Anti-collision algorithm using Bin slot in RFID System

In this paper, we present a dynamic power adjustment (DPA) scheme for a reader to speed up the tag identification (ID) time in a RFID system. By using TDMA frames, the proposed DPA can adaptively increase or decrease the transmission power of a reader. A factor is designed to adjust the transmission power of a reader by considering two aspects. The first aspect increases the power to read more tags, if the number of idle state far exceeds the number of collided state. The second aspect cut power to reduce the number of tag readings, if the number of idle state is much smaller than the number of collided state. The proposed DPA is simulated using NS-2. In the simulation, we design three different topologies which place tags in three distributions, uniform, random, and hotspot. From the simulation results, we demonstrate that the proposed DPA can speed up the tag identification time, particularly when a large number of tags are placed in hotspot distribution.

Collision is a familiar problem in a RFID (radio frequency identification) system. How to solve this problem effectively is very important to the whole RFID system. A RFID system is always made up of two indispensable components: one is the tag, the other is the reader. Collisions occur when there are so many tags within the interrogation zone of a reader communicating with the reader synchronously. Binary search algorithm is an important anti-collision algorithm to solve the collision problems. But the main disadvantage of any existing algorithm based on binary search algorithm is the rate of identifying the identification codes (IDs) of tags is slow. In this paper, an improved anti-collision algorithm is proposed. Using this algorithm will recognize more tags in less time compared with other existing algorithms

Radio Frequency Identification (RFID) system is a new communication technology identifying one or more objects simultaneously in favor of using electromagnetic waves. In RFID systems, tags and readers communicate together over a shared wireless channel, and their signals may collide during transmission process and collision problem may occur in these systems. When two or more tags want to communicate with the reader, this collision problem may occur. This collision problem will waste the time for identification and it is also energy consuming as well and consequently reduces efficiency of the tag identification process. Therefore, it is required to attempt minimizing collision occurrence and decrease possibility of collision by using RFID anti-collision algorithms. In this project a novel Anti-collision Algorithm was suggested, which is called Enhance Dynamic Tree Slotted Aloha (EDTSA) by combining Tree slotted ALOHA and Advance Dynamic Framed Slotted Aloha Anti-Collision Algorithms and using Cubic Spline-based tag estimation technique. We have designed this algorithm by using C# programming language in visual studio 2008. The final results has simulated and compared with other algorithms. Simulated results also have illustrated that proposed algorithm can improve the efficiency of RFID systems.

In RFID systems, identifying the tag attached to the subject begins with the request from a reader. When the reader sends a request, multiple tags in the reader's interrogation zone simultaneously respond to it, resulting in collision. The reader needs the anti collision algorithm which can quickly identify all the tags in the interrogation zone. We propose the Enhanced Slotted Binary Tree Algorithm with Intelligent Separation (IS-ESBT). In IS-ESBT, a collision can be prevented because the tags which match with the prefix of the reader's request respond as followings; the group of tags with an even number of 1's in the bits to the prefix + 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup> bits responds in slot 0, while the group of tags with an odd number of 1's responds in slot 1. The IS-ESBT generates the request prefix so that the only existing tags according to the response in the corresponding slot. That is, it decreases the tag identification time by reducing the overall number of requests.

CNCAA: A new anti-collision algorithm using both collided and non-collided parts of information

In this paper, we focus on configuring a low cost RFID (Radio Frequency IDentification) system with less RFID readers and low density RFID tag textiles for stable and accurate self-localization for an omni-directional mobile robot. An RFID system using multiple RFID readers and high density RFID tags has already been applied to an indoor mobile robot self-localization. However, the system production cost is relatively high. To reduce the production cost of the system while maintaining the self-localization performance, we redesign two new RFID systems configured with 20 RFID readers and 5 RFID readers enlarging the size of an RFID reader antenna. Particularly, a new likelihood function of the tag detection with the redesigned large size RFID reader antenna is proposed for Monte Carlo Localization (MCL). Furthermore, we come up with a novel arrangement of RFID tags installed in a hexagon pattern. The new arrangement of ID tags enables both low cost ID tag installation and high performance of self-localization. We examine the performances of robot self-localization with less RFID readers and lower density RFID tags installed on the floor based on MCL(Monte Carlo localization). The simulation demonstrates the validity of our proposed configuration of the RFID based self-localization.

This study presents a distributed antenna structure operating at a frequency of 915 MHz to increase the tag identification sensitivity for passive radio frequency identification (RFID) systems. An experimental RFID system is set up to demonstrate the proposed structure. Experimental results indicate that using four distributed patch antennae can improve tag identification in passive RFID systems.

Anti-collision protocols for radio frequency identification (RFID) tag reading processes are designed to reduce the frequency of collisions and to quickly identify all RFID tags during a tag reading collision process. In this paper, we propose a tree-based anti-collision algorithm using a bit change sensing unit (TABCS) based on the bi-slotted collision tracking tree algorithm (BSCTTA) algorithm. The proposed algorithm can identify bits returned from tags using a bit change sensing unit, even in the event of multiple collisions. The algorithm rapidly generates a unique prefix that identifies each tag and reduces the total number of bits. Simulation results show that the proposed algorithm reduces the cost of tag identification compared with legacy algorithms, such as the query tree algorithm with a bit change sensing unit (QT-BCS) or BSCTTA. When the number of tags is 10000, the average number of tags identified per second in TABCS is improved by 4%, and TABCS requires 28% fewer steps to successfully identify one tag compared to BSCTTA.

Under-determined blind separation becomes poorer with increasing number of tags, to the point where it cannot separate source tag signals, reducing overall system performance. This paper proposes a parallelizable identification anti-collision algorithm based on non-negative matrix factorization and adaptive ID sequence grouping of binary tree slots. The number of tags in each group can be controlled within the optimum range by selecting a reasonable number to retained source signal separation in the RFID system, which will greatly improve system performance. With the Matlab software numerical calculation and simulation, the results show that tag identification rate improves from 152.8% to 359.2% compared with the blind separation and dynamic bit-slot group algorithm using the same multi-antenna technology for 4–16 antennas, while increasing tag identification speed from 60% to 78.4%. Thus, the proposed algorithm provides high efficiency and low cost and will have very good application for fast identification of large numbers of tags.

Dynamic time slot frame ALOHA algorithm is currently the most widely used anti-collision technology in radio frequency identification (RFID) system. Based on the traditional ALOHA algorithm analysis, we propose an improved algorithm. The algorithm is based on a packet adaptive ALOHA anti-collision algorithm (PA-ALOHA). First, the reader scans and counts the time slots which are randomly selected by tags, and sends it to each tag. The tags, then, adjust accordingly the time slot that enable the reader to skip idle slots and collision slots, adaptively allocate effective slots, and then identify tags rapidly. The algorithm employs packet and dynamically adjusts the frame size and other strategies, in order to reduce the time of processing slots. Simulation results show that PA-ALOHA algorithm improves the efficiency and stability of the system and reduce the transmission overhead. Especially, when the number of tags is over 1000, the algorithm throughput is still above 70% that has been greatly improved system efficiency than conventional ALOHA algorithm.

Dynamic frame slotted Aloha (DFSA) has been widely adopted to solve the anticollision problem in a radio frequency identification (RFID) system. In a DFSA procedure, the interrogator needs to continuously estimate tag backlog and select a new frame length for identifying the backlog. Intuitively, the accuracy of the tag estimator will affect the read performance. Hence, a considerable amount of research effort has been invested to improve the accuracy of backlog estimation. The improvement in general comes at the expense of large computation load and may lead to a serious challenge if one needs to implement such a kind of estimators in a real RFID system. This paper analyzes the influence of estimation error on read performance. Based on the analysis, we propose a feasible and easy-to-implement anticollision algorithm. Our proposed algorithm can achieve a normalized throughput of 35% that is very close to the theoretical maximum 36.1% for an EPCglobal UHF Class-1 Generation-2 system. The easy-to-implement advantage of our algorithm comes at the expense of only 1% reduction in normalized throughput as compared with the case where maximum throughput can be obtained. The results obtained are useful in designing fast and efficient interrogators. Note to Practitioners - A fast and efficient anticollision algorithm is required in many applications such as warehouse and supply chain management. Since most RFID interrogators are built with a single-chip microprocessor, whose computation ability or memory is limited. From the implementation point of view, a feasible algorithm should consider the compromise between complexity and performance. In order to easily implement the anticollision algorithm in a real RFID system, the proposed algorithm is based on a simple but sufficiently accurate method rather than complex models. The results obtained can be useful for the industry to develop fast and efficient RFID interrogators.

The RFID (radio frequency identification) is a technology that automatically identifies objects containing the electronic tags by using radio frequency. In RFID system, the reader needs the anti collision algorithm for fast identifying all of the tags in the interrogation zone. This paper proposes the tree based anti collision algorithm using parity bit (ACPB) to arbitrate the tag collision. The proposed algorithm identifies tags without checking all the bits in the tags. The reader uses the parity bit which is added to the tag IDs. If there are two collided bits in tags, then reader identify tags by the parity concept. The reader can identify two tags using ACPB algorithm. ACPB can reduce the number of the requests from the reader, thus it shortens the time of identifying all of the tags in the interrogation zone.

In order to solve multi-tag collision problem in radio frequency identification system, many anti-collision algorithms have been proposed, such as query tree algorithm, bi-slotted collision tracking tree algorithm (BSCTTA). In this paper, an enhanced collision tracking tree algorithm is proposed to improve the performance of BSCTTA. The proposed algorithm generates prefix depending on the first collided bit, and then eliminates the idle timeslots and reduces the collided timeslots. Moreover, the proposed algorithm can identify two tags in a timeslot if there is only one collided bit in the response data, and can truncate unvalued data when two collided bits are detected. The simulation results show that the proposed algorithm reduces the communication bits and query cycles than other algorithms, therefore enhances the identification efficiency and identification speed of radio frequency identification system.

Radio-frequency identification (RFID) systems have been deployed to detect and identify missing products by affixing them with cheap passive RFID tags and monitoring them with RFID readers. Existing missing tag detection and identification protocols require the tag population to contain only those tags whose IDs are already known to the reader. However, in reality, tag populations often contain tags with unknown IDs, called unexpected tags. These unexpected tags cause unexpected false positives, i.e. , due to them, missing tags are detected as present. We take the first step toward addressing the problem of detecting and identifying missing tags from a population that contains unexpected tags. Our protocol, RUN, uses standardized frame slotted Aloha for communication between tags and readers. It executes multiple frames with different seeds to reduce the effects of unexpected false positives. At the same time, it minimizes the missing tag detection and identification time by first estimating the number of unexpected tags in the population and then using it along with the false-positive probability to obtain optimal frame sizes and minimum number of times Aloha frames should be executed to mitigate the effects of false positives. RUN works with multiple readers with overlapping regions. It is easy to deploy, because it is implemented on readers as a software module and does not require any modifications to tags or to the communication protocol between the tags and the readers. We implemented RUN along with four major missing tag detection and identification protocols, namely, TRP, IIP, MTI, and SFMTI, and the fastest tag ID collection protocol TH and compared them side by side. Our performance evaluation results show that RUN is the only protocol that achieves required reliability in the presence of unexpected tags, whereas the best existing protocol achieves a maximum reliability of only 67%. RUN identifies 100% of missing tags in the presence of unexpected tags, whereas the best existing protocol identifies a maximum of only 60% of missing tags.

Radio Frequency IDentification (RFID) technology successfully integrates radio transmitter and receiver, small size memory space and control circuitry to remotely store and retrieve data via wireless RF transceiver. As low-cost RFID tag can be massively manufactured by semiconductor industry, new applications associated with RFID technology have emerged rapidly such as inventory tracking, book storage and management, and airport baggage handling. Generally an RFID system is composed of many RFID tags (or tagged objects), at least one RFID reader, and one backend application system with database. An RFID tag gains its operation energy from query signals that are radio waves transmitted by RFID reader. Once a tag responds the query with its stored information to RFID reader, usually a unique identity number or string, the RFID system can recognize the tag carrier and perform required business logic operation. As RFID technique is widely used in supply chain management, the corresponding RFID application systems are expected to process and manage large amount of tagged objects at a predefined period of time regularly. Therefore, for large-scaled RFID applications, tag reading throughput is very critical since it will affect the total data processing time. To measure tag reading throughput of a RFID system, two performance criteria are usually adopted: tag reading delay and reader energy consumption [5]. As RFID reader and tag always communicate over a shared wireless channel, it is very easy to have signal collisions during a normal tag identification process when multiple tags exist in reader’s interrogation area. Signal collision results in query or data retransmission and eventually increases communication overhead and time delay of tag identification. Hence, an efficient tag collision arbitration mechanism is very important and critical for RFID systems to achieve effective performance. Existing RFID tag identification schemes can be classified into aloha-based solutions [3, 10, 12-13, 16, 21, 23-24] and tree-based solutions [1, 2, 4, 6-9, 14-15, 17-20, 22]. In aloha-based schemes, a reader estimates the number of tags in its interrogation area and broadcasts the total number of timeslots to each tag. Then each RFID tag randomly selects its own timeslot to transmit its ID without knowing which timeslots have been selected by other tags. By distributing tag responses to distinct timeslots instead of getting all tag responses at the same time, aloha-based schemes effectively reduce the probability of signal collision. However, aloha-based schemes have tag starvation problem in which certain tags may not