WO2010095923A2

WO2010095923A2 - Wireless sensor network system

Info

Publication number: WO2010095923A2
Application number: PCT/MY2010/000024
Authority: WO
Inventors: Wan Hasmi Wan Kamal; Ahmad Rizal; Abdul Rahim Abdul Hamid; Ahmad Nizar; Badrul Hisham; Muhammad Asbari; Mohd Arif Safaruddin Mohd Najmi
Original assignee: Mimos Bhd
Current assignee: Mimos Bhd
Priority date: 2009-02-18
Filing date: 2010-02-18
Publication date: 2010-08-26
Anticipated expiration: 2011-08-18
Also published as: MY164514A; WO2010095923A3

Abstract

The present invention provides a wireless sensor network (WSN) (200) having a main coordinator (210), a site coordinator (400) and a method therefor. The WSN (100) comprises a plurality of site coordinators (220), each forms a site WSN (290) and functioned by its own, and collectively, the plurality of site WSNs (290) forms the WSN (200). Each site coordinator (220) is operable to collect and store data collected/acquired from the respective site WSN (290) and to route out the collected/acquired data to the main coordinator (210) as appropriately.

Description

Wireless Sensor Network System

Field of Invention

The present invention relates to a wireless sensor network. More particularly, the present invention relates to a wireless sensor network for precision agriculture field deployment.

Background of the Invention

Wireless sensor network (WSN) has been used to be deployed in a field of interest to cooperatively monitor physical or environmental conditions with sensors integrated with wireless transmission technologies. A WSN usually includes end (sensor) devices, router devices and a coordinator.

The advantage behind WSN technology is that it has a multi-hop or mesh network capabilities to send and route messages and data from source to final destination, and with this ability, the wireless range problem is not an issue. However, there is certain limitation in implementing the wireless sensor network for high number of sensors due to low and limited battery power and also limited memory space inside the controller unit.

ZigBee network, for example, was originated for home automation application. In such application, power supply is generally not a concern for routers and end devices as direct power supply is easily accessible. When WSN is deployed in a field where the power supply is not easily accessible, the network may need to rely on portable power source, such as batteries, which has limited power supply over time. Further, a WSN with single coordinator is not meant for large scale network due to lack of memory space and resources.

FlG. 1 illustrates a typical WSN known in the art. The WSN includes a plurality of routers that collect data from the sensor motes and direct to the coordinator via an ad-hoc network. The coordinator may be a gateway that further directs the sensed information to other network via any wireless communication means, such as Wi-Fi and GSM. As mentioned, such network contains limited number of sensors, thereby the field coverage is also limited.

US patent publication no. US2006/0268745 discloses a clustering method of WSN to minimize energy consumption. It uses same sensor motes as site coordinator to handle the cluster network.

US patent publication no. US2008/0037569 discloses a method and apparatus for wireless communication in a mesh network using _soft proxies. It suggests a network expansion for large area deployment. The apparatus too uses same sensor motes for expansion with soft algorithm as proxy device.

Summary of the Invention

In one aspect of the present invention, there is provided a wireless sensor network (WSN) having a main coordinator. The WSN comprises a plurality of site coordinators, each forms a site WSN and functioned by its own, and collectively, the plurality of site WSNs form the WSN. Each site coordinator is operable to collect and store data collected/acquired from the respective site WSN and to rout out the collected/acquired data to the main coordinator as appropriately.

In one embodiment, operationally, each site WSN (290) works independently, where one of the site WSNs is operable in a sleep mode while other site WSNs are operable in an operating mode. The site coordinator may be integrated with a routing unit.

In another embodiment, the WSN is expandable by including one or more site WSN, each manages by a site coordinator.

In accordance with another aspect, there is provided a site coordinator of a site WSN (290). The site coordinator comprises a data storage unit; a coordinator microcontroller (MCU) for coordinating data collected/acquired within the site WSN; and a routing MCU for routing the collected/acquired data collectively to other site WSN. the data collected/acquired through the coordinator MCU is stored in the data storage unit, and the collected/acquired data are routed to other WSN as appropriately through the routing MCU.

In one embodiment, the coordinating MCU, the routing MCU and the data storage unit are interconnected through I2C connection. Operationally, the routing MCU may be initialized as master when the coordinating MCU is initialized as slave.

In another embodiment, the coordinating MCU is connected to the routing MCU via a bidirectional data line and a bidirectional clock line. In a further aspect of the present invention, there is provided a method of collecting/acquiring data from a WSN. The method comprises initializing a routing MCU as master; initializing a coordinating MCU as slave; storing the collected/acquired data into a data storage unit; and routing the stored data to other WSN.

In one embodiment, the method further comprises requesting the coordinator MCU for receiving data; and pooling the request made by the routing MCU.

Brief Description of the Drawings

This invention will be described by way of non-limiting embodiments of the present invention, with reference to the accompanying drawings, in which:

FIG. 1 illustrates a typical wireless sensor network (WSN);

FIG. 2 illustrates a wireless sensor network (WSN) in accordance with one embodiment of the present invention;

FIG. 3 illustrates a WSN in accordance with another embodiment of the present invention;

FIG. 4 illustrates a schematic diagram showing the architecture of a site coordinator in accordance with one embodiment of the present invention; and

FIG. 5 illustrates a flow diagram of the coordinator in accordance with one embodiment. Detailed Description of the Invention

In line with the above summary, the following description of a number of specific and alternative embodiments is provided to understand the inventive features of the present invention. It shall be apparent to one skilled in the art, however that this invention may be practiced without such specific details. Some of the details may not be described at length so as not to obscure the invention. For ease of reference, common reference numerals will be used throughout the figures when referring to the same or similar features common to the figures.

FIG. 2 illustrates a wireless sensor network (WSN) 200 in accordance with one embodiment of the present invention. The WSN 200 comprises a main coordinator 210, a plurality of site coordinator 220, a plurality of routers 240 and sensor motes 250 for each coordinator 210, 220. Briefly, the coordinators that include the main coordinator 210 and the site coordinator 220, each comprises generally a microcontroller (MCU), a memory unit, a transceiver and power source. The microcontroller works in conjunctions with the memory unit controls the general operations of the coordinator and process data acquired from the sensor motes 250. The transceiver is provided for wireless communications between a coordinator and other coordinators as well as the sensor motes 250. The power source for powering up the coordinator is preferably portable power sources, such as battery, capacitor or the like, to allows the coordinators to be deployed without any geographical limitations. More preferably, the power source may incorporate a solar panel or any energy harvesting means to prolong the period for power source replacement. Each of the sensor motes 250 comprise one or more sensors that collectively acquires and gathers the relevant data for transmitting to the coordinators. The sensors include imaging sensor, thermometer, and many others depending on the type of information required for that field. The wireless sensor network 200 is clustered into a plurality of smaller WSN 290, wherein each of the WSN 290 is managed by a main coordinator 210 or site coordinator 220. Similar to an ordinary WSN, data collected by the sensor motes 250 are forwarded to the respective coordinator 210, 220 via the nearest router 240. The main coordinator 210 is a WSN coordinator integrated with one or more communication interface, such as Wi-Fi and GSM, for communicating with foreign networks. Each site coordinator 220 on the other hand is couple with a router 240 for routing the collected data. As each clustered network is relatively smaller, it can now be easier to manage and the power consumed in each network is relatively lower. Further, as the number of hops has been increased by the clustered smaller networks each having its own coordinator 210, 220 within a small WSN. It can be realized that when a relatively small WSN, each deploys with a coordinator for managing the data flow, is used, distributed power management controls can also be achieved to offer an efficient use of resources on the coordinator and routers by separating the sensor motes into cluster. On top of the resources management, which includes power, memory managements, the smaller WSN 290 permits expansion for large-scale deployment when needed.

FIG. 3 illustrates a WSN 300 in accordance with another embodiment of the present invention. The WSN 300 comprises a main coordinator 310, a plurality of site coordinator 320, a plurality of routers 340 and sensor motes 350 for each coordinator 310, 320. The WSN 300 operates in substantially a same way as the WSN 200 of FIG. 2, where WSN 300 too is clustered into a plurality of smaller WSN 390, 395, wherein each of the WSN 390, 395 is managed by the main coordinator 310 or the site coordinator 320 respectively. Operationally, not all WSN 390, 395 are running at the same time. In FIG. 3, the WSNs 390 are in sleep mode while the WSN 395 is in operating mode. The sleep

FIG. 4 illustrates a schematic diagram showing the architecture of a site coordinator 400 in accordance with one embodiment of the present invention. The site coordinator 400 comprises a coordinator microcontroller 410, a routing microcontroller 420 and a memory block 430. Operationally, the coordinator microcontroller 410 initializes its I2C module as default Slave. The routing microcontroller 420 on the other hand initializes its I2C module as default Master, as opposed to the conventional WSN routings where the I2C module is initialized as default Slave for routing all transmissions it receives. When the coordinator microcontroller 410 establishes a new WSN Personal Area Network (PAN), and set as a Slave to the network organizes its child motes and transfers data. During operations, the coordinator microcontroller 410 is usually busying with its own PAN data handling. The memory block unit 430 is adapted in between the coordinator microcontroller 410 and the routing microcontroller 420 for handling the data acquired by the coordinator microcontroller 410. When time suits, the routing microcontroller 420 reads the data stored in the memory block and route it out accordingly. Further, the availability of memory block 430 also reduces the risk of losing data during the operations when it is interrupted In the present embodiment, the coordinator 400 adapted two-wire I2C interface for communication between the coordinator microcontroller 410 and the routing microcontroller 420. The two-wire I2C interface includes a bidirectional data line and a bidirectional clock line. The bidirectional clock line is also connected to the memory block 430

FIG. 5 illustrates a flow diagram of the coordinator 400 in accordance with one embodiment. The operations are conducted among coordinating microcontroller 410, routing microcontroller 420 and the memory block 430. At step 510, data are transferred from other WSN network to the routing microcontroller 420. At step 512, the routing microcontroller 420 sets I2C as Master and the coordinator microcontroller 410 sets I2C as Slave. At step 514, the data received by the routing microcontroller 420 is stored at the memory block 430. The memory block 430 acknowledges receipt and stored of the data at step 516. The routing microcontroller 420 requests the coordinator microcontroller 410 to receive data at step 518. The request is polled at step 520 at the coordinator microcontroller 410. At step 522, the coordinator microcontroller 410 is engaged for handling and coordinating the pooling requests from the routing microcontroller 420. A negative acknowledgement (NACK) is according feedback to the routing MCU 420 to indicate that the coordinator MCU 410 is busy and not ready to receive new data at step 524. At step 526, the routing microcontroller 420 sets the I2C to slave and standby mode, and the coordinator microcontroller 410 sets I2C as Master. Still at step 526, the coordinator microcontroller 410 reads the stored data from the memory block 430. At step 528, the memory block 430 acknowledges the coordinator. The stored data is then relay a new network accordingly to at step 530. Such method provides a simple one way data transfer technique for the coordinator 400 for transmitting data. Such method can be used to transfer data in the other directions.

The present invention is adapted with system and method suitable for precision agriculture, among others.

The present invention, in one embodiment, provides a WSN clustered into a plurality of site WSNs, each site WSN is limited in a relatively smaller sensor network size and manages by a site coordinator for coordinating data transmission on an ad-hoc or mesh network basis. Data accumulated by the site coordinator is ultimately routed to a main coordinator that generally provides a long range communication interface. As the WSN is clustered, the site WSN can be managed as a single WSN, where the power drawn by each site WSN can be managed effectively by putting one or more of the site WSNs in sleep mode when others are operating. The data collected by each site coordinator is temporary maintained in a data storage unit integrated in the site coordinator, and when appropriate, the data is routed to the main coordinator for transmission.

In another embodiment, the present invention provides a site coordinator having a coordinating microcontroller (MCU), a routing MCU and a storage unit. The coordinating MCU is provided to coordinate the collections and storage the acquired data from the sensor network in the storage unit. When appropriate, the stored data is routed accordingly. The site coordinator uses a I2C bus 2 wire connection for communication between the coordinating MCU, routing MCU and the storage unit.

In yet another embodiment, the present invention provides a method of transmitting data and command between both microcontrollers within the site coordinator device. The synchronization routine offered minimizing data clashing and data lost.

While specific embodiments have been described and illustrated, it is understood that many changes, modifications, variations and combinations thereof could be made to the present invention without departing from the scope of the invention.

Claims

Claims:

1. A wireless sensor network (WSN) (200) having a main coordinator (210), the WSN (100) comprising: a plurality of site coordinators (220), each forms a site WSN (290) and functioned by its own, and collectively, the plurality of site WSNs (290) form the WSN (200), wherein each site coordinator (220) is operable to collect and store data collected/acquired from the respective site WSN (290) and to route out the collected/acquired data to the main coordinator (210) as appropriately.

2. The WSN (200) according to claim 1, wherein operationally, each site WSN (290) works independently, where one of the site WSNs (395) is operable in a sleep mode while other site WSNs (390) are operable in an operating mode.

3. The WSN (200) according to claim 1 , wherein the site coordinator (220) is integrated with a routing unit.

4. The WSN (200) according to claim 1, wherein the WSN (200) is expandable by including one or more site WSN (290), each manages by a site coordinator (220).

5. A site coordinator (400) of a site WSN (290), the site coordinator (400) comprising: a data storage unit (430); a coordinator microcontroller (MCU) (410) for coordinating data collected/acquired within the site WSN (290); and a routing MCU (420) for routing the collected/acquired data collectively to other site WSN (290), wherein the data collected/acquired through the coordinator MCU (410) is stored in the data storage unit (430), and the collected/acquired data are routed to other WSN (290) as appropriately through the routing MCU (420).

6. The site coordinator (400) according to claim 5, wherein the coordinating MCU (410), the routing MCU (420) and the data storage unit (430) are interconnected through I2C connection.

7. A method of collecting/acquiring data from a WSN (290), the method comprising: initializing (512) a routing MCU (420) as master; initializing (512) a coordinating MCU (410) as slave; storing (514) the collected/acquired data into a data storage unit (430); and routing (530) the stored data to other WSN.

8. The method according to claim 7, further comprising: requesting (518) the coordinator MCU (410) for receiving data; and pooling (520) the request made by the routing MCU (420).