JP2005124123A - Access space photo-sensor communication apparatus and access space photo-sensor network system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily realize a cablesless photo-sensor network by allowing a streetlamp to have an optical communication function by solving a problem that costs are increased since an optical fiber cable and cabling are required for constructing a conventional optical access network. <P>SOLUTION: An access space sensor communication apparatus (ASOSM) 100 comprises optical transmitting/receiving sections 110, 120, 130 wherein optical transmitting sections and optical receiving sections are accommodated, internal buses 101, 102 connecting these optical transmitting/receiving sections, a control section 170 and the same mouthpiece 1 as an ordinary illumination lamp, the optical transmitting/receiving sections 110, 120 are used for optical communication network adjacent ASOSMs, and the optical transmitting/receiving section 130 is used for illumination on the street and optical communication with a communication apparatus under control of the illumination. The ASOSM 100 is installed in place of a conventional streetlamp, thereby illuminating the street and constructing an optical sensor network between ASOSMs. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides an illumination module (illumination lamp) used as streetlight illumination with an optical communication function so that it can be used as ordinary illumination, and at the same time allows communication between adjacent illuminations. Is equipped with sensors such as temperature, humidity, atmospheric pressure, odor, microphone, camera, gas detection, etc., so that a sensor network can be realized, and there are terminals that have means necessary for optical communication under illumination In this case, the present invention relates to an access space optical sensor communication device that allows the terminal to communicate via a sensor network, and an access space optical sensor network system using the access space optical sensor communication system.

  Conventionally, the streetlight has only a lighting function. FIG. 2 shows a conventional general illumination lamp. In this case, when a current flows from the base 1 to the metal member 2 and the electrode 3, the arc tube 4 emits light, and the surroundings are illuminated through the outer tube 5 such as a glass member.

  Recently, white light-emitting diodes (white LEDs) have become widespread due to technological advances, and the conventional illumination lamp as shown in FIG. 2 is changing to white LEDs. White LEDs are considered to become more popular in the future because they have lower power consumption and higher durability than conventional illumination lamps (for example, Non-Patent Document 1). However, having only a function of illumination is no different from the conventional illumination lamp.

  On the other hand, as shown in FIG. 4, the conventional access network passes an underground cable 11 from the service node 10 and extends an overhead cable 13 from the feeder line 12 to the protector 14 of the subscriber's home 20. A method in which a subscriber secures communication means is common. For this reason, there is a problem that the cost of a necessary cable is high for each subscriber when constructing an access network, and furthermore, the installation cost of the cable is also high. In addition, since the cable is stretched over the aerial space, there is a problem that the appearance is broken.

  In addition, when realizing the network architecture for collecting information of every place, such as sensor networks, using only the existing access network, each sensor is connected with a cable, so that the necessary cable cost is further increased. Becomes higher.

  Although there are many ideas for configuring a sensor network with wireless terminals, there is a problem of how to save power of the deployed wireless terminals and how to extend the life of the wireless terminals.

  Furthermore, although it has been proposed to use a white LED for communication (Non-patent Document 2), application in a sensor network is not considered.

"White LEDs are here and there," Nikkei Electronics, March 31, 2003, pp108-115 Kominato, Haruyama, Nakagawa “Proposal of interactive communication system using illumination light (visible light)”, IEICE Technical Report DSP 2002-145, January 2003, pp 41-46

  As described above, the present invention provides a lightless communication function between the adjacent lighting modules, while the conventional streetlight lighting module has only a lighting function. An object of the present invention is to provide an access space optical sensor communication device that enables communication.

  In addition, in view of the above-described problems when a sensor network is realized using an existing access network or a wireless terminal, the present invention uses an illumination device installed on a conventional utility pole as an access space optical sensor communication device. An object of the present invention is to provide an access space optical sensor network system that is cable-less and does not require a separate power supply facility by replacing and installing a plurality.

  Further, the present invention provides a sensor detection network by providing each access space light sensor communication device with sensors such as air temperature, humidity, atmospheric pressure, odor, microphone, camera, and gas detection. To provide an access space optical sensor network system in which terminals equipped with means necessary for communication with a sensor communication device exist under illumination, and the terminals can communicate with each other via a sensor network. .

  It is another object of the present invention to provide an access space optical sensor network system in which the operation, management, maintenance, lifetime, etc. of the entire system are more effective in the construction of the access space optical sensor network system.

  An access space optical sensor communication device according to the present invention includes N (N ≧ 3) optical transmission / reception units each accommodating an optical transmission unit and an optical reception unit, an internal bus connecting these optical transmission / reception units, a control unit, A power supply interface unit that is the same as a base of a normal illumination lamp, and at least two optical transmission / reception units are used for optical communication between adjacent access space optical sensor communication devices, and the remaining at least one optical transmission / reception unit Are used for illumination and optical communication with a communication device under the illumination.

  In addition, the access space optical sensor communication device of the present invention is a signal branching device that takes in a signal addressed to a communication device of an internal bus between an optical transmission / reception unit used for optical communication with a communication device under illumination and an internal bus. And a signal multiplexing unit that multiplexes a signal from the communication device with a signal on the internal bus.

  In the access space optical sensor communication device of the present invention, at least the optical transmission / reception unit used for optical communication between adjacent access space optical sensor communication devices includes an optical axis adjustment unit for adjusting the transmission / reception direction of the optical signal.

  In the access space optical sensor communication device of the present invention, at least an optical transmission / reception unit used for optical communication between adjacent access space optical sensor communication devices is provided with a return switch, and the control unit can turn the switch on and off.

  Furthermore, the access space optical sensor communication device of the present invention comprises at least one or more sensors such as temperature, humidity, atmospheric pressure, odor, gas, camera, microphone, etc., and information on the sensors at predetermined time intervals by the control unit. Enable transmission.

  The access space optical sensor network system according to the present invention has a plurality of such access space optical sensor communication devices installed in place of street lamps on the road, and performs optical communication between the access space optical sensor communication devices together with the illumination on the road. Configure the sensor network.

  In addition, the access space optical sensor network system of the present invention connects the communication network under the illumination by the access space optical sensor communication device by connecting the optical sensor network to a communication network (for example, the Internet) mainly using the Internet protocol. The Internet can be accessed via the access space optical sensor communication device.

  Similarly, the access space optical sensor network system of the present invention similarly stores the sensor information of the access space optical sensor communication device in a database via any application on the Internet by connecting the optical sensor network to the Internet or the like. It can be so.

  Furthermore, the access space optical sensor network system of the present invention includes a physical plane that physically installs, maintains, and manages physical devices such as an access space optical sensor communication device and an outdoor pillar on which the device is installed. A plurality of access space optical sensors installed in a plane A control plane that performs communication control for establishing communication using a communication protocol while using wireless or optical wireless between communication devices, and a plurality of access space optical sensors in the control plane Established on the data plane and the data plane to establish optical communication for data communication using the optical transmitter / receiver provided in the access space optical sensor communication device to transmit data signals after the communication device establishes communication An application plane that implements an application using the data communication performed, and Down, the control plane, the data plane, so as to perform the communication procedure in the order of the application plane.

  Furthermore, in the access space optical sensor network system of the present invention, the access space optical sensor communication devices are installed in two rows one-dimensionally, and if any access space optical sensor communication device in one row fails, An access space optical sensor communication device is used to form a detour to enable communication.

  According to the present invention, an access space optical sensor communication device (ASOSM) having a communication function can be easily replaced with a conventional street light, so that an optical sensor network can be easily realized along with street lighting. Also, since it is optical communication, wide area and high speed communication can be secured. Furthermore, only the power lines for supplying power to the ASOSM such as utility poles and street lamps are provided on the aerial space, which eliminates the need for conventional communication cables and is effective in maintaining the beauty of the city.

  In addition, the ASOSM of the present invention has an electrical interface (base) equivalent to that of an existing streetlight illumination lamp, so that the power supply of the communication module is ensured. Therefore, a sensor configured with a conventional wireless terminal is used. There is no network power problem.

  Further, since the ASOSM of the present invention also functions as illumination, any terminal having the necessary optical communication means can communicate via a network configured with ASOSM under the ASOSM illumination. In addition, it can be used as a monitoring system by installing a sensor such as a camera in ASOSM and sensing objects and people under illumination at night. Further, by installing sensors such as temperature, humidity, atmospheric pressure, odor, gas, etc. in ASOSM and sensing these information at desired time intervals, they can be used as various detection systems.

  Furthermore, according to the present invention, the operation, management, and maintenance of the entire system becomes more effective by the communication method using four separated planes (physical plane, control plane, data plane, and application plane) in the access space optical sensor network. Become.

  In addition, for example, when installing ASOSM in a place such as a road, the life of the entire system is further extended by arranging ASOSM in one row in two rows and in one dimension, and the access space optical sensor system can be Effective for long-term use.

  FIG. 1 shows a configuration diagram of an embodiment of an access space optical sensor communication device of the present invention. Hereinafter, the access space optical sensor communication device is abbreviated as ASOSM. In FIG. 1, the ASOSM 100 includes the three optical transmission / reception units 110, 120, and 130, but of course, the number does not necessarily have to be three.

  The optical transmission / reception unit 110 enables access space optical communication (FSO: Free Space Optoics) of the right-side ASOSM and cableless optical communication. The optical transmission unit 111, the optical reception unit 112, the optical transmission drive unit 113, The reception amplifying unit 114 is configured. Similarly, the optical transmission / reception unit 120 enables access spatial optical communication (FSO) with the adjacent ASOSM. The optical transmission unit 121, the optical reception unit 122, the optical transmission drive unit 123, and the optical reception amplification unit 124 Composed. Here, LEDs, lasers, etc., such as visible light and infrared rays, are used for the optical transmitters 111 and 121. In addition, a photodiode (PD) or the like is used as the light receiving units 112 and 122. The optical transceivers 110 and 120 are connected by internal buses 101 and 102 to enable transmission and reception of signals with adjacent ASOSMs. Reference numerals 115 and 125 denote signal folding switches.

  Further, in order to enable efficient communication with the adjacent ASOSM, the optical transmission / reception units 110 and 120 adjust the optical axis to set the optical reception level to a desired value, respectively. 126 are provided.

  The optical transmission / reception unit 130 enables optical communication with a communication terminal existing under the illumination function and the illumination, and includes an optical transmission unit 131, an optical reception unit 132, an optical transmission drive unit 133, and an optical reception amplification unit 134. Is done. Here, the light transmitting unit 131 uses, for example, a visible white LED in order to serve as illumination. A photodiode (PD) or the like is used for the optical signal unit 134. A signal branching unit (Drop function unit) 140 and a signal multiplexing unit (ADD function) 150 are arranged between the optical transmission / reception unit 130 and the internal buses 101 and 102, and the communication terminals under illumination and the adjacent ASOSM are connected to each other. It is possible to send and receive signals between.

  A desired sensor can be mounted on the sensor unit 160. For example, sensors such as temperature, humidity, atmospheric pressure, camera, microphone, and odor can be mounted. The sensor information can be transmitted to the adjacent ASOSM via, for example, the optical transceivers 110 and 120 at a desired interval.

  The control unit 170 controls each unit in the ASOSM 100. For example, on / off of the switches 115 and 125, the transmission timing of sensor information, and the like are controlled by the control unit 170. The AC-DC converter 180 converts alternating current fed through the base 1 into direct current, and sends the direct current to each part in the ASOSM 100.

  The appearance of the ASOSM 100 is basically the same as that of the conventional illumination lamp as shown in FIG. 2, and the whole is covered with an outer tube or the like. Thereby, the function of illumination is achieved simultaneously with the optical communication function without a cable.

  Next, the operation of the access space optical sensor communication device (ASOSM) of the present invention will be described with reference to FIG. In FIG. 3, each ASOSM 100 is installed in place of an existing streetlight, and it is assumed that necessary power is supplied from the base 1. The operation will be described below while focusing on the central ASOSM 100, but the same applies to the left and right ASOSMs.

  In the central ASOSM 100, the optical receiving unit 112 receives an optical signal from the right ASOSM and converts it into an electric signal, and the amplifying unit 114 amplifies the electric signal and sends it to the internal bus 101. The electric signal of the internal bus 101 is input to the optical transmission driving unit 123, and the driving unit 123 drives the optical transmission unit 121, so that the optical signal is transmitted to the adjacent ASOSM.

  On the other hand, the optical receiving unit 122 receives an optical signal from the adjacent ASOSM and converts it into an electrical signal, which is amplified by the amplifying unit 124 and sent to the internal bus 102. The electric signal of the internal bus 102 is input to the optical transmission drive unit 113, and the drive unit 113 drives the optical transmission unit 111, so that the optical signal is transmitted to the right ASOSM.

  The electric signal of the internal bus 101 is also input to the signal branching unit 140. In the signal branching unit 140, if there is a signal addressed to a communication terminal under the illumination of the central ASOSM 100, the signal is captured and sent to the optical transmission / reception driving unit 133. As a result, the optical transmission drive unit 133 drives the optical transmission unit 131 (for example, optical modulation drive), and an optical signal is transmitted to the communication terminal under illumination. The optical signal from the communication terminal under the illumination of the central ASOSM 100 is received by the optical receiving unit 132, converted into an electric signal, amplified by the amplifying unit 134, and input to the signal multiplexing unit 150. The signal multiplexing unit 150 multiplexes the signal with the signal on the internal bus 102 and sends it out.

  Further, the sensor information of the desired sensor mounted on the sensor unit 160 is sent to the internal buses 101 and 102 at a predetermined timing under the control of the control unit 170.

  In FIG. 3, for example, when there is no ASOSM adjacent to the left, the central ASOSM 100 functions as a termination device by turning on the return switch 125 at the front stage of the optical transceiver 120 by the control unit 70. Similarly, when there is no right-side ASOSM, the central ASOSM 100 becomes a termination device by turning on the return switch 115 in the preceding stage of the optical transceiver 110.

  FIG. 5 is a conceptual diagram of an access space optical sensor network using the access space optical sensor communication device (ASOSM) of the present invention. In FIG. 5, the service node 10 and the underground cable 11 are the same as the conventional access network of FIG. 4, but the ASOSM 100 of the present invention is deployed from the feeder line 12 to the subscriber home 20 as much as necessary. Optical space communication is performed between each ASOSM, and a cableless access space optical sensor network is configured. Thereby, the overhead cable 13 in the conventional access network of FIG. 4 is unnecessary. In addition, the ASOSM 100 only needs to be replaced with a lamp installed on a conventional utility pole or the like. Only the power line that supplies power to the ASOSM, which replaces the utility pole and streetlight, is used on the aerial space, and the optical space communication path is substituted for the conventional subscriber line, so that no communication cables are required, so that the beauty of the city is maintained. Furthermore, since the ASOSM 100 also serves as night illumination, no separate lamp is required. In addition, since the ASOSM 100 has an electrical interface (base) equivalent to that of an existing street lamp, the power supply of the module is secured, so that a sensor network is configured with a wireless terminal that has been assumed in the past. No power problem.

  FIG. 6 shows a basic configuration of an access space optical sensor network to which the access space optical sensor communication device (ASOM) of the invention is applied. As described above, the ASOSM 100 is basically installed on a utility pole. Access space optical communication (optical cableless communication) is performed between the ASOSMs 100 existing in each power pole to form an optical sensor network. Sensor information and the like are processed via the media converter 200 and the 300 gateway 400, for example, on the application system 510, the resolver 520, and the database 530 on the Internet 500. In addition, the ASOSM 100 present in each power pole can be used as illumination, and further, under illumination, communication using illumination light is possible only in a local place affected by illumination. A few specific examples of the optical sensor network are shown below. The Internet 500 may be, for example, an intranet or a unique regional network.

  FIG. 7 shows an example in which a camera, temperature, humidity, and the like are mounted on the ASOSM sensor unit to realize a regional monitoring system. First, the ASOSM 100 is installed on a streetlight that exists on a telephone pole in a certain area. Here, position information, date / time information, and ASOSM node information by GPS (Global Positioning System) or the like are registered in the ASOSM 100 before installation. Next, optical communication is performed between adjacent ASOSMs 100 to form an optical sensor network. Here, by providing each ASOSM 100 with a camera, when a dynamic object is detected in the range where the camera is captured, a photograph of the camera and related information (ASOSM node information, position information, date / time, temperature, humidity, etc.) are transmitted to the Internet 500. It can be accommodated in the database 530 via any of the above application systems 510. In particular, since the camera works under illumination at night, more effective photographs can be stored in the database 500. By constructing such a system, it can be applied to a monitoring system in the area where the ASOSM 100 is installed.

  For example, it is assumed that all residents living in the area have RFID (Radio Frequency Identification) tags. Further, when a resident outside the area enters the area where the ASOSM 100 is installed, a dynamic object having no RFID tag is recognized as the presence of a non-safe object candidate. In that case, it is assumed that the recognized object is stored in the database 530 by taking a picture of the intruder with a camera provided in the ASOSM 100. If a crime occurs in that area, the photo on the database 530 is effective as valuable evidence.

  FIG. 8 shows an example in which the Internet is accessed by a communication terminal existing under the illumination of the ASOSM 100 via a network configured by the ASOSM 100 installed on the utility pole. By providing the communication terminal with the visible light communication module, the Internet 500 can be accessed by visible light communication between the communication terminal existing under illumination and the ASOSM 100. Even if the communication terminal moves, communication can be continued by a general handover function when the communication terminal moves under an adjacent illumination within an arbitrary time. In the case of a conventional hot spot, it is common to install a communication device or antenna at each point and communicate with the communication device using a wired line on the Internet. If a device is replaced with an ASOSM 100, and there are a plurality of adjacent ASOSMs 100 and a network can be configured, there is an advantage that communication is possible within a limited range where the illumination is under the illumination. For this purpose, it is necessary to provide the communication terminal with visible light communication means.

  FIG. 9 is an example in which the temperature, humidity, gas detection (for example, CO2 detection) and the like are mounted on the sensor unit of the ASOSM 100 installed on the utility pole to realize a local temperature, humidity, and CO2 detection system. Also by configuring a network similar to that of the first embodiment, information such as temperature, humidity, and gas detection in the area where the ASOSM 100 is installed can be grasped in real time at a desired time interval. For example, real-time information on temperature and humidity can be used as basic information for businesses linked to changes in temperature and humidity (for example, eating, drinking, clothing, agriculture, etc.), and regarding gas detection, environmental protection for local residents Effective as basic information for the viewpoint.

  This is an example of an access space optical sensor network architecture separated into four planes (layers) of a physical plane 1000, a control plane 1100, a data plane 1200, and an application plane 1300 as shown in FIG.

  The physical plane 1000 physically installs, maintains, and manages physical devices such as an access space optical sensor communication device (ASOSM) 100 and outdoor poles such as streetlight poles or telephone poles that set the ASOSM. For example, when the ASOSM 100 is installed, information on the installation position is provided in advance in the ASOSM using GPS (Global Positioning System) or the like. In addition, when installing the ASOSM 100 on each power pole or streetlight pole, the installation is performed at a position where each ASOSM can sufficiently communicate. When sufficient requirements for communication are prepared in the physical plane 1000, communication control is negotiated in the control plane 1100.

  In the control plane 1100, control signals such as negotiation between the ASOSMs 100 are transmitted and received using position information and communication protocols between the ASOSMs 100, and communication establishment at a control signal level is realized between the plurality of ASOSMs 100. As communication means of the control plane 1100, wireless or optical wireless communication is used. When the control plane 1100 establishes communication at the control signal level, the data plane 1200 establishes data communication link.

  In the data plane 1200, high-speed and large-capacity data communication is performed between the ASOSMs 100 established in the control plane 1100 using a multi-hop network using optical wireless communication. The position information of the opposite ASOSM is obtained, and a data communication link by optical wireless communication (FSO) is established between the ASOSMs. The advantages of using optical wireless communication are that there are no legal restrictions compared to wireless, and high-speed and large-capacity communication is possible. Moreover, the conventional weak point of the optical wireless communication in the outdoors, the influence by the obstruction, etc. can be cleared by considering the distance between the street lights or the utility poles and the physical environmental conditions. For example, the distance between street lights or utility poles is extremely short compared to conventional optical wireless communication for outdoor use, and there is no problem because the visibility between the street lights is basically good. Note that wireless communication using high bandwidth may be used instead of optical wireless communication.

  In the application plane 1300, various applications using sensors can be implemented. For example, as shown in FIG. 7, when a camera is assumed as a sensor, services such as local crime prevention can be performed as a camera sensor network by utilizing the high speed and large capacity of optical wireless communication. In addition, the streetlight alone / thing-to-thing communication using visible light communication shown in FIG.

  By separating the planes as shown in FIG. 10, when a failure or the like occurs, it is easy to manage and maintain the plane in which the cause of the failure occurs. For example, when a physical device is not operating normally on the physical plane, negotiation on the control plane is also impossible, and in that case, it can be estimated that the physical device is abnormal. This is an effective means for establishing a spatial light sensor network.

  Normally, streetlight poles and utility poles are installed on both sides of the road at almost equal intervals. Therefore, in this embodiment, when the access space optical sensor communication device (ASOSM) is installed in a two-row one-dimensional manner (double one-dimensional) on the road, when an ASOSM in one row fails, the ASOSM in the other row Is used to form a detour and maintain space optical communication (FSO).

FIG. 11A shows a case where an access space optical sensor network is configured by one-dimensionally arranging ASOSM (sensor nodes) 100 in a line (hereinafter referred to as a simple one-dimensional model), and FIG. 11B shows the ASOSM (sensor node) 100. The two-dimensional array sensor network is configured by arranging the two-dimensionally in two rows (hereinafter referred to as a double one-dimensional model (no detour)). The one-dimensionally arranged ASOSM in FIG. 11A is simply arranged as 1, 2, 3,..., N, and is an image installed on one side of a road, for example. On the other hand, ASOSM of duplexed one-dimensional array of FIG. 11 _{(b), ASOSMa 1, ..., a n} , and ASOSMb _1, ..., _{b n} is be images that are respectively disposed on both sides of the road Communicate information between gateways (GW) 400 independently. However, the information acquired by ASOSMa _i and b _i is the same or almost the same. In addition, as a premise, ASOSMa _i, if either of the system of _{b i} functions, all information is that it is possible to arrive at the GW400.

In this embodiment, the bypass method 1 or the bypass method 2 as shown in FIGS. 11C and 11D is realized in the double one-dimensional model of FIG. 11B. In the detour method 1 in FIG. 11C, when the sensor node a _i or b _i fails, information can be transferred from the sensor node a _{i + 1} or b _{i + 1} to b _i or a _i . In other words, if either sensor node a _i or b _i is functioning in all i, it is assumed that all information on the system can reach the gateway (GW) 400. Note that the information obtained by the sensor nodes a _i and b _i is basically the same and serves as a backup for each other. FIG. 12 shows an alternative route setting algorithm for realizing the alternative method 1. On the other hand, in the bypass method 2 in FIG. 11D, if the sensor node a _i fails, information is transferred via a _{i + 1} → b _{i + 1} → b _i → b _i−1 → a _i−1. All information on the system can reach the GW. FIG. 13 shows an alternative route setting algorithm for realizing the alternative method 2.

The difference between the detour method 1 and the detour method 2 shown in FIGS. 11 (c) and 11 (d) is the difference between the sensor network system on the sensor network system unless the sensor node b _i on the opposite side of the sensor node a _i failed in the detour method 1. If the information can reach the GW, but the sensor node b _i−1 , b _i , b _{i + 1} on the opposite side of the sensor node a _i that has failed in the bypass method 2 is not operating normally, the information on the sensor network system Is not reachable to the GW.

  Hereinafter, the reliability in the four models shown in FIG. 11 (simple one-dimensional model, double one-dimensional model (no detour), double one-dimensional model (detour method 1), double one-dimensional model (detour method 2)). The sex evaluation will be described.

<Evaluation method>
In obtaining the operating rate of the entire sensor network system, the following two points are used as the previously proposed conditions.
(1) Let λ be the failure rate per unit time of each node, and let the failure probability distribution be an exponential function.
(2) The data acquired at the node i is transferred in the order of the nodes i-1, i-2,..., And finally transferred from the node 1 to the GW. Information from the GW to the node i is transferred to the node i via the nodes 1, 2,..., I-1.

したがって、時刻ｔにおいて全ての情報がＧＷに到着可能な確率Ａ（ｔ）は、式（２）のようになる。

The operation rate of the entire sensor network system in the four models shown in FIG. 11 is as follows.
(A) Simple one-dimensional model In FIG. 11 (a), when the lifetimes of nodes 1,..., N are X ₁ ,... X _n , the probability P {Xi ≦ x } Is the cumulative distribution function of Xi and is given by equation (1).

Accordingly, the probability A (t) that all information can arrive at the GW at time t is expressed by Equation (2).

(B) Double one-dimensional model (no detour)
As shown in FIG. 11B, in a model in which sensor nodes a ₁ ,..., A _n , b ₁ ,..., B _n are installed on both sides of the road and transfer information to the GW independently, If either of the nodes a ₁ and b ₁ is functioning, it is assumed that all information can reach the GW. The probability A (t) that all information can arrive at the GW at the time t at this time is expressed by Equation (3).

(C) Double one-dimensional model (bypass method 1)
The establishment A (t) at which all information can arrive at the GW at the time t is expressed by Equation (4).

となる。ここで、ＴｉとＮが独立であるならば、Ｘの分布は式（６）となる。
次にＰ＾＝Ｐ｛Ｔ１＋…Ｔｋ≦ｘ｝を求める。

ここで、ｉ番目のセンサノードから正常動作しているとすると、正常動作している全てのセンサノード数は（２ｎ−ｉ＋１）個であるので、λｉ＝（２ｎ＋１−ｉ）λを式（７）に代入し、式（８）を得る。

よって、全ての情報がＧＷに到着可能な確率Ａ（ｔ）は、式（９）となる。

(D) Double one-dimensional model (bypass method 2)
The probability P {X ≦ x} that the lifetime X of the entire system is x hours or less is obtained. Assuming that all 2n sensor nodes are operating at time 0, let T _{1 be} the time when the first sensor node fails and T ₂ the time from T ₁ until the second sensor node fails. If the number of sensor node failures at the time when the entire system becomes inoperative is N, the time until the system becomes inoperative is

It becomes. Here, if Ti and N are independent, the distribution of X is expressed by Equation (6).
Next, P ^ = P {T1 +... Tk ≦ x} is obtained.

Here, assuming that the i-th sensor node is operating normally, the number of all normally operating sensor nodes is (2n−i + 1), so that λi = (2n + 1−i) λ is expressed by the equation (7). ) To obtain equation (8).

Therefore, the probability A (t) that all information can arrive at the GW is expressed by Equation (9).

  Note that P {N = k} is obtained by simulation based on the route setting algorithm shown in FIG. 13 because it is difficult to calculate directly when N is particularly large. FIG. 14 shows the result.

<Evaluation results>
In order to consider the system reliability effect of the bypass method, the number of FITs is assumed to be about 10,000 FITs from the hardware configuration shown in FIG. 3, and the evaluation is performed based on the failure rate λ = 1 × 10 ⁻⁵ (cases / hour). . The size of the sensor network is n = 10 to 30 (in the case of a double one-dimensional model, the number of sensor nodes on one side only).

  FIG. 15 shows the operating rates of the four models for n = 10, 20, and 30. For example, when n = 20 and the time to failure when the operation rate of the entire system is 90% is compared in each model, the simple one-dimensional model in FIG. 11A is 0.06 years, and the time in FIG. The double one-dimensional model (no detour) is 0.22 years, the double one-dimensional model of FIG. 11C (detour method 1) is 0.51 years, and the double one-dimensional model of FIG. The method 2) is 0.85 years, and the effectiveness of the system as a life extension method can be confirmed by the double one-dimensional model to which the detour methods 1 and 2 of FIGS. 11C and 11D are applied.

  FIG. 16 shows the number of sensor nodes satisfying 90% of the overall system operation rate versus the time until failure. It can be seen that with the increase in the number of sensor nodes, the detour methods 1 and 2 have less time to failure than the detour method. The effectiveness of the detour methods 1 and 2 shown in FIGS. 1C and 1D can be confirmed against the increase in the number of sensor nodes.

FIG. 17 shows the failure rate that satisfies the overall system operation rate of 90% versus the time to failure. The hardware configuration scale of the sensor node for maintaining the system operation rate in the time until an arbitrary failure can be understood. For example, when designing a sensor network with a time to failure of one year, with n = 10, the sensor node failure rate is λ = 1.2 × 10 ⁻⁵ (FIT number 12000), bypass method 2 is within λ = 7.5 × 10 ⁻⁶ (FIT number 7500), and when n = 20, λ = 8.5 × 10 ⁻⁶ (FIT number 8500) in the detour method 1, and λ = 8.5 in the detour method 2. The hardware configuration must be within 5.0 × 10 ⁻⁶ (FIT number 5000). In other words, with respect to the hardware scale capable of ensuring reliability, the bypass method 1 has a design margin of 1.7 times.

  From the above, when the hardware scale of the access space optical sensor device itself is large and when the system reliability of the entire sensor network is emphasized, the detour method 1 of FIG. 11C is effective.

<Cost evaluation>
A cost comparison of the four models shown in FIG. 11 is performed to consider the cost advantage of the detour method. As shown in FIGS. 11A and 11B, the number of sensor nodes is doubled in the simple one-dimensional model and the double one-dimensional model, and the cost is also doubled. Further, as shown in FIG. 11 (c), in the detour method 1, when the sensor node a _i or b _i fails, the sensor node a _{i + 1} or b _{i + 1} detours to b _i or a _i , and then b _i or Information is transferred from a _i to a _i-1 or b _i-1 . That is, the sensor node a _i needs to set a route to a _{i + 1} , a _i−1 , b _{i + 1} , b _i−1 , and it is necessary to secure two routes for detouring by one sensor node alone. On the other hand, in the detour method 2 shown in FIG. 11D, when the sensor node a _i or b _i fails, it is necessary to set a route only between the sensor nodes a _{i ± 1} and b _{i ± 1} .

Therefore, assuming that the cost of the optical transmission / reception unit of ASOSM in FIG. 1 is α and the cost of the common unit (internal bus, control unit, streetlight communication unit, sensor unit, etc.) is β, each cost (C _1D , C _Dual1D, the _{C method1, C method2) seeking,} and _{C 1D = 2nα + nβ 1D,} C dual1D = 4nα + nβ dual1D, C method2 = 8nα + nβ method1, C method2 = 6nα + nβ method2. At present, the cost α of the optical module part is high, and the cost specific gravity of the entire system α is considered high. The common part of the model are assumed to be the cost of comparable _{(β 1D ≒ β dual1D ≒ β} method1 ≒ β method2).

Naturally, the double one-dimensional model costs twice as much as the simple one-dimensional model, and if the detour method is realized, the detour method 1 requires 1.5 times and the detour method 2 doubles the cost. . Considering only the two bypass methods, C _method1 = 1.33 × C _method2 , and the cost of the bypass method 1 is about 1.3 times higher than that of the bypass method 2, and the bypass method becomes larger as the sensor network relative becomes larger. The cost advantage of 2 is high. That is, in the large-scale sensor network system, when it is desired to realize a cost-priority network, the bypass method 2 is effective.

  As mentioned above, although the Example of this invention was described, it cannot be overemphasized that this invention is not restricted to the Example mentioned here.

It is a block diagram of one Example of the access space optical sensor communication apparatus of this invention. It is a block diagram of the conventional lamp for illumination. It is operation | movement explanatory drawing of the access space optical sensor communication apparatus of this invention. It is a conceptual diagram of the conventional access network. It is a conceptual diagram of the access space optical sensor network of this invention. It is a basic block diagram of the access space optical sensor network of this invention. It is a figure explaining Example 1 of the access space optical sensor network of this invention. It is a figure explaining Example 2 of the access space optical sensor network of this invention. It is a figure explaining Example 3 of the access space optical sensor network of this invention. It is a figure explaining Example 4 of the access space optical sensor network of this invention. It is a figure explaining Example 5 of the access space optical sensor network of this invention. 10 is a detour setting algorithm of the detour method 1 according to the fifth embodiment. 10 is a detour setting algorithm of the detour method 2 according to the fifth embodiment. It is an example of the simulation result of the arrival possibility establishment to the gateway of all the information in the detouring method. It is the evaluation result 1 of Example 5. It is the evaluation result 2 of Example 5. It is the evaluation result 3 of Example 5.

Explanation of symbols

1 base 100 access space optical sensor communication device (ASOSM)
110, 120, 130 Optical transmission / reception unit 115, 125 Signal folding switch 116, 126 Optical axis adjustment unit 140 Signal branching unit 150 Signal multiplexing unit 160 Sensor unit 170 Control unit 180 AC-DC conversion unit 400 Gateway 500 Internet

Claims (10)

Each of N (N ≧ 3) optical transmission / reception units each accommodating an optical transmission unit and an optical reception unit, an internal bus connecting these optical transmission / reception units, a control unit, and the same power supply as a base of a normal illumination lamp Interface part for
At least two optical transmission / reception units are used for optical communication between adjacent access space optical sensor communication devices, and the remaining at least one optical transmission / reception unit is used for optical communication with illumination and communication devices under illumination. An access space optical sensor communication device. The access space optical sensor communication device according to claim 1.
Between the optical transmission / reception unit used for optical communication with the communication device under illumination and the internal bus, a signal branching unit that takes in the signal addressed to the communication device on the internal bus, and a signal from the communication device on the internal bus An access space optical sensor communication device comprising: a signal multiplexing unit for multiplexing with a signal. The access space optical sensor communication device according to claim 1 or 2,
The optical transmission / reception unit used for optical communication between at least adjacent access spatial optical sensor communication devices includes an optical axis adjustment unit for adjusting a transmission / reception direction of an optical signal. In the access space optical sensor communication device according to any one of claims 1 to 3,
An access space optical sensor communication apparatus, comprising: an optical transmission / reception unit used for optical communication between at least adjacent access space optical sensor communication apparatuses, wherein a turn-back switch is provided, and the switch can be turned on and off by a control unit. The access space optical sensor communication device according to any one of claims 1 to 4,
An access space optical sensor comprising at least one sensor such as temperature, humidity, atmospheric pressure, odor, gas, camera, microphone, etc., and capable of transmitting sensor information at a predetermined time interval by a control unit. Communication device.   An optical sensor that installs a plurality of access space optical sensor communication devices according to any one of claims 1 to 5 in place of street lamps on a road, and performs optical communication between the access space optical sensor communication devices together with illumination on the road An access space optical sensor network system comprising a network. The access space optical sensor network system according to claim 6,
The optical sensor network is mainly connected to a communication network using the Internet protocol, and the communication device under the illumination by the access space optical sensor communication device can access the communication network via the access space optical sensor communication device. Access space optical sensor network system. The access space optical sensor network system according to claim 6,
The optical sensor network is connected to a communication network mainly using the Internet protocol, and information on sensors provided in the access space optical sensor communication device can be stored in a database via any application on the communication network. Features an access space optical sensor network system. The access space optical sensor network system according to claim 6,
A physical plane that physically installs, maintains, and manages a physical device such as an access space optical sensor communication device and an outdoor pillar on which the device is installed, and a plurality of access space optical sensor communication devices that are installed on the physical plane A control plane that implements communication control for establishing communication using a communication protocol while using wireless or optical wireless communication, and a data signal is transmitted after a plurality of access space optical sensor communication devices establish communication on the control plane Therefore, using the optical transmission / reception unit provided in the access space optical sensor communication device, the data plane for establishing optical communication for data communication, and the application plane for executing the application using the data communication established in the data plane The physical plane, the control plane, the data plane, and the application Access spatial light sensor network system, characterized in that the order of Npuren continue to perform the communication procedure. The access space optical sensor network system according to claim 6,
When access space optical sensor communication devices are installed in two rows in a one-dimensional manner, and any access space optical sensor communication device in one row fails, a bypass is routed using the access space optical sensor communication device in the other row. An access space optical sensor network system characterized in that it can be formed and communicated.

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