JP2010239338A - Radio communication apparatus, communication method in radio network system, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform low-delay and power saving control based on beacon synchronization while complying with constraint on continuous communication hours. <P>SOLUTION: This radio communication apparatus uses a band having a communication constraint for data communication between radio nodes with synchronization using a beacon. The apparatus includes a beacon transmission part 82 for transmitting the beacon, a data transmission part 81 for transmitting data, and a transmission control part 83 which prohibits the transmission of the data by the data transmission part 81 during a first period before the transmission of the beacon by the beacon transmission part 82. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wireless communication apparatus, a communication method in a wireless network system, and a program for performing data communication between wireless nodes using a band with communication restrictions and synchronizing with beacons.

  In recent years, downsizing and cost reduction of devices and facilities in wireless nodes have been promoted, and wireless sensor networks have been attracting attention. In a wireless sensor network, there are restrictions on power consumption, processing capability, memory, and the like of a wireless communication device installed in a wireless node. In particular, since the wireless communication devices constituting the wireless node are almost battery driven, power saving measures are taken.

  For this reason, in a low-traffic wireless communication system such as a sensor network, when there is no data transmission / reception and the wireless communication function is not used, the wireless node is set to a sleep state to save power. Yes. In such intermittent communication, considering the sleep control of the wireless communication device at the transmission side wireless node and the reception side wireless node, how is the transmission timing and reception timing between the transmission wireless node and the reception wireless node? Synchronizing is an important design item.

When performing multi-hop communication while performing the above-described sleep control, synchronization is performed using a beacon (see, for example, Non-Patent Document 1).
For example, as shown in FIG. 6, the wireless communication device of each wireless node periodically transmits a beacon (hereinafter referred to as a reception timing notification beacon) with a period T in order to notify its reception timing. Then, the wireless communication apparatus waits for reception of a transmission start signal for a certain period immediately after transmitting this reception timing notification beacon (T101).

  When transmitting data, each wireless node first waits for reception of a reception notification beacon from the transmission destination wireless node (T102). When the reception timing notification beacon of the transmission destination wireless node is received, first, a transmission start signal is transmitted to the transmission destination wireless node (T103). Upon receiving the transmission start signal, the wireless node determines that there is data to be transmitted to itself and enters a data reception waiting state (T104). Subsequently, after transmitting the transmission start signal, the transmission source wireless node transmits data to be transmitted to the transmission destination wireless node. (T104).

  At this time, if the timing of the reception timing notification beacon of each wireless node is exchanged in advance, the reception waiting period of the reception timing notification beacon of the transmission source is shortened, so that low delay and power saving control can be realized.

In Proceeding of ICC 2004, Paris, Paris, France, June 2004, “Power-Efficient Rendez-Vous Schemes for Sense Wireless Sensor Networks” En-YiA. Lin, Jan M .; Rabaey Berkeley Wireless Research Center University of California, Barkley, USA

  By the way, in a specific frequency band, for example, a 950 MHz band in Japan, continuous communication time is limited. That is, when data transmission is performed at a transmission radio wave intensity of 10 mW, data transmission must be prohibited for 100 milliseconds after 100 milliseconds have elapsed since the start of transmission. In addition, when data transmission is performed with a transmission radio wave intensity of 1 mW, there is a restriction that data transmission must be prohibited for 100 msec after 1 second has elapsed since the start of transmission.

  The period T shown in FIG. 6 is a value larger than 1 second, and the above 100 msec and 1 second do not depend on the beacon transmission period. Therefore, when the reception timing notification beacon is transmitted, if the above-described restrictions are violated, the transmission destination wireless node needs to delay transmission of the reception timing notification beacon as shown in FIG. In this case, the power saving method described above cannot be used. This is a problem in performing power saving control.

  The present invention has been made in order to solve the above-described problem, and realizes power saving control based on beacon synchronization while complying with restrictions on continuous communication time, a wireless communication device, a communication method in a wireless network system, and a program The purpose is to provide.

  In order to achieve the above object, the wireless communication device of the present invention is a wireless communication device that performs data communication between wireless nodes using a band having communication restrictions and synchronizing with a beacon, and transmits the beacon. A data transmission unit that transmits data, and a communication control unit that prohibits data transmission by the data transmission unit in a first period before beacon transmission by the beacon transmission unit. is there.

  In addition, the communication method in the wireless network system of the present invention is a wireless network that uses a band with communication restrictions, performs synchronization by beacons, and performs data communication between wireless nodes including a beacon transmission unit and a data transmission unit. A wireless communication method in the system, the step of prohibiting data transmission by the data transmission unit during a first period before beacon transmission by the beacon transmission unit, and a transmission request from outside before the beacon transmission by the beacon transmission unit The data transmission time is measured, and if the data transmission time has no problem, the data transmission unit is caused to transmit the data even during the first period before the beacon transmission. And a step of controlling as described above.

  In addition, the program of the present invention is executed on a computer of a wireless communication apparatus that uses a band with communication restrictions, synchronizes with a beacon, and performs data communication between wireless nodes including a beacon transmission unit and a data transmission unit. A step of prohibiting data transmission by the data transmission unit during a first period before beacon transmission by the beacon transmission unit, and a transmission request from outside before beacon transmission by the beacon transmission unit Measure the data transmission time, and control the data transmission unit to transmit the data even in the first period before the beacon transmission if there is no problem in the data transmission And a step of executing.

According to the present invention, it is possible to realize power saving control based on beacon synchronization while complying with restrictions on continuous communication time, and to provide a wireless communication device in a wireless network system, a communication method in a wireless network system, and a program Can do.
In particular, by prohibiting data transmission during the first period before beacon transmission, it is possible to comply with restrictions on continuous communication time and there is no need to change beacon transmission timing, so low delay and power saving control based on beacon synchronization Is possible. In addition, if the transmission time of the data requested to be transmitted from the outside before the beacon transmission is measured and the measured time is a transmission time with no problem in data transmission, even if it is the first period before the beacon transmission By controlling the transmission of data, efficient data transmission with no dead time can be achieved.

It is a figure which shows an example of the system configuration | structure of the radio | wireless network system which concerns on embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless communication apparatus which concerns on embodiment of this invention. It is the block diagram which expanded and showed the structure of the program which the transmission control part of the radio | wireless communication apparatus which concerns on embodiment of this invention performs. It is a flowchart which shows operation | movement of the radio | wireless communication apparatus which concerns on embodiment of this invention. It is the figure which defined on the time axis the 2nd period when the radio | wireless communication apparatus which concerns on embodiment of this invention instruct | indicates data transmission. It is a figure which shows the transmission timing of the beacon and data in the radio | wireless communication apparatus of background art. It is a figure which shows the transmission timing of the beacon and data in a radio | wireless communication apparatus.

  Hereinafter, embodiments of the present invention will be described in detail.

FIG. 1 is a diagram showing a system configuration of a wireless network system according to an embodiment of the present invention.
As shown in FIG. 1, a wireless network system 100 according to the present embodiment includes PCs or gateways 10 and 20 and a plurality (9 in the figure) of wireless nodes 1 to 9.

The PCs or gateways 10 and 20 are nodes that are connected to an external network such as the Internet via wired or wireless communication and can communicate with the external network. The PC or gateway 10, 20 can be supplied with necessary power by a predetermined wiring.
Each of the wireless nodes 1 to 9 is installed with a battery-driven wireless communication device capable of bidirectional communication. Here, it is assumed that multihop communication is performed between the wireless nodes 1 to 9 while performing sleep control. In addition to the data transmission source and the data transmission destination, the wireless communication device operates between the data transmission source and the data transmission destination as a relay station.

  The internal configuration of the transmission system of the radio communication device 8A installed in the radio node 8 is shown in FIG. As illustrated in FIG. 2, the wireless communication device 8A includes a data transmission unit 81, a beacon transmission unit 82, and a transmission control unit 83.

The data transmission unit 81 transmits data transferred via the PC or the gateways 10 and 20 to the wireless communication devices of the other nodes 1 to 7 and 9 connected to the network.
The beacon transmission unit 82 transmits the reception timing notification beacon described with reference to FIGS. 6 and 7 to the wireless communication devices of the other nodes 1 to 7 and 9 connected to the network.

The transmission control unit 83 has a function of prohibiting data transmission by the data transmission unit 81 during a first period (Tt-1 in FIG. 5) before beacon transmission by the beacon transmission unit 82.
Before the beacon transmission by the beacon transmission unit 82, the transmission control unit 83 measures the transmission time of data requested to be transmitted from the outside, such as other wireless communication devices including the PC and the gateways 10 and 20, and transmits this data. If there is no problem in the transmission time, it has a function of controlling the data transmission unit 81 to transmit data even in the first period before the beacon transmission, and moreover than the first period. When data transmission by the data transmission unit 81 is not performed in the previous second period (Tt-2 in FIG. 5), the data transmission unit 81 also has a function of controlling data transmission. Details of both functions will be described later.

  In the above description, only the configuration of the wireless communication device 8A is shown. However, the wireless communication devices of the other nodes 1 to 7 and 9 have the same configuration except that the PC or gateways 10 and 20 are connected. Have. In addition, the first period described above is, for example, 100 milliseconds when communication is performed in the 950 MHz band, and the second period is 100 milliseconds when the transmission radio wave intensity is 1 mW, and 1 second when the transmission radio wave intensity is 10 mW. And

FIG. 3 is a block diagram showing the structure of a program executed by the transmission control unit 83 of the radio communication apparatus 8A according to the present embodiment in a functional manner.
As shown in FIG. 3, the transmission control unit 83 includes a main control unit 830, a transmission request acquisition unit 831, a timer monitoring unit 832, a beacon transmission control unit 833, and a data transmission control unit 834.

  The main control unit 830 performs sequence control of the transmission request acquisition unit 831, the timer monitoring unit 832, the beacon transmission control unit 833, and the data transmission control unit 834. Thereby, data transmission by the data transmission unit 81 is prohibited during the first period before the beacon transmission by the beacon transmission unit 82, and the transmission time of the data for which there was a transmission request from the outside before the beacon transmission by the beacon transmission unit 82 As a transmission control unit 83 that controls the data transmission unit 81 to transmit data even during the first period before beacon transmission if the transmission time has no problem in transmission of this data. The function is realized.

The transmission request acquisition unit 831 acquires a data transmission request transmitted from each of the wireless communication devices of the other nodes 1 to 7 and 9 including the PC or the gateway 10 and passes it to the main control unit 830.
The timer monitoring unit 832 monitors the first period and the second period described above under the control of the main control unit 830 and outputs a timeout signal to the main control unit 830. The beacon transmission control unit 833 performs beacon transmission control of the beacon transmission unit 82 under the control of the main control unit 830, and the data transmission control unit 834 transmits data of the data transmission unit 81 under the control of the main control unit 830. Take control.

FIG. 4 is a flowchart showing the operation of the wireless communication device 8A according to the present embodiment.
Hereinafter, the operation of the wireless communication device 8A according to the present embodiment shown in FIGS. 2 and 3 will be described in detail with reference to the flowchart of FIG. 4 and FIGS.

  The transmission control unit 83 (main control unit 830) controls the beacon transmission unit 82 at a constant cycle via the beacon transmission control unit 833. Thereby, the beacon transmission part 82 transmits a beacon. When the transmission request acquisition unit 831 receives a data transmission request from each wireless communication device of the other nodes 1 to 7 and 9 including the PC or the gateway 10 and the transmission request acquisition unit 831 acquires the request, The control unit 830 controls the data transmission unit 81 via the data transmission control unit 834 to perform data transmission.

The main control unit 830 controls the data transmission unit 81 for a certain period (first period) immediately before causing the beacon transmission unit 82 to transmit a beacon, and causes data transmission when it is necessary to perform data transmission. There is no data transmission failure.
On the other hand, the main control unit 830 receives the data transmission request from the wireless communication devices of the other nodes 1 to 7 and 9 including the PC or the gateway 10 (Step S401 “Yes”). Before the beacon transmission by the beacon transmission unit 82 (step S402 “Yes”), the transmission time of the data requested to be transmitted from the outside is measured (step S403). If the transmission time has no problem in the transmission of this data (step S403) S404 “Yes”), a transmission permission notification is issued to the data transmission unit 81 (step S406), and the data transmission unit 81 is controlled to transmit data even during a certain period immediately before the beacon transmission.

  That is, the main control unit 830 analyzes the transmission data, calculates the transmission time from the data amount, determines whether transmission is possible within a certain period immediately before the beacon transmission, and permits or denies transmission based on the result. To control. That is, if the data subject to the transmission request cannot be transmitted within a certain period before the beacon transmission, the transmission is refused (step S407), and this is sent to the requesting PC or other node 1 including the gateway 10 Notify each of the wireless communication devices ˜7 and 9.

  Here, when the communication is performed in the 950 MHz band as the immediately preceding fixed period, the implementation is easiest if the period is 100 milliseconds. The timer monitoring unit 832 monitors this 100 ms and notifies the main control unit 830 when a timeout occurs. The main control unit 830 performs the data transmission described above within this period.

  As described above, according to the wireless communication apparatus according to the present embodiment, transmission control unit 83 (main control unit 830) performs data transmission by data transmission unit 81 during the first period before beacon transmission by beacon transmission unit 82. By prohibiting transmission, restrictions on continuous communication time can be observed, and it is not necessary to change the beacon transmission timing. Therefore, low delay and power saving control based on beacon synchronization are possible.

  Also, the transmission control unit 83 (main control unit 830) measures the transmission time of data for which there was a transmission request from the outside before the beacon transmission by the beacon transmission unit 82, and if the transmission time has no problem in data transmission. Even in the first period before beacon transmission, by controlling the data transmission unit 81 to transmit data, efficient data transmission with no dead time can be achieved.

  Also, according to the wireless communication apparatus according to the present embodiment, for example, as shown in FIG. 5, the main control unit 830 further performs a certain period (first period: Tt−1) immediately before beacon transmission. If data transmission is not performed during the previous certain period (second period: Tt-2), even if it is controlled to perform data transmission within the period of the beacon transmission time that is a certain period immediately before beacon transmission. Good.

  That is, in the transmission presence / absence determination process in step S404 of the flowchart of FIG. 4, when it is determined that transmission is not possible (step S404 “No”), the main control unit 830 determines whether transmission is possible in the previous certain period. If it is determined (step S405) and it is determined that transmission is possible (step S405 “Yes”), the data transmission unit 81 is allowed to transmit data based on the transmission request via the data transmission control unit 834 (step S406). If it is determined that communication is not possible (step S405 “No”), the data transmission unit 81 is controlled via the data transmission unit 834 to refuse communication (step S407), and the requesting PC or gateway 10 is included. This is notified to the wireless communication devices of the other nodes 1 to 7 and 9.

  As a result, more efficient data communication can be realized and there is no need to change the beacon transmission timing. This is limited to a case where the amount of data transmission in a certain period immediately before the beacon transmission and a certain period before the time is sufficiently small.

  When using the 950 MHz band, the fixed period immediately before the beacon transmission is set to 100 milliseconds when the transmission radio wave intensity is 1 mW and 1 second when the transmission radio wave intensity is 10 mW. This is the easiest to implement.

Further, all the functions of the transmission control unit 83 shown in FIG. 3 may be realized by software, or at least a part thereof may be realized by hardware.
For example, the data processing in which the transmission control unit 83 prohibits the data transmission by the data transmission unit 81 during the first period before the beacon transmission by the beacon transmission unit 82 may be realized on a computer by one or a plurality of programs. In addition, at least a part of it may be realized by hardware.

  In addition, the wireless communication method in the wireless network system according to the present embodiment uses, for example, a band with communication restrictions in FIGS. 1 and 2, and synchronizes with a beacon to transmit data with the beacon transmission unit 82. 4 is a wireless communication method in the wireless network system 100 that performs data communication between the wireless nodes 1 to 9 including the unit 81. For example, in FIG. 4, a first period before the beacon transmission by the beacon transmission unit 82 in FIG. 5 (Tt-1), the step of prohibiting data transmission by the data transmission unit 81 (S407), and the transmission time of the data requested to be transmitted from the outside before the beacon transmission by the beacon transmission unit 82 is measured ( S401 “Yes” to S403), if the transmission time has no problem in the data transmission, the first period before the beacon transmission Step (S404 "Yes", S406) even be controlled so as to perform transmission of the data to the data transmission unit is one having a, a.

1-9 Wireless node 8A Wireless communication device 10, 20 PC or gateway 81 Data transmission unit 82 Beacon transmission unit 83 Transmission control unit 100 Wireless network system 830 Main control unit 831 Transmission request acquisition unit 832 Timer monitoring unit 833 Beacon transmission control unit 834 Data transmission controller

Claims (8)

A wireless communication device that performs data communication between wireless nodes by synchronizing with a beacon,
A beacon transmitter for transmitting the beacon;
A data transmission unit for transmitting data;
A transmission control unit that prohibits data transmission by the data transmission unit in a first period before beacon transmission by the beacon transmission unit;
A wireless communication apparatus comprising:   The wireless communication apparatus according to claim 1, wherein the wireless communication apparatus is used in a frequency band in which continuous communication time is restricted. The transmission control unit
Measure the transmission time of data for which there was a transmission request from the outside before the beacon transmission by the beacon transmission unit, and if the transmission time has no problem in the data transmission, it is the first period before the beacon transmission, 3. The wireless communication apparatus according to claim 1, wherein control is also performed to cause the data transmission unit to transmit the data. 4. The first period is:
The wireless communication apparatus according to any one of claims 1 to 3, wherein the communication time is 100 milliseconds when communication is performed in a 950 MHz band. The transmission control unit
When data transmission by the data transmission unit is not performed in the second period further before the first period before the beacon transmission, the data transmission unit is controlled to transmit the data. The wireless communication device according to any one of claims 1 to 3, wherein the wireless communication device is characterized in that: The second period is:
6. The wireless communication apparatus according to claim 5, wherein when performing communication in a 950 MHz band, the time is 100 milliseconds when the transmission radio wave intensity is 1 mW, and 1 second when the transmission radio wave intensity is 10 mW. It is a communication method in a wireless network system that performs data communication between wireless nodes including a beacon transmission unit and a data transmission unit by synchronizing with a beacon,
Prohibiting data transmission by the data transmission unit in a first period before beacon transmission by the beacon transmission unit;
Measure the transmission time of data for which there was a transmission request from the outside before the beacon transmission by the beacon transmission unit, and if the transmission time has no problem in the data transmission, it is the first period before the beacon transmission, Also controlling the data transmission unit to transmit the data;
A communication method in a wireless network system, comprising: A program that is executed by a computer of a wireless communication apparatus that performs data communication between wireless nodes including a beacon transmission unit and a data transmission unit by synchronizing with a beacon,
Prohibiting data transmission by the data transmission unit in a first period before beacon transmission by the beacon transmission unit;
Measure the transmission time of data for which there was a transmission request from the outside before the beacon transmission by the beacon transmission unit, and if the transmission time has no problem in the data transmission, it is the first period before the beacon transmission, Also controlling the data transmission unit to transmit the data;
A program characterized by having executed.

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