JP6892995B2 - Radio communication systems, radios, and programs - Google Patents

Description

The present invention relates to a radio communication system, a radio, and a program in which a plurality of radios perform RIT communication.

In recent years, a method using RIT (Receiver Initiated Transmission) has been studied (for example, Patent Document 1). The RIT method is a method in which the RIT Data Request Frame is periodically transmitted from the receiver to the transmitter, and the transmitter transmits the target data to be transmitted in synchronization with the received RIT Data Request Frame.

In the conventional CSL (Coordinated Sampled Listening) method, the receiver is in the reception standby state at predetermined intervals, and when the target data is generated, the transmitter continuously transmits Wakeup Sequence for a period of a predetermined interval or longer. On the other hand, in the RIT method, even if the interval between the RIT Data Request Frames becomes long, it is not necessary to continuously transmit the Wakeup Sequence unlike the CSL method, and the radio band is not occupied. Therefore, in the RIT method, the communication success rate is improved as compared with the CSL method.

JP-A-2015-53593

However, in the RIT method, when the target data is generated, the RIT Data Request Frame from the transmission destination of the target data is simply kept waiting. Therefore, as the communication volume of the system increases and the communication frequency increases, the occupancy ratio of the reception standby state waiting for the RIT Data Request Frame from the destination increases for the entire period. Then, simply waiting for the RIT Data Request Frame from the destination cannot receive the target data from another radio, so that deadlock between the target data may occur and the success rate of communication establishment may decrease. ..

In view of such a problem, an object of the present invention is to provide a wireless communication system, a wireless device, and a program that suppress a decrease in the communication success rate even if the communication frequency is high.

In order to solve the above problems, in the wireless communication system of the present invention, the first radio communicates with the second radio in a RIT system in which the first radio periodically attempts to transmit the RIT Data Request Frame, and the first radio communicates with the second radio. If the target data is data to be transmitted, it is first reception waiting state in which the reception waiting of the RIT data Request Frame, upon receiving the RIT data Request Frame from the second radio at the first reception waiting state , A transmission control unit that transmits the target data to the second radio, and a second reception standby that transmits the RIT Data Request Frame and enables reception of the target data for the transmitted RIT Data Request Frame for a predetermined period after the transmission. The second radio is in the first reception standby state if there is target data, and when the RIT Data Request Frame is received from the first radio in the first reception standby state, the second radio is provided with a reception control unit that is in a state. A transmission control unit for transmitting target data to the first radio unit is provided, and the reception control unit of the first radio unit is in the first reception standby state when the transmission timing of the RIT Data Request Frame is reached in the first reception standby state. In parallel with this, the RIT Data Request Frame is transmitted to the second radio to enter the second reception standby state.

In order to solve the above problems, the radio of the present invention that performs RIT-type communication that attempts to periodically transmit the RIT Data Request Frame is the RIT Data Request Frame if there is target data that is the data to be transmitted. When the RIT Data Request Frame is received from another radio in the first reception standby state in the first reception standby state, the transmission control unit that transmits the target data to the other radio and the RIT The reception control unit includes a second reception standby state in which the Data Request Frame is transmitted and the target data can be received for the transmitted RIT Data Request Frame for a predetermined period after the transmission. When the transmission timing of the RIT Data Request Frame comes in the 1 reception standby state, the RIT Data Request Frame is transmitted to another radio in parallel with the transmission standby state, and the second reception is received. It will be in the standby state.

In order to solve the above problems, the program of the present invention, a computer that communicates RIT system periodically attempts to send the RIT Data Request Frame, if the target data is data to be transmitted, RIT Data Request When the RIT Data Request Frame is received from another radio in the first reception standby state in which the reception standby of the frame is performed, the transmission control unit that transmits the target data to the other radio and the transmission control unit The reception control unit functions as a reception control unit that is in the second reception standby state in which the RIT Data Request Frame is transmitted and the target data can be received for the transmitted RIT Data Request Frame for a predetermined period after the transmission. When the transmission timing of the RIT Data Request Frame comes in the first reception standby state, while maintaining the first reception standby state, in parallel with this, the RIT Data Request Frame is transmitted to another radio. The second reception standby state is set.

According to the present invention, it is possible to suppress a decrease in the communication success rate even if the communication frequency is high.

It is explanatory drawing which showed the schematic structure of the wireless communication system. It is a functional block diagram which showed the schematic structure of the radio. It is the first figure for demonstrating the RIT method. It is a 2nd figure for demonstrating the RIT method. It is a figure for demonstrating the RIT method of the comparative example. It is a figure which shows the relationship between the communication frequency and the communication success rate in the comparative example. It is a figure for demonstrating the improved RIT system. It is a figure which shows the relationship between the communication frequency and the communication success rate in the improved RIT system.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, other specific numerical values, etc. shown in the embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are designated by the same reference numerals to omit duplicate description, and elements not directly related to the present invention are not shown. To do.

(Wireless Communication System 100)
FIG. 1 is an explanatory diagram showing a schematic configuration of a wireless communication system 100. As shown in FIG. 1, the wireless communication system 100 includes a wireless device 110 and a gateway device 112. For example, the wireless communication system 100 is associated with a smart meter. A smart meter is, for example, a device used when supplying gas from a gas company to a consumer and automatically reads the amount of gas used.

The radio 110 is provided in each smart meter and at least transmits / receives data used in the smart meter. The gateway device 112 is installed in association with the smart meter, collects data of one or more radios 110, and distributes data to one or more radios 110. The center device 114 is a device composed of a computer or the like and belongs to the administrator side of the wireless communication system 100 such as a gas company or an electric power company, collects data of the gateway device 112, and collects data for the gateway device 112. To deliver. A plurality of groups G of the radio 110 that communicates with the center device 114 via the gateway device 112 and the gateway device 112 are provided.

Here, wireless communication is executed between the gateway device 112 and the center device 114 using, for example, a communication network such as a mobile phone network including a base station 116 or a PHS (Personal Handyphone System) network. Further, wireless communication is executed between the radios 110 and between the radios 110 and the gateway device 112, for example, through a RIT (Receiver Initiated Transmission) method described later.

In this embodiment, smart meters are arranged for each of a plurality of consumers. Further, the smart meter is associated with the radio 110 or the gateway device 112, respectively, and the center device 114 collects the smart meter information or controls the smart meter through the radio 110 or the gateway device 112. Therefore, the radio 110 and the gateway device 112 are arranged at a plurality of positions where the consumer exists.

In the wireless communication system 100 for smart meters, multi-hop communication based on the RIT method is performed between a plurality of wireless devices 110. The RIT method is used for multi-hop communication in which data is transmitted and received between terminals (nodes) by a relay method and the route of the terminal can be changed according to the radio wave condition, and the communication standard IEEE802.154 / 4e It is a communication method that realizes low power consumption in compliance with. In this embodiment, an improved RIT method to which a technique for suppressing a decrease in the communication success rate is applied is adopted. Hereinafter, the configuration of the radio 110 will be described, and then the improved RIT system will be described in detail.

(Radio 110)
FIG. 2 is a functional block diagram showing a schematic configuration of the radio 110. The radio 110 includes a communication unit 150, a storage unit 152, and a central control unit 154. The communication unit 150 establishes wireless communication with the gateway device 112 and another radio 110. The storage unit 152 is composed of a ROM, a RAM, a flash memory, an HDD, and the like, and stores programs and various data used in the radio 110.

The central control unit 154 is composed of a CPU and a DSP, and controls the entire radio 110 by using a program stored in the storage unit 152. Further, the central control unit 154 functions as a communication control unit 160 (transmission control unit, reception control unit) and a memory control unit 162.

The communication control unit 160 controls the communication unit 150 and performs improved RIT-type multi-hop communication with the gateway device 112 and other radios 110.

The storage control unit 162 acquires data such as the amount of gas used from a smart meter provided with its own unit (radio 110) and stores it in the storage unit 152. Further, the storage control unit 162 stores the data transmitted from the gateway device 112 and the other radio 110 in the storage unit 152.

In this way, the radio 110 stores the data of the smart meter and the data received from the other radio 110 and the gateway device 112, and the data stored in the storage unit 152 can be stored in the storage unit 152 as needed by the other radio. It is transmitted to 110 or the gateway device 112. Hereinafter, such data to be transmitted will be referred to as target data.

Further, the communication control unit 160 functions as a transmission control unit when transmitting the target data to the other radio 110, and functions as a reception control unit when receiving the target data from the other radio 110.

FIG. 3 is a first diagram for explaining the RIT method. Here, a case where the radios 110a and 110b perform RIT type wireless communication will be described. As shown in FIG. 3, the radio 110a (second radio) and the radio 110b (first radio) have RIT Data Request Frames (in the figure, in the figure) at preset intermittent operation intervals (MAC RIT Period). (Indicated by frame RFa and frame RFb) is transmitted. The RIT Data Request Frame has a frame configuration similar to that of the MAC unit of the communication standard IEEE802.154.

Specifically, the frames RFa and RFb transmitted by the radios 110a and 110b include, for example, a network ID (PANID: Personal Area Network ID) of the own unit (radio 110a, 110b) and a PAN to which the own unit is added. Identification information) and address information (identification information for identifying each radio 110 included in the wireless communication system 100) and the like are included. Further, the radios 110a and 110b store network IDs and address information related to other radios 110 that transmit target data to their own units in the storage unit 152, and the frames RFa and RFb store the network IDs. And address information is also included.

Then, after the transmission of the frames RFa and RFb, the radios 110a and 110b are put into the WD (RIT Data Wait Duration) and the second reception standby state for a predetermined period set in advance. The second reception standby state is a state in which the central control unit 154 controls the communication unit 150 so that the function required for receiving the target data is effective.

FIG. 4 is a second diagram for explaining the RIT method. As shown in FIG. 4, when the target data TDFa is acquired in the radio 110a or the target data TDFa is generated internally, the radio 110a is in the first reception standby state as shown by hatching in FIG. Become. The first reception standby state is a state in which the central control unit 154 controls the communication unit 150 so that the functions required for receiving the frames RFa and RFb are effective.

Then, the radio 110a receives the frame RFb transmitted by the radio 110b. If the network ID and address information included in the frame RFb indicate the own device, the radio 110a transmits the target data TDFa to the radio 110b.

Since the radio 110b is in the second reception standby state after transmitting the frame RFb, it is possible to receive the target data TDFa transmitted by the radio 110a.

As described above, in the RIT method, the target data TDFa can be received by the radio 110b intermittently transmitting the frame RFb. Therefore, for example, the power consumption can be significantly reduced as compared with the CSL (Coordinated Sampled Listening) method in which the transmitter continuously transmits the Wakeup Frame called Wakeup Sequence to promote the reception of the receiver.

FIG. 5 is a diagram for explaining the RIT method of the comparative example. As shown in FIG. 5, in the comparative example, it is assumed that the radio device 10a acquires the target data TDFa to be transmitted to the radio device 10b, or the target data TDFa to be transmitted to the radio device 10b is generated internally. Similarly, it is assumed that the target data TDFb to be transmitted to the radio 10a by the radio 10b is acquired, or the target data TDFb to be transmitted to the radio 10a is generated internally.

As described above, after the generation (acquisition) of the target data TDFa and TDFb, the radios 10a and 10b are in the first reception standby state. Then, in the radios 10a and 10b in the first reception standby state, the frames RFa and RFb are not transmitted even when the transmission timing of the frames RFa and RFb is reached.

As a result, the radios 10a and 10b do not transmit the frames RFa and RFb, and the target data TDFa and TDFb are not transmitted from the radio 10a to the radio 10b and from the radio 10b to the radio 10a. It ends up. That is, the communication between the radios 10a and 10b is deadlocked and fails (so-called matchmaking problem).

The deadlock here refers to the following states. That is, in the specification that the radio 10a does not transmit the frame RFa in the first reception standby state, it is assumed that the radio 10a is in the first reception standby state waiting for the frame RFb transmitted from the radio 10b. .. At this time, it means that the radio 10b is in the first reception standby state waiting for the frame RFa transmitted from another radio (for example, the radio 10a).

In FIG. 5, for example, the first reception standby state ends when the preset setting period T elapses. When the set period T elapses and the first reception standby state ends, the target data TDFa and TDFb are discarded, for example.

As the communication volume of the wireless communication system 100 increases and the communication frequency increases, in the RIT method, the occupancy ratio of the first reception standby state waiting for the RIT Data Request Frame increases with respect to the entire period. As a result, as described above, both of the two radios 10a and 10b are in the first reception standby state, the probability of failure of communication between the two radios 10a and 10b increases, and the success rate of communication establishment. Will decrease.

FIG. 6 is a diagram showing the relationship between the _{communication frequency λ Link and the communication success rate S in the comparative example.} In FIG. 6, there are 10 sets of one radio 10a and one radio 10b, and the same set of radios 10a and 10b perform bidirectional communication (one-to-one bidirectional communication is performed). The intermittent operation interval is 5 [s], and the data frame length is 20 [ms]. In FIG. 6, the horizontal axis represents the communication frequency λ _Link [S ^-1 ], and the vertical axis represents the communication success rate S (Success Rate S).

As shown in FIG. 6, when the communication frequency λ _Link becomes high between the two radios 10a and 10b and the above-mentioned matchmaking problem occurs, the communication success rate S is greatly reduced. For example, when the communication frequency lambda _Link is ^{10 -1,} the communication success rate S is lowered to 60% approximately. Here, the case where the radios 10a and 10b perform one-to-one bidirectional communication has been described as an example, but the case where the radios 10a and 10b perform one-to-many (many-to-one) bidirectional communication has been described. Even so, similarly, when the communication frequency λ _Link increases, the communication success rate S decreases due to the matchmaking problem.

FIG. 7 is a diagram for explaining an improved RIT method. As shown in FIG. 7, in the improved RIT method, the radios 110a and 110b transmit the frames RFa and RFb at the transmission timing of the frames RFa and RFb even in the first reception standby state. ..

For example, the radio 110b enters the first reception standby state after the generation (acquisition) of the target data TDFb, and waits for the reception of the frame RFa from another radio 110a. However, when the transmission timing of the frame RFb is reached during the first reception standby state, the radio 110b transmits the frame RFb. At this time, the radio 110b is maintained in the first reception standby state (the function required for reception of the communication unit 150 is enabled).

Since the radio 110a is in the first reception standby state after the generation (acquisition) of the target data TDFa, the frame RFb from the radio 110b can be received.

After receiving the frame RFb, the radio 110a transmits the target data TDFa to the radio 110b. In the radio 110a, the first reception standby state is released after the target data TDFa is transmitted. The radio 110b receives the target data TDFa, and the first reception standby state is maintained even after the reception.

Subsequently, the radio 110a reaches the transmission timing of the frame RFa, and the radio 110a transmits the frame RFa. Since the radio 110b is in the first reception standby state, it can receive the frame RFa from the radio 110a.

After receiving the frame RFa, the radio 110b transmits the target data TDFb to the radio 110a. In the radio 110b, the first reception standby state is released after the target data TDFb is transmitted. The radio 110a receives the target data TDFb.

FIG. 8 is _{a diagram showing the relationship between the communication frequency λ Link} and the communication success rate S in the improved RIT method. In FIG. 8, as in the above comparative example, there are 10 sets of one radio 10a and one radio 10b, and bidirectional communication is performed between the same sets of radios 10a and 10b (1 to 1). The two-way communication is performed), the intermittent operation interval is 5 [s], and the data frame length is 20 [ms]. In FIG. 8, the horizontal axis represents the communication frequency λ _Link [S ^-1 ], and the vertical axis represents the communication success rate S (Success Rate S).

As shown in FIG. 8, in the improved RIT method, _{even if the communication frequency λ Link} is high between the two radios 10a and 10b, the above-mentioned matchmaking problem is avoided, and therefore, as compared with the comparative example. The decrease in the communication success rate S is suppressed. Here, the case where the radios 10a and 10b perform one-to-one bidirectional communication has been described as an example, but the case where the radios 10a and 10b perform one-to-many (many-to-one) bidirectional communication has been described. Even so, similarly, the decrease in the communication success rate S is suppressed as compared with the comparative example.

As described above, in the improved RIT method, the radio 110 transmits the RIT Data Request Frame even in the first reception standby state when the transmission timing of the RIT Data Request Frame is reached. Therefore, even if the target data TDFa and TDFb are generated (acquired) in both of the two radios 110a and 110b and are in the first reception standby state, communication between the two radios 110a and 110b is possible. Become. _{That is, even if the communication frequency λ Link} increases in the wireless communication system 100, it is possible to suppress a decrease in the communication success rate S. Specifically, it was confirmed by computer simulation that the communication success rate S can be maintained at a value close to 100% even when _{the communication frequency λ Link} becomes 10 ^-1.

Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the claims, which naturally belong to the technical scope of the present invention. Understood.

For example, in the above-described embodiment, the case where the improved RIT method is applied to multi-hop communication has been described, but the present invention is not limited to multi-hop communication, and for example, a plurality of radios 110 for a repeater such as a gateway device 112. It can also be used as a communication mode in which is communicated individually. Specifically, there is an application example in which a plurality of various sensors for home security are arranged in a house or the like, and the radio 110 provided in each sensor communicates with the repeater individually. When the radio 110 is provided in the sensor for home security, it is conceivable that the target data TDFa and TDFb such as alarm information are generated at the same time in the plurality of radios 110. In this case, in the above-mentioned comparative example, the possibility of deadlock is high, but in the case of the wireless communication system 100 of the above-described embodiment, the occurrence of deadlock can be suppressed.

Further, in the above-described embodiment, the radios 110a and 110b are in the first reception standby state when the target data TDFa and TDFb are generated (acquired), and for example, the first reception is completed when the transmission of the target data TDFa and TDFb is completed. The case where the standby state ends has been described. However, for example, when the radios 110a and 110b transmit the target data TDFa and TDFb to the plurality of radios 110, the first is until the transmission of the target data TDFa and TDFb to all of the plurality of radios 110 is completed. 1 The reception standby state may be continued. Further, the first reception standby state may be terminated when a preset predetermined period elapses, as in the second reception standby state.

Also provided are a program that causes the computer to function as the radio 110, and a storage medium such as a computer-readable flexible disk, magneto-optical disk, ROM, CD, DVD, or BD that records the program. Here, the program refers to a data processing means described in an arbitrary language or description method.

The present invention can be used for radio communication systems, radios, and programs in which a plurality of radios perform RIT communication.

100 Radio communication system 110 Radio 110a Radio (second radio)
110b radio (first radio)
160 Communication control unit (transmission control unit, reception control unit)
TDFa, TDFb Target data RFa, RFb frame (RIT Data Request Frame)

Claims (3)

A wireless communication system in which the first radio communicates with the RIT method in which the first radio periodically attempts to transmit the RIT Data Request Frame to the second radio.
The first radio is
If the target data is data to be transmitted, the RIT Data Request will first reception waiting state in which the reception waiting of the Frame, the from the second wireless device in the first reception waiting state RIT Data Request When the frame is received, the transmission control unit that transmits the target data to the second radio and
A reception control unit that is in a second reception standby state in which the RIT Data Request Frame is transmitted and the target data can be received for the transmitted RIT Data Request Frame for a predetermined period after the transmission.
With
The second radio is
If there is the target data, the first reception standby state is set, and when the RIT Data Request Frame is received from the first radio in the first reception standby state, the target data is transmitted to the first radio. Equipped with a transmission control unit
The reception control unit of the first radio unit
When the transmission timing of the RIT Data Request Frame comes in the first reception standby state, the RIT Data Request Frame is transmitted to the second radio in parallel with the first reception standby state. A wireless communication system that transmits data and enters the second reception standby state. It is a radio that performs RIT communication that attempts to transmit RIT Data Request Frame periodically.
If the target data is data to be transmitted, the RIT Data Request will first reception waiting state in which the reception waiting of the Frame, the other radios in the first reception waiting state RIT Data Request Frame Is received, the transmission control unit that transmits the target data to the other radio, and
A reception control unit that is in a second reception standby state in which the RIT Data Request Frame is transmitted and the target data can be received for the transmitted RIT Data Request Frame for a predetermined period after the transmission.
With
The reception control unit
When the transmission timing of the RIT Data Request Frame comes in the first reception standby state, the RIT Data Request Frame is transmitted to the other radio in parallel with the first reception standby state. A radio that transmits and enters the second reception standby state. A computer that performs RIT-type communication that periodically attempts to transmit the RIT Data Request Frame.
If the target data is data to be transmitted, the RIT Data Request will first reception waiting state in which the reception waiting of the Frame, the other radios in the first reception waiting state RIT Data Request Frame Is received, the transmission control unit that transmits the target data to the other radio, and
A reception control unit that is in a second reception standby state in which the RIT Data Request Frame is transmitted and the target data can be received for the transmitted RIT Data Request Frame for a predetermined period after the transmission.
To make it work
The reception control unit
In the first reception waiting state, at the transmission timing of the RIT Data Request Frame, while maintaining the first reception waiting state, in parallel to this, the RIT Data Request Frame to the other radios A program that transmits and enters the second reception standby state.

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