Abstract:
This paper presents a library management design based on radio-frequency identification (RFID) and Cortex-M3 technologies. This attribute is through RFID technology to achieve intelligent library and solve problems of book’s position, collection and low efficiency of return and borrow books. In this paper, a typical management system has proposed using various functional blocks. According to the research and application of RFID and anti-collision algorithm, through analysis of the current library management system(LMS), traditional barcode technology is out-date. RFID tags can read by the reader automatically without manual operation. The reader is used by Cortex-M3 processor. Therefore, a RFID-based smart management system of the library is proposed.
Keywords:
radio-frequency identification (RFID); anti-collision algorithm; library management system(LMS)
1. Introduction
Now the development of information technology brings library automatically and digitally. Mostly libraries are used bar-code technology. But the quantity of library books is huge, easy to put books in wrong bookshelves, particularly the work of check out books.RFID technology has slowly begun to replace the traditional barcodes on library items (books, CDs, DVDs, etc.) The RFID tag can contain identifying information, such as a book's title or material type, without having to be pointed to a separate database. The information is read by an RFID reader, which replaces the standard barcode reader commonly found at a library's circulation desk. It may replace or be added to the barcode, offering a different means of inventory management by the staff and self service by the borrowers. It can also act as a security device, taking the place of the more traditional electromagnetic security strip.
Radio-frequency identification (RFID) is a technology that uses radio waves to transfer data from an electronic tag, called RFID tag or label, attached to an object, through a reader for the purpose of identifying and tracking the object. Some RFID tags can be read from several meters away and beyond the line of sight of the reader. The application of bulk reading enables an almost-parallel reading of tags. The tag's information is stored electronically. The RFID tag includes a small RF transmitter and receiver. An RFID reader transmits an encoded radio signal to interrogate the tag. The tag receives the message and responds with its identification information. Many RFID tags do not use a battery. Instead, the tag uses the radio energy transmitted by the reader as its energy source. The RFID system design includes a method of discriminating several tags that might be within the range of the RFID reader.
To use the system ,the reader simply their own library cards and literature on the borrowing under the equipment, the RFID lending system will automatically scan and identify the readers personal information and literature label information.Borrow process is completed,the printer will automatically print out borrow list kept by the readers. Returned,the reader of the literature sent to recycling equipment,equipment installed RFID reader can automatically scan books label record.Literature by a conveyor belt to the recycling cart after the consolidation shelves,ready once again to borrow. The process of lend book is shown in Figure 1[1].
Figure 1. Figure’s name
2. Library-Mangement System Representation
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2.1. LMS block diagram
The block diagram of the proposed LMS is given in Figure 2 and the functional details of each of the blocks are described as follows.
2.2. RFID Tag Block
The RFID tag block describes the communication RFID tag and RFID reader. The RFID reader through the antenna to send out a certain frequency RF signals, when the label close to the intelligent terminal to obtain the induced current generated energy, sending out its own code and other information is read and decoded reader sent ROM or RAM to handle, and then information transmitted to the wireless network database server.
· high-frequency energy emission, active RFID tags and provide energy;
· transmit signal modulation for data transmission to the RF tag;
· receive and demodulate the radio signal from the RF tag.
2.3. RFID Reader Block
We have developed handheld RFID reader CORTEX-M3-based microcontroller, can within a certain region of the frequency of 915MHz UHF tag read and write, easy to carry, as a man-machine interface touch screen, easy to operate. The block diagram of the proposed LMS is given in Figure 3.
Control module features: transmit signal modulation for data transmission to the RF tag;
· data management system software to communicate, and perform the action instruction;
· control and radio frequency tag communication process;
· signal encoding and decoding;
· the implementation of anti-collision algorithm;
· between the reader and the tag data encryption and decryption;
· in between the reader and the tag authentication.
2.4. Anti-collision algorithm research
In the radio frequency identification (RFID) systems work, can not rule out the possibility there will be more than one label at the same time the role of reader range. In addition to some special RFID applications, a system in general, the same below all use the same tag frequency, so there is a collision occurs during transmission problems. When more than one label to the reader the same time send their stored information, will result in transmission of information interfere with each other, leading to loss of information. This is called the collision (Collision) problem. Solve the collision problem in several ways. The traditional methods of radio technology: ALOHA basic algorithm, random delay algorithm, Slotted ALOHA method, the frame slot ALOHA algorithm, dynamic framed slotted ALOHA method and packet frame slot ALOHA algorithm (GFSA) and so on.
· ALOHA basic algorithm: This algorithm is a simple basic anti-collision algorithm, ALOHA algorithm features: the system is simple, random large collision rate, the system utilization is low, there is an error of sentences, only read-only label.
· Random delay algorithm (P-ALOHA): a random retransmission delay mode and increases the range of random variation, reducing the impact for the system load is not too many cases, such as access control systems. But when the number of tags is large, the required delay is longer, resulting in slower read rate and a greater chance of error. Therefore not suited to our need to design algorithms[2].
· Slotted ALOHA method (SA): SA algorithm because of the reader within the control of the synchronization time slot to transmit data, the time zone may be on collision reduced by half. But only relative to the terms of the basic algorithm, and can not meet the needs of multi-tag identification requirements of a large number of collisions, and still limited to read-only tag.
· Frame slot ALOHA algorithm (FSA): FSA algorithm ALOHA algorithm is an extension of another method. This algorithm features: a large amount of information for transmission applications. But when the label is much larger than the number of slot number, the time to read labels will greatly increase the number on the label is far less than the number of time slots, the slot will result in waste[3].
· Dynamic Frame Slotted ALOHA Act (DFSA): As the number of slots in the frame N is dynamically generated, and its slot number variable, the FSA algorithm to solve the waste problem in the time slot. When a reader queries a collision more, it provides more time slots, until the time slot has a unique label so far, thus greatly improving the throughput. However, the dynamic selection of the number of slots will be very difficult[4].
· Packet frame slot ALOHA algorithm (GFSA): frame slot ALOHA algorithm limited the maximum number of time slots per frame 256. When the tag number is far greater than 256, the system can not be improved by increasing the number of slot throughput. To address this problem, taking into account the binary tree search algorithm grouping ideas, first a large number of labels can be divided into several groups, in each application DFSA algorithm can greatly improve the lot of the recognition rate of labeling applications. In the DFSA algorithm based on the packet frame slot ALOHA algorithm (GFSA). When the number of more than 354 labels all labels will be divided into two or more groups, respectively, each tag reader to identify, which can very well improve the system throughput. The more tags, grouping algorithm GFSA advantages of the more obvious.
Through software and hardware to achieve the anti-collision algorithm process. Cortex-M3 microprocessor that uses anti-collision algorithm is very simple hardware implementation, the processor and chip TRF7960 RFID applications in addition to four between the SPI bus is connected, there is an interrupt input and power input. As the Cortex-M3 processor has a wealth of resources in complex RFID identification system, you can even add the operating system, so this algorithm to achieve higher application value.
Software, the program execution flow is as follows, starting a label to enter the ID status by GROUP_SELECT command and set its internal counter to 0. Then you can loop the following process[5]:
· Power-Off (power-down state): the instrument can not be activated when reading the label, the label is in the state.
· Ready (ready state): When the reader power, the label to get the beam into electrical energy for internal work in the state of the chip.
· ID (collision state): When the label trying to send their card number to the reader in this state.
· Data Exchange (data exchange state): When the label has been identified to the reader, and was selected, in this state.
The process of program execution is shown in Figure 4.
3. Design of Hardware system
The design of the main chip is ST Microelectronics (ST) companies of the STM32 family microprocessors and CC1100. STM32 family of 32-bit Flash microcontrollers from ARM's groundbreaking Cortex-M3 core, which is designed to set and meet high performance, low power, real-time applications, competitive price in one area of embedded requirements. Chipcon's CC1100 is a low-cost, low-power single-chip RF transceiver chip, mainly used in 315,433,868 and 915MHz ISM (industrial, medical and scientific) and SRD (Short Range Device) frequency band. RF transceiver integrates a highly configurable modem, the modem supports various modulation formats, the data transfer rate up to 500kbps. Integrated in the modem by turning up on the Forward Error Correction option, performance can be improved.
3.1. System Parts
System from the function is divided into five parts:
· Control part, the data sending and receiving part, the serial communication part of the user display and input section and the wireless communication part. Controlled in part by the STM32 microcontroller and microprocessor crystal structure, control the entire system work
· .Sending and receiving data in part by the CC1100, crystal and an antenna. Which, CC1100 by the group into a digital and analog parts. In part through the parallel port and interrupt number and STR710 microcontroller communication.
· Analog part is responsible for sending and receiving radio frequency card operation, send the main driver to complete the antenna, the energy carrier to provide 915MHz register set according to the transmitted data modulation; to receive part of the completion of the RF transmit signal and card detection, demodulation and processing according to register settings .
· Wireless communication part of the nRF903 is NORDIC's three sections (433/868/915MHz) single-chip wireless transceiver chip, using the Bluetooth core technology design, in a 32-foot chip includes three sections of high-frequency emission, high frequency receiver, PLL synthesizer, I / Q modulation, I / Q demodulation, multi-channel switching, asynchronous communication interface, is the most integrated wireless data transmission products. Single-chip serial port can be connected directly to the use of other RF transceiver chip, which is not available, can be widely used in wireless data transmission product design.
· User display and input some of the major SED1335F0A and LCD ADS7843.
3.2. Hardware Design
STM32 family the process hardware part of the system board based on ST Microelectronics (ST) microprocessor , external expansion RAM and FLASH memory in order to run an embedded operating system , wireless network card connected via the USB interface for communication with a PC terminal . The design of hardware shown in Figure5.
Figure 2. Figure’s name
4. Conclusions
In this paper,the functional blocks of a LMS have been developed.The design of reader used Cortex-M3 processor can enhance the recognition rate of RFID tags.So, the design of library management system based on RFID and anti-collision algorithm can be applied into different places.
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