Laura Arjona

Influence of the Distribution of Tag IDs on RFID Memoryless Anti-Collision Protocols

In recent years, Radio Frequency Identification (RFID) has become very popular. The main feature of this technology is that RFID tags do not require close handling and no line of sight is required between the reader and the tags. RFID is a technology that uses radio frequencies in order to identify tags, which do not need to be positioned accurately relative to the reader. Tags share the communication channel, increasing the likelihood of causing a problem, viz., a message collision. Tree based protocols can resolve these collisions, but require a uniform tag ID distribution. This means they are very dependent of the distribution of the IDs of the tags. Tag IDs are written in the tag and contain a predefined bit string of data. A study of the influence of the tag ID distribution on the protocols’ behaviour is proposed here. A new protocol, called the Flexible Query window Tree (FQwT) is presented to estimate the tag ID distribution, taking into consideration the type of distribution. The aim is to create a flexible anti-collision protocol in order to identify a set of tags that constitute an ID distribution. As a result, the reader classifies tags into groups determined by using a distribution estimator. Simulations show that the FQwT protocol contributes to significant reductions in identification time and energy consumption regardless of the type of ID distribution.

Energy-Aware RFID Anti-Collision Protocol

The growing interest in mobile devices is transforming wireless identification technologies. Mobile and battery-powered Radio Frequency Identification (RFID) readers, such as hand readers and smart phones, are are becoming increasingly attractive. These RFID readers require energy-efficient anti-collision protocols to minimize the tag collisions and to expand the reader’s battery life. Furthermore, there is an increasing interest in RFID sensor networks with a growing number of RFID sensor tags. Thus, RFID application developers must be mindful of tag anti-collision protocols. Energy-efficient protocols involve a low reader energy consumption per tag. This work presents a thorough study of the reader energy consumption per tag and analyzes the main factor that affects this metric: the frame size update strategy. Using the conclusion of this analysis, the anti-collision protocol Energy-Aware Slotted Aloha (EASA) is presented to decrease the energy consumption per tag. The frame size update strategy of EASA is configured to minimize the energy consumption per tag. As a result, EASA presents an energy-aware frame. The performance of the proposed protocol is evaluated and compared with several state of the art Aloha-based anti-collision protocols based on the current RFID standard. Simulation results show that EASA, with an average of 15 mJ consumed per tag identified, achieves a 6% average improvement in the energy consumption per tag in relation to the strategies of the comparison.

A High Throughput Anticollision Protocol to Decrease the Energy Consumption in a Passive RFID System

One of the main existing problems in Radio Frequency Identification (RFID) technology is the tag collision problem. When several tags try to respond to the reader under the coverage of the same reader antenna their messages collide, degrading bandwidth and increasing the number of transmitted bits. An anticollision protocol, based on the classical Binary Tree (BT) protocol, with the ability to decrease the number of bits transmitted by the reader and the tags, is proposed here. Simulations results show that the proposed protocol increases the throughput with respect to other recent state-of-the-art protocols while keeping a low energy consumption of a passive RFID system.

Scalable RFID Tag Estimator With Enhanced Accuracy and Low Estimation Time

The knowledge of the number of tags is critical in many radio frequency identification (RFID) applications. This paper is concerned with the problem of estimating an RFID tag population size when the number of tags is much higher than the frame size. A novel estimation scheme called “Scalable Minimum Mean Square Error” (sMMSE) is proposed. The proposed estimator updates the frame size by considering two key parameters: One determines the limit of the slots occupancy at which the frame size should be increased, and the other one sets the frame size increase factor. A formal study is provided to adjust these parameters with the aim of lowering the estimation error while scaling to highly populated tag sets. Numerical results indicate that sMMSE significantly decreases the normalized estimation error and maintains a low estimation time compared to existing strategies.

Reducing Transmitted Bits in a Memoryless RFID Anti-collision Protocol

The use of Radio Frequency Identification (RFID) technologies is growing. RFID enables data to be collected from many objects, for identification and other purposes. One of the main disadvantages in tag identification, known as the tag collision problem, is becoming significant, since it leads to the increase in the number of transmitted bits and identification time. The window methodology is created with the aim to manage the number of transmitted bits by the tags. As a result, tags transmit exclusively the bits defined by the window instead of sending their full ID value on every response. This paper presents a protocol with a standardized window. The window size is transmitted as the exponent of power of 2. Simulations show that the proposed solution with standarized window size reduces the number of bits transmitted by the reader, with respect to other protocols using the window, which results in a lower number of total bits in the identification process.

Hardware based analysis of RFID anti-collision protocols based on the standard EPCglobal Class-1 Generation-2

Radio Frequency Identification (RFID) technology is undergoing a remarkable development in the last few years. In this technology, identification information is exchanged between two devices: readers and tags. If two tags attempt to transmit simultaneously, a collision is produced. This phenomena, known as the tag collision problem, is becoming increasingly important, since it leads to an increase in the number of reader transmitted bits and identification delay, in addition to a wastage of energy and bandwidth. In this context, protocols based on the EPCglobal Class-1 Generation-2 (EPC C1G2) standard arbitrate collisions by adjusting the transmission frame size. The standard presents an uncertainty in the selection of the frame size, since it does not specify the exact value. This has led to many different alternatives. This paper presents a hardware analysis of the most relevant anti-collision protocols which deal with this uncertainty. The focus of this analysis is to design and evaluate with VHDL the tags chip design in order to extract the number clock cycles a tag employs to be identified.

Hardware based design and performance evaluation of a tree based RFID anti-collision protocol

The growing concern in tracking, identification and localization systems has turn Radio Frequency Identification (RFID) technology into a mainstream in scientific research. In this technology, the phenomena known as the tag collision problem is becoming increasingly important, since it leads to a wastage of bandwidth, energy, and an increase in identification delay. There- fore, anti-collision protocols are required to mitigate collisions. Tree based protocols constitute one of the two main types of Radio Frequency IDentification (RFID) anti-collision protocols. Inside this group, Collision Tree (CT) protocol constitutes a representa- tive strategy, since some other strategies are based on it. The focus of this work is to design and evaluate with VHDL the CT tags chip design in order to extract the number of clock cycles required by the reader to identify a set of tags. A stability analysis is also per- formed. Simulations results show that the total number of clock cycles is linearly influenced by the tags ID length.