JP2011010121A - Information processing apparatus and method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption while suppressing the decline of throughput in an ad hoc network.SOLUTION: An ATIM reception number count unit 141 counts the number of ATIM received in an ATIM window. When the ATIM is received in the ATIM window, a decision value calculation unit 142 calculates a decision value Dof this time on the basis of the number A of the received ATIM in the ATIM window of this time, weight α, weight β, and a decision value Dof the previous time. On the basis of the decision value D, a threshold Sand a threshold S, an awake level is determined. A power supply setter 133 sets power supply to the next ATIM window corresponding to the awake level. This invention is applicable to a communication device for instance.

Description

  The present invention relates to an information processing apparatus, method, and program, and more particularly, to an information processing apparatus, method, and program capable of suppressing power consumption of a terminal while suppressing a decrease in throughput in an ad hoc network. .

  Conventionally, wireless LAN (Local Area Network) communication methods include an infrastructure mode in which terminals communicate with each other via an access point, and an ad hoc mode in which terminals communicate with each other without using an access point.

  A network formed by a plurality of terminals communicating in the ad hoc mode is referred to as an ad hoc network. In an ad hoc network, each terminal communicates with other terminals in the vicinity (within a communicable range) in an ad hoc mode, so that information transmitted from a source terminal is transmitted to another terminal via another terminal. Is transmitted. That is, since a communication infrastructure such as an access point is not required, a flexible network configuration is possible, and it is easy to use for emergency communication at the time of a disaster or a small network such as an office or a home.

  In the infrastructure mode, each terminal needs to be located within the communicable range of the access point. However, in the ad hoc network, there is no restriction on the position of the terminal due to such a communication infrastructure. That is, when the terminal is a mobile communication device such as a mobile phone, the advantages of the ad hoc network can be utilized more strongly.

  However, in that case, the communication device is often driven using a battery as a power source. Therefore, in an ad hoc network, it is important to suppress the power consumption of the terminal.

  IEEE (Institute of Electrical and Electronic Engineers) 802.11 wireless LAN standard defines PSM (Power Saving Mode), which is a low-consumption operation mode, for terminals.

  PSM transitions between an awake state (Awake) in which data can be transmitted / received and a sleep state (Sleep) in which data is not transmitted / received but operates with the minimum necessary power to reduce power consumption. The PSM controls the terminal so that the time spent in the awake state is shortened as much as possible and the time spent in the sleep state is lengthened as much as possible in order to further reduce the power consumption of the terminal.

  In the case of PSM, a terminal that transmits data enters an awake state before transmitting the data and sends a transmission notice signal called ATIM (Announcement Traffic Indication Message). All terminals participating in the network transmit and receive this ATIM while continuing the awake state for a certain time at every beacon transmission interval (beacon interval) that is a synchronization signal. A period (notice period) for transmitting or receiving the ATIM is referred to as an ATIM window.

  The terminal that receives the ATIM during the ATIM window continues to awake and receives data. The terminal that has not received the ATIM shifts to the sleep state until the next ATIM window, and suppresses power consumption.

  Since the power saving of the terminal contributes to the extension of the communicable period of the battery-driven terminal, it is a very important consideration in the ad hoc network. Therefore, various studies have been made on further power saving.

  For example, a method has been considered in which information is exchanged between surrounding nodes, the surrounding state is always known, the period of the awake window of the transmission partner is known, and communication is performed with the minimum number of awake states without using ATIM. (For example, refer nonpatent literature 1 and nonpatent literature 2).

  In addition, a method has been considered in which each node observes the network status and dynamically adjusts the length of the ATIM window (see, for example, Non-Patent Document 3). In this case, power is saved by starting with the smallest ATIM window size and adjusting to the minimum ATIM window size while moving up and down according to the rules.

  Furthermore, in single-hop MANET (Mobile Ad hoc Network), instead of opening an ATIM window at every beacon interval, each node can open an ATIM window at some beacon intervals according to a predetermined rule. (See, for example, Non-Patent Document 4). That is, in each beacon interval, control is performed so as to reduce the number of nodes that are in an awake state and reduce beacon contention that occurs when the number of nodes participating in the network increases. In this case, power saving is performed by reducing the number of awake nodes in the entire network.

  Further, a method of transitioning to a sleep state during the beacon interval after data reception has been considered (for example, see Patent Document 1).

E.-S. Jung and N. H. Vaidya, An Energy Efficient MAC Protocol for Wireless LANs. In Proceedings of INFOCOM 2002, pp. 1756-1764, New York, NY, USA, Jun. 2002. S. Takeuchi, K. Yamazaki, K. Sezaki, and Y. Yasuda, An Improved Power Saving Mechanism for MAC Protocol in Ad Hoc Networks, IEEE GLOBECOM 2004, vol.5, pp. 2791-2796, Dec. 2004. T.-C. Huang, J.-H. Tan, and C.-C. Huang, A Traffic-Load Oriented Power Saving Mechanism for MAC Protocol in Ad Hoc Networks, IEEE Wireless Communications and Networking Conference, WCNC pp. 242- 247, Mar. 2007. C.-M. Chao, J.-P. Sheu, and I.-C. Chou, An Adaptive Quorum-Based Energy Conserving Protocol for IEEE 802.11 Ad Hoc Networks, IEEE Trans. Mobile Computing, vol.5, no.5 , pp.560-570, May. 2006.

JP 2006-303888 A

  However, in the methods described in Non-Patent Document 1 and Non-Patent Document 2, it is necessary for all nodes to implement a special protocol for communication without using this ATIM, and nodes are frequently added or deleted. It has been difficult to build a flexible network as is done.

  Further, in the method described in Non-Patent Document 3 and the method described in Patent Document 1, the ATIM window is always opened in all beacon intervals. Therefore, if data transmission / reception is not frequently performed, unnecessary ATIM windows (ATIM windows in a beacon interval in which data transmission / reception is not performed) may occur frequently, which may increase unnecessary energy consumption.

  Furthermore, in the case of the method described in Non-Patent Document 4, each node does not always open the ATIM window at every beacon interval. Therefore, as shown in FIG. There are cases where the timing for opening the ATIM window does not match (nodes B) do not mesh. In this way, even if one node opens the ATIM window, if the other node does not open the ATIM window, ATIM is not exchanged. Therefore, data transmission / reception cannot be performed between the nodes during the beacon interval.

  That is, in the case of the method described in Non-Patent Document 4, the communication efficiency deteriorates, the communication throughput decreases, and as a result, the power consumption may increase. Further, since the communication efficiency is poor, this method is not suitable for transmitting broadcast packets.

  The present invention has been proposed in view of such a situation, and an object thereof is to suppress power consumption of a terminal while suppressing a decrease in throughput.

  One aspect of the present invention is an information processing apparatus that transmits / receives data to / from another information processing apparatus, and a communication unit that communicates with the other information processing apparatus, and a control that controls power supply in the information processing apparatus. Means, a calculation means for calculating a judgment value indicating a tendency of the frequency of the data transmission / reception by the communication means, using the number of reception notice signals for notifying the transmission of the data, and the calculation means calculated by the calculation means Determining means for determining a frequency of a notice period that is a period for receiving the transmission notice signal based on a determination value and in which an operation state of the information processing apparatus is in an awake state in which the data can be transmitted and received; In accordance with the frequency of the notice period determined by the determining means, it is determined in advance so that all the information processing devices simultaneously enter the notice period at least once within a predetermined control period. According to a predetermined pattern that is, an information processing apparatus including an operation setting means for performing until the next of the notice period, the operation setting of said control means.

  The calculation unit calculates the determination value by adding a multiplication result of the past determination value and a predetermined first weighting factor and a multiplication result of the received number and a predetermined second weighting factor. can do.

  Weight setting means for setting the first weight coefficient and the second weight coefficient may be further provided.

  The determination unit compares the determination value with a predetermined first threshold value and a second threshold value to determine an awake level representing the frequency of the notice period by level, and the operation setting unit includes the determination unit According to the pattern determined for each awake level determined by the means, operation setting of the control means can be performed until the next notice period.

  Threshold setting means for setting the first threshold and the second threshold can be further provided.

  When the transmission notice signal is not received during the notice period, the operation setting means sets the operation state of the information processing apparatus to a sleep state in which the data transmission / reception is impossible until the next notice period. When the transmission notice signal is received during the notice period, the operation state of the information processing apparatus can be set to the awake state until the next notice period.

  Control period length setting means for setting the length of the control period can be further provided.

  The communication means can communicate with the other information processing apparatus in an ad hoc mode.

  The communication unit can perform wireless communication with the other information processing apparatus.

  One aspect of the present invention is also an information processing method of an information processing device that transmits and receives data to and from another information processing device, wherein the calculation unit uses the number of reception notification signals that notify the transmission of the data. Calculating a determination value indicating a tendency of the frequency of data transmission / reception by the communication means, and a determination means is a period for receiving the transmission notice signal based on the calculated determination value, wherein the information The operating state of the processing device determines the frequency of the notice period when the data transmission / reception becomes an awake state, and the operation setting means determines at least within a predetermined control period according to the determined frequency of the notice period. Control power supply in the information processing apparatus until the next notice period according to a predetermined pattern so that all the information processing apparatuses are simultaneously in the notice period at one time. Is an information processing method for performing the operation setting of the control means.

  According to another aspect of the present invention, a computer that transmits and receives data to and from another information processing apparatus, a communication unit that communicates with the other information processing apparatus, a control unit that controls power supply in the information processing apparatus, Based on the determination value calculated by the calculation means, a calculation means for calculating a judgment value indicating a tendency of the frequency of the data transmission / reception by the communication means, using the number of transmission notice signals for notifying the transmission of data. Deciding means for determining the frequency of the notice period which is a period for receiving the transmission notice signal and the operation state of the information processing apparatus is in an awake state in which the data can be transmitted and received, and the decision means In accordance with the frequency of the notice period that has been made, it is determined in advance that all the information processing devices are simultaneously in the notice period at least once within a predetermined control period. According to a predetermined pattern, a program for functioning as an operation setting means for performing until the next of the notice period, the operation setting of said control means.

  In one aspect of the present invention, a judgment value indicating a tendency of the frequency of data transmission / reception is calculated using the number of reception of transmission notice signals for notice of data transmission, and the transmission notice signal is calculated based on the calculated judgment value. The frequency of the notice period in which the operation state of the information processing apparatus is in an awake state in which data can be transmitted and received is determined, and predetermined control is performed according to the determined notice period frequency. The power supply in the information processing apparatus is controlled until the next notice period according to a predetermined pattern so that all the information processing apparatuses become the notice period simultaneously at least once within the period.

  According to the present invention, particularly in an ad hoc network, it is possible to suppress power consumption of a terminal while suppressing a decrease in throughput.

It is a schematic diagram explaining the example of communication in the case of controlling opening and closing of an ATIM window according to a predetermined rule. It is a block diagram which shows the structural example of the ad hoc network system to which this invention is applied. It is a figure explaining the example of the basic communication in an ad hoc network. It is a block diagram which shows the main structural examples of the communication apparatus of FIG. It is a figure explaining the opening / closing pattern of the ATIM window for every awake level. It is a flowchart explaining the example of the flow of an opening / closing control process. It is a flowchart explaining the example of the flow of an electric power supply setting process. It is a figure which shows the example of the value of a parameter. It is a figure which shows the example of the mode of a change in power consumption when changing a weight. It is a figure which shows the example of the mode of a change in power consumption when changing a threshold value. It is a figure explaining the ATIM window pattern to compare. It is a figure explaining the example of an experimental result. It is a block diagram which shows the other structural example of the communication apparatus of FIG. It is a block diagram which shows the main structural examples of the personal computer to which this invention is applied.

Hereinafter, modes for carrying out the invention (hereinafter referred to as embodiments) will be described. The description will be given in the following order.
1. First embodiment (ad hoc network)
2. Second embodiment (communication device)
3. Third embodiment (personal computer)

<1. First Embodiment>
[Description of ad hoc network]
FIG. 2 is a block diagram showing a configuration example of an ad hoc network system to which the present invention is applied.

  The ad hoc network system 100 illustrated in FIG. 2 is a system that forms an ad hoc network in which the communication devices 101-1 to 101-4 are terminals (nodes) and the nodes perform wireless communication in the ad hoc mode.

  In the ad hoc network system 100, each of the communication devices 101-1 to 101-4 is connected to another node within the communicable range as indicated by the double arrows 102-1 to 102-4. And wireless communication. A double arrow 102-1 indicates wireless communication between the communication device 101-1 and the communication device 101-2, a double arrow 102-2 indicates wireless communication between the communication device 101-1 and the communication device 101-3, A double arrow 102-3 indicates wireless communication between the communication device 101-2 and the communication device 101-4, and a double arrow 102-4 indicates wireless communication between the communication device 101-3 and the communication device 101-4. Yes.

  That is, the communication device 101-2 and the communication device 101-3 exist within the communicable range of the communication device 101-1, and the communication device 101-1 and the communication device 101-4 are within the communicable range of the communication device 101-2. Exists. Similarly, the communication device 101-1 and the communication device 101-4 exist within the communicable range of the communication device 101-3, and the communication device 101-2 and the communication device 101- exist within the communicable range of the communication device 101-4. 3 exists.

  As described above, in an ad hoc network, information is generally transmitted via a node. For example, in the ad hoc network system 100 of FIG. 2, when information is transmitted from the communication device 101-1 to the communication device 101-4, the communication device 101-1 and the communication device 101-4 are within the communication range of each other. Even if it does not exist, the information is transmitted to the communication device 101-4 via the communication device 101-2 and the communication device 101-3.

  In other words, the ad hoc network is composed only of nodes and does not require a communication infrastructure such as an access point. Therefore, the ad hoc network not only facilitates network construction, but also allows a flexible network configuration.

  For example, in the ad hoc network system 100 of FIG. 2, if the communication device 101-2 of FIG. 2 moves within the communicable range of the communication device 101-3, the communication device 101-2 and the communication device 101-3 are further connected. Wireless communication is also possible, and a new transmission line is formed. For example, if the communication device 101-4 moves out of the communicable range of the communication device 101-3, wireless communication indicated by the double arrow 102-4 becomes impossible.

  Furthermore, for example, if a new communication device (not shown) is added to the ad hoc network system 100, a new transmission path is formed. Further, for example, if the communication device 101-1 is detached from the ad hoc network system 100, not only the number of nodes but also the transmission path is reduced.

  In general, an ad hoc network having such a feature is, for example, an emergency communication network in the event of a disaster in which the reliability of the communication infrastructure decreases, a network of environmental observation equipment in which it is difficult to install the communication infrastructure, or a communication It is suitable for use in small networks such as offices and homes where cost reduction of infrastructure installation is required.

  The communication devices 101-1 to 101-4 of the ad hoc network system 100 in FIG. 2 may be any device, such as a mobile phone or a smartphone, or a netbook or PDA having a communication function. (Personal Digital Assistants) or a mobile communication device such as a notebook personal computer. In the following, the communication devices 101-1 to 101-4 are referred to as communication devices 101 when it is not necessary to distinguish between them.

  In the case of a network that performs communication in infrastructure mode, each node needs to be located within the communication range of the access point. However, in general, the node of an ad hoc network is limited in the position of a terminal by such a communication infrastructure. No. That is, the ad hoc network has a feature that it is suitable for a network having a mobile communication device such as a mobile phone as a node.

  That is, it can be said that the ad hoc network is suitable for a case where a node is a communication device that performs wireless communication with each other and is driven by a battery.

  The communication devices 101 in FIG. 2 perform wireless communication with each other by a predetermined communication method such as IEEE802.11. Of course, the communication between the communication devices 101 may be wired communication, but wireless communication is more suitable for an ad hoc network because a more flexible network can be constructed. Therefore, in the following description, it is assumed that the communication apparatuses 101 exchange information by wireless communication. Since the following description is basically applicable to wired communication, description of wired communication is omitted, and is performed only when necessary.

  The communication device 101 is driven using a battery as a power source. Of course, the communication device 101 may be driven by using an external power source such as a commercial power source as a power source. However, in an ad hoc network, a battery-driven node is preferable in order to construct a flexible network as described above. It is.

  Such a movable communication device cannot make the battery infinitely large for reasons such as portability, and since its capacity is practically limited, the continuous drive time is prolonged, that is, the power consumption is reduced. It becomes important.

  In general, nodes in ad hoc networks use PSM (Power Saving Mode) in order to reduce power consumption, and awake state (Awake) in which data can be sent and received, while data cannot be sent and received is the minimum necessary Control is performed to appropriately switch between two states, a sleep state (Sleep) that operates with power and suppresses power consumption.

  The communication device 101 of the ad hoc network system 100 performs power control for further reducing power consumption.

  Note that the number of the communication devices 101 constituting the ad hoc network system 100 is arbitrary. Further, the positional relationship between the communication apparatuses 101 and the communication partner (transmission path) are also arbitrary.

  Next, power control in an ad hoc network to which PSM is applied will be described. FIG. 3 is a diagram illustrating an example of basic communication in an ad hoc network.

  FIG. 3 shows an operation state during communication between the nodes A to C. Node B is located within the communicable range of node A, and node C is located outside the communicable range of node A. Communication between the nodes A to C is controlled at every beacon interval, which is a beacon transmission interval for synchronization. A beacon interval A indicated by a double arrow 111-1 indicates a case where information (DATA) is transmitted from the node A to the node B. A beacon interval B indicated by a double-pointed arrow 111-2 indicates that none of the nodes A to C transmits information.

  First, the case of beacon interval A will be described.

  Each node enters a communicable awake state in order to transmit and receive an ATIM (Announcement Traffic Indication Message) for a predetermined period apart from a period for transmitting and receiving data (DATA) at each beacon interval. The period of the awake state indicated by the double arrow 112-1 is referred to as an ATIM window. The length of this ATIM window is common to each node.

  During this ATIM window, the node A having data to be transmitted transmits an ATIM in advance of data transmission to another node (that is, the node B) within the communicable range. The node B that has received the ATIM from the node A and has decided to receive the data transmitted from the node A receives a response signal (ACK) informing that the ATIM is received and the data is received during the ATIM window. Return to node A.

  The node B that has returned ACK continues the awake state even after the end of the ATIM window in order to receive the data transmitted from the node A. The node A that has received the ACK also continues the awake state after the end of the ATIM window in order to transmit data. During the awake state, node A transmits data (DATA) to node B, and node B receiving the data transmits ACK notifying node A that the data has been received. . When node A receives the ACK, the communication between node A and node B ends. This communication is performed during the beacon interval A.

  This awake state continues until the end of the beacon interval A. However, in practice, when the beacon interval A ends, the next beacon interval starts and the next ATIM window starts, so the awake state continues as it is.

  On the other hand, since node C did not receive ATIM during the ATIM window period, it transitions to the sleep state until the beacon interval A ends after the end of the ATIM window, and suppresses power consumption. When beacon interval A ends, the next beacon interval is started and the next ATIM window is started.

  As described above, the node that transmits data, the node that receives data, and the node that does not transmit and receive data perform different operations.

  Next, the case of beacon interval B will be described.

  When data transmission / reception is not performed as in the beacon interval B, the nodes A to C operate in the same manner and are in an awake state during the ATIM window indicated by the double arrow 112-2. The sleep state is entered until interval B ends.

  In this way, a node that does not transmit or receive data transitions from the awake state to the sleep state after the end of the ATIM window, and the sleep state is continued until the beacon interval ends, thereby reducing the power consumption of each node. Figured.

  The communication apparatus 101 controls the opening and closing of the ATIM window and further reduces the number of ATIM windows, thereby further reducing power consumption. At this time, if the number of ATIM windows is simply reduced, the number of nodes that cannot communicate increases, which may reduce the throughput. The communication apparatus 101 further suppresses power consumption while suppressing a decrease in throughput.

[Device Configuration]
FIG. 4 is a block diagram illustrating a main configuration example of the communication apparatus 101 in FIG.

  As illustrated in FIG. 4, the communication device 101 includes a control unit 121, a wireless transmission / reception unit 122, an opening / closing control unit 123, and a power supply unit 124.

  The control unit 121 controls the entire communication device 101. That is, the control unit 121 controls operations of the wireless transmission / reception unit 122, the opening / closing control unit 123, the power supply unit 124, and other processing units (not shown).

  The wireless transmission / reception unit 122 performs wireless communication with another communication apparatus 101 via the antenna 122A in a predetermined manner. The wireless transmission / reception unit 122 modulates and transmits information and signals and receives and demodulates the information and signals through the wireless communication. For example, the wireless transmission / reception unit 122 modulates and transmits signals such as ATIM and ACK, or modulates and transmits transmission data supplied from the control unit 121. For example, the radio transmission / reception unit 122 demodulates a radio signal received via the antenna 122A, supplies the obtained data to the control unit 121, or acquires a signal such as ATIM or ACK. Further, the wireless transmission / reception unit 122 supplies the acquired ATIM to the awake level setting unit 131 and the power management unit 171 and supplies a beacon to the beacon interval count unit 135.

  The opening / closing control unit 123 controls the opening / closing of the ATIM window for wireless communication performed in the wireless transmission / reception unit 122, and appropriately suppresses an unimportant awake state, thereby reducing power consumption.

  In the case of the beacon interval for transmitting data, the opening / closing control unit 123 controls the opening / closing of the ATIM window, as in the case of the general PSM described with reference to FIG. Also in the case of a beacon interval for receiving data, the opening / closing control unit 123 controls the opening / closing of the ATIM window basically as in the case of the general PSM described with reference to FIG. However, in the case of a beacon interval in which no data is transmitted / received, the opening / closing control unit 123 determines an awake level and causes the ATIM window to be opened / closed at a frequency according to the level.

  The awake level is information (leveled) indicating the frequency of the ATIM window. Although details will be described later, the opening / closing control unit 123 determines the awake level according to the tendency of the frequency of data transmission / reception of the communication apparatus 101.

  The open / close control unit 123 includes an awake level setting unit 131, a threshold / weight supply unit 132, a power supply setting unit 133, a control section length supply unit 134, and a beacon interval count unit 135.

  The awake level setting unit 131 determines an awake level for each beacon interval (for each ATIM window).

  The awake level setting unit 131 includes an ATIM reception number counting unit 141, a judgment value calculation unit 142, a judgment value holding unit 143, and a level determination unit 144.

  The ATIM reception number counting unit 141 counts the number of ATIMs received in the ATIM window by the wireless transmission / reception unit 122, and holds the count value. The ATIM reception number counting unit 141 provides the count value held in response to a request from the determination value calculation unit 142 to the determination value calculation unit 142.

  Determination value calculation unit 142 calculates a determination value used for determining the awake level. Although details will be described later, the judgment value is a parameter indicating a tendency of the frequency of data transmission / reception of the node (communication device 101). The tendency of the frequency of data transmission / reception occurs based on various factors such as node performance and role, network configuration, data transmission pattern, and their temporal changes. In other words, it can be said that the tendency of the frequency of data transmission / reception indicates such network characteristics. That is, the determination value calculation unit 142 calculates a determination value that is a parameter indicating the characteristics of the ad hoc network system 100.

  The judgment value calculation unit 142 includes the ATIM reception number (count value) counted by the ATIM reception number counting unit 141, the weight supplied by the threshold / weight supply unit 132, and the past held by the judgment value holding unit 143. Are obtained, and a judgment value is calculated using them. The judgment value calculation unit 142 supplies the calculated judgment value to the judgment value holding unit 143 and the level determination unit 144.

  The judgment value holding unit 143 holds the judgment value calculated by the judgment value calculation unit 142 and provides the judgment value held in response to a request from the judgment value calculation unit 142 to the judgment value calculation unit 142. Further, the judgment value holding unit 143 can appropriately delete a judgment value that is no longer needed.

  The level determination unit 144 determines the awake level. The level determination unit 144 determines the awake level using the determination value calculated by the determination value calculation unit 142 and the threshold value supplied by the threshold value / weight supply unit 132. A method for determining the awake level will be described later. The level determination unit 144 notifies the power supply setting unit 133 of the determined awake level.

The threshold / weight supply unit 132 supplies “weight (α and β)”, which is a coefficient used for calculation of the determination value, to the determination value calculation unit 142 based on a request from the determination value calculation unit 142. Further, the threshold / weight supply unit 132 supplies “threshold values (S ₁ and S ₂ )” used for level determination to the level determination unit 144 based on the request of the level determination unit 144.

The threshold / weight supply unit 132 includes a threshold holding unit 151 and a weight holding unit 152. The threshold holding unit 151 includes a storage medium such as a RAM (Random Access Memory), and holds preset thresholds (S ₁ and S ₂ ). The weight holding unit 152 includes a storage medium such as a RAM, and holds preset weights (α and β). The threshold value / weight supply unit 132 reads out and supplies the threshold value and weight from these holding units.

  The power supply setting unit 133 performs setting for controlling the opening and closing of the ATIM window according to the awake level notified from the level determination unit 144 of the awake level determination unit 131. The ATIM window is opened and closed by switching between the awake state and the sleep state. That is, the power supply setting unit 133 controls power supply. For this purpose, the power supply setting unit 133 controls the operation of the power supply control unit 182 and the timer 172.

  The power supply setting unit 133 acquires the value of the control section length N, which is a parameter indicating the length of the control section of the ATIM window opening / closing control, from the control section length supply section 134. The length of the control section is indicated by the number of beacon intervals. That is, the value of the control section length N is a positive integer.

  In addition, the power supply setting unit 133 acquires a count value from the beacon interval counting unit 135, that is, a value indicating what number of beacon intervals of the control section length N the current beacon interval corresponds to.

  Further, the power supply setting unit 133 acquires a determination result as to whether or not ATIM is received from the determination unit 181 of the power management unit 171.

  The power supply setting unit 133 uses these values to perform opening / closing control of the ATIM window according to the awake level determined by the level determination unit 144, that is, operation setting of the power supply control unit 182 and the timer 172. More specifically, the power supply setting unit 133 determines the time until the next ATIM window and the operation state (whether it is an awake state or a sleep state), and the power supply control unit 182 and the timer so as to operate according to the determination. The operation setting of 172 is performed.

  The control section length supply unit 134 supplies the value of the control section length N to the power supply setting unit 133 based on a request from the power supply setting unit 133. Although details will be described later, the value of the control section length N is used for power supply setting.

  The control section length supply unit 134 includes a control section length holding unit 161. The control section length holding unit 161 has a storage medium such as a RAM (Random Access Memory), for example, and holds a preset value of the control section length N. The control section length supply unit 134 reads and supplies the value of the control section length N from the control section length holding unit 161.

  The beacon interval counting unit 135 monitors the operation of the wireless transmission / reception unit 122 and counts the number of times a beacon is transmitted, that is, the beacon interval. In addition, this count value is information for the power supply setting unit 133 to grasp which beacon interval of the control section length N corresponds to the current beacon interval. Therefore, the count value may be any value as long as it indicates how many beacon intervals of the control section length N correspond to the current beacon interval. For example, the count value may be initialized for each control section length N.

  The power supply unit 124 supplies power to the entire communication apparatus 101. More specifically, the power supply unit 124 supplies power to the control unit 121, the wireless transmission / reception unit 122, and the open / close control unit 123 and controls the power supply as indicated by a thick arrow. Of course, the power supply unit 124 also supplies power to other processing units (not shown) of the communication apparatus 101.

  The power supply unit 124 includes a power management unit 171, a timer 172, and a battery unit 173.

  The power management unit 171 supplies the power supplied from the battery unit 173 to the control unit 121, the wireless transmission / reception unit 122, and the opening / closing control unit 123. The power management unit 171 controls power supply to each processing unit.

  The power management unit 171 includes a determination unit 181 and a power supply control unit 182.

  Based on the ATIM supplied from the wireless transmission / reception unit 122, the determination unit 181 determines whether an ATIM is received during the ATIM window. The determination unit 181 supplies the determination result to the power supply setting unit 133 of the open / close control unit 123.

  The power supply control unit 182 operates based on the setting of the power supply setting unit 133 and controls power supply to each processing unit. That is, the power supply control unit 182 switches between the awake state and the sleep state. In the awake state, for example, the power supply control unit 182 supplies each processing unit with sufficient power to perform a normal operation. On the other hand, in the sleep state, the power supply control unit 182 suppresses the power supply to each processing unit to the minimum necessary. For example, the power supply control unit 182 blocks the power supply to the wireless transmission / reception unit 122 so that the wireless transmission / reception unit 122 cannot communicate. Furthermore, the power supply control unit 182 blocks power supply to the module that controls the wireless transmission / reception unit 122 in the control unit 121. Thus, the power supply control unit 182 suppresses the power supply, so that the power consumption of the communication apparatus 101 is significantly suppressed in the sleep state.

  Of course, the power supply control unit 182 may control power supply to other processing units. In the sleep state, the power supply control unit 182 may supply minute power without completely shutting off the power supply to the wireless transmission / reception unit 122 and the control unit 121. Furthermore, the power control by the power supply control unit 182 need not be performed in units of processing units, and may be performed in any units. For example, it is possible to control the power supply of a part of the processing unit.

  The timer 172 performs timing processing. For example, the timer 172 measures the time set in the power supply setting unit 133 and notifies the power management unit 171 that the time has elapsed.

  The battery unit 173 is a power source of the communication device 101 that supplies power. The battery unit 173 supplies power to each unit of the communication apparatus 101 via the power management unit 171 and also supplies power to the timer 172. The power supply to the timer 172 may be performed via the power management unit 171.

[Description of ATIM window open / close control]
Next, the opening / closing control of the ATIM window by the opening / closing control unit 123 will be described.

  In the case of a general PSM, as described with reference to FIG. 3, an ATIM window is provided in every beacon interval. That is, the node is in an awake state once every beacon interval regardless of whether data is transmitted or received.

  Since the node that transmits data needs to transmit ATIM, it is necessary to open the ATIM window (become an awake state). However, in the case of a node that does not have data to be transmitted, that is, a node that receives ATIM, an ATIM window is unnecessary if ATIM is not received.

  In general, it is rare that all nodes constantly transmit and receive data. In many cases, data transmission / reception is performed only in a part of the transmission path of the ad hoc network (that is, between the nodes). In other words, in a normal case, there is a beacon interval at which each node does not transmit or receive data. The smaller the number of data transmissions in the entire network, the greater the number of such beacon intervals.

  Since the ATIM window of the beacon interval that does not receive such an ATIM is unnecessary and consumes power wastefully, the more sparse data transmission and reception in the entire network, the more unnecessary power consumption of each node. Will increase. In other words, the power consumption of the node can be reduced by reducing this unnecessary ATIM window.

  However, the node cannot grasp whether or not the node within the communicable range transmits data until the ATIM is received. Therefore, it is difficult to completely eliminate unnecessary ATIM windows without any information.

  However, transmission / reception of data is not performed completely at random, but is performed so that data is transmitted from the transmission source to the transmission destination. Therefore, generally, there are many trends in the flow of data when viewed from the entire network. Due to such a tendency, for example, a node with a small number of data transmission / reception and a node with a large number of times may occur. Even in one node, there are cases where there are times when data transmission / reception is high and low.

  The open / close control unit 123 of the communication apparatus 101 further reduces power consumption by controlling the number of ATIM windows in accordance with such a data transmission / reception tendency.

  More specifically, the opening / closing control unit 123 does not open the ATIM window in all beacon intervals (transition to the awake state), but if the number of data receptions (actually, the number of ATIMs received) is large, If the window frequency is increased and the number of data receptions is small, the ATIM window frequency is decreased (the beacon interval at which the ATIM window is not opened is increased).

  This will be described more specifically. The power supply setting unit 133 of the open / close control unit 123 determines the opening / closing pattern of the ATIM window according to the awake level determined by the awake level setting unit 131, and the power supply control unit 182 and the timer so as to operate as described above. The operation setting of 172 is performed.

  FIG. 5 is a diagram for explaining an opening / closing pattern of the ATIM window for each awake level.

  The control of the ATIM window is performed for each control section composed of a plurality of continuous beacon intervals. The control section length N indicating the length of the control section (number of beacon intervals), which is a control unit of this ATIM window, is arbitrary. In the following description, the control section length N = 3. That is, the control section 201 is configured by a beacon interval 211 to beacon interval 213, and the control section 202 is configured by a beacon interval 214 to beacon interval 216.

  An ATIM window 221 to an ATIM window 226 indicate the respective ATIM windows of the beacon interval 211 to the beacon interval 216.

  When the awake level is “1”, the ATIM window (ATIM window 221 and ATIM window 224) is used only in the first beacon interval (beacon interval 211 and beacon interval 214) of each control period, as indicated by arrows 231 and 234. ) Is opened. In other words, in other beacon intervals (beacon interval 212 and beacon interval 213, and beacon interval 215 and beacon interval 216), the ATIM window is not opened and the sleep state is maintained. That is, in this case, the power consumption is reduced as compared with a general PSM because the ATIM window 222, the ATIM window 223, the ATIM window 225, and the ATIM window 226 are omitted.

  When the awake level is “2”, as indicated by arrows 232 and 235, the first beacon interval (beacon interval 211 and beacon interval 214) of each control period and the next beacon interval (beacon interval 212 and The ATIM window (ATIM window 221 and ATIM window 222 and ATIM window 224 and ATIM window 225) of the beacon interval 215) is opened. In other words, in the last beacon interval (beacon interval 213 and beacon interval 216) of each control period, the ATIM window is not opened and the sleep state is maintained. That is, in this case, the power consumption is reduced as compared with a general PSM because the ATIM window 223 and the ATIM window 226 are omitted.

  When the awake level is “3”, as indicated by arrows 233 and 236, the ATIM window (ATIM window 221 to ATIM window 226) in all beacon intervals (beacon interval 211 to beacon interval 216) of each control period. Is opened. That is, in this case, the power consumption is the same as in the case of a general PSM.

  The awake level setting unit 131 obtains a determination value calculated based on the number of ATIM receptions, and when the frequency of data transmission / reception tends to be high based on the determination value, the awake level of the node is set in the ATIM window. Is set to “3”.

  In addition, when the frequency of data transmission / reception tends to be medium, the awake level setting unit 131 sets the awake level of the node to “2” where the frequency of the ATIM window is medium.

  Furthermore, when the frequency of data transmission / reception tends to be low, the awake level setting unit 131 sets the awake level of the node to “1” where the frequency of the ATIM window is low.

  The tendency of the frequency of data transmission / reception occurs based on various factors such as node performance and role, network configuration, data transmission pattern, and their temporal changes. In other words, it can be said that the tendency of the frequency of data transmission / reception indicates such network characteristics. That is, the awake level setting unit 131 sets the awake level according to the characteristics of the ad hoc network system 100 and controls the opening and closing of the ATIM window.

  If the frequency of the ATIM window is simply reduced, the power consumption is reduced, but the opportunity for data transmission may be reduced. That is, the throughput may be reduced. However, by controlling as described above, the frequency of the ATIM window can be appropriately controlled according to the tendency of data transmission / reception. That is, the communication apparatus 101 can reduce power consumption while suppressing a decrease in throughput.

  The pattern of the ATIM window at each awake level is arbitrary, and the ATIM window may be opened and closed with a pattern other than that shown in FIG. For example, when N = 6, the control section 201 and the control section 202 in FIG. 5 are one control section, and when the awake level is 1, the ATIM window 221 and the ATIM window 222 are opened, and when the awake level is 2 The ATIM window 221 to ATIM window 224 may be opened, and when the awake level is 3, the ATIM window 221 to ATIM window 226 may be opened. Of course, other patterns may be used. Further, the number of awake levels is also arbitrary.

  However, for example, as shown by arrows 231 to 236 in FIG. 5, regardless of the awake level, all the communication apparatuses 101 may perform ATIM in the first beacon interval (beacon interval 211 and beacon interval 214) of each control interval. A window may be opened. In this way, by making all nodes open the ATIM window in a part of the beacon interval of the control interval, that is, in the control interval, at least once, all the nodes are in the ATIM window at the same time. By doing so, it is possible to suppress a state in which the timing of the ATIM window does not mesh between nodes, and to suppress a decrease in throughput.

[Process flow]
Next, the flow of the above-described ATIM window opening / closing control will be described.

  When performing communication in the ad hoc mode, the communication apparatus 101 that does not hold data to be transmitted opens an ATIM window at a predetermined timing in order to receive data transmitted from another communication apparatus 101. At this time, the communication apparatus 101 executes an opening / closing control process to perform opening / closing control of the ATIM window. An example of the flow of the opening / closing control process will be described with reference to the flowchart of FIG.

  When the opening / closing control process is started, in step S101, the power supply control unit 182 starts an ATIM window at a predetermined time such as the start time of a beacon interval, for example, according to the time measurement result of the timer 172. If the communication apparatus 101 is in the sleep state immediately before that, the power supply control unit 182 starts supplying power to the wireless transmission / reception unit 122 and the like. That is, the communication apparatus 101 transitions from the sleep state to the awake state. Further, when the communication apparatus 101 is in an awake state immediately before the predetermined time, the power supply control unit 182 maintains the supply of power to the wireless transmission / reception unit 122 and the like. That is, the communication apparatus 101 maintains an awake state.

  In step S <b> 102, the wireless transmission / reception unit 122 monitors the ATIM, and when receiving the ATIM, supplies it to the awake level setting unit 131 and the power management unit 171. The ATIM reception number counting unit 141 of the awake level setting unit 131 counts the number of ATIM receptions by the wireless transmission / reception unit 122.

  In step S <b> 103, the power supply control unit 182 ends the ATIM window at a predetermined time after a predetermined time elapses from the start time of the beacon interval, for example, according to the time measurement result of the timer 172.

Here, in step S104, determination value calculating section 142 calculates the current determination value _{D n.} For example, the judgment value calculation unit 142 acquires the count value, that is, the ATIM reception number A in the current ATIM window from the ATIM reception number counting unit 141. Further, the judgment value calculation unit 142 requests and acquires the weight α and weight β held in the weight holding unit 152 from the threshold / weight supply unit 132. Furthermore, the judgment value calculation unit 142 acquires the previous judgment value D _n−1 held in the judgment value holding unit 143. Then, the determination value calculation unit 142 calculates the current determination value D _n based on the ATIM reception number A, the weight α and the weight β, and the previous determination value D _n−1 , and the following equation (1): Use to calculate.

In Expression (1), the weight α indicates the weight of the previous determination value D _n−1 . That is, the weight α is a parameter that controls the degree of influence of the past data transmission / reception tendency (awake level). On the other hand, the weight β indicates the weight of the ATIM reception number A. That is, the weight β is a parameter that controls the degree of influence of the current ATIM reception count.

  The larger the value of the weight α, the greater the influence of the past state (data transmission / reception tendency). That is, it becomes insensitive to the change in the data transmission / reception trend, and the awake level is difficult to change. On the other hand, the larger the value of the weight β, the greater the influence of the current ATIM reception number. In other words, it becomes sensitive to changes in data transmission / reception trends, and the awake level is likely to change.

  The optimum values of the weight α and the weight β vary depending on the network characteristics and the like. In addition, the calculation method of a judgment value is arbitrary. The determination value calculation unit 142 may calculate the determination value using an expression other than the expression (1) described above. However, since the past trend and the recent situation change amount can be appropriately reflected in the judgment value by using the above-described formula (1), the judgment value calculation unit 142 can be applied to more diverse network characteristics. On the other hand, an appropriate judgment value can be calculated.

  When the current determination value is calculated by the recursive function as described above, in step S105, the determination value holding unit 143 holds the current determination value calculated in step S104. In step S106, the ATIM reception number counting unit 141 initializes the ATIM reception number. For example, the ATIM reception number counting unit 141 resets the count value to the initial value “0”.

  In step S107, the determination unit 181 determines whether the wireless transmission / reception unit 122 has received an ATIM during the current ATIM window based on the ATIM supplied from the wireless transmission / reception unit 122. When it is determined that the ATIM has been received, the communication apparatus 101 needs to receive data during the remaining period of the beacon interval. Therefore, if it is determined that ATIM has been received, the process proceeds to step S108.

  In step S108, the power supply control unit 182 continues to supply power to the wireless transmission / reception unit 122 and the like and maintains an awake state until the next ATIM window (next beacon interval) in order to receive data. . When the process of step S108 ends, the opening / closing control process ends.

  In this case, since the communication apparatus 101 has received the data, it operates as a node that transmits the data in the next beacon interval.

  If it is determined in step S107 that no ATIM is received during the ATIM window, data is not transmitted from the other communication apparatus 101 in the beacon interval. Therefore, the process proceeds to step S109 in order to control the opening and closing of the ATIM window according to the characteristics of the network as described above.

In step S109, the level determination unit 144 acquires the current determination value D _n calculated in step S104 from the determination value holding unit 143 (or from the determination value calculation unit 142). Further, the level determination unit 144 requests and acquires the threshold value S ₁ and the threshold value S ₂ held in the threshold value holding unit 151 from the threshold value / weight supply unit 132. Then, the level determining unit 144, their judgment value D _n, and, based on a threshold S ₁ and a threshold S _2, to determine the awake level using the following equation (2).

In other words, this judgment value D _n is when the threshold S ₁ is smaller than, awake level is set to "1". Further, when the current determination value D _n is _equal to or greater than the threshold value S ₁ and equal to or less than the threshold value S ₂ , the awake level is set to “2”. Further, this judgment value D _n is larger than the threshold value S _2, the awake level is set to "3".

The value of the threshold S ₁ and the threshold S ₂ is arbitrary as long a positive number. These optimum values vary depending on network characteristics and the like.

As described above, the level determining unit 144 determines the awake level by the magnitude of the value of the judgment value D _n. As shown in Expression (1), the value of the determination value D _n increases as the number of ATIM receptions increases. That is, the higher the awake level is set for the node (communication device 101) having the higher data transmission / reception frequency.

  When the awake level is determined, in step S110, the power supply setting unit 133 performs power supply setting. Details of the power supply setting process will be described later.

  When the power supply setting is completed, in step S111, the power supply control unit 182 cuts off the power supply to the wireless transmission / reception unit 122 and the like according to the power supply setting, transitions from the awake state to the sleep state, and the next ATIM window Until sleep. When the process of step S111 is terminated, the opening / closing control process is terminated.

  In this case, since no data is received, the communication apparatus 101 operates as a node that receives data even in the next beacon interval. That is, the communication apparatus 101 performs this opening / closing control process in the beacon interval that opens the ATIM window next time.

  Next, an example of the flow of the power supply setting process executed in step S110 of FIG. 6 will be described with reference to the flowchart of FIG.

  When the power supply setting process is started, the power supply setting unit 133 first requests and acquires the control section length N held in the control section length holding unit 161 from the control section length supply unit 134. . In addition, the power supply setting unit 133 requests and acquires a count value from the beacon interval count unit 135.

  In step S131, the power supply setting unit 133 determines whether or not the current beacon interval is the first beacon interval in the control interval based on the count value acquired from the beacon interval count unit 135 and the like.

  As described with reference to FIG. 5, the ATIM window is opened in the first beacon interval in any of the awake level 1 to the awake level 3. Therefore, if it is determined that the beacon interval is the first time, the process proceeds to step S132.

  In step S132, the power supply setting unit 133 determines whether or not the awake level determined in step S109 of FIG. 6 is “1”. If it is determined that the awake level is “1”, the process proceeds to step S133.

  As shown in FIG. 5, in the case of awake level 1, the ATIM window is opened only in the first beacon interval of the control interval. Therefore, in step S133, the power supply setting unit 133 determines the next ATIM window as the third beacon interval (next next beacon interval) from the current time. In this case, as described with reference to FIG. 6 (step S111), the sleep state is maintained for all the periods until the next ATIM window (the remaining period of the current beacon interval and two beacon intervals). .

  If it is determined in step S132 that the awake level is not “1”, the process proceeds to step S134. As described with reference to FIG. 5, in the case of the awake level 2 or the awake level 3, the ATIM window is opened also in the second beacon interval of the control section.

  Therefore, in step S134, the power supply setting unit 133 determines the next ATIM window as the next beacon interval. In this case, as described with reference to FIG. 6 (step S111), the sleep state is maintained throughout the period until the next ATIM window (the remaining period of the current beacon interval).

  If it is determined in step S131 that it is not the first beacon interval, the process proceeds to step S135.

  In step S135, the power supply setting unit 133 determines whether or not the current beacon interval is the second beacon interval of the control interval based on the count value acquired from the beacon interval count unit 135 and the like.

  As described with reference to FIG. 5, the ATIM window is opened in the second beacon interval when the awake level is “2” or “3”. Therefore, when it is determined that the beacon interval is the second time, the process proceeds to step S136.

  In step S136, the power supply setting unit 133 determines whether or not the awake level determined in step S109 in FIG. 6 is “2”. If it is determined that the awake level is “2”, the process proceeds to step S137.

  As shown in FIG. 5, in the case of the awake level 2, the ATIM window is not opened in the last beacon interval of the control interval. Accordingly, in step S137, the power supply setting unit 133 determines the next ATIM window as the second beacon interval (next next beacon interval) from the present time. In this case, as described with reference to FIG. 6 (step S111), the sleep state is maintained for all the period until the next ATIM window (the remaining period of the current beacon interval and the next beacon interval). .

  If it is determined in step S136 that the awake level is not “2”, that is, it is awake level 3, the process proceeds to step S134. As described with reference to FIG. 5, in the case of the awake level 3, the ATIM window is opened also in the last beacon interval of the control section.

  Therefore, as described above, the power supply setting unit 133 determines the next ATIM window as the next beacon interval in step S134.

  If it is determined in step S135 that it is not the second beacon interval, that is, the third beacon interval, the process proceeds to step S134. As described with reference to FIG. 5, the third beacon interval is the last beacon interval of the control section. In addition, the ATIM window is opened only in the case of the awake level 3 in the third beacon interval. Therefore, as described above, the power supply setting unit 133 determines the next ATIM window as the next beacon interval in step S134.

  When the process of step S133, step S134, or step S137 ends, the process proceeds to step S138.

  In step S138, the power supply setting unit 133 performs operation settings of the power management unit 171 and the timer 172 according to the determination in step S133, step S134, or step S137. That is, the power supply setting unit 133 sets the timer 172 to measure the time until the next ATIM window, the communication apparatus 101 maintains the sleep state for the period until the next ATIM window, and starts the next ATIM window. The power management unit 171 is set so as to transit to the awake state at the time.

  When the process of step S138 is completed, the power supply setting process is terminated, the process returns to step S110 of FIG. 6, and the processes after step S111 are performed.

  As described above, by controlling opening and closing of the ATIM window, the communication apparatus 101 can reduce power consumption while suppressing a decrease in throughput.

[simulation]
Next, a simulation of such ATIM window opening / closing control will be described.

  The simulation is performed using the network simulator QualNet (ver4.5). Since the nodes are single-hop, 30 fixed nodes that do not move within the range of 200 m × 200 m are arranged so that all the nodes are within the range where wireless communication is possible. The simulation time is 300 s, the beacon interval is 100 ms, and the ATIM window length is 30 ms. In addition, the routing protocol used Bellman Ford, where each node exchanges information by broadcasting data.

  It is assumed that CBR (Constant Bit Rate) packet communication is performed randomly in synchronization with the beacon. FIG. 8A shows a range that the set value can take. The number of communication execution nodes is 15 and a network that operates with PSM and has a relatively low communication frequency. For communication of CBR packets, a pair of a transmission node and a reception node is determined, and the transmission node transmits packets to the reception node for every transmission interval from the transmission start time to the reception node until the number of transmission packets is exhausted. If the transmission time ends before the transmission of all the transmission packets, the untransmitted packet cannot be transmitted.

  The power consumption in each state is shown in Fig. 8B. The awake state is a transmit mode in which data is transferred, a receive mode in which data is received, and an idle mode in which neither data is received nor transmitted but is awake and wastes power. It is divided into three. On the other hand, the power consumption in the sleep mode (Sleep mode) is 4.5 mW, which is significantly smaller than the awake state of 100 mW or more.

  Note that the control section length N = 3. The pattern of the ATIM window at each awake level is the same as the pattern described with reference to FIG. In the simulation, the case where this control method is applied, the case where the ATIM window is opened in every beacon interval, and the case where the length of the beacon interval is three times are compared.

Next, the values of the weight α, the weight β, the threshold value S ₁ , and the threshold value S ₂ are determined. An experiment was performed in which one communication environment in which random values were set in accordance with the setting conditions described above was created, and a threshold value and a weight value having the lowest power consumption common to all nodes participating in the simulation were determined.

First, the weight α is determined. The graph of FIG. 9A shows the result of changing the weight α with the weight β = 8, the threshold S ₁ = 0.1, the threshold S ₂ = 1. The weights α and β are values that determine the number of times the ATIM window is opened based on the number of ATIMs received (that is, the communication frequency of the node). According to the equation (1), the larger the value of the weight α and the weight β, the longer the period in which the frequency of the ATIM window becomes higher. Conversely, the smaller the values, the lower the number of times that the ATIM window is opened.

  In other words, in general, by reducing the values of the weight α and the weight β, the ATIM window is not easily opened and the frequency of transition to the awake state is reduced, so the sleep state is prolonged and power consumption is suppressed. . However, if the values of the weight α and the weight β are too small, there is a high possibility that the transmission request destination node is in the sleep state. In this case, since transmission / reception of data becomes impossible, the number of times the node transmitting data opens the ATIM window increases. This may increase the power consumption of the node that transmits data.

  When the value of the weight α is “1”, the awake level finally converges to “3”, and the ATIM window is opened in all beacon intervals. That is, it becomes the same as the case of general PSM.

  On the other hand, when the value of the weight α is “0”, the awake level finally converges to “1”. That is, the ATIM window is opened once every three beacon intervals. That is, it becomes the same as general PSM when the length of the beacon interval is tripled.

  In this simulation, PSM is set to operate in an environment with relatively low communication frequency. Therefore, since the decrease in power consumption due to the increase in the period of the sleep state of the node receiving data is superior to the increase in power consumption due to the increase in the number of transmission attempts due to transmission errors in the node transmitting data, This control method reduces power consumption compared to general PSM.

  Depending on the value of the weight α, the power consumption changes as shown in the graph of FIG. 9A. Therefore, the value of the weight α is “0.3” when the power consumption is minimized.

Next, the power consumption corresponding to the value of the weight β when the weight α = 0.3, the threshold S ₁ = 0.1, and the threshold S ₂ = 1 is shown in the graph of FIG. 9B.

  When the value of the weight β is “0”, the awake level finally converges to “1”, and the ATIM window is opened once every three beacon intervals. That is, it becomes the same as general PSM when the length of the beacon interval is tripled.

  As shown in FIG. 9B, when the value of the weight β is “3”, the power consumption is suppressed most. Accordingly, the value of the weight β is set to “3”.

Next, the power consumption corresponding to the value of the threshold S ₁ when the weight α = 0.3, the weight β = 3, and the threshold S ₂ = 1 is shown in the graph of FIG. 10A. The threshold value S ₁ and the threshold value S _2, from the judgment value D _n, a threshold value for determining the awake level representing the open or many times ATIM window during three beacon interval. When threshold value S ₁ = 0, there is no setting of awake level 1 (all nodes are set to awake level 2 or awake level 3). Therefore, in this case, the power consumption of the entire network increases as compared to the case where all settings of awake level 1 to awake level 3 exist.

As shown in FIG. 10A, the power consumption is most suppressed when the threshold value S ₁ = 0.075, and therefore, the value of the threshold value S ₁ is set to “0.075”.

Finally, determine the threshold _{S 2.} And a weight alpha = 0.3, and the weight beta = 3, indicating when the threshold value _S 1 = 0.075, the power consumption according to the value of the threshold _{S 2} in the graph of FIG. 10B. If threshold S ₂ = 0.075, that is, threshold S ₁ = threshold S ₂ , there is no setting for awake level 2. Therefore, power consumption is large. As shown in FIG. 10B, the power consumption is most suppressed when the threshold value S ₂ = 1, and the value of the threshold value S2 is set to “1”.

  A method for controlling the opening and closing of the ATIM window according to the characteristics of the network described above (proposed), a general PSM method (802.11) when the method and the beacon interval length are the same, and the length of the beacon interval FIG. 11 shows an ATIM window pattern in each case with a general PSM method (Interval * 3) when the length is 3 times.

  As illustrated in FIG. 11, it is assumed that the control section 301 includes beacon intervals 311 to 313 and the control section 302 includes beacon intervals 314 to 316.

  In the case of the first general PSM method (802.11), the ATIM window is opened in all beacon intervals like the ATIM window 321 to the ATIM window 326. In the case of the second general PSM method (Interval * 3), the ATIM window is opened once every three beacon intervals, as in the ATIM window 331 and the ATIM window 332.

  Furthermore, in the case of this method (proposed) for controlling the opening and closing of the ATIM window according to the characteristics of the network, the ATIM window 341 to ATIM window 346 are opened according to the awake level as described above with reference to FIG. It is.

As described above, the final weight and threshold values are weight α = 0.3, weight β = 3, threshold S ₁ = 0.075, and threshold S ₂ = 1. FIG. 12 is a diagram for explaining an example of the simulation result in this case.

  FIG. 12A is a diagram showing a comparison of power consumption of each method, and FIG. 12B is a diagram showing a comparison of throughput of each method. As shown in FIG. 12A, the power consumption is lowest in the case of the second general PSM method (Interval * 3), and is about 37% of that in the case of the first general PSM method (802.11). Reduced. On the other hand, the power consumption of this method is reduced by about 30% compared to the case of the first general PSM method (802.11), and the second general PSM method ( It is larger than the case of Interval * 3).

  However, as shown in FIG. 12B, in the case of the second general PSM method (Interval * 3), the throughput is significantly reduced, compared to the case of the first general PSM method (802.11). It decreases by about 33%. On the other hand, in the case of this method, the throughput is about 2% lower than that in the case of the first general PSM method (802.11).

  Thus, in the case of this method, compared with the case of the first general PSM method (802.11), it is possible to reduce the power consumption by about 30% while suppressing the reduction of the throughput to about 2%. it can.

  As described above, the communication apparatus 101 can suppress power consumption while suppressing a decrease in throughput. In FIG. 4, the wireless transmission / reception unit 122 may separate the transmission unit and the reception unit. That is, the power supply control for the transmission unit and the power supply control for the reception unit may be different from each other.

  In the above description, the number of ATIM windows for a control section composed of a plurality of consecutive beacon intervals is controlled. However, the present invention is not limited to this, and the control section is a single beacon interval. It is also possible to open the ATIM window a plurality of times, and to control the number of ATIM windows during one beacon interval. For example, in FIG. 5, the control section 201 and the control section 202 may be beacon intervals, and the number of ATIM windows provided therein may be controlled according to the awake level. The control method in that case can be basically performed in the same manner as described above, only by changing the unit (for example, the name of the period) for which control is performed.

  That is, in this case as well, it is desirable to provide at least one timing at which all nodes are in the ATIM window during each beacon interval.

<2. Second Embodiment>
[Device Configuration]
In the first embodiment, it has been described that the parameters of the weight α, the weight β, the threshold value S ₁ , the threshold value S ₂ , and the control section length N are set in advance. It may be variable according to the communication status.

  FIG. 13 is a block diagram showing another configuration example of the communication apparatus of FIG. A communication apparatus 401 shown in FIG. 13 corresponds to the communication apparatus 101 of FIG. 4 and has basically the same configuration as the communication apparatus 101.

  However, the communication device 401 in FIG. 13 includes an open / close control unit 423 instead of the open / close control unit 123 of the communication device 101. In addition, the communication device 401 further includes an input unit 425. The input unit 425 is a user interface such as a button or a switch that accepts an instruction from the user. The input unit 425 supplies the received user instruction to the opening / closing control unit 423.

  The opening / closing control unit 423 basically has the same configuration as the opening / closing control unit 123. However, the open / close control unit 423 includes a threshold / weight supply unit 432 instead of the threshold / weight supply unit 132, and includes a control section length supply unit 434 instead of the control section length supply unit 134.

  The threshold / weight supply unit 432 further includes a threshold setting unit 451 and a weight setting unit 452 in addition to the threshold holding unit 151 and the weight holding unit 152.

  The wireless transmission / reception unit 122 supplies information serving as a parameter representing the communication status, such as the received ATIM, to the threshold / weight supply unit 432 and the control interval length supply unit 434.

The threshold setting unit 451 sets the threshold S ₁ and the threshold S ₂ to optimum values according to the communication status based on information supplied from the wireless transmission / reception unit 122 or a user instruction supplied from the input unit 425. For example, the threshold setting unit 451 generates a graph as illustrated in FIG. 10A or FIG. 10B based on information supplied from the wireless transmission / reception unit 122 or a user instruction supplied from the input unit 425, and the power consumption is reduced. as best lowered, it sets the threshold value _{S 1} and the threshold _{S 2.} The threshold value holding unit 151 holds the values of the threshold value S ₁ and the threshold value S ₂ set by the threshold value setting unit 451.

  The weight setting unit 452 sets the weight α and the weight β to optimum values according to the communication status based on the information supplied from the wireless transmission / reception unit 122 and the user instruction supplied from the input unit 425. For example, the weight setting unit 452 generates a graph as shown in FIG. 9A or 9B based on information supplied from the wireless transmission / reception unit 122 or a user instruction supplied from the input unit 425, and the power consumption is reduced. The weight α and the weight β are set so as to be the lowest. The weight holding unit 152 holds the values of the weight α and the weight β set by the weight setting unit 452.

  The control section length supply unit 434 has a control section length setting unit 461 in addition to the control section length holding unit 161.

  The control section length setting unit 461 sets the control section length N to an optimum value according to the communication status based on the information supplied from the wireless transmission / reception unit 122 and the user instruction supplied from the input unit 425. The control section length holding unit 161 holds the value of the control section length N set by the control section length setting unit 461. The ATIM window pattern of each awake level is set according to the value of this control section length N by the power supply setting unit 133, for example.

  The judgment value calculation unit 142, the level determination unit 144, and the power supply setting unit 133 perform various processes using the various parameters set in this way. Since each processing content is the same as that described in the first embodiment, the description thereof is omitted.

  Thus, by making each parameter variable, the communication apparatus 101 can perform more appropriate control of the ATIM window with respect to the characteristics of the network. That is, the communication apparatus 101 can more appropriately reduce power consumption while suppressing a decrease in throughput.

<3. Third Embodiment>
[Personal computer]
The series of processes described above can be executed by hardware or can be executed by software. In this case, for example, it may be configured as a personal computer as shown in FIG.

  In FIG. 14, a CPU (Central Processing Unit) 501 of the personal computer 500 performs various processes according to a program stored in a ROM (Read Only Memory) 502 or a program loaded from a storage unit 513 to a RAM (Random Access Memory) 503. Execute the process. The RAM 503 also appropriately stores data necessary for the CPU 501 to execute various processes.

  The CPU 501, ROM 502, and RAM 503 are connected to each other via a bus 504. An input / output interface 510 is also connected to the bus 504.

  The input / output interface 510 includes an input unit 511 including a keyboard and a mouse, a display including a CRT (Cathode Ray Tube) and an LCD (Liquid Crystal Display), an output unit 512 including a speaker, and a hard disk. A communication unit 514 including a storage unit 513 and a modem is connected. The communication unit 514 performs communication processing via a network including the Internet.

  A drive 515 is connected to the input / output interface 510 as necessary, and a removable medium 521 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory is appropriately mounted, and a computer program read from them is It is installed in the storage unit 513 as necessary.

  When the above-described series of processing is executed by software, a program constituting the software is installed from a network or a recording medium.

  For example, as shown in FIG. 14, the recording medium is distributed to distribute the program to the user separately from the apparatus main body, and includes a magnetic disk (including a flexible disk) on which the program is recorded, an optical disk ( It only consists of removable media 521 consisting of CD-ROM (compact disc-read only memory), DVD (including digital versatile disc), magneto-optical disc (including MD (mini disc)), or semiconductor memory. Rather, it is composed of a ROM 502 on which a program is recorded and a hard disk included in the storage unit 513, which is distributed to the user in a state of being pre-installed in the apparatus main body.

  The program executed by the computer may be a program that is processed in time series in the order described in this specification, or in parallel or at a necessary timing such as when a call is made. It may be a program for processing.

  Further, in the present specification, the step of describing the program recorded on the recording medium is not limited to the processing performed in chronological order according to the described order, but may be performed in parallel or It also includes processes that are executed individually.

  Further, in this specification, the system represents the entire apparatus composed of a plurality of devices (apparatuses).

  In addition, in the above description, the configuration described as one device (or processing unit) may be divided and configured as a plurality of devices (or processing units). Conversely, the configurations described above as a plurality of devices (or processing units) may be combined into a single device (or processing unit). Of course, a configuration other than that described above may be added to the configuration of each device (or each processing unit). Furthermore, if the configuration and operation of the entire system are substantially the same, a part of the configuration of a certain device (or processing unit) may be included in the configuration of another device (or other processing unit). . That is, the embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

  100 ad hoc network system, 101 communication device, 122 wireless transmission / reception unit, 123 switching control unit, 124 power supply unit, 131 awake level setting unit, 132 threshold / weight supply unit, 133 power supply setting unit, 134 control section length supply unit, 135 beacon interval count unit, 141 ATIM reception number count unit, 142 judgment value calculation unit, 143 judgment value holding unit, 144 level determination unit, 151 threshold holding unit, 152 weight holding unit, 161 control section length holding unit, 171 power management Unit, 172 timer, 173 battery unit, 181 determination unit, 182 power supply control unit, 401 communication device, 423 open / close control unit, 425 input unit, 432 threshold / weight supply unit, 434 control interval length supply unit, 451 threshold setting unit 452 weight setting unit, 461 control section length setting unit

Claims (11)

An information processing apparatus that transmits / receives data to / from another information processing apparatus,
Communication means for communicating with the other information processing apparatus;
Control means for controlling power supply in the information processing apparatus;
A calculation means for calculating a judgment value indicating a tendency of the frequency of the data transmission / reception by the communication means, using the number of reception notification signals for notifying the transmission of the data;
Based on the determination value calculated by the calculation means, a period for receiving the transmission advance notice signal, and an advance notice period in which the operation state of the information processing apparatus is in an awake state in which the data can be transmitted and received A determination means for determining the frequency of
In accordance with the frequency of the advance notice period determined by the determining means, at least once within the predetermined control period, in accordance with a predetermined pattern that is set in advance so that all the information processing devices simultaneously enter the advance notice period. An information processing apparatus comprising: an operation setting unit configured to perform an operation setting of the control unit until the advance notice period. The calculation unit calculates the determination value by adding a multiplication result of the past determination value and a predetermined first weighting factor and a multiplication result of the received number and a predetermined second weighting factor. The information processing apparatus according to claim 1. The information processing apparatus according to claim 2, further comprising weight setting means for setting the first weight coefficient and the second weight coefficient. The determination means compares the determination value with a predetermined first threshold value and a second threshold value to determine an awake level that represents the frequency of the notice period divided into levels,
The information processing apparatus according to claim 1, wherein the operation setting unit performs operation setting of the control unit until the next notice period according to the pattern determined for each awake level determined by the determination unit. . The information processing apparatus according to claim 4, further comprising threshold setting means for setting the first threshold and the second threshold. When the transmission notice signal is not received during the notice period, the operation setting means sets the operation state of the information processing apparatus to a sleep state in which the data transmission / reception is impossible until the next notice period. The information processing apparatus according to claim 1, wherein, when the transmission notice signal is received during the notice period, the operation state of the information processing apparatus is set to the awake state until the next notice period. The information processing apparatus according to claim 1, further comprising: a control period length setting unit that sets a length of the control period. The information processing apparatus according to claim 1, wherein the communication unit communicates with the other information processing apparatus in an ad hoc mode. The information processing apparatus according to claim 1, wherein the communication unit performs wireless communication with the other information processing apparatus. An information processing method for an information processing apparatus that transmits / receives data to / from another information processing apparatus,
The calculation means calculates a judgment value indicating a tendency of the frequency of the data transmission / reception by the communication means, using the number of reception notice signals for notifying the transmission of the data,
The determination means is a period for receiving the transmission advance notice signal based on the calculated judgment value, and the advance notice period in which the operation state of the information processing apparatus is in an awake state in which the data can be transmitted and received. Determine the frequency of
In accordance with the determined frequency of the notice period, the operation setting means, according to a predetermined pattern that is set in advance so that all the information processing devices are simultaneously in the notice period at least once within the predetermined control period, An information processing method for performing operation setting of a control means for controlling power supply in the information processing apparatus until the next notice period. A computer that sends and receives data to and from other information processing devices
A communication means for communicating with the other information processing apparatus;
Control means for controlling power supply in the information processing apparatus;
A calculating means for calculating a judgment value indicating a tendency of the frequency of the data transmission / reception by the communication means, using the number of transmission notice signals for notifying the transmission of the data;
Based on the determination value calculated by the calculation means, a period for receiving the transmission advance notice signal, and an advance notice period in which the operation state of the information processing apparatus is in an awake state in which the data can be transmitted and received Determining means for determining the frequency of
In accordance with the frequency of the advance notice period determined by the determining means, at least once within the predetermined control period, in accordance with a predetermined pattern that is set in advance so that all the information processing devices simultaneously enter the advance notice period. A program for functioning as an operation setting means for setting the operation of the control means until the notice period.

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