefore, if the azimuth angle γ is the direction of the flow Li at the time t in the node radio station N k , the following equation holds.

[Equation 3]
DMDII (N k ) Li (t)
= MAX {<PAI Hj1, γ, Nk (t) −PII Hj1 (t)>
<PAI Hj2, γ, Nk (t) -PII Hj2 (t)> ...} (7)

DMDII (N k ) Li (t) in Definition 7 represents the locally detected high priority flow MDII detected locally as shown in block (a) of FIG. Represents. The following parameters are then defined:

<Definition 8> The maximum value PMDII (N k ) Li (t) of the propagated injection interval deviation is back-propagated by the node radio station N k + 1 →. This is a deviation value from the packet injection interval of the packet arrival interval of the high priority flow propagated from k + 1 to the node radio station N k . This PMDII (N k ) Li (t) is a high-priority flow that is most affected by contention from the node radio station N k + 1 to the destination radio station D, as shown in block (b) of FIG. Is the value propagated back to the node radio station Nk .

The source radio station of the low priority flow Li operates based on the maximum value of errors occurring in any high priority flow at all node radio stations in the middle of the flow Li. Accordingly, the node radio station N k propagates MAX {DMDII (N k ) Li (t), PMDII (N k ) Li (t)} toward the source radio station. Therefore, the following equation holds.

[Equation 4]
PMDII (N k-1 ) Li (t)
= MAX {DMDII ( Nk ) Li (t), PMDII ( Nk ) Li (t)}
(8)

  As shown in block (c) of FIG. 15, this is the larger of the value obtained in block (a) in FIG. 15 and the value obtained in block (b).

Here, a method of back-propagating information such as MDII between node radio stations will be described. When the node radio station N k handling the flow Li receives PMDII (N k ) Li (t) from the node radio station N k + 1 , PMDII (N k−1 ) Li (t calculated using the equation (8). ) And the communication ID of the flow Li are temporarily stored in an internal memory (not shown). When the node radio station N k receives the RTS signal from the node radio station N k-1 , the node radio station N k includes PMDII (N k-1 ) Li (t) including the same communication ID as the communication ID of the RTS signal and the communication ID. If the set is stored in the memory, PMDII (N k−1 ) Li (t) is added to the CTS signal in response to the RTS signal and transmitted (ie, propagates backward). In this way, by determining whether or not to propagate back based on the communication ID of the flow, the information necessary for flow rate control such as MDII is not transmitted from the source wireless station without knowing the source wireless station of the flow. Back-propagated towards the station. Information for executing flow rate control of a high-priority flow, which will be described later, is also reversely propagated toward the source wireless station of the high-priority flow.

As described above, the source wireless station S of the low priority flow Li finally detects and acquires the maximum value PMDII (S) Li (t) of the packet arrival interval error of the high priority flow. In the present embodiment, since the difference between the packet injection interval PII of the high priority flow and the packet arrival interval PAI is used, the same control is possible even if the PII of the high priority flow changes. The source wireless station S of the flow Li uses this PMDII (S) Li (t) to adaptively control the flow rate of the flow Li.

Next, a method of back-propagating information related to other high-priority flows detected on the high-priority flow toward the source wireless station of the high-priority flow will be described. FIG. 16 shows that when the route {S → N 1 ... → N k−1 → N k → N k + 1 →... → D} is the route from the source radio station to the destination radio station of the high priority flow, The average packet arrival interval and the average packet injection interval of other high priority flows in the vicinity of the high priority flow detected in each node radio station that transmits the packet signal of the priority flow are represented by the high priority flow. It is a figure which shows roughly the process made to propagate back toward the transmission origin radio station.

  The high priority flow not only uses the error of its packet arrival interval, but also aims to select a uniform packet injection interval for all route coupled high priority flows. Therefore, in addition to a certain high priority flow (for example, flow H1), when there is another high priority flow (for example, H2, H3,...) Route-coupled to this high priority flow, the high priority flow The average packet injection interval (PII) and average packet arrival interval (PAI) of the other detected high priority flows H2, H3,... Are calculated so that the source of H1 can calculate a new set value. It is necessary to propagate back toward the source radio station of the degree flow H1. Similarly, the other high-priority flows H2, H3,... That have been route-coupled repeat the above process to calculate their new set values, and eventually converge to a common set value. Here, the following parameters are defined.

<Definition 9> The average packet arrival interval DAPAI (N k ) Hi (t) detected at the intermediate node radio station N k of the high priority flow Hi at time t is the other high level detected in the direction of the flow Hi. It is an average value of the packet arrival intervals of the priority flow. If the direction of the high priority flow Hi is the azimuth angle γ, the following equation holds.

[Equation 5]
DAPAI (N k ) Hi (t)
= AVG {<PAI Hj1, γ, Nk (t)><PAI Hj2, γ, Nk (t)>.
(9)

  Here, AVG {<a> <b>...} Indicates an average value of the arguments <a>, <b>,. In addition, the following parameters are defined.

<Definition 10> The average packet injection interval DAPIII (N k ) Hi (t) detected at the intermediate node radio station N k of the high priority flow Hi at time t is the other high detected in the direction of the flow Hi. This is the average value of the priority injection packet injection intervals.

Definitions 9 and 10 represent the average PAI and average PII of the high priority flows locally detected at the node radio station Nk , as shown in block (a) of FIG. In addition, the following parameters are defined:

<Definition 11> The propagated average packet arrival interval PAPAI (N k ) Hi (t) is measured by the node radio station N k + 1 →... → D of the high priority flow Hi, and the node radio station N k + 1 to the node radio It is the average value of the PAI of the high priority flow propagated to the station Nk .
<Definition 12> propagated average packet injection interval PAPII (N k) Hi (t ) is measured by the high priority flow H i of the node radio station N k + 1 → ... → D , node from the node radio station N k + 1 It is the average value of the PII of the high priority flow propagated to the radio station Nk .

Definitions 11 and 12 show that, as shown in block (b) of FIG. 16, the average PAI and average PII of all high priority flows detected from the node radio station N k + 1 to the destination radio station D are It represents the value back-propagated towards the radio station Nk . Therefore, the following equation holds.

[Equation 6]
PAPAI (N k-1 ) Hi (t)
= AVG {DAPAI (N k ) Hi (t), PAPAI (N k ) Hi (t)}
(10)
[Equation 7]
PAPIII (N k-1 ) Hi (t)
= AVG {DAPIII ( Nk ) Hi (t), PAPIII ( Nk ) Hi (t)}
(11)

PAPAI (N k-1 ) Hi (t) and PAPII (N k-1 ) Hi (t) were obtained in block (a) of FIG. 16, as shown in block (c) of FIG. The average value of the value and the value obtained in block (b). Specifically, these values are an average value of the PAI, and PII obtained, and the resulting PAI and PII at the node radio station N k-1 at the node radio station N k to D, node wireless station N It is an average value (weighted average value) calculated by weighting so that PAI and PII obtained at a node radio station close to k−1 are more important.

Thus, PAPAI (S) Hi (t) and PAPII (S) Hi (t) are respectively the average packet arrival interval and average of all other high priority flows route-coupled to the high priority flow Hi. It is a value indicating the packet injection interval, and is finally a value detected by the source wireless station S of the high priority flow Hi. Specifically, these values are average values (weighted average values) calculated by weighting so that the PAI and PII obtained at the node radio station close to the source radio station S are more important. The source radio station S of the high priority flow Hi uses this information to adaptively control the flow rate of the high priority flow Hi.

  Next, feedback control executed in the source wireless station of each flow will be described. In the following discussion, the packet injection interval (PII) at the source radio station is considered as a reference measure for flow rate control. The packet injection rate (PIR: unit, number of packets / second) of the flow at the source wireless station is calculated by the following equation.

[Equation 8]
PIR = 1 / PII (12)

  For example, if the PII at the source radio station is 20 milliseconds, PIR = 50 packets / second.

  Here, first, feedback type control in a low-priority flow source radio station will be described. Here, referring again to the description of the PID control described above, in order to make any control decision, first, an error is caused in the PID controller (corresponding to the controller 21 in FIGS. 7 to 9) provided in the source radio station. The term needs to be calculated. The following equation is used for this calculation.

[Equation 9]
"Error e sensed at its source radio station S for any low priority flow Li"
= PII-PAI = PMDII (S) Li (t) (13)

  When the error e (n) and the time interval Δt between two consecutive errors are calculated, a new packet injection interval PII of the low priority flow at the source radio station Li (S) of the low priority flow (New) is calculated as follows from the previous packet injection interval PII (old) of the low priority flow.

The values of parameters k p , k i and k d need to be adjusted to obtain optimal performance. About the performance of a controller, it shows in description of the simulation result which concerns on this embodiment below.

  Next, feedback type control in the high-priority flow source radio station will be described. In the source radio station S of the high priority flow Hi, the error is calculated by the following equation.

[Equation 10]
e
= AVG {PII Hi (t), PAPII (S) Hi (t)}
-PAPA (S) Hi (t) (15)

When this error e is calculated, proportional control is introduced to obtain the value of the new packet injection interval PII Hi (t) from the previous packet injection interval PII (old) of the high priority flow, which is the high priority. This is a new set value of the degree flow Hi. Information on this new set value is transmitted to a nearby low priority flow using the RTS signal and the CTS signal. The new PII Hi (t) = PII (new) is calculated by the following equation.

[Equation 11]
PII (new) = PII (old) −k p × e (n) (16)

Here, the parameter k p needs to be adjusted to obtain optimum performance.

  When a high-priority flow H1 detects another high-priority flow and changes its flow rate, and then detects that there is no other high-priority flow in the vicinity for a specified time period The flow rate of the high priority flow H1 is returned to its original flow rate.

  19 to 23 are flowcharts showing packet transmission / reception control processing executed by the management control unit 105 of the node radio station 1 of FIG. 2 as the flow rate control method according to the present embodiment.

  In FIG. 19, first, in step S1, the variable beam antenna 101 is controlled so as to be rotated and scanned every predetermined azimuth angle (for example, 30 degrees) with a rotating sector pattern, and a received signal is received. In step S2, a predetermined signal is received. It is determined whether or not a received signal having a signal strength level equal to or higher than the threshold value is received. If YES, the process proceeds to step S3. If NO, the process proceeds to step S8. In step S8, it is determined whether there is a packet signal to be transmitted. After performing step S12 of the PAI deletion process, the process returns to step S1. If YES in step S9, the process proceeds to step S9. If NO, it is determined whether the packet signal to be transmitted is a subroutine in FIG. 23 and is a beacon signal. If YES, the process proceeds to step S10. On the other hand, if NO, the process proceeds to step S11. After transmitting a beacon signal with an omni pattern in step S10, the process returns to step S1. On the other hand, in step S11, other signals are transmitted in the sector pattern or adaptive control pattern, that is, as shown in FIG. 13, after transmitting according to the radiation pattern corresponding to each signal, 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 and the signal strength level of the received signal is measured. In step S5, it is determined whether or not the received signal is a beacon signal. While the process proceeds to S6, the process proceeds to Step S7 when NO. In step S6, the contents of the AS table are updated based on the node radio station ID in the packet information, the detected azimuth angle, and the signal strength level, and then the process returns to step S1. On the other hand, in step S7, other signal reception processing which is a subroutine of FIGS. 20 to 22 is executed, and then the process returns to step S1.

  In the control flow of FIG. 19, 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.

  20 to 22 are flowcharts showing other signal reception processing (step S7), which is a subroutine of FIG.

  In step S31 of FIG. 20, first, it is determined whether or not an RTS signal is received from a radio station belonging to a high priority flow in the vicinity of the flow to which the own station belongs. If a radio station belonging to the high priority flow in the vicinity is a destination radio station of the high priority flow, it is determined whether a CTS signal is received from the destination radio station. When step S31 is YES, the process proceeds to step S35, and when NO, the process proceeds to step S32. In step S32, it is determined whether or not a low priority flow CTS signal including PMDII is received. If YES, the process proceeds to step S40. If NO, the process proceeds to step S33. In step S33, it is determined whether or not a high priority flow CTS signal including PAPAI and PADII has been received. If YES, the process proceeds to step S55 in FIG. 22, whereas if NO, the process proceeds to step S34. In step S34, a packet signal that is not involved in the flow rate control method according to the present embodiment is received, an appropriate process is executed, and the process returns to the original main routine.

  In step S35, it is determined whether or not the own station is a radio station that transmits a low priority flow packet signal. If YES, the process proceeds to step S36. If NO, the process proceeds to step S51 in FIG. In step S51, based on the received RTS signal or CTS signal, the PAI is calculated using Equation (5) and stored in the PAI table, the communication ID of the high priority flow to which the signal belongs, and the PII in the signal Are stored in the PII table. Next, in step S52, it is determined whether or not the own station is a high-priority flow source wireless station. If YES, the process proceeds to step S53, and if NO, the process proceeds to step S54. In step S53, the PIR of the high priority flow is calculated based on the average value of the deviation (PII-PAI) for each flow calculated based on the PAI table and the PII table of the own station. Specifically, the error signal value e (n) is calculated using Equation (15) based on the PAI table and the PII table of the own station, and the calculated error signal value e (n) and the high priority flow are calculated. Based on the previous packet injection interval PII, a new packet injection interval PII of the high priority flow is calculated using Equation (16). Next, the packet injection interval PII (or the packet injection rate PIR from the equation (12)) of the high-priority flow in which the local station is transmitting the packet signal as the source wireless station is updated, and the process returns to the original main routine. . In step S54, the average PAI and average PII values of other flows in the vicinity of the own station flow are calculated as PAPAI and PAPII for the own station flow from the own station PAI table and PII table, respectively. The PAPAI and PAPII are propagated back to the source radio station of the high priority flow using the CTS signal. This back propagation is executed by adding PAPAI and PAPII to the CTS signal responding to the RTS signal when receiving the RTS signal including the communication ID that matches the communication ID of the flow of the local station. . After executing step S54, the process returns to the original main routine.

  Referring to FIG. 20 again, in step S36, based on the reception time of the received RTS signal or CTS signal, PAI is calculated using equation (5), stored in the PAI table, and the received signal Are stored in the PII table. Next, in step S37, it is determined whether or not the own station is a low-priority flow source radio station. If YES, the process proceeds to step S38. If NO, the process proceeds to step S39. In step S38, from the previous packet injection interval PII of the low-priority flow to which the local station belongs based on PMDII calculated using Formula (13) based on the PAI table and PII table of the local station, Formula (14) Is used to calculate a new packet injection interval PII. Next, the packet injection interval PII (or the packet injection rate PIR from the equation (12)) of the low priority flow in which the local station is transmitting the packet signal as the transmission source radio station is updated, and the process returns to the original main routine. .

  On the other hand, in step S39, DMDII is calculated based on the PAI table and the PII table of the own station, and is then propagated back to the source radio station of the low priority flow using the CTS signal as PMDII. This back propagation is executed by adding PMDII to the CTS signal responding to the RTS signal and transmitting it when receiving the RTS signal including the communication ID that matches the communication ID of the flow of the local station. After execution of step S39, the process returns to the original main routine.

  In step S55, it is determined whether there is a PAI in the PAI table of the own station. If YES, the process proceeds to step S56. If NO, the process proceeds to step S56A. In step S56, the PAPAI in the received CTS signal and the PAI in the PAI table of the own station are averaged and updated as a new PAPAI, and the PAPII in the received CTS signal and the PII in the PII table of the own station are updated. On average, the new PAPII is updated, and the process proceeds to step S57. In step S56A, PAPAI and PAPII in the received CTS signal are acquired as new PAPAI and PAPII, and the process proceeds to step S57. In step S57, it is determined whether or not the own station is a high-priority flow source radio station. If YES, the process proceeds to step S58. If NO, the process proceeds to step S59. In step S58, an error signal value e (n) is calculated using equation (15) based on the new PAPAI and PAPII, and the calculated error signal value e (n) and the previous flow of the high priority flow are calculated. Based on the packet injection interval PII, a new packet injection interval PII of the high priority flow is calculated using Equation (16). Next, the packet injection interval PII (or the packet injection rate PIR from the equation (12)) of the high-priority flow in which the local station is transmitting the packet signal as the source wireless station is updated, and the process returns to the original main routine. .

  Also, in step S59, new PAPAI and PAPII are propagated back to the source radio station of the high priority flow using the CTS signal. This back propagation is executed by adding PAPAI and PAPII to the CTS signal responding to the RTS signal when receiving the RTS signal including the communication ID that matches the communication ID of the flow of the local station. . After execution of step S59, the process returns to the original main routine.

  In step S40, it is determined whether or not there is a PAI in the PAI table of the own station. If YES, the process proceeds to step S41, and if NO, the process proceeds to step S41A. In step S41, PMDII in the received CTS signal is compared with DMDII calculated from the PII table and PAI table of the own station, and a larger value is updated as new PMDII, and the process proceeds to step S42. In step S41A, PMDII in the received CTS signal is acquired as a new PMDII, and the process proceeds to step S42. In step S42, it is determined whether or not the own station is the source radio station of the low priority flow. If YES in step S42, the process proceeds to step S43. If NO, the process proceeds to step S44. In step S43, the new PMDII is set as the error signal value e (n), and the equation (14) is used based on the error signal value e (n) and the previous packet injection interval PII of the low priority flow. Then, a new packet injection interval PII of the low priority flow is calculated. Next, the packet injection interval PII (or the packet injection rate PIR from the equation (12)) of the low priority flow in which the local station is transmitting the packet signal as the transmission source radio station is updated, and the process returns to the original main routine. .

  In step S44, the new PMDII is back-propagated toward the source wireless station of the low priority flow using the CTS signal. This back propagation is executed by adding PMDII to the CTS signal responding to the RTS signal and transmitting it when receiving the RTS signal including the communication ID that matches the communication ID of the flow of the local station. After execution of step S44, the process returns to the original main routine.

  FIG. 23 is a flowchart showing a PAI deletion process (step S12) which is a subroutine of FIG. In step S61 of FIG. 23, it is determined whether or not an RTS signal or a CTS signal has not been received for a time Δt for each high-priority flow. If YES, the process proceeds to step S62. Return to the routine. In step S62, the PAI for the high priority flow is deleted from the PAI table, and then the process returns to the original routine.

  As described above, according to the present embodiment, a control device for a wireless network that includes a plurality of wireless stations and performs packet wireless communication using a plurality of packet flows having different priorities between the wireless stations. Is provided. In the control device, the packet signal of each packet flow includes data indicating the current packet injection interval (PII) of the packet flow to which the packet signal belongs. When each radio station handling a high priority flow among the plurality of packet flows receives a packet signal of a high priority flow different from the high priority flow handled by each radio station, the received packet signal The packet injection interval (PII) of the different high-priority flow is acquired from the above, and the packet arrival interval (PAI) of the packet signal of the different high-priority flow is calculated. The wireless stations that handle the high-priority flow and other than the source wireless station of the high-priority flow may transmit the acquired packet injection interval (PII) and the calculated packet arrival interval ( PAI) is propagated back to the source radio station of the high priority flow. Further, the source radio station of the high priority flow is configured such that the packet injection interval (PII) acquired at the source radio station, the packet arrival interval (PAI) calculated at the source radio station, Based on the propagated packet injection interval (PII) and packet arrival interval (PAI), the packet injection interval of the high priority flow is controlled to transmit the packet signal of the high priority flow. Still further, when each radio station handling a low priority flow of the plurality of packet flows receives the packet signal of the high priority flow, the radio station injects the packet of the high priority flow from the received packet signal. An interval (PII) is obtained, a packet arrival interval (PAI) of the packet signal of the high priority flow is calculated, and the acquired packet injection interval (PII) and the calculated packet arrival interval (PAI) The deviation (MDII) of is calculated. A wireless station that handles the low-priority flow and that is other than the low-priority flow source wireless station uses the calculated deviation (MDII) as the low-priority flow source wireless station. Back-propagated towards Based on the deviation (MDII) calculated at the source radio station and the back-propagated deviation (MDII), the source radio station of the low priority flow determines the packet injection interval of the low priority flow. The low priority flow packet signal is transmitted under control.

  Preferably, the high-priority flow source radio station is a weighted average of the packet injection interval (PII) acquired at the source radio station and the back-propagated packet injection interval (PII). An average value of packet injection intervals (PAPIII) is calculated, and a packet arrival interval that is a weighted average of the packet arrival interval (PAI) calculated at the source wireless station and the back-propagated packet arrival interval (PAI). An average value (PAPAI) is calculated, an average value of the current packet injection interval (PII) of the high priority flow and the average value of the calculated packet injection intervals (PAPII), and the calculated packet arrival interval And calculate the error with the average value (PAPAI) of the above, and using the proportional control method based on the calculated error, packet injection of the high priority flow To control the interval.

  Further preferably, the low-priority flow source radio station preferably has a maximum deviation value which is a maximum value of the deviation (MDII) calculated in the source radio station and the back-propagated deviation (MDII). (PMDII) is calculated, and a packet injection interval of the low priority flow is controlled using a proportional, integral and derivative (PID) control method based on the calculated maximum deviation (PMDII).

  Therefore, according to the present embodiment, according to the packet transmission / reception control process executed by each node radio station in the ad hoc radio network, the priority of each flow in the ad hoc radio network in which flows with different priorities exist. Can support QoS of the flow. Thereby, the low priority flow can be controlled so as to minimize the interference of the low priority flow with respect to the high priority flow, and the throughput of the high priority flow can be increased.

  Next, a simulation for performance evaluation by simulation of the ad hoc wireless network according to the present embodiment and the result thereof will be described.

  The present inventors evaluated the performance of an ad hoc wireless network using a flow rate control method according to an embodiment of the present invention by simulation using a QualNet network simulator (see Non-Patent Document 18). ). In the simulation, a directional MAC based on IEEE802.11 (see Non-Patent Document 16) is considered, and the protocol according to the proposed embodiment is implemented only when the variable beam antenna 101 is used. The simulation is an electronically controlled waveguide array antenna device that is in the form of a pseudo-switching beam antenna that is steered discretely every azimuth of 30 degrees and covers a range of 360 degrees (see Non-Patent Document 16). Was used as the directional variable beam antenna 101. The quorum network simulator has been modified in order to implement the protocol according to this embodiment. Table 1 shows the set of parameters used for the simulation.

  First, the performance evaluation of an ad hoc wireless network in which the flow rate control method according to the present embodiment is implemented and the source wireless station of the low priority flow operates as a node wireless station including the low priority flow controller LPC will be described.

  To simplify the discussion, there are six node radio stations per column, and two of the end node radio stations each act as a source radio station and a destination radio station whenever necessary. Assume a lattice topology. The performance evaluation of the low priority flow controller LPC was performed under the two topologies set as follows in the lattice topology.

(A) A single high priority flow along the first column of the grid and a single low priority flow along the second column of the grid: the roots of both flows generate route coupling Are sufficiently close to each other (hereinafter referred to as the first topology).
(B) A single high priority flow along the second column of the grid and two low priority flows along the first and third columns of the grid: all three routes have root cups They are physically close enough to generate a ring (hereinafter referred to as second topology).

  In the simulation, in order to clearly show the gain obtained in the protocol according to the present embodiment, the influence of the routing protocol is removed using a static route. In addition, a static route was used in order not to generate any control packet due to the routing protocol. Instead of randomly selecting the source radio station and destination radio station pair, select the source radio station and destination radio station pair where there is a conflict between the high priority flow and the low priority flow. , Artificially created a situation where the effect of packet injection interval control can be demonstrated.

  As the first simulation result, the performance of the low-priority flow controller LPC when the above-described first topology, that is, one high-priority flow and one low-priority flow exists will be described.

  24 to 27 show the performance of the low priority flow controller LPC when there is one high priority flow and one low priority flow. The desired setting value Rp for the high priority flow packet injection interval (PII) is 20 milliseconds, ie, the desired packet injection rate (PIR) is 50 packets per second. For a packet size of 512 bytes and a packet transmission rate (PDR) of 100%, the expected throughput at a packet injection interval PII = 20 milliseconds is 204.8 kbps.

  FIG. 24 shows temporal changes between the packet arrival interval of the high priority flow and the packet injection interval of the low priority flow when there is a single high priority flow and a single low priority flow. It is a graph. In the simulation shown in FIG. 24, the flow rate adaptive control of the low priority flow (L) is performed to protect the high priority flow (H). In the simulation shown in FIG. 24, the initial values of PII (H) for the high priority flow and PII (L) for the low priority flow are both 20 milliseconds. A high-priority flow cannot maintain the flow rate of the high-priority flow when the low-priority flow route-coupled to it is operating at PII (L) = 20 milliseconds. The degree flow PII increases immediately and rapidly to protect the flow rate of the high priority flow. The low-priority flow PII gradually decreases after this rapid increase and, on average, settles to (approximately) PII (L) = 60 milliseconds.

FIG. 25 is a table showing the corresponding packet transmission rate and throughput results when adaptive packet injection rate control is executed as flow rate control according to the present embodiment. The high priority flow can maintain a throughput of 204 kbps with a packet transmission rate of 1. The throughput of the low priority flow is 53 kbps, and the packet transmission rate is 0.999. The values of the parameters k p , k i and k d in the equation (14) used in obtaining this simulation result are adjusted to be 0.8, 0.1 and 0.1 by experiment, respectively. .

  FIG. 26 and FIG. 27 show the operation of the system when the flow rate of the low priority flow is manually changed instead of using the controller that executes the flow rate control according to the present embodiment under the above conditions. It is a graph to show. Each of these graphs fixes the high-priority flow packet injection interval PII (H) to 20 msec (milliseconds) (that is, the flow rate of the high-priority flow is fixed at 50 packets per second) and the low-priority flow. The throughput and packet transmission rate of each flow with respect to the packet injection interval of the low priority flow when the packet injection interval of the flow is manually increased are shown. When both the high priority flow and the low priority flow are set to PII = 20 milliseconds, the throughput of the high priority flow is 129 kbps, its packet transmission rate is 0.63, and the low priority flow Has a throughput of 124 kbps and a packet transmission rate of 0.6. Here, the PII of the low priority flow was manually changed, and the throughput and packet transmission rate of the high priority flow were measured. Increasing the low priority flow PII (PII (L)) increases both the throughput and packet transmission rate of the high priority flow. In the case where PII (L) = 60 milliseconds or more, the high priority flow reaches the peak value of throughput of 204 kbps, and the packet transmission rate is 0.993. Thus, PII (L) = 60 milliseconds is the manually adjusted optimal setting for the low priority flow, and when this setting is set, the high priority flow is brought to its desired level. Can be held. This state is to be achieved by the low priority flow controller according to the present embodiment (see FIG. 24). The throughput of the low priority flow when this set value is set is 67 kbps.

  As the next simulation result, the performance of the low-priority flow controller LPC when the above-described second topology, that is, one high-priority flow and two low-priority flows exists will be described.

  FIG. 28 shows an adaptive packet as flow rate control according to the present embodiment in the case where one high priority flow H and two low priority flows L1 and L2 exist and all are route-coupled to each other. The time change between the packet arrival interval of the high priority flow H and the packet injection interval of the low priority flows L1 and L2 when the injection rate control is executed (that is, when the low priority flow controller LPC is operated). FIG. 29 is a table showing the corresponding packet transmission rate and throughput. In the simulations of FIGS. 28 and 29, adaptive flow rates for the two low priority flows to protect the flow rate of the high priority flow H and maximize the throughput of the low priority flows L1 and L2 themselves. Control is taking place. The desired set value Rp of the high priority flow packet injection interval (PII) is 20 milliseconds, that is, the packet injection rate (PIR) is 50 packets per second.

  In the simulation of FIG. 28, the initial values of the high-priority flow packet injection interval PII (H) and the low-priority flow packet injection intervals PII (L1) and PII (L2) are 20 milliseconds. In order to show the control operation of the low priority flow controller LPC, the communication of the high priority flow H and the first low priority flow L1 is started simultaneously at the time of 30 seconds after the simulation starts and is continued until the end of the simulation. On the other hand, the communication of the second low priority flow L2 is started at a time of 110 seconds after the start of the simulation and stopped at a time of 180 seconds after the start of the simulation. If the low priority flow L2 does not exist, the temporal change in the operation of the low priority flow controller LPC is the same as in the previous case. However, when the communication of the low priority flow L2 is started, the PIIs of the low priority flows L1 and L2 both increase immediately and rapidly, and the packet injection interval PII (H) of the high priority flow H is set to PII (H ) = 20 milliseconds. The PII of both low priority flows gradually decreases after this rapid increase and on average settles to (approximately) PII (L) = 220 milliseconds. When the low priority flow L2 is stopped, the PII of the low priority flow L1 settles to its original value as shown.

Referring to FIG. 29, the high priority flow can hold a throughput of 204.8 kbps with a packet transmission rate of 1, as in the simulation results shown in FIGS. The throughput of the first low priority flow L1 is 35.15 kbps, its packet transmission rate is 0.99, the throughput of the second low priority flow L2 is 17.5 kbps, and its packet transmission rate is 1. The difference in throughput between the low-priority flows L1 and L2 is due to the fact that the flow L1 operates with different PII (L1) when the flow L2 exists and when it does not exist. The values of the parameters k p , k i and k d in equation (14) used in obtaining this simulation result are 0.8, 0.5 and 0.2, which were experimentally adjusted. . When there is no controller that executes flow rate control according to the present embodiment, the throughput of the high priority flow H is 82.06 kbps, and at this time, the packet transmission rate is 0.4.

  Next, the performance evaluation of an ad hoc wireless network in which the flow rate control method according to the present embodiment is implemented and the high-priority flow source wireless station operates as a node wireless station including the high-priority flow controller HPC will be described. In this simulation, the performance evaluation of the high priority flow controller HPC was performed under the topology set as follows in the above-mentioned lattice topology.

(C) Two high priority flows were selected along each of the first and second columns of the grid. The routes of both flows are physically close enough to cause route coupling (hereinafter referred to as the third topology).

  FIG. 30 shows a case where adaptive packet injection rate control is executed as flow rate control according to the present embodiment when two high priority flows H1 and H2 exist and are coupled to each other (ie, high priority). Fig. 31 is a graph showing temporal changes in packet injection intervals of the high priority flows H1 and H2 when the flow controller HPC is operated, and Fig. 31 is a table showing corresponding packet transmission rates and throughputs. In the simulations of FIGS. 30 and 31, the packet injection interval of the two high priority flows H1 and H2 is optimized to maximize the packet transmission rate and throughput, and fairness is set between the high priority flows H1 and H2. To achieve this, adaptive flow rate control is performed for high priority flows H1 and H2.

  In the simulation results shown in FIG. 30, the two high-priority flow source radio stations guarantee the maximum packet rate and maximum throughput achievable in the ad hoc wireless network communication system without packet loss. In addition, the packet injection interval is optimized. The graph of FIG. 30 shows that both high priority flows H1 and H2 are adapted to match their PII to a common set point to protect each other after they have first suddenly increased their PII. Shows that If the common setting value of this packet injection interval is shortened beyond the processing capacity of the system, an error will be introduced as a deviation of PAI from PII. These two high priority flows then rapidly increase their PII and minimize errors.

According to the simulation results shown in FIG. 31, when using the adaptive high priority flow controller HPC, the packet transmission rate of both high priority flows H1 and H2 increases from about 0.6 to about 1. In addition, their throughput increases from 124 kbps and 129 kbps to 131 kbps and 132 kbps, respectively. In this way, fairness can be dynamically achieved in a distributed manner among a plurality of route coupled high priority flows. The value of the parameter k p of which is used to obtain the simulation result, empirically tuned formula (16) is 0.1.

  The simulation results described above are evaluations of the low-priority flow controller LPC and the high-priority flow controller HPC in the lattice topology of an ideal environment without overhead. Next, the evaluation of the system performance in the random topology will be described. The simulation result will be described.

  In this simulation, a directional MAC protocol equipped on the receiver side based on a rotating sector having a position tracking mechanism such as the directional MAC protocol developed by the present inventors was implemented (see Non-Patent Document 16). In this simulation, a network-recognized routing protocol such as the directional routing protocol developed by the present inventors was used (see Non-Patent Document 8). In order to show the effectiveness of the flow rate control method according to the embodiment of the present invention in a practical scenario involving overhead of various control packets in the MAC layer and the routing layer, the MAC protocol and the routing protocol according to the present embodiment are shown. A flow rate control method was implemented. In a random topology having 100 node radio stations in a square bounded area of 1500 m × 1500 m, one source radio station and destination radio station pair as a high priority flow is randomly selected and low priority Five more pairs of source radio stations and destination radio stations as a flow were randomly selected. The system performance was evaluated both when each node radio station was statically arranged and when each node radio station moved within the area.

  First, a simulation result when each node radio station is statically and randomly arranged in a region will be described with reference to FIGS. 32 and 33.

  FIG. 32 shows the performance of high-priority flows when coexisting with five low-priority flows composed of node radio stations that implement the flow rate control method, when each low-priority flow does not execute flow rate control, This is shown in comparison with a case where a high priority flow operates independently and no other flows exist. If the high priority flow operates alone, this results in a throughput of approximately 86 kbps. If the other five low priority flows are introduced and no flow rate control is performed, the throughput of this high priority flow degrades to approximately half of its previous value, as is apparent from FIG. Even if there is a low-priority flow, if the flow rate control method according to this embodiment is used in each low-priority flow, the throughput of the high-priority flow is that the high-priority flow is operating independently. It is almost the same as the value when

  FIG. 33 shows a case where each low priority flow does not use flow rate control (or when priority is not assigned) and a case where flow rate control according to the present embodiment is used (when priority is assigned). 5 shows the performance of five low priority flows in the two scenarios. Even after the introduction of the flow rate control method according to the present embodiment, the low priority flow can continue to hold 90% of its average throughput when no flow control is performed. This is not because the flow rate of the low priority flow was not lowered enough to hold the flow rate of the high priority flow. When the packet injection rate of the low priority flow is optimally controlled, congestion is reduced, and thus packet loss is negligibly small by optimizing the use of the medium. In addition to protecting high priority flows, the flow rate control scheme according to this embodiment can further maximize the throughput of low priority flows, and packet signals can be processed by the network at that time. Infused at optimal rate.

  Next, with reference to FIG. 34 and FIG. 35, a simulation result when each node radio station moves in the area will be described. In order to show that the flow rate control method according to the embodiment of the present invention is robust even in a continuously changing topology, the node radio station apparatus is moving at 0-10 meters per second. The protocol according to this embodiment was tested and evaluated. Congestion information is backpropagated at high speed to the low-priority flow source radio station, and the source radio station can adaptively determine the control amount of the flow rate, so it is possible to achieve better performance. is there.

  FIG. 34 shows the performance of the high priority flow in the flow rate control method according to the embodiment of the present invention when the low priority flow does not execute the flow rate control, when the high priority flow operates independently, and This is shown in comparison with the case where no flow exists. A high priority flow results in a throughput of approximately 133 kbps when operating alone. When the other five low priority flows are introduced and no flow rate control is performed, the throughput of this high priority flow is less than approximately one third of its previous value, as is apparent from FIG. It deteriorates until. Even if there is a low priority flow, if the flow rate control method according to the embodiment of the present invention is used, the throughput of this high priority flow increases to approximately 127 kbps.

  FIG. 35 shows a case where each low priority flow does not use flow rate control (or when priority is not assigned) and a case where flow rate control according to the present embodiment is used (when priority is assigned). 5 shows the performance of five low priority flows in the two scenarios. The most interesting part of this evaluation is that, after introducing the flow rate control method (or packet injection rate control method) according to this embodiment, the low priority flow may rather improve its average throughput. It is shown. This improvement is possible because optimal control of the low-priority flow packet injection rate reduces network congestion and results in optimal use of the media with minimal packet loss.

FIG. 2 is a plan layout view of a plurality of node radio stations 1-1 to 1-9 constituting an ad hoc radio network that is an embodiment according to the present invention. It is a block diagram which shows the internal structure of each node radio station 1 of FIG. It is a figure which shows the general format of the packet data used in the ad hoc wireless network of FIG. (A) is a figure which shows the format of the RTS packet signal used in the ad hoc wireless network of FIG. 1, (b) is a figure which shows the format of the CTS packet signal used in the ad hoc wireless network of FIG. FIG. 9 is a diagram illustrating problems in the prior art, and when an omni antenna is used, a low priority flow on the route {S 2 -D 2 } disturbs a high priority flow on the route {S 1 -D 1 }. It is a top view which shows the case where it does. FIG. 2 is a block diagram schematically illustrating a basic feedback controller applied to the ad hoc wireless network of FIG. 1. When the feedback controller of FIG. 6 is applied to the ad hoc wireless network of FIG. 1 and there is a single high priority flow and a single low priority flow that are route-coupled to each other, FIG. 2 is a block diagram schematically showing a flow rate control device based thereon. Based on the priority when the feedback controller of FIG. 6 is applied to the ad hoc wireless network of FIG. 1 and there is a single high priority flow and a plurality of low priority flows that are route coupled to each other. FIG. 3 is a block diagram schematically showing a flow rate control apparatus. When the feedback controller of FIG. 6 is applied to the ad hoc wireless network of FIG. 1 and there are a plurality of high-priority flows and a plurality of low-priority flows that are route-coupled to each other, based on priority It is a block diagram which shows a flow rate control apparatus schematically. In this embodiment, when the sector pattern is set and used for the variable beam antenna 101 of FIG. 2, the low priority flow on the route {S 2 -D 2 } is the high priority on the route {S 1 -D 1 }. It is a top view which shows that it can exist simultaneously with a degree flow. It is a figure which shows transmission zone TZn ((alpha), (beta), R) of the node radio station 1-n formed of the variable beam antenna 101 of FIG. 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. 3 is a table showing an example of a packet arrival interval table (PAI table) stored in the database memory 154 of FIG. 2. 3 is a table showing an example of a packet injection interval table (PII table) stored in the database memory 154 of FIG. 2. The maximum value of the high-priority flow packet injection interval in the vicinity of the low-priority flow detected in each node radio station that transmits the packet signal of the low-priority flow is sent to the source radio station of the low-priority flow. It is a figure which shows schematically the process made to back propagate toward. The average packet arrival interval and the average packet injection interval of other high priority flows in the vicinity of the high priority flow detected in each node radio station transmitting the packet signal of the high priority flow are expressed as the high priority. It is a figure which shows roughly the process made to back propagate toward the transmission origin radio | wireless station of a flow. 2 is a timing chart showing types of radiation patterns and radio communication protocols at each node radio station used in the ad hoc radio network of FIG. 1. It is a timing chart which shows the operation | movement of the beacon signal used in the ad hoc wireless network of FIG. 3 is a flowchart showing packet transmission / reception control processing executed in accordance with the management control unit 105 of the node wireless station 1 in FIG. 2. FIG. 20 is a first part of a flowchart showing other signal reception processing (step S <b> 7) that is a subroutine of FIG. 19. FIG. FIG. 20B is a second part of a flowchart showing other signal reception processing (step S <b> 7) that is a subroutine of FIG. 19. FIG. FIG. 20 is a third part of a flowchart showing other signal reception processing (step S <b> 7) that is a subroutine of FIG. 19. FIG. 20 is a flowchart showing PAI deletion processing (step S12), which is a subroutine of FIG. It is a simulation result of this embodiment, and when there is a single high priority flow and a single low priority flow, the packet arrival interval of the high priority flow and the packet injection interval of the low priority flow It is a graph which shows the time change of. It is a table | surface which shows the result of the adaptive packet injection rate control when it is a simulation result of this embodiment, and there exists a single high priority flow and a single low priority flow. It is a simulation result of this embodiment, and is a graph showing the throughput of each flow with respect to the packet injection interval of the low priority flow when there is a single high priority flow and a single low priority flow. . FIG. 9 is a graph showing simulation results of the present embodiment, and a packet transmission rate of each flow with respect to a packet injection interval of a low priority flow when there is a single high priority flow and a single low priority flow. It is. It is a simulation result of this embodiment, and the time between the packet arrival interval of the high priority flow and the packet injection interval of the low priority flow when there is one high priority flow and two low priority flows It is a graph which shows a change. It is a table | surface which shows the result of the adaptive packet injection | pouring rate control when it is a simulation result of this embodiment, and one high priority flow and two low priority flows exist. It is a simulation result of this embodiment, and is a graph showing the temporal change of the packet injection interval of each high priority flow when there are two high priority flows. It is a table | surface which is a simulation result of this embodiment, and shows the result of adaptive packet injection rate control when two high priority flows exist. In the simulation result of the present embodiment, when a plurality of node radio stations are statically and randomly arranged in a region and only a high priority flow exists, a high priority flow and five low priority flows exist When the flow rate control is not performed, and when the flow rate control is performed when the high priority flow and the five low priority flows exist, the graphs show a comparison of the throughput of the high priority flow. In the simulation result of the present embodiment, when a plurality of node radio stations are statically and randomly arranged in a region, and there are a high priority flow and five low priority flows, a low relative to the presence or absence of flow rate control. It is a graph which shows the average throughput of a priority flow. In the simulation result of the present embodiment, when a plurality of node radio stations move within a region and only a high priority flow exists, there are a high priority flow and five low priority flows. FIG. 6 is a graph showing a comparison of throughput of high priority flows when no flow is performed and when flow rate control is performed when there are high priority flows and five low priority flows. In the simulation result of the present embodiment, when a plurality of node radio stations move in an area and there are a high priority flow and five low priority flows, the average of the low priority flows with respect to the presence or absence of flow rate control It is a graph which shows a throughput.

Explanation of symbols

1, 1-1 to 1-9... Node wireless station,
10, 20 ... subtractor,
11 ... Controller,
12 ... Plant equipment,
21 ... Flow controller,
22 ... Flow system in the network,
23 ... System for back-propagating the flow rate,
24 ... High priority flow set value controller,
101 ... Variable beam antenna,
102 ... circulator,
103. Radiation pattern 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,
160. Spread code generator.

Claims (6)

  1. In a control device for a wireless network that includes a plurality of wireless stations and performs packet wireless communication using a plurality of packet flows having different priorities between the wireless stations,
    The packet signal of each packet flow includes data indicating the current packet injection interval (PII) of the packet flow to which the packet signal belongs,
    When each radio station handling a high priority flow among the plurality of packet flows receives a packet signal of a high priority flow different from the high priority flow handled by each radio station, the received packet signal To obtain the packet injection interval (PII) of the different high priority flow from, and calculate the packet arrival interval (PAI) of the packet signal of the different high priority flow,
    Radio stations that handle the high-priority flow and that are other than the source radio station of the high-priority flow use the acquired packet injection interval (PII) and the calculated packet arrival interval (PAI). And back-propagating toward the high-priority flow source radio station,
    The source radio station of the high priority flow is back-propagated with the packet injection interval (PII) acquired at the source radio station and the packet arrival interval (PAI) calculated at the source radio station. Based on the packet injection interval (PII) and the packet arrival interval (PAI), the packet injection interval of the high priority flow is controlled and the packet signal of the high priority flow is transmitted.
    When each radio station that handles a low priority flow among the plurality of packet flows receives the packet signal of the high priority flow, the radio station receives a packet injection interval (PII) of the high priority flow from the received packet signal. ) To calculate the packet arrival interval (PAI) of the packet signal of the high priority flow, and the deviation between the acquired packet injection interval (PII) and the calculated packet arrival interval (PAI) ( MDII)
    A radio station that handles the low priority flow and that is other than the source radio station of the low priority flow directs the calculated deviation (MDII) to the source radio station of the low priority flow Backpropagating
    Based on the deviation (MDII) calculated at the source radio station and the back-propagated deviation (MDII), the source radio station of the low priority flow determines the packet injection interval of the low priority flow. A control device for a wireless network, characterized by controlling and transmitting a packet signal of the low priority flow.
  2. The source radio station of the above high priority flow is
    Calculating an average value (PAPII) of packet injection intervals that is a weighted average of the packet injection interval (PII) acquired at the source wireless station and the back-propagated packet injection interval (PII);
    Calculating an average value (PAPAI) of packet arrival intervals which is a weighted average of the packet arrival interval (PAI) calculated at the source wireless station and the back-propagated packet arrival interval (PAI);
    An error between the average value of the current packet injection interval (PII) of the high priority flow and the average value of the calculated packet injection intervals (PAPI) and the average value of the calculated packet arrival intervals (PAPAI) 2. The control apparatus for a wireless network according to claim 1, wherein a packet injection interval of the high priority flow is controlled using a proportional control method based on the calculated error.
  3. The source radio station of the low priority flow is
    Calculating a maximum deviation value (PMDII) which is a maximum value of the deviation (MDII) calculated in the source wireless station and the back-propagated deviation (MDII);
    3. The packet injection interval of the low priority flow is controlled using a proportional, integral and derivative (PID) control method based on the calculated maximum deviation (PMDII). A control device for the described wireless network.
  4. In a control method for a wireless network including a plurality of wireless stations and performing packet wireless communication using a plurality of packet flows having different priorities between the wireless stations,
    The packet signal of each packet flow includes data indicating the current packet injection interval (PII) of the packet flow to which the packet signal belongs,
    When each radio station handling a high priority flow among the plurality of packet flows receives a packet signal of a high priority flow different from the high priority flow handled by each radio station, the received packet signal To obtain the packet injection interval (PII) of the different high priority flow from, and calculate the packet arrival interval (PAI) of the packet signal of the different high priority flow,
    Radio stations that handle the high-priority flow and that are other than the source radio station of the high-priority flow use the acquired packet injection interval (PII) and the calculated packet arrival interval (PAI). And back-propagating toward the high-priority flow source radio station,
    The source radio station of the high priority flow is back-propagated with the packet injection interval (PII) acquired at the source radio station and the packet arrival interval (PAI) calculated at the source radio station. Based on the packet injection interval (PII) and the packet arrival interval (PAI), the packet injection interval of the high priority flow is controlled and the packet signal of the high priority flow is transmitted.
    When each radio station that handles a low priority flow among the plurality of packet flows receives the packet signal of the high priority flow, the radio station receives a packet injection interval (PII) of the high priority flow from the received packet signal. ) To calculate the packet arrival interval (PAI) of the packet signal of the high priority flow, and the deviation between the acquired packet injection interval (PII) and the calculated packet arrival interval (PAI) ( MDII)
    A radio station that handles the low priority flow and that is other than the source radio station of the low priority flow directs the calculated deviation (MDII) to the source radio station of the low priority flow Backpropagating
    Based on the deviation (MDII) calculated at the source radio station and the back-propagated deviation (MDII), the source radio station of the low priority flow determines the packet injection interval of the low priority flow. A control method for a wireless network, characterized in that the packet signal of the low priority flow is transmitted under control.
  5. The source radio station of the above high priority flow is
    Calculating an average value (PAPII) of packet injection intervals that is a weighted average of the packet injection interval (PII) acquired at the source wireless station and the back-propagated packet injection interval (PII);
    Calculating an average value (PAPAI) of packet arrival intervals which is a weighted average of the packet arrival interval (PAI) calculated at the source wireless station and the back-propagated packet arrival interval (PAI);
    An error between the average value of the current packet injection interval (PII) of the high priority flow and the average value of the calculated packet injection intervals (PAPI) and the average value of the calculated packet arrival intervals (PAPAI) 5. The control method for a wireless network according to claim 4, wherein a packet injection interval of the high priority flow is controlled using a proportional control method based on the calculated error.
  6. The source radio station of the low priority flow is
    Calculating a maximum deviation value (PMDII) which is a maximum value of the deviation (MDII) calculated in the source wireless station and the back-propagated deviation (MDII);
    6. The packet injection interval of the low priority flow is controlled using a proportional, integral and derivative (PID) control method based on the calculated maximum deviation (PMDII). A control method for the described wireless network.
JP2004287482A 2004-09-30 2004-09-30 Control apparatus and control method for wireless network Pending JP2006101400A (en)

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