Wooseok Ryu

A SIMULATION NETWORK MODEL TO EVALUATE RFID MIDDLEWARES

High-performance radio-frequency identification (RFID) is a challenging issue for large-scale enterprises. As a key component of an RFID system, RFID middleware is an important factor to measure the performance of the system. To evaluate the feasibility of an RFID middleware, the performance of the RFID middleware should be carefully evaluated in various RFID-enabled business environments. However, the construction of an RFID testbed requires a lot of time, money, and human resources because it involves numerous tagged items and a large number of deployed readers. We must provide a meaningful input tag stream representing various business activities, rather than random data. This paper presents a novel simulation model for the virtual construction of RFID testbeds. To ensure the semantic validity of the input tag stream, the proposed RFID simulation network (RSN) extends Petri nets by including sets of functions that represent unique characteristics of RFID environments such as the uncertainty of communications and tag movement patterns. By configuring appropriate functions, the RSN automatically generates an input tag stream that matches the distribution of real data. We demonstrate that the RSN model correctly reflects data from real-world environments by comparing input tag streams from real RFID equipment and from the RSN model.

A test data generation tool for testing RFID middleware

This paper presents a noble RFID data generation tool to enable efficient and low cost testing of the RFID middleware. RFID systems have been widely used in many business areas such as supply-chain management and yard management. As a key component of RFID system, the RFID middleware should be carefully evaluated from various environments. However, taking a variety of tests for RFID middleware is very complex and costly process because it requires construction of test environments such as deploying RFID devices, tagging of product items, and so on. For instance, the stress testing of RFID middleware needs to deploy millions of tags which take lots of money, time and human recourses. To solve these problems, we design virtual readers and tags for constructing virtual environment instead of real devices. Using virtual devices, we implement a test data generation tool which generates tag stream data for testing the RFID middleware. To simulate real RFID environment, we first define several parameters for representing real environments. By configuring the parameters, this tool can generate test data set which emulates various business scenarios. We also define several measurement metrics which are related to four factors like group, redundancy, noisy as well as route to verify the correctness of the generated data set. The experimental results show that our testing tool is cable for facilitating RFID middleware test.

LIT Middleware: Design and Implementation of RFID Middleware Based on the EPC Network Architecture

Radio Frequency Identification (RFID) technology can be used to significantly improve the efficiency of business processes by providing the capability of automatic identification and data capture. RFID system must implement functions to posses the enormous event data generated quickly by RFID readers. The proliferation of RFID tags and readers will require dedicated middleware solutions that manage readers and process event data. In this paper, we describe our middleware (called LIT Middleware) architecture with key features and also illustrate overall functional components of the middleware software as well as the system framework. Our component based middleware architecture provides extensibility, scalability and abstraction, and is also compatible with EPCglobal standards.

Demonstration of an RFID middleware: LIT ALE manager

The sharp increase of RFID tags and readers require dedicated middleware solutions that manage readers and process event data. In this paper, we demonstrate a RFID middleware called LIT ALE Manager system with key features and also illustrate overall functional components of the middleware system with implementation techniques.

Transaction Processing for Complete Reading of Semi-passive Sensor Tag

This paper deals with the problem of incomplete reading of sensing value stored in the semi-passive sensor tag and proposes a mechanism for complete reading without losing sensed value. The Cold Chain management system requires complete retrieval of a sensed data to keep track of freshness goods. However, reading the sensed data would be interfered by RF environment such as a jamming, obstacle and so on. This study found that interference could lead to loss of the sensed data. To solve this problem, we propose the transaction processing mechanism that guarantees complete reading of the sensed data. To do this, we present dynamic resizing of packet and recovery mechanism for complete reading of tag data to execute read transaction. These techniques improve the reliability of reading operation as well as speeds up of reading the mass data. The major contribution of this paper is to provide complete mechanism for reading a sensed data completely without any loss of a data from semi-passive sensor tag.

Generation of RFID test datasets using RSN tool

This paper presents an RSN Tool to generate input datasets for testing RFID middleware. As RFID middleware takes an important role in entire RFID systems, its performance should be carefully evaluated under various business conditions. In general, evaluation of the RFID middleware requires a huge cost because the numerous RFID readers and tags need to be deployed to acquire the tag event stream. To facilitate low-cost testing of the middleware, we propose the RSN Tool which provides means of designing a virtual RFID infrastructure and generates a tag event stream automatically for the virtual infrastructure. Using the RSN Tool, we can easily obtain a semantically valid dataset, which captures both physical characteristics of RF communications and business activities of tags’ movements. This is a major differentiation point of our work compared from previous works, which merely create the randomized dataset based on a set of virtual RFID readers. We also discuss a step-by-step usage of the RSN Tool from the creation of a virtual infrastructure to the generation of tag events. The experimental analysis shows that the RSN Tool can create the near-real dataset, which closely reflects business activities of the real RFID infrastructure.

Extension of RFID Middleware Platform for Handling Active Sensor Tags

This paper discusses the problem of handling active RFID tags in the RFID middleware. Application Level Events specification provides standard APIs for the RFID middleware. The basic role of the specification is the filtering and collection for the RFID data. However, this does not cope with the active tags because active tags are battery-powered. Indiscreet requests to the active tags will exhaust the battery of the active sensor tags. Moreover, the specification does not support the asynchronous communication, such as alert, which is a unique feature of the active sensor tags. This paper proposes an extended RFID middleware platform to support handling of the active tags. To do this, we present new APIs for handling active tags based on Application Level Events 1.1 specification. Presented Notification API and ANSpec provide the way to get notification some from the active tags asynchronously. We also provide extended APIs which enables discreet query to the active tags for reducing repeat report. The implementation shows that the extended middleware platform generates alert messages for the active tags. The main contribution of this paper is to define an extended APIs and develop a middleware platform for handing active tags as well as supporting passive tags.

A Reprocessing Model Based on Continuous Queries for Writing Data to RFID Tag Memory

This paper investigates the problem of writing data to passive RFID tag memory and proposes a reprocessing model for assuring the atomicity and durability of writing transactions in volatile RF communications. This study is motivated by the need to support persistent writing transactions of RFID tag data despite asynchronous and intermittent RF connections. The problem arises when the tag disappears from the interrogation area of the reader before all data is written completely. The disconnection during the process of a write operation causes the tag data to be inconsistent. To solve the problem, we propose an asynchronous wake-up reprocessing model for resuming unsuccessful write operations. The basic idea is to use a continuous query scheme for asynchronously detecting re-observations of unsuccessfully written tags. To achieve this, we employ a continuous query index, which monitors the tag stream continuously and finds unsure tags efficiently. We also discuss implementation issues for the proposed model. This shows that the reprocessing model processes unsuccessful operations completely and avoids inconsistent data, despite volatile characteristics in the RF communications.

Optimization of continuous query processing for RFID sensor tag data stream

In RFID system, RFID tags emit data continuously and sensed by RFID access point. RFID data are appears in form of stream data items to RFID host. By this RFID data collecting, RFID system provides identification information of objects which tags attached to users. However, some applications require not only identification information but also monitoring objects status. To address this requirement, RFID sensor tag, which embed sensor device into RFID tag, is used to identify object and measure the objects status. RFID host is responsible for processing sensor tag data stream. Each data item consists of both identification information and sensing information. In RIFD host, Continuous query extract the useful information from the RFID sensor tag data stream. Users registered Continuous queries in RFID host and continuous query executes as every new data item arrives. In this paper, we focus on improvement performance of continuous query processing over RFID Sensor Tag data stream. An efficient technique is proposed for continuous query processing. First we analysis the properties of RFID sensor tag data. Based on RFID sensor tag data properties, we process continuous query in two steps. It respectively leverages query index structure and dynamic query predicates scheduling techniques to improve performance of continuous query processing. Finally, our experimental results show it outperforms the other continuous query processing techniques for RFID sensor tag data stream.

An RSN Tool : A Test Dataset Generator for Evaluating RFID Middleware

Evaluation of RFID middleware is a complex process due to its cost for constructing a test bed involving RFID readers and tags. An input dataset of the RFID middleware is a tag event stream from connected readers. A randomly generated dataset can be considered for stress testing, but this cannot guarantee whether the middleware can provide correct answers on given dataset. To enable this, the dataset should be meaningful to represent tags’ activities based on business rules. This paper presents an RSN Tool which generates semantic datasets based on tags’ behavior. The basic idea is to virtualize RFID environments in a point of business processes. To do this, the RSN Tool provides a modeling of real world RFID environments using graph representations, and execution mechanisms of tags’ movements under several business rules. The experimental result shows that the RSN Tool can create a semantic valid dataset which reflects tags’ behavior.