Techno-Sciences, Inc. 9.04.1-2 Wireless Smart Sensor Network with Localization Capability
. 9.04.1-2 Wireless Smart Sensor Network with Localization Capability
Wireless network smart sensors play a very important role in homeland security and first responder (HLS-FR) applications. A smart sensor can reduce a large amount of data measured from a single sensor, a cluster of sensors, or an array of sensors to simple, human readable information for quick decision-making. Without the need to lay many long cables, these wireless sensors can be easily deployed for surveillance and monitoring environmental and hazardous conditions. Integrated with networking capability, these wireless sensors can be linked to form a wireless sensor network that can pass and exchange data among sensors and to the Internet for easy access with a common web browser. The activity of a malfunctioned or damaged sensor can be quickly taken over by the adjacent sensors. In some specific HLS-FR applications, it is desirable to have a wireless smart sensor that can report its location inside and outside a building or in a moving vehicle, container, or vessel with accuracy as small as thirty centimeters. The wireless smart sensor could use the latest GPS, differential GPS, or other advanced localization techniques or technologies to identify its location.
NIST is conducting research and development work on communication and connectivity standards for smart and wireless sensors for HLS-FR applications. We are currently working with IEEE and industry to standardize wireless communication interfaces for networking smart sensors. Hence, we are soliciting proposals for the development of a wireless sensor network that has localization capability, operating both indoor and outdoor. A node of the wireless sensor network, where sensors or actuators can be connected, is defined as the wireless Transducer Interface Module
(TIM). Each TIM must have at least 500 Kbytes of memory space available for developing smart sensor application programs by the user. The wireless TIMs should be designed for compatibility with the IEEE 1451 family of standards. It is recommended that the proposing party be thoroughly familiar with IEEE 1451. Copies of the standards can be acquired from IEEE at 1-800-678-4333. The awardee(s) might need detailed information about the IEEE 1451 standards and their implementations developed at NIST..
The expected Phase 1 result is the delivery of three units of wireless TIMs with early demonstration capability showing concepts of sensor localization indoor and outdoor, wireless networking, IEEE 1451.x TEDS, etc. The network and TIMs would be retained by NIST, with the understanding that the contractor would be provided access to the equipment if successful in receiving a Phase 2 award. It is expected that a Phase 2 effort will result in the construction and demonstration of a full-function prototype suitable for commercialization.
(a) Identification and Significance of the Problem or Opportunity 3
(b) Phase I Technical Objectives 4
(c) Phase I Work Plan 4
c.1 Detailed Project Description and Background 5
c.1.1 Task 1: Developing TIM Hardware 5
3.2 Task 2: Developing Communication Protocols for the TIM Network (Gil, please try to make this sound more intelligent 8
c.1.2 Task 3: Development and Implementation of Algorithms for Signal Processing and Fusion of Data 9
c.1.3 Task 4: Achieving Localization: Algorithms and Hardware 9
(d) Related Research or R&D 15
d.1 Smart Dust: Large-Scale Low Power Flexible Sensor Network 15
(e) Key Personnel and Bibliography of Related Work 15
(f) Relationship with Future R&D 16
(g) Facilities and Equipment 20
(h) Consultants and Subcontracts 20
(i) Potential Commercial Applications and Follow-on Funding Commitment 21
(j) Cooperative Research and Development Agreements (CRADA) 21
(k) Guest Researcher 21
(l) Cost Sharing 21
Abstract
We propose to develop a distributed network of small sensors that can monitor the environment, communicate with each other, locate sensed objects, perform distributed computations, and reach joint decisions by fusing the data the individual sensors acquire. Each node of the network will include several sensors, a microprocessor and a transceiver. We expect there to be anywhere from ten to hundreds and perhaps thousands of nodes in the network. The connectivity of the network will depend on the transmitting power and the distance between nodes. We expect nodes be at least be able to transmit to their nearest neighbors.
Potential Commercial Application of the Research:
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Key words
Smart sensors, sensor network, localization, transducer interface module, IEEE 1451, data fusion
(a) Identification and Significance of the Problem or Opportunity
We propose to develop a distributed network of small sensors that can monitor the environment, communicate with each other, locate sensed objects, perform distributed computations, and reach joint decisions by fusing the data the individual sensors acquire. Each of the network nodes, which are often referred to as wireless Transducer Interface Modules (TIMs), will include several sensors, one or two microprocessors and a transceiver. We expect there to be anywhere from ten to hundreds and perhaps thousands of nodes in the network. The connectivity of the network will depend on the transmitting power and the distance between nodes. We expect nodes be at least be able to transmit to their nearest neighbors. Figure 1.1 illustrates the ad-hoc sensor network.
To design and fabricate the network, we will use a combination of new hardware and software algorithms. The unique aspects of the proposed network will include:
· Use of both narrow band operation for communication and ultra-wide band for localization.
· Integration of MEMS chemical and vibrational sensors.
· Unique signal processing algorithms to decipher sensed data.
· Unique algorithms to achieve localization.
· Development of our own application specific integrated circuits (ICs), as well as incorporation of existing ICs.
· Application of 3-dimensional fabrication technology where integrated circuits can be stacked vertically.
· Application of unique antenna designs and high-K dielectrics that allow for use of unusually small geometries.
· Extremely high value micron size 3D interdigitated capacitors to facilitate energy storage in very small volumes.
In order to achieve processing, fusion and localization across the network, we plan to utilize energy-efficient short-range RF communication, sensing and processing at each node, and develop ad-hoc networking algorithms for reliable communication and fusion. The network will exploit multiplexing of transmissions in time and frequency, by combining time-division multiple access (TDMA) with frequency-division multiple access (FDMA). We plan to have the network self-assemble whereby the multiple access slots are reused across the network with large enough reuse distances to avoid interference. As a result, each TIM will communicate “within its cell” with a small number of other nodes, at a small number of operating frequencies, and a small number of time allocations. Information will be sensed and will then be fused with that of other TIMs to make network-wide decisions. The information will be communicated digitally using frequency shift keying (FSK) modulation. Location determination will be achieved through a combination of algorithms, which will rely on both narrow and ultra-wide band communication.
(b) Phase I Technical Objectives
* Phase 1: TIMs (centimeter scale): In the first phase of our program, we plan to develop an ad-hoc wireless network of between ten and twenty nodes. These smart nodes or TIMs will be several centimeters in dimension. Each TIM will contain a narrow band transceiver, one or two microprocessors, and one or more of the following sensors: vibration, acoustical, temperature and optical. An ultra-wideband transceiver may also be included to help perform location determination. The system will be integrated into a multi-level device, fabricated on printed circuit (PC) boards. The TIMs will mainly utilize commercially off the shelf (COTS) integrated circuits. Of course, a standard GPS receiver can readily be included into the TIM unit for outdoor location with meter level accuracy. The network will assemble itself and establish communications using a TDMA protocol.
Note that after we develop a working network using only vibration and/or temperature sensors, we plan to add complexity and modularity by introducing the IEEE 1451 Standard. This will give rise to TIMS that contain two microprocessors, but has the advantage of added flexibility. We describe how we plan to implement the 1451 Standard in section C.1.1.
* Phase 2: Tiny TIMs (sub-centimeter scale): In Phase 2, we will concentrate on reducing the size of our sensor nodes to sub-centimeter dimensions. To achieve we will use both, COTS parts, as well as IC’s that we design and fabricate ourselves. As we have done in previously[1-3], the fabrication process will be accomplished using the MOSIS facility, and the post processing will be performed at local laboratories. (The MOSIS facility allows for the fabrication of chips, in lots consisting of 40 die, that are well within the Phase 2 budget of this project.) To reduce the antenna geometry required, we will increase the operating frequency of our circuits, as well as use high-K dielectric antenna substrates. We also plan to increase the number of nodes from between the 10 and 20 developed in Phase 1, to approximately 100 in Phase 2. In this phase, 3D stacking of chips will be performed to greatly reduce the footprint.
(c) Phase I Work Plan
Phase 1 of our program consists of four generals tasks. Here we briefly summarize the 4 general tasks. Then we provide detailed task descriptions and backgrounds
· Task 1 is aimed at developing the hardware for prototyping the wireless nodes. Each TIM includes environmental sensors, one or two microcontrollers and a transceiver. This task is aimed at identifying the proper sensors and integrated circuit components and assembling them into a TIM node. This will require designing the system, fabricating printed circuit boards and assembling the unit.
· Task 2 is aimed at developing and implementing the communication protocols which will enable the sensor nodes to communicate with each other wirelessly. This will require establishing methodologies for digital communication, designing network protocols so the network can self-assemble, establish a TDMA framework, generate compression algorithms, data packaging and error corrections codes. Once these algorithms are developed, the microprocessors will be programmed to implement the communication protocols.
· Task 3 is aimed at developing algorithms to perform signal processing of data. Once data is taken at the individual nodes, decisions must be made to understand the data. Here we will develop signal processing algorithms to extract meaningful trends and information for the network. Once algorithms are developed, they will be programmed into the microprocessor in the TIM.
· Task 4 is aimed at developing the technology for localization. In this task we plan to develop several methods for localizing the network nodes and the position of the sensed environmental factors. These methods include (1) GPS, (2) Signal Hopping, (3) Received Signal Strength Indication (RSSI), (4) Active Radar, (5) Ranging by Phase Delay. A GPS receiver will be incorporated into each node for outdoor networks. In addition we will determine relative positions by the order in which the network establishes itself with Signal Hopping. The RSSI outputs on the transceivers will give us a description of the distance between nodes by indicating the power level that one node receives wireless signal from another. The Active Radar and Ranging by Phase delay use additional RF hardware to determine location and will be designed in Phase 1, and implemented if time and resources are available.
c.1 Detailed Project Description and Background
In Phase 1 of the program we will develop an ad-hoc, self-assembled network of approximately twenty TIMS. The overall plans were described in the bullet item in Section 1. Here, we describe more details of the Phase 1 hardware and network algorithms.
c.1.1 Task 1: Developing the TIM Hardware
The generic operational structure of a TIM network node consists of one or more analog sensors which take data on the environment. This information is then digitized and stored in the microprocessor. The data stored in the microprocessor is then distributed wirelessly to the network using the transmitter. The receiver part of the TIM obtains information from the other nodes in the network. This information is then stored in the microprocessor. The microprocessor serves two major functions. First, it processes and helps fuse the data from its own sensors with the data it receives from the rest of the network to help in the distributed network decision making. In addition, the microprocessor must control the communication algorithm for the TIM network. In other words, it must tell its own transceiver when to receive information from other nodes, and direct when to transmit its own data and decisions. A functional diagram of a TIM node is given in Figure 3.1.
Figure 3.1: TIM Functional Diagram
Sensors
For our sensor input we plan to take a modular approach. This allows us to take data from different sources. This will be achieved using a device independent program in the microprocessor. However, for our initial implementation, we plan to start with acoustic, optical and temperature sensors. For the optical sensor, we will use a photodiode. For the acoustic sensor, which will also serve as the vibration detector, we will employ a MEMS microphone. The temperature sensor is also millimeter sized, and provides a eight bit digital output. In our background work we have already investigated the characteristics of these sensors. We connected several of the sensors with the microprocessor using the I2C bus, and found this approach is flexible in that it allows for a wide variety of sensors to be used in a single node. The only difficulty is that the sensors must be preconditioned with I2C capability For our initial prototypes, an analog interface will also be provided with an ADC converter. Figure 2.2 shows the prototyped sensor systems mounted on small PC boards we designed and fabricated in our background investigation.
IEEE 1451 Standard
For this work, NIST has requested that we explore using the IEEE 1451 standards for smart transducer interface. With this interface the sensor must include binary information indicating its function and address in a Transducer Electronic Data Sheet (TEDS) to the Smart Transducer Interface Module (STIM), and ultimately to the microprocessor or Network Application Processor (NCAP). We will make every effort to use this standard. However, our previous experience has indicated that many sensors, which are developed for implementation with microprocessors and networks, do not yet have this standard built-in. In order to help comply with the request to use IEEE 1451 standard, we plan to use the following approach. The sensor STIM will in itself be an independent micro-controlled module that ultimately will connect to the NCAP. The STIM’s microprocessor will be programmed to access the various sensors that are attached to it. Accessing the various sensors will depend on the protocol that the sensor supports. For example, a sensor may simply supply analog values. These values will then be read on a specific A-to-D input line on the STIM’s microcontroller. Overall, the STIM’s microcontroller will be programmed to read and store data values from each sensor. The data will then be formatted with the information from the respective sensor’s TEDS. Information in the TEDS will be stored in the internal ERPOM, or an EPROM attached to the STIM’s microprocessor. In response to a request from the NCAP, the STIM’s microcontroller will send the requested data using the TII protocol. The NCAP will then transmit the information to the other nodes on the network using the TDMA protocols, which are discussed below. We plan to implement this STIM configuration with the PIC microcontroller.