Super RFID System Based on Sensor Network

Abstract: This paper combines RFID and wireless sensor network technologies, proposes a super RFID system based on sensor networks, introduces the composition and architecture of the system, and the new requirements of the system for Savant. It points out that the integration of RFID technology and sensor network technology may be a new development trend.

Keywords: RFID; wireless sensor network; super RFID

1 Introduction

Radio Frequency Identification (RFID), also known as electronic tag (E-Tag), is a technology that uses radio frequency signals to automatically identify target objects and obtain relevant information. The super RFID system based on sensor networks (hereinafter referred to as the super RFID system) combines the technical characteristics of RFID and sensor networks. It inherits the characteristics of RFID that automatically identifies targets using radio frequency signals, and at the same time realizes the active perception and communication functions of wireless sensor networks. The super RFID based on sensor networks is not a passive tag technology. It can actively monitor the environment and record relevant data, and can actively issue an alarm when necessary.

2 Technical integration of RFID and wireless sensor networks

2.1 Introduction to sensor network technology
The progress of micro-electromechanical systems (MEMS), wireless communication and microelectronics technology has made it possible to design and develop low-cost, low-power, multi-functional micro sensors. These micro sensors are small in size and have sensing, data processing and communication components. In the next few years, there will even be ultra-low-power SoCs that integrate wireless communication, microprocessors and MEMS sensing and actuation components on a single chip. Many sensors (or actuators) with communication and computing capabilities are connected wirelessly, collaborate with each other, interact with the physical world, and jointly complete specific application tasks. This is called a sensor network.

Compared with traditional sensors, sensor networks are easy to deploy, that is, the location of sensor nodes does not need to be determined in advance or carefully designed, and can be placed anywhere. The deployment and maintenance costs are low and they have high flexibility. Sensor networks are composed of a large number of cheap nodes that can be placed within the range of physical phenomena to obtain higher observation accuracy and have a higher cost-effectiveness. Sensor networks have a large number of redundant nodes, and even if some nodes fail, it will not affect the function of the entire system, so they have better robustness. Sensor network nodes have computing power, can collaborate with each other, and can complete tasks that traditional sensors cannot complete.

2.2 Technical integration of RFID and wireless sensor networks
The combination of RFID technology and sensor network technology may be a future development trend. Sensor networks generally do not care about the location of nodes, so they generally do not use global identification for nodes. RFID technology has a unique advantage in node identification. Combining the two to form a network can make up for each other's shortcomings. It can not only focus the main energy of the network on data, but also use the identification function of RFID to easily find the location of the node when it is necessary to consider the specific information of a specific node.

3 Composition of the Super RFID System

The super RFID system adopts a hierarchical structure, which is divided into three levels: terminal nodes, gateway nodes and upper-level users, as shown in Figure 1.

Figure 1 Composition of Super RFID

The terminal node consists of two parts: a large number of ordinary sensor nodes and super RFID tags. In addition to the basic RFID wireless marking function, the super RFID node is also equipped with a micro sensor, which can actively sense the temperature and humidity, position movement, smoke, electromagnetic environment, sound and other information of the node marking object, and can actively report the sensed information.

The intelligent processing nodes with sensor devices act as gateway nodes, which have two functions: (1) reading and aggregating information from super RFID nodes and sensor nodes; (2) analyzing the read information and monitoring environmental information in real time. Active gateway nodes read RFID tag information when necessary and send it to upper-level users through the sensor network; of course, RFID node information can also be read by handheld readers at any time.

The upper-layer users mainly refer to the external networks that directly communicate with the intelligent gateway nodes, such as the Internet or GSM network. In addition, the wireless sensor network and the existing wireless communication terminals (such as mobile phones) cannot communicate well. It is a good choice to use the existing network to send the processed information to the user terminal.

4 Architecture

The super RFID system integrates wireless sensor networks and RFID technology. Therefore, when designing the system architecture, the characteristics of both should be taken into consideration. The system architecture is shown in Figure 2.

Figure 2 System architecture diagram

Savant software is a "middleware" that processes the tag or sensor data (event data) stream obtained from one or more readers. It is a common data management architecture for enterprises and is installed on a hierarchical, distributed server. The Savant of this system has three data sources. It can come from the reader in a traditional way, can receive information from sensor nodes, and can also receive information actively sent by super RFID. Based on the tree-like hierarchical structure of Savant and according to its classification, a unified hierarchical Savant architecture is defined. According to the definition of the Auto-ID Standards Committee, Savant should include three required standard modules: event management system (EMS), real-time memory data structure (RIED) and task management system (TMS). Some other optional standard program modules can be defined by users. Figure 3 is the architecture of Savant.

Figure 3 Savant architecture

In Figure 3, the event management system is applied on the Edge Savant (ES) to collect tag reading events. It communicates with the reader application and manages the event stream sent by the reader. The "reading adapter" and "reader interface" in the EMS architecture can be regarded as a common interface. For the Edge Savant, the reading adapter communicates directly or indirectly with the reader and collects the events detected by the reader, and then writes these events to the reader interface. For the Internal Savant, it is the parent node or superior of the Edge Savant s. The IS collects EPC data from its subordinate Edge Savant, so the "reading adapter" and "reader interface" can be regarded as a common network data access interface.

RIED is an in-memory database used to store Edge Savant information. Edge Savant stores and organizes events sent by readers. The Event Management System (EMS) provides a framework for filtering and recording events, and the recorder can save events in the database. When the database handles a large number of events, RIED provides the same interface as the database, but with better real-time performance. Applications can access RIED through JDBC or native Java interfaces.

Savant software manages and monitors data based on user-defined tasks. TMS is responsible for managing tasks sent to local Savant by upper-level Savant or enterprise applications. Savant TMS makes it easy to maintain distributed Savants, and tasks written to TMS can obtain all properties of Savant.

5 Conclusion

This paper combines RFID and wireless sensor network technologies, proposes a super RFID system based on sensor networks, introduces the composition and architecture of the system and the new requirements of the system for Savant, and points out that the integration of RFID technology and sensor network technology may be a new development trend.